bogartmcqueen

968 6 spd pinion shaft bearing preload (.20mm + measured zero preload) locks the shaft. I don't find an update of correction from Porsche. Anyone run into this?

chudson

OK, I'll break the silence. There are not a lot of transmission builders on this forum. There is one who is knowledgeable (can't remember his user ID at this time) and perhaps he will see this and respond.

I've got a couple of boxes to eventually build, but also have plenty of spares so getting to them is not high on the priority list.

Cliff

KevinGross

What do you mean "locks the shaft?" Adding the preload will make the shaft more difficult to turn, which is the way it's supposed to be with new bearings. But it should not be locked ie impossible to turn. The factory manual gives the spec range for turning torque. By the way, the + 0.20 (or 0.30) is just to get you started, an initial preload to add. It is not possible to accurately measure and set S4 shimming (rear pinion bearing) simply by measuring freeplay, shimming to that value + 0.30 mm. The accurate measurement comes from measuring turning torque and adjusting S4 to get it into the specified range, preferably about the middle of the range. Hope this helps.

chudson

And there he is!!

Thanks Kevin - I had a brain lapse on your user ID

Cliff

bogartmcqueen

Hi Kevin,
Thanks for the reply. When I say locked the shaft, I meant could not be turned by hand. I have remeasured and reshimmed S4 for 1.5mm (.006") of preload and
can manually turn the shaft with good resistance, but very smooth.
I have scoured the factory manual and cannot find a turning torque spec for this operation. Do you have a section / page # with the spec?
Thanks,
Greg

bogartmcqueen

Hi Kevin,
Thanks for the reply. When I say locked the shaft, I meant could not be turned by hand. I have remeasured and reshimmed S4 for 1.5mm (.006") of preload and
can manually turn the shaft with good resistance, but very smooth.
I have scoured the factory manual and cannot find a turning torque spec for this operation. Do you have a section / page # with the spec? Or do you have the spec
handy?
Thanks,
Greg

951and944S

1.5mm is ten times .006".

.006" = .15mm.

Are you sure about your measurements...?

T

bogartmcqueen

Thanks for the edit. Yes, should read .15mm and not 1.5mm - duh!

KevinGross

Hi Greg,

On page 39-19 of the workshop manual, last para tells us the turning torque should be 200 to 400 Ncm [ie, 2 - 4 Nm] for new bearings, 50 to 60 Ncm for used bearings. I use the rather pricey tool that is shown in the manuals, but there are other less expensive options. (Actually, the factory tool which I think was listed as US1064 years ago is a pain to use at times, because its internal spring can sometimes cause the reading to oscillate due to "sticktion" in the new bearings.)

Hope this helps. Let me know if you have other questions. Good luck!

bogartmcqueen

Hi Kevin,
Thanks for the specs. My manual does not give these specs on 39-19 or anywhere else I can find. The printing date on 39-19 is a year later than the
other pages in the manual so maybe they forgot to include turning torque.
I set the preload @ .16mm during E setting for pinion depth and measured with in/lb meter @ 35 in/lbs x .113nm per in/lb for a total of 3.96nm. Should
be ok.
Thanks again for the help with the specs on this - much appreciated!
Greg