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Join Date: Oct 2001
Location: San Carlos, CA US
Posts: 5,553
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G50 diff preload.
I cannot seem to find the pre-load value for a G50 Diff. Maybe I am looking in the wrong place. If someone has these values ready, please share.
1. Differential bearing preload (Nm, inch pounds, whatever you have) 2. Backlash, x.xx milimeters, 0.00x thousands of inch. 3. Measurement point for the backlash, (at the edge of the ring?)
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Porsche 2005 GT3, 2006 997S with bore-scoring Exotic: Ferrari F360F1 TDF, Ferrari 328 GTS Disposable Car: BMW 530xiT, 2008 Mini Cooper S Two-wheel art: Ducati 907IE, Ducati 851 |
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12-16-2025, 06:34 AM
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Join Date: Oct 2016
Location: WA
Posts: 379
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I believe this all should be in the final drive, differential section of the WSM. Do you have that? There are some copies floating around. I could email you it if you send me a PM.
1) Preload is determined by measuring 'space in the case' with some pre determined shims at S1, S2 installed and a pressing constant of 0.40mm. 2) Should be printed on the gear itself in mm, i.e. F 0.16 3) Measurement is 'approx. 80mm' from the edge of Porsche tool 9145 to the tip of VW382/10. |
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12-16-2025, 07:07 AM
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Join Date: Mar 2019
Posts: 1,642
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The factory uses a "0.40mm constant" preload. In rotational torque, it's about 40 in lb for new bearings or something over 15 in lbs for used bearings. If your used bearings are below that amount with the factory shims, they're worn. Or the side cover is...not where it once was.
Backlash is engraved on the ring gear, in mm (The "f" number). The factory set the gear sets up for quietest operation, not strength, so there's that. Double check your work with the yellow gear marking compound (NOT blue dykem or anything like that. Yellow gear marking compound ONLY) If you're not using the factory backlash tools, approximate the heel of the ring gear (the biggest diameter part, the outer edge). Dan |
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12-16-2025, 07:25 AM
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PCA Member since 1988
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Why the yellow instead of the blue?
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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12-17-2025, 12:20 AM
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Join Date: Mar 2019
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The yellow gear marking compound is a thick paste specifically made for high visibility and verifying the contact pattern between the ring and pinion gears. Dykem is a liquid machinists use for laying out places to scribe lines.
Last edited by dannobee; 12-17-2025 at 09:23 AM.. |
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12-17-2025, 09:18 AM
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Join Date: Jan 2022
Posts: 208
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Hi
All the info you need should be here: https://forums.pelicanparts.com/porsche-911-technical-forum/1157509-guy-his-garage-attempts-rebuild-g50.html Cheers |
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12-17-2025, 09:29 AM
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PCA Member since 1988
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Thanks.
__________________
1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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