 Transmission Help, 901 differential bearing clearance |
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| Al Meredith |
 Feb 3 2026, 03:27 PM
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#1
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Senior Member  Group: Members Posts: 983 Joined: 4-November 04 From: Atlanta, ga Member No.: 3,061  |
I have the PORSCHE 901 transmission rebuild manual and it tells me to have 15.8 to 20.6 FT LBS drag on the DIF.. I'm reading about 5 FT/LB. with the same diff and case ( no gears installed )There is also very slight visitable and feelable back and forth (left and right) at the CV flanges. Should I install shims ? HELP AL
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| mgphoto |
Feb 3 2026, 05:15 PM
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"If there is a mistake it will find me" Group: Members Posts: 1,380 Joined: 1-April 09 From: Los Angeles, CA Member No.: 10,225 Region Association: Southern California |
QUOTE(Al Meredith @ Feb 3 2026, 01:27 PM)  I have the PORSCHE 901 transmission rebuild manual and it tells me to have 15.8 to 20.6 FT LBS drag on the DIF.. I'm reading about 5 FT/LB. with the same diff and case ( no gears installed )There is also very slight visitable and feelable back and forth (left and right) at the CV flanges. Should I install shims ? HELP AL If you are bottoming out the cover and only getting 5 ft lbs there is an issue. Don’t remember o ring out I believe. I think you need the gear stack in to measure the backlash. 914 factory manual is missing some data. |
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| oldie914 |
Feb 4 2026, 01:47 AM
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#3
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Member Group: Members Posts: 118 Joined: 2-May 10 From: Germany Member No.: 11,680 Region Association: None |
The value for the drag when turning the differential only applies to new bearings because bearing drag drops after it has been run for a few hundred miles. Turning resistance is still there but very hard to measure.
I always make an idiot check on differential bearing preload first time I put it in the case. Install the side cover without the O-ring with nuts on three studs. Back off two nuts and measure the clearance between side cover and the case with a feeler guage. Should be abour 0.20mm. |
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