I purchased your Fast Road suspension kit because of this series. Can’t wait to have it installed and try it out! Thanks for sharing all the research and thinking behind your product. A small but vocal minority of us on TH-cam love this deep dive content. Excellent stuff guys!
That’s great and thank you for watching and enjoying the series and also for purchasing the kit! You will love the difference it makes to the chassis. Make sure to drop us an email too at sakes@suspensionsecrets.co.uk so we can build and send your full suspension setup pdf sheet with our recommended settings for you when running our kit too 👍
AMAZING! Should be an award for best video series of the year. Was at the track on Monday and a couple of us were talking about your series. Spreading the good word. Keep them coming. Cheers!
Thanks very much for the kind words! We are really pleased you’re enjoying the series and always open to hear anything you would like to see us do or explain too 👍
Excellent series! Its great to see the impact each mod itteration makes to the handling and tyre temps and especially hearing the drivers feedback at the end makes it easier to understand the changes of each component on the car. This really shows the value of the products. After a few years tracking with the oem setup I was orgianlly planning for the rear toelinks only...but with each episode im watching im tempted to do more 😂 Its always a slippery sloap 😀 Great work guys!!
Thanks for the comment and really pleased you’re enjoying the series! Yes it’s very interesting to see and each mod really does make a big difference to the chassis. The circuit handling pack (where we got to in this episode) is a great position to be in with the GT4 as it address so many of the key areas of improvement with the car and the difference compared to standard is unbelievable. It also still drives very nicely on the roads 👍
When you lower a road car the distance between the roll centre and the CG increases not decreases. The roll centre is usually lower than the CG therefore lowering the CG increases roll.
Thanks for the comment. Yes that’s correct that when lowering a car the roll centres do also go lower in most cases (increasing the distance between CoG and roll centre and therefore increasing roll moment). However with the Porsche GT4 chassis in particular, the LCA lengths and the top mount to chassis mounting angles are such that when lowering the chassis the centre of gravity actually lowers more than the distance that the roll centre is displaced by. Therefore reducing the roll moment. This is only true to a certain point as past a specific point the geometry switches and this reverses so the roll centre distance increases faster than COG. That said we will also be addressing roll centre correction later in the series as it is an area not covered enough 👍
Thank you for a well-documented and explained rationale for the changes being made. A breath of fresh air in the world of car modification hype and bluster! I appreciate that a real time measurement of tire temperatures is ideal, but many of us are using basic pyrometers in the hot pits. How much of a spread in temperatures should we expect or aim for given the time lag of the measurement?
Thanks for the comment and really pleased you are enjoying the series. An ideal spread when using a tyre pyrometer is a spread of 12-15 degrees C from inside edge to outer edge with the inside being the hottest.
@@SuspensionSecrets Thank you. This is similar to what I've heard in the past. With this range of temperatures, do you expect relatively even wear across the tire's width?
This has to be the best suspension track set up videos out there. Really enjoying the videos. One question is when would you try a stiffer sway bar? I would have thought if you had too much body roll you would try a stiffer sway bar.
Thanks for the comment and really pleased you’re enjoying the series. Yes the anti roll bars could also be an option as they work in conjunction with the coil springs through the corners. When deciding which route to take there are a few factors to consider. Firstly, the overall stiffness of the car, which in the GT4 case it feels very soft everywhere, over bumps, under braking and on throttle you can feel the car pitch and dive too. Therefore in order to solve the body roll, pitch and dive the springs are the only option that address all of these areas. If the car felt quite stiff and flat on throttle and brakes but head a lean through the corners only then the roll bars would definitely be the best action to take 👍
Another great video. My understanding is if you increase the spring stiffness the same front and rear then the weight distribution doesn’t change so tyre load and grip stays the same (ignoring geo changes). So is the advantage of a stiffer setup is that it makes the car more responsive to driver input? Or does grip increase as well?
Thanks for the comment. The stiffer springs don’t affect weight distribution as you have said 👍 what they do affect is chassis roll stiffness. This means that with the same force applied to a car with a stiffer roll stiffness compared to exactly the same car with a softer roll stiffness, the chassis will roll (physically rotate) less. However the energy output still needs to be the same, so instead of rolling and flexing the springs, it physically rocks the whole car up onto the tyres almost leaning the entire car over (we are exaggerating here to create a more visual image). Therefore, this increased lean of the car needs to be matched with additional camber to lean onto. The mixture of both of these effects generates more grip. But the tyre has to be capable of delivering that level of grip too so it doesn’t just push through the tyre and cause under or oversteer. So there is always a fine balance and it is very possible to make the car too stiff as well for these reasons 👍
Curious though, why not a stiffer roll bar rather than stiffer springs? I feel the compromise to reduce roll via stiffer springs is a huge one sacrificing so much comfort and mechanical grip on less than smooth surfaces, or rain.
In the case of the GT4 there are a few reasons. The springs on the GT4 as standard are significantly too soft. So under heavy braking and hard throttle the chassis pitched and heaved forwards and backwards too leading to further instability. The anti roll bars wouldn’t address this as they would only activate through the corners. With the new springs fitted the car still doesn’t feel too stiff to drive and feels nice and planted on the roads over bumps and undulations too. A further reason is that we wanted to lower the car beyond what the stock adjustment allowed which required shorter springs all round. Therefore we were able to address all of the issues, pitch, heave, roll and ride height all with a single spring change to much better rates. There is also the added benefit that when designing the natural frequency of the chassis (to determine optimal spring rates) there are much more incrimental options available in coil springs than there are in any roll bars meaning we could get within 10N of the rates we wanted the overall roll rate of the chassis to be 👍 The GT4 with these springs fitted is still more complaint than the standard suspension on our F80 M3 is on the roads showing how under sprung the chassis is as standard 👍
Presumably the compliance of the suspension on the road is much stiffer now due to the new springs. I appreciate there’s always a compromise but worth mentioning as I’d imagine it was a better road car package utilising setup from the first step?
We still use our car on the roads so can give you direct feedback on this too 👍 yes the car is naturally now firmer than it was before but it is still perfectly useable and comfortable on the roads. In fact it took us by surprise how good the kit still felt on the roads as we all agreed it still feels more complaint than our F80 M3 on the roads which just has eibach springs and standard shocks 👍 so the vast improvements in track handling abilities are well worth the trade off for the slight reduction in road comfort 👍
@@SuspensionSecretsthat’s really good to know! Having had a f80 on eibach springs many years ago I thought that drove absolutely fine on the road. Are you able to take interested customers for a spin in your car to help them decide?
The new shorter spring up front has less usable stroke than the OE spring, why wouldn't you go with a longer spring at the same rate and get more usable range? Wouldn't the increased preload with a longer aftermarket spring also improve the turn in responsiveness? The amount you lowered car on the heavier springs, I know you won't strike the ground when the chassis heaves but the approach and departure angle of the 718 is such that you still strike the rear underbody and particularly front wheel vanes when you are briskly moving on B roads. The diffuser is expensive too
Thanks for the comment. The need for stroke is reduced with a stiffer spring as the stiffer rate moves less with the same forces exerted through it compared to a softer equivalent. The shorter spring is required to get the chassis lower as we went as low as possible with the stock length springs and we still weren’t at an optimum chassis height hence the new shorter spring combination. With regards to preload, no it doesn’t have much effect at all. That’s why on the vast majority of racing cars, the coil springs also have helper springs (like our setup) to keep the spring engaged on full droop. To put preload into the assembly with a longer aftermarket spring, you would also be increasing ride height over oem which isn’t a goal of ours. The preload of around 5-10mm is actually totally negligible though when compared to the forces exerted by the mass of the car and the cornering loads when on the ground. It is only effective for rebound purposes in full droop. But we don’t intend to be using full droop anytime soon. The turn in responsiveness is much better improved using rake angle, ride height, caster and toe settings to make the chassis respond the driver inputs. With regards to the underbody, our bump stops are still engaged before the chassis bottoms out despite the ratio alteration. We use our car on the roads a lot (particularly on B roads all around our HQ) and we are yet to bottom out the underbody. The most we have done is kissed the front splitter on heavy compression whilst on the brakes but that’s it 👍 a small price to pay for the heavy handling improvements.
Really enjoying the content, thanks for all the effort you put into this series! Just curious, did you tweak the toe settings at all? Would love to know if you made any changes and what they’re set to now, if you don’t mind sharing 🙏
Hi, really pleased you’re enjoying the series! The rear toe settings have remained the same throughout the different setups with camber being altered 👍 Front toe however moved to toe out from toe in when we started to go more track focused 👍
@@margseirg we don’t give the numbers out in here as in order to provide our customers with settings we first take in a lot of information about their car, setup, driving style and main use of the car so we can ensure our settings work at their most optimum 👍 We also reserve our settings for our customers (in person and online) as a perk of buying from our online store you automatically qualify for a free suspension setup sheet from us 👍
Thanks for the comment. Yes it absolutely can be. At the time of filing it wasn’t a factor that actually came to mind but some of our awesome viewers (including yourself) pointed this out and we are taking a much deeper dive into that in an episode coming soon 👍
Thanks for the comment. Yes it absolutely can be. At the time of filing it wasn’t a factor that actually came to mind but some of our awesome viewers (including yourself) pointed this out and we are taking a much deeper dive into that in an episode coming soon 👍
I agree with your premise on bump/rebound travels and avoiding the complications of having a variable rate by coming on/off the bump stop, but it’s worth noting that by effectively increasing the bump stop gap while lowering the car you’re increasing the likelihood that in a big compression the whole underbody will slam into the ground or the wheel into the top of the arch (since that bump stop rate isn’t there to ramp up and keep you off the ground or the tyre away from the arch top), there’s also a lot of guide vanes under the car you’ll potentially damage when doing that. I appreciate it’s a niche case and that your inherently stiffer springs are also helping you out here too and while it’s definitely not something you’ll see at Silverstone it could be relevant for places like Nurburgring or Cadwell.
Thanks for the comment 👍 when we designed the kit this was a major consideration and critical element of the design specification. We carried out measurements on the chassis deck height and only increased the bump travel enough to ensure that the bump stops are still engaged before the vanes hit the ground or the tyre makes contact with the top of the wheel arch liner. So with the cups fitted it really is win win. We still drive this car out on the roads too with the current setup on there and have encountered scenarios where we use up all available travel and the bump stops are still the first point of engagement so the kit is perfect to use on every circuit and the roads too 👍
@@JamieCole-wl9lo you could do but this would feel very unstable to drive with the chassis wallowing around in all directions for the driver. It would also over load the tyre under high speed cornering such as at Silverstone. There is a fine line between too soft and too stiff but the oem setup definately lies in too soft when the correct camber is working the tyre properly 👍
The later set up is far enough along to dial out some of the rear camber. Front tyres are doing very little from after mid corner. Mass of the rear end doing the steering for you. Worth experimenting with a bit more rear toe in. Just to take a bit of temp off of the rear inner and make the chassis less sensitive to changing track conditions. If the drivers prefer that. You'll know at the first pit stop by the state of the tyres and No. of excuses the driver comes back with.
Interestingly the heat on the inner edges isn’t actually due to the rear camber. The camber we have in was actually driven by the drivers wanting more to get the balance of the chassis dialled in. Both professional drivers said exactly the same thing so we are really happy with the balance now front to rear 👍 In the inner edge heat is actually due to the exhaust running directly behind the wheels and heating the inner edges from heat soak from the exhaust system. We will have a video coming on this soon and we will be trying to limit that to improve tyre temps further 👍
Roll centre correction is another factor that can be altered too and can be corrected after lowering the chassis but is much more involved to correct. Either moving the roll centre or the centre of gravity reduces the roll moment and as we were already changing the springs it made sense to move the centre of gravity at the same time for the sake of efficiency. We will be taking a look into roll centres later in the series though 👍
Great content. Do you run stiffer springs because you're limited to the stock damper? Some people (E-motion Engineering) talk about running (relatively) soft springs and relying on the damper to handle as much of the dynamic forces as possible.
Thanks for the comment. It’s always best to use springs to control a chassis and then use the damper to control the springs and the lateral chassis movements. Spring rates are very important to vehicle dynamics as they affect the natural frequency of the chassis which is absolutely key to developing the correct handling behaviour and using the tyre effectively. Once the natural frequency is determined through spring and anti roll bar rates, the dampers can then be used to control transitions in load 👍 so definitely best to start with the springs as the OEM damping range (with them in stiff mode) still have a enough damping force to control the new spring rates and the chassis 👍 Just using firmer dampers usually results in a chassis that feels too wallowy through long corners and aggressive and harsh through faster transition corners. 👍
Like the series, but... Lowering the car that much (especially on McPherson) usually messes up roll center location and moves it down sugnificantly. So, distance between roll center and CG actually increases, which can be counteracted by stiffer springs or sway bars. So.. lowering the car introduces more roll, but usually helps with lateral load transfer. Also, static camber is there to compensate roll, so if your measures to reduce body roll are effective you should need less static camber, unless you have other factors that might call to add some (like more grip and higher g-forces)
Excellent video and right where I am with my modifications. Is your spring kits sold on its own? I can’t lower mine anymore because of driveways and road conditions.
Thank you! Awesome, our spring kits aren’t sold as a standalone as they build up the rest of the kit which makes everything work together perfectly, the stiffer spring, damper ratio correction and added caster/camber to produce the differences in the video 👍
Same as me. Already have manthey racing kit which is shims, top mounts and rear toe links so just after the springs as I don’t want to go that low? @suspensionsecrets
Yes we are still on the OEM dampers as the spring rates we use are still inside the range of operation for the oem dampers (with the button pressed inside the car). In terms of cambers, we are now in the mid to high 3’s at the front and the mid to high 2’s at the rear but it is worth mentioning that these camber settings are only needed to be so high due to the stiffer springs supplied in our package 👍
@@SuspensionSecrets I´m curious whether you also ran into issues with rubbing between the wheel arch and the rear tires as I did with my (981) GT4 at mor than 2,5 (deg/min) degree of negative camber.
Yes we have just developed our full kinematics kit for the GT4RS after track tests and driver feedback 👍 we also have a soft spring conversion kit in the making to make the car less aggressive for pure road use.
We haven’t found the tyres to be a limitation just yet. Before increasing tyre widths it’s much more important to ensure that you are using the full width of the tyre which is why we implemented the live tyre temperature sensors. If you are not fully using the width of your tyres then increasing tyre size before this point is a bit like sticking a plaster over a problem. Now that we are using the full widths of the front and rear tyres we will be looking at increasing widths down the line at the front and rear to increase grip further 👍
That’s a great idea and part of the Vbox that we need to delve deeper into. We could look back on the 3 track days in a video comparing some more in depth data from each 👍
Another great video. I thought the GT4 was Porsche's track-focussed-road version of the 718 but didn't realise the GT department would leave so much scope for aftermarket improvement. Is the car now no longer realistic to use on the road (i.e too firm, excess tyre wear) ?
Thanks for the comment. Yes there is plenty left on the table and almost a lot more in the GT4 as it is held back even further as standard so it can’t compete with its GT3 counterparts 👍 In terms of road use, we still use our car on the roads and drive it to and from track and on the weekends too. It actually surprised us how nice it still feels to drive out in the roads. In fact it’s actually more complaint over bumps than our F80 M3 which is still just running standard shocks and eibach lowering springs. When we designed the kit, keeping it useable out on the roads was a key decision factor 👍
@@SuspensionSecrets what about tire wear? With the high camber and toe settings, I imagine the car is now only suitable for trips to and from the track. No more joy rides/commute and road trips 😢
Yes 👍 the standard dampers are actually very good in terms of performance and the range of the damper was enough that we were able to alter the spring rates within the abilities of the OEM dampers. At this point we haven’t found the dampers to be a limiting factor at all, only the spring rates of the coil springs as we introduced more and more grip into the chassis with setup.
I purchased your Fast Road suspension kit because of this series. Can’t wait to have it installed and try it out! Thanks for sharing all the research and thinking behind your product. A small but vocal minority of us on TH-cam love this deep dive content.
Excellent stuff guys!
That’s great and thank you for watching and enjoying the series and also for purchasing the kit! You will love the difference it makes to the chassis.
Make sure to drop us an email too at sakes@suspensionsecrets.co.uk so we can build and send your full suspension setup pdf sheet with our recommended settings for you when running our kit too 👍
AMAZING! Should be an award for best video series of the year.
Was at the track on Monday and a couple of us were talking about your series. Spreading the good word. Keep them coming.
Cheers!
Thanks very much for the kind words! We are really pleased you’re enjoying the series and always open to hear anything you would like to see us do or explain too 👍
Excellent series! Its great to see the impact each mod itteration makes to the handling and tyre temps and especially hearing the drivers feedback at the end makes it easier to understand the changes of each component on the car.
This really shows the value of the products.
After a few years tracking with the oem setup I was orgianlly planning for the rear toelinks only...but with each episode im watching im tempted to do more 😂
Its always a slippery sloap 😀
Great work guys!!
Thanks for the comment and really pleased you’re enjoying the series!
Yes it’s very interesting to see and each mod really does make a big difference to the chassis.
The circuit handling pack (where we got to in this episode) is a great position to be in with the GT4 as it address so many of the key areas of improvement with the car and the difference compared to standard is unbelievable. It also still drives very nicely on the roads 👍
When you lower a road car the distance between the roll centre and the CG increases not decreases. The roll centre is usually lower than the CG therefore lowering the CG increases roll.
Thanks for the comment. Yes that’s correct that when lowering a car the roll centres do also go lower in most cases (increasing the distance between CoG and roll centre and therefore increasing roll moment). However with the Porsche GT4 chassis in particular, the LCA lengths and the top mount to chassis mounting angles are such that when lowering the chassis the centre of gravity actually lowers more than the distance that the roll centre is displaced by. Therefore reducing the roll moment. This is only true to a certain point as past a specific point the geometry switches and this reverses so the roll centre distance increases faster than COG.
That said we will also be addressing roll centre correction later in the series as it is an area not covered enough 👍
@@SuspensionSecrets You should make a video on this. Would love to see it.
Great video. Looks very professional setup. Do you have a workshop for basic initial wheel alignment set up on all types of cars?
Thank you for a well-documented and explained rationale for the changes being made. A breath of fresh air in the world of car modification hype and bluster! I appreciate that a real time measurement of tire temperatures is ideal, but many of us are using basic pyrometers in the hot pits. How much of a spread in temperatures should we expect or aim for given the time lag of the measurement?
Thanks for the comment and really pleased you are enjoying the series. An ideal spread when using a tyre pyrometer is a spread of 12-15 degrees C from inside edge to outer edge with the inside being the hottest.
@@SuspensionSecrets Thank you. This is similar to what I've heard in the past. With this range of temperatures, do you expect relatively even wear across the tire's width?
This has to be the best suspension track set up videos out there. Really enjoying the videos.
One question is when would you try a stiffer sway bar? I would have thought if you had too much body roll you would try a stiffer sway bar.
Thanks for the comment and really pleased you’re enjoying the series. Yes the anti roll bars could also be an option as they work in conjunction with the coil springs through the corners.
When deciding which route to take there are a few factors to consider. Firstly, the overall stiffness of the car, which in the GT4 case it feels very soft everywhere, over bumps, under braking and on throttle you can feel the car pitch and dive too. Therefore in order to solve the body roll, pitch and dive the springs are the only option that address all of these areas.
If the car felt quite stiff and flat on throttle and brakes but head a lean through the corners only then the roll bars would definitely be the best action to take 👍
Great video. I’ll be in touch to buy your fast road setup for my g87. Keep up the good work 👍
Thank you and really pleased you’re enjoying the series! Great we look forward to hearing from you 👍
@@SuspensionSecrets will need your help to decide between the handling pack 1 and the full kinematics kit. Look forward to speaking with you
Another great video. My understanding is if you increase the spring stiffness the same front and rear then the weight distribution doesn’t change so tyre load and grip stays the same (ignoring geo changes). So is the advantage of a stiffer setup is that it makes the car more responsive to driver input? Or does grip increase as well?
Thanks for the comment. The stiffer springs don’t affect weight distribution as you have said 👍 what they do affect is chassis roll stiffness. This means that with the same force applied to a car with a stiffer roll stiffness compared to exactly the same car with a softer roll stiffness, the chassis will roll (physically rotate) less. However the energy output still needs to be the same, so instead of rolling and flexing the springs, it physically rocks the whole car up onto the tyres almost leaning the entire car over (we are exaggerating here to create a more visual image). Therefore, this increased lean of the car needs to be matched with additional camber to lean onto. The mixture of both of these effects generates more grip. But the tyre has to be capable of delivering that level of grip too so it doesn’t just push through the tyre and cause under or oversteer. So there is always a fine balance and it is very possible to make the car too stiff as well for these reasons 👍
Curious though, why not a stiffer roll bar rather than stiffer springs? I feel the compromise to reduce roll via stiffer springs is a huge one sacrificing so much comfort and mechanical grip on less than smooth surfaces, or rain.
In the case of the GT4 there are a few reasons. The springs on the GT4 as standard are significantly too soft. So under heavy braking and hard throttle the chassis pitched and heaved forwards and backwards too leading to further instability. The anti roll bars wouldn’t address this as they would only activate through the corners.
With the new springs fitted the car still doesn’t feel too stiff to drive and feels nice and planted on the roads over bumps and undulations too.
A further reason is that we wanted to lower the car beyond what the stock adjustment allowed which required shorter springs all round. Therefore we were able to address all of the issues, pitch, heave, roll and ride height all with a single spring change to much better rates.
There is also the added benefit that when designing the natural frequency of the chassis (to determine optimal spring rates) there are much more incrimental options available in coil springs than there are in any roll bars meaning we could get within 10N of the rates we wanted the overall roll rate of the chassis to be 👍
The GT4 with these springs fitted is still more complaint than the standard suspension on our F80 M3 is on the roads showing how under sprung the chassis is as standard 👍
Presumably the compliance of the suspension on the road is much stiffer now due to the new springs.
I appreciate there’s always a compromise but worth mentioning as I’d imagine it was a better road car package utilising setup from the first step?
We still use our car on the roads so can give you direct feedback on this too 👍 yes the car is naturally now firmer than it was before but it is still perfectly useable and comfortable on the roads. In fact it took us by surprise how good the kit still felt on the roads as we all agreed it still feels more complaint than our F80 M3 on the roads which just has eibach springs and standard shocks 👍 so the vast improvements in track handling abilities are well worth the trade off for the slight reduction in road comfort 👍
@@SuspensionSecretsthat’s really good to know! Having had a f80 on eibach springs many years ago I thought that drove absolutely fine on the road.
Are you able to take interested customers for a spin in your car to help them decide?
Awesome! Love this series you're doing
Really pleased you’re enjoying it!
The new shorter spring up front has less usable stroke than the OE spring, why wouldn't you go with a longer spring at the same rate and get more usable range? Wouldn't the increased preload with a longer aftermarket spring also improve the turn in responsiveness?
The amount you lowered car on the heavier springs, I know you won't strike the ground when the chassis heaves but the approach and departure angle of the 718 is such that you still strike the rear underbody and particularly front wheel vanes when you are briskly moving on B roads. The diffuser is expensive too
Thanks for the comment. The need for stroke is reduced with a stiffer spring as the stiffer rate moves less with the same forces exerted through it compared to a softer equivalent. The shorter spring is required to get the chassis lower as we went as low as possible with the stock length springs and we still weren’t at an optimum chassis height hence the new shorter spring combination.
With regards to preload, no it doesn’t have much effect at all. That’s why on the vast majority of racing cars, the coil springs also have helper springs (like our setup) to keep the spring engaged on full droop. To put preload into the assembly with a longer aftermarket spring, you would also be increasing ride height over oem which isn’t a goal of ours. The preload of around 5-10mm is actually totally negligible though when compared to the forces exerted by the mass of the car and the cornering loads when on the ground. It is only effective for rebound purposes in full droop. But we don’t intend to be using full droop anytime soon.
The turn in responsiveness is much better improved using rake angle, ride height, caster and toe settings to make the chassis respond the driver inputs.
With regards to the underbody, our bump stops are still engaged before the chassis bottoms out despite the ratio alteration. We use our car on the roads a lot (particularly on B roads all around our HQ) and we are yet to bottom out the underbody. The most we have done is kissed the front splitter on heavy compression whilst on the brakes but that’s it 👍 a small price to pay for the heavy handling improvements.
Really enjoying the content, thanks for all the effort you put into this series!
Just curious, did you tweak the toe settings at all? Would love to know if you made any changes and what they’re set to now, if you don’t mind sharing 🙏
Hi, really pleased you’re enjoying the series! The rear toe settings have remained the same throughout the different setups with camber being altered 👍
Front toe however moved to toe out from toe in when we started to go more track focused 👍
@@SuspensionSecrets Can you give us numbers?
@@margseirg we don’t give the numbers out in here as in order to provide our customers with settings we first take in a lot of information about their car, setup, driving style and main use of the car so we can ensure our settings work at their most optimum 👍
We also reserve our settings for our customers (in person and online) as a perk of buying from our online store you automatically qualify for a free suspension setup sheet from us 👍
Can the heat that show on the inside of the rear tire be also contributed by the over axle exhaust pipe
Thanks for the comment. Yes it absolutely can be. At the time of filing it wasn’t a factor that actually came to mind but some of our awesome viewers (including yourself) pointed this out and we are taking a much deeper dive into that in an episode coming soon 👍
Thanks for the comment. Yes it absolutely can be. At the time of filing it wasn’t a factor that actually came to mind but some of our awesome viewers (including yourself) pointed this out and we are taking a much deeper dive into that in an episode coming soon 👍
I agree with your premise on bump/rebound travels and avoiding the complications of having a variable rate by coming on/off the bump stop, but it’s worth noting that by effectively increasing the bump stop gap while lowering the car you’re increasing the likelihood that in a big compression the whole underbody will slam into the ground or the wheel into the top of the arch (since that bump stop rate isn’t there to ramp up and keep you off the ground or the tyre away from the arch top), there’s also a lot of guide vanes under the car you’ll potentially damage when doing that. I appreciate it’s a niche case and that your inherently stiffer springs are also helping you out here too and while it’s definitely not something you’ll see at Silverstone it could be relevant for places like Nurburgring or Cadwell.
Thanks for the comment 👍 when we designed the kit this was a major consideration and critical element of the design specification. We carried out measurements on the chassis deck height and only increased the bump travel enough to ensure that the bump stops are still engaged before the vanes hit the ground or the tyre makes contact with the top of the wheel arch liner.
So with the cups fitted it really is win win. We still drive this car out on the roads too with the current setup on there and have encountered scenarios where we use up all available travel and the bump stops are still the first point of engagement so the kit is perfect to use on every circuit and the roads too 👍
@@SuspensionSecrets good stuff, nice work :-)
Can you not use body roll to induce camber gain/loss to help with yaw?
@@JamieCole-wl9lo you could do but this would feel very unstable to drive with the chassis wallowing around in all directions for the driver. It would also over load the tyre under high speed cornering such as at Silverstone. There is a fine line between too soft and too stiff but the oem setup definately lies in too soft when the correct camber is working the tyre properly 👍
The later set up is far enough along to dial out some of the rear camber.
Front tyres are doing very little from after mid corner. Mass of the rear end doing the steering for you.
Worth experimenting with a bit more rear toe in. Just to take a bit of temp off of the rear inner and make the chassis less sensitive to changing track conditions.
If the drivers prefer that. You'll know at the first pit stop by the state of the tyres and No. of excuses the driver comes back with.
Interestingly the heat on the inner edges isn’t actually due to the rear camber. The camber we have in was actually driven by the drivers wanting more to get the balance of the chassis dialled in. Both professional drivers said exactly the same thing so we are really happy with the balance now front to rear 👍
In the inner edge heat is actually due to the exhaust running directly behind the wheels and heating the inner edges from heat soak from the exhaust system.
We will have a video coming on this soon and we will be trying to limit that to improve tyre temps further 👍
No roll Centre correction? Wouldnt that help even more with roll?
Roll centre correction is another factor that can be altered too and can be corrected after lowering the chassis but is much more involved to correct. Either moving the roll centre or the centre of gravity reduces the roll moment and as we were already changing the springs it made sense to move the centre of gravity at the same time for the sake of efficiency.
We will be taking a look into roll centres later in the series though 👍
so what final aligment did you setup?
Great content. Do you run stiffer springs because you're limited to the stock damper? Some people (E-motion Engineering) talk about running (relatively) soft springs and relying on the damper to handle as much of the dynamic forces as possible.
Thanks for the comment. It’s always best to use springs to control a chassis and then use the damper to control the springs and the lateral chassis movements. Spring rates are very important to vehicle dynamics as they affect the natural frequency of the chassis which is absolutely key to developing the correct handling behaviour and using the tyre effectively. Once the natural frequency is determined through spring and anti roll bar rates, the dampers can then be used to control transitions in load 👍 so definitely best to start with the springs as the OEM damping range (with them in stiff mode) still have a enough damping force to control the new spring rates and the chassis 👍
Just using firmer dampers usually results in a chassis that feels too wallowy through long corners and aggressive and harsh through faster transition corners. 👍
@@SuspensionSecrets I really appreciate the detailed response. Looking forward to the next episode!
Awsome progress, what’s the rough price for the set up including the parts without the springs please.
Like the series, but...
Lowering the car that much (especially on McPherson) usually messes up roll center location and moves it down sugnificantly. So, distance between roll center and CG actually increases, which can be counteracted by stiffer springs or sway bars. So.. lowering the car introduces more roll, but usually helps with lateral load transfer.
Also, static camber is there to compensate roll, so if your measures to reduce body roll are effective you should need less static camber, unless you have other factors that might call to add some (like more grip and higher g-forces)
Excellent video and right where I am with my modifications. Is your spring kits sold on its own? I can’t lower mine anymore because of driveways and road conditions.
Thank you! Awesome, our spring kits aren’t sold as a standalone as they build up the rest of the kit which makes everything work together perfectly, the stiffer spring, damper ratio correction and added caster/camber to produce the differences in the video 👍
@@SuspensionSecretsI already have camber plates, toe arms and shims. So I don’t want to buy it all again
Same as me. Already have manthey racing kit which is shims, top mounts and rear toe links so just after the springs as I don’t want to go that low? @suspensionsecrets
@@SuspensionSecrets there is 2 of us here wanting springs. Surly there are more of us who have all the other mods already.
So you did keep the OEM Dampers? And what camber were dialed in finally?
Yes we are still on the OEM dampers as the spring rates we use are still inside the range of operation for the oem dampers (with the button pressed inside the car).
In terms of cambers, we are now in the mid to high 3’s at the front and the mid to high 2’s at the rear but it is worth mentioning that these camber settings are only needed to be so high due to the stiffer springs supplied in our package 👍
@@SuspensionSecrets I´m curious whether you also ran into issues with rubbing between the wheel arch and the rear tires as I did with my (981) GT4 at mor than 2,5 (deg/min) degree of negative camber.
Any GT4 RS mods yet to stop it bouncing about, I think 120 NM rear springs might be worth a go.
Yes we have just developed our full kinematics kit for the GT4RS after track tests and driver feedback 👍 we also have a soft spring conversion kit in the making to make the car less aggressive for pure road use.
What is your opinion on tire size? In the US at this point most shops have us change to a 19” wheel so we can fit 265 width front tires.
We haven’t found the tyres to be a limitation just yet. Before increasing tyre widths it’s much more important to ensure that you are using the full width of the tyre which is why we implemented the live tyre temperature sensors. If you are not fully using the width of your tyres then increasing tyre size before this point is a bit like sticking a plaster over a problem.
Now that we are using the full widths of the front and rear tyres we will be looking at increasing widths down the line at the front and rear to increase grip further 👍
If you have a solution to run 19s in the rear with PCCBs let me know. @@SuspensionSecrets
Pre and post mod optimal lap times would be quite interesting too, remove some of the traffic effect
That’s a great idea and part of the Vbox that we need to delve deeper into. We could look back on the 3 track days in a video comparing some more in depth data from each 👍
@@SuspensionSecrets yeah that would be great, can just video stitch together the best 3 sectors for eg.
Brilliant boys
Thank you! Glad you’re enjoying the series!
Another great video. I thought the GT4 was Porsche's track-focussed-road version of the 718 but didn't realise the GT department would leave so much scope for aftermarket improvement. Is the car now no longer realistic to use on the road (i.e too firm, excess tyre wear) ?
Thanks for the comment. Yes there is plenty left on the table and almost a lot more in the GT4 as it is held back even further as standard so it can’t compete with its GT3 counterparts 👍
In terms of road use, we still use our car on the roads and drive it to and from track and on the weekends too. It actually surprised us how nice it still feels to drive out in the roads. In fact it’s actually more complaint over bumps than our F80 M3 which is still just running standard shocks and eibach lowering springs. When we designed the kit, keeping it useable out on the roads was a key decision factor 👍
@@SuspensionSecrets what about tire wear? With the high camber and toe settings, I imagine the car is now only suitable for trips to and from the track. No more joy rides/commute and road trips 😢
What tyre pressure you using?
Between 30 and 33 psi hot across the axles 👍
Love it - 🎉🎉🎉
Thank you 🙌
Any reason only spring changes?
Yes 👍 the standard dampers are actually very good in terms of performance and the range of the damper was enough that we were able to alter the spring rates within the abilities of the OEM dampers. At this point we haven’t found the dampers to be a limiting factor at all, only the spring rates of the coil springs as we introduced more and more grip into the chassis with setup.
@@SuspensionSecretswas wondering exactly this, thanks for the information!