Diff pinion torque
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Mad Mart
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Diff pinion torque
Apparently the rear axle on PUS had a bit of a whine, so whilst I have it on the garage floor I thought I may as well look into it. The only reason I can think of is that the pinion nut is not torqued correctly, either to tight or not tight enough. The diff is of the collapsible spacer type. I have marked the relevent positions on the nut, pinion flange & diff casing but that will get me back to where I started from. If I fit a new collapsible spacer, what torque do I need to tighten it to, as I only have the settings for the shimmed type diff..
Sprintless for the first time in 35+ years. 
... Still Sprintless.
Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
... Still Sprintless.Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
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MIG Wielder
- TDC Member
- Posts: 2336
- Joined: Sun Mar 16, 2008 2:52 pm
Re: Diff pinion torque
Hi Martin, Wow ! I've just read this bit of the Sprint workshop manual and this looks like the PH.D. of Dolomite maintenance !
As I understand it, to replace that collapsable spacer the entire diff; has to be dismantled. The difficult bit looks like measuring the " pinion height " with a dial gauge and a dummy pinion ( another special tool ) and you then have to fit a shim pack. Then you set up the pinion pre-load. This looks like it is done with the crown wheel removed.
So to answer your question , the setting procedure is.....tighten the nut to 90 lbf ft; and check the preload on the pinion of 26 - 29 lbf in using a special gauge 18G 207E.( This looks like a weight driven low reading balance bar. I assume this is the torque required to just rotate the pinion.)
You then gradually tighten the nut up to a maximum of 120 lbf ft, to get this figure of 26 - 29 lbf in at the pinion. There are dire warnings about exceeding this figure and leaving an over-collapsed spacer in place.
So if you have the half-shafts and crown wheel out, if you can devise a means of measuring the pinion pre-load torque to just rotate it, assuming the pinion nut just needs tightening to somewhere below 120 lbf ft, you should be O.K.
Assuming the collapsable spacer isn't damaged somehow I suppose.
26 -29 lbf in is just over 2 lbf ft, I think , so way below standard torque-wrench settings
Cheers Mart,
Tony.
As I understand it, to replace that collapsable spacer the entire diff; has to be dismantled. The difficult bit looks like measuring the " pinion height " with a dial gauge and a dummy pinion ( another special tool ) and you then have to fit a shim pack. Then you set up the pinion pre-load. This looks like it is done with the crown wheel removed.
So to answer your question , the setting procedure is.....tighten the nut to 90 lbf ft; and check the preload on the pinion of 26 - 29 lbf in using a special gauge 18G 207E.( This looks like a weight driven low reading balance bar. I assume this is the torque required to just rotate the pinion.)
You then gradually tighten the nut up to a maximum of 120 lbf ft, to get this figure of 26 - 29 lbf in at the pinion. There are dire warnings about exceeding this figure and leaving an over-collapsed spacer in place.
So if you have the half-shafts and crown wheel out, if you can devise a means of measuring the pinion pre-load torque to just rotate it, assuming the pinion nut just needs tightening to somewhere below 120 lbf ft, you should be O.K.
Assuming the collapsable spacer isn't damaged somehow I suppose.
26 -29 lbf in is just over 2 lbf ft, I think , so way below standard torque-wrench settings
Cheers Mart,
Tony.