Thrust washer for spider gears - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**raggedjim** · 11-20-2023, 10:10 PM

I have looked the internet from one end to the other looking for the thrust washers (or shims) that go behind the spider gears in a 12 bolt chevy truck positrac rearend. If anyone has any idea where I should look for them it would be appreciated.

Thanks, Rg

After much research and gnashing of teeth I found GM #3957940 for the washers BUT most places have them back ordered. Tom's differentials has them in stock so I have them ordered. I'll update once they come in.

Tom's has a good catalog of differential parts. https://tomsdifferentials.com/

Washers came in and installed easily. Most of the ones you will find online are NOT the correct ones! If they have the lip around the id they are not for our trucks.

Good luck, Rg

Mike C · 11-20-2023, 10:23 PM

https://www.jegs.com/i/Yukon+Gear/80...CABEgJcSPD_BwE

**raggedjim** · 11-20-2023, 10:58 PM

Thanks Mike, I saw those but I read some reviews saying they didn't fit early eaton units, only aftermarket units, here's a quote from the website...

Response from Differential Expert:
· 2 years ago
YSPTW-044 is a pinion gear thrust washer with an Outside Dia of 1.665", Inside Dia of 0.811, and a 0.088" tall lip surrounding the cross pin shaft . this thrust washer is designed to fit aftermarket Eaton and Yukon Duragrip limited slips that have spider gears machined with the corresponding recess., it does not fit the early OEM Eaton limited slips.

I'm wondering if the washers for the spider gears on the open carriers are the same as the early oem posi units. The crosspins are the same for both so I'm thinking they could be.

Thanks, Rg

**raggedjim** · 11-30-2023, 07:36 PM

Added info in first post.

Rg

Mike C · 11-30-2023, 11:09 PM

Thanks for coming back and updating this post.

**raggedjim** · 12-01-2023, 10:21 AM

No problem, I can't be the only person who has ever had trouble finding them.

11-20-2023, 10:10 PM	#1
raggedjim Senior Member Join Date: Jun 2002 Location: Murray, Kentucky Posts: 3,453	Thrust washer for spider gears I have looked the internet from one end to the other looking for the thrust washers (or shims) that go behind the spider gears in a 12 bolt chevy truck positrac rearend. If anyone has any idea where I should look for them it would be appreciated. Thanks, Rg After much research and gnashing of teeth I found GM #3957940 for the washers BUT most places have them back ordered. Tom's differentials has them in stock so I have them ordered. I'll update once they come in. Tom's has a good catalog of differential parts. https://tomsdifferentials.com/ Washers came in and installed easily. Most of the ones you will find online are NOT the correct ones! If they have the lip around the id they are not for our trucks. Good luck, Rg __________________ Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd '73 Firebird - https://67-72chevytrucks.com/vboard/...d.php?t=853203 Last edited by raggedjim; 11-30-2023 at 07:36 PM. Reason: added information

11-20-2023, 10:23 PM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Re: Thrust washer for spider gears https://www.jegs.com/i/Yukon+Gear/80...CABEgJcSPD_BwE __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

11-30-2023, 07:36 PM	#4
raggedjim Senior Member Join Date: Jun 2002 Location: Murray, Kentucky Posts: 3,453	Re: Thrust washer for spider gears Added info in first post. Rg __________________ Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd '73 Firebird - https://67-72chevytrucks.com/vboard/...d.php?t=853203

11-30-2023, 11:09 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Re: Thrust washer for spider gears Thanks for coming back and updating this post. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

12-01-2023, 10:21 AM	#6
raggedjim Senior Member Join Date: Jun 2002 Location: Murray, Kentucky Posts: 3,453	Re: Thrust washer for spider gears No problem, I can't be the only person who has ever had trouble finding them. __________________ Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd '73 Firebird - https://67-72chevytrucks.com/vboard/...d.php?t=853203

11-20-2023, 10:58 PM	#3
raggedjim Senior Member Join Date: Jun 2002 Location: Murray, Kentucky Posts: 3,453	Re: Thrust washer for spider gears Thanks Mike, I saw those but I read some reviews saying they didn't fit early eaton units, only aftermarket units, here's a quote from the website... Response from Differential Expert: · 2 years ago YSPTW-044 is a pinion gear thrust washer with an Outside Dia of 1.665", Inside Dia of 0.811, and a 0.088" tall lip surrounding the cross pin shaft . this thrust washer is designed to fit aftermarket Eaton and Yukon Duragrip limited slips that have spider gears machined with the corresponding recess., it does not fit the early OEM Eaton limited slips. I'm wondering if the washers for the spider gears on the open carriers are the same as the early oem posi units. The crosspins are the same for both so I'm thinking they could be. Thanks, Rg __________________ Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd '73 Firebird - https://67-72chevytrucks.com/vboard/...d.php?t=853203 Last edited by raggedjim; 11-20-2023 at 11:18 PM.



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