I just finished the rebuild of my 915 (synchro, dogteeth, bearings, miscellaneous, preload, backlash, pinion clearance). Never worked on a gearbox before. These videos were a extraordinary complement to the 'Zimmermann' Wiki files. The occasional email got answered too! Thanks Kurt for helping me out!!!
Thank you SO MUCH for producing these videos! I’ve got a 911 trans that I damaged and partially disassembled and have been slacking on putting it back together.
Awesome series. Thanks so much for posting. I’m about to send my transaxle out for rebuild and this has helped me go into the process much more informed.
Excellent and thanks Kurt! It would be beneficial to your viewers to see you cover the maintenance of the 5th/reverse detent system. It was somewhat glossed over in this video. I highly recommend that anyone who services one of these transmissions take the time to remove the two roll pins and remove the components for cleaning both the components and the bore. I once saw a gearbox that was freshly rebuilt by a local shop get stuck in 5th gear because there was 50 years of worn synchro debris and gunk built up to the point of preventing the detent system from moving freely. Under these circumstances the components will not freely fall out of the bore for servicing. You can insert/force a series 7mm steel balls into the bore from the 5th/reverse shift rod hole to slowly force the components out of the bore. Then take an 8mm ream or pipe brush to clean the bore. Thanks again!
Hi Richard, We always remove all hammer in plugs and detents, springs and spacers. Not sure about your removal technique but I guess if it works for you then great. Our cleaning process requires all parts to be out as we vapor blast then media tumble the cases. We will try and show more of this process on the next video. Kurt
I would like to attempt this. I have rebuilt my 3.2 engine with no previous experience but this looks more complicated with tolerances. and special tools required.
Yes, the only way to do this job right is to have the tooling. To buy all the tooling required to set up the transaxle you are going to have spend somewhere between $12,000 to $15,000. So unless you are going into the transaxle business probably best to have a shop that has the tools do the work for you. Kurt
I just bought a 79' 911 SC and it will not go into first gear, all other gears are fine, no noise or grinding. It's like a hard stop trying to select first. Is this a common problem? The vehicle has 75k miles.
Most likely the first gear synchro ring has peeled out of the dog teeth and it is mechanically blocking the slider. This is not uncommon for these transmissions. The transmission will need to come out and apart to resolve the issue. Thanks Kurt
@@klassikats after watching your build videos, I was thinking the same thing. I’m dropping my car off tomorrow, I’ll let you know how it goes. Thank you, been watching all your vids, very well done
Argument with a friend over downshifting and whether double clutching, with a throttle blip in neutral to match revs, or a single shift with a throttle blip to match, is better for the 915 gearbox. Seems to me both methods match revs, shift fork and selector move and by matching revs, the synchros would experience less abuse. Friend maintains that only double clutching saves synchro and wear. What is your opinion? Great video series, thanks!
George, You friend is correct. The purpose of double clutching is to bring the gear sets as close to as possible in speed. Putting your foot on the clutch and revving the engine does nothing for gear set speeds. Personally unless there is an issue with the synchro's just drive it normally, foot on the clutch shift gears and keep driving. Kurt
@@klassikats I wish I was as skilled and experienced as you are in the mechanics of Porsche gear boxes, so I could visualize-understand exactly what’s going on in the double clutch versus single clutch methods. Is the double clutch better because the 915 is in neutral, clutch out, during the rev matching throttle blip? It seems like the input shaft would speed back up since it is re-connected to the engine, as the clutch comes out, gear in neutral…before the second clutch and shift to lower gear. Isn’t the 915 in neutral also, as you pass into a lower gear, even if momentarily? Please forgive my inability to quickly understand this subject, which I find interesting, as I get back into racing and working on my old RSR.
This has been an excellent and very informative series, much appreciated! I do have one quick question; can you explain why it is important to assemble everything without oil? Thank you!
I do explain this in the video, but the short answer is the bearings and shaft components need to be clamped against each other without the presence of oil so that the individual components as less likely to spin on the shaft. Kurt
@@klassikats Thank you for the explanation. I did watch the series in its entirety, but must have missed it. Thanks for all the work on this, I imagine it was quite a lot to video, edit and get put together. Really helpful!
I just finished the rebuild of my 915 (synchro, dogteeth, bearings, miscellaneous, preload, backlash, pinion clearance). Never worked on a gearbox before. These videos were a extraordinary complement to the 'Zimmermann' Wiki files. The occasional email got answered too! Thanks Kurt for helping me out!!!
Glad to have helped
Kurt
Thank you Kurt and wife! Nicely detailed, excellent vid!
Thank you fancypants. Sarah
Awesome video, thanks for sharing.
Thanks for watching!
Kurt
Thank you SO MUCH for producing these videos! I’ve got a 911 trans that I damaged and partially disassembled and have been slacking on putting it back together.
Your welcome and glad that I can help
Kurt
Incredible workmanship . Best I've seen .
Thank you
Kurt
Great set of videos. Thanks
Glad you like them!
Thanks Kurt. Excellent series of videos.
Glad you like them!
and thanks for watching
Kurt
Your videos are always appreciated!
Glad you like them!
And Thanks for watching
Awesome series. Thanks so much for posting. I’m about to send my transaxle out for rebuild and this has helped me go into the process much more informed.
Glad to help
Kurt
Well done everything is according to the rules of the art :) Just Perfect, I download because really excellent work
Thank you very much!
Excellent and thanks Kurt! It would be beneficial to your viewers to see you cover the maintenance of the 5th/reverse detent system. It was somewhat glossed over in this video. I highly recommend that anyone who services one of these transmissions take the time to remove the two roll pins and remove the components for cleaning both the components and the bore. I once saw a gearbox that was freshly rebuilt by a local shop get stuck in 5th gear because there was 50 years of worn synchro debris and gunk built up to the point of preventing the detent system from moving freely. Under these circumstances the components will not freely fall out of the bore for servicing. You can insert/force a series 7mm steel balls into the bore from the 5th/reverse shift rod hole to slowly force the components out of the bore. Then take an 8mm ream or pipe brush to clean the bore. Thanks again!
Hi Richard,
We always remove all hammer in plugs and detents, springs and spacers. Not sure about your removal technique but I guess if it works for you then great. Our cleaning process requires all parts to be out as we vapor blast then media tumble the cases.
We will try and show more of this process on the next video.
Kurt
Lovely, as always.
Thanks Joe,
and thanks for watching
Kurt
I would like to attempt this. I have rebuilt my 3.2 engine with no previous experience but this looks more complicated with tolerances. and special tools required.
Yes, the only way to do this job right is to have the tooling. To buy all the tooling required to set up the transaxle you are going to have spend somewhere between $12,000 to $15,000. So unless you are going into the transaxle business probably best to have a shop that has the tools do the work for you.
Kurt
I just bought a 79' 911 SC and it will not go into first gear, all other gears are fine, no noise or grinding. It's like a hard stop trying to select first. Is this a common problem? The vehicle has 75k miles.
Most likely the first gear synchro ring has peeled out of the dog teeth and it is mechanically blocking the slider. This is not uncommon for these transmissions. The transmission will need to come out and apart to resolve the issue.
Thanks Kurt
@@klassikats after watching your build videos, I was thinking the same thing. I’m dropping my car off tomorrow, I’ll let you know how it goes. Thank you, been watching all your vids, very well done
Argument with a friend over downshifting and whether double clutching, with a throttle blip in neutral to match revs, or a single shift with a throttle blip to match, is better for the 915 gearbox.
Seems to me both methods match revs, shift fork and selector move and by matching revs, the synchros would experience less abuse. Friend maintains that only double clutching saves synchro and wear. What is your opinion?
Great video series, thanks!
George,
You friend is correct. The purpose of double clutching is to bring the gear sets as close to as possible in speed. Putting your foot on the clutch and revving the engine does nothing for gear set speeds. Personally unless there is an issue with the synchro's just drive it normally, foot on the clutch shift gears and keep driving.
Kurt
@@klassikats I wish I was as skilled and experienced as you are in the mechanics of Porsche gear boxes, so I could visualize-understand exactly what’s going on in the double clutch versus single clutch methods.
Is the double clutch better because the 915 is in neutral, clutch out, during the rev matching throttle blip?
It seems like the input shaft would speed back up since it is re-connected to the engine, as the clutch comes out, gear in neutral…before the second clutch and shift to lower gear.
Isn’t the 915 in neutral also, as you pass into a lower gear, even if momentarily?
Please forgive my inability to quickly understand this subject, which I find interesting, as I get back into racing and working on my old RSR.
This has been an excellent and very informative series, much appreciated! I do have one quick question; can you explain why it is important to assemble everything without oil? Thank you!
I do explain this in the video, but the short answer is the bearings and shaft components need to be clamped against each other without the presence of oil so that the individual components as less likely to spin on the shaft.
Kurt
@@klassikats Thank you for the explanation. I did watch the series in its entirety, but must have missed it. Thanks for all the work on this, I imagine it was quite a lot to video, edit and get put together. Really helpful!