Pattern check - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ChadW · 09-24-2022, 05:17 PM

Put a yukon posi in my 10 bolt. First time messing with diffs. Got backlash to .007 and ran a pattern. Can anyone tell me what this pattern is saying? Good or bad?
Posted via Mobile Device

**mongocanfly** · 09-24-2022, 08:12 PM

Looks pretty good to me... I've never seen a contact patch that wide as in 2nd pic though

**Ironangel** · 09-25-2022, 11:13 AM

The first and third pic dont look bad, the second pic (drive side) looks like a well worn gear set. Was that thing whining before the you installed the posi? I think your close enough considering that is a high mileage gear set... Scroll down to the bottom of page 8 of this link, it indicates that a used set of gears only the coast side of the gears should be read... I think your good to go

https://www.randysworldwide.com/impo...PDATED2021.pdf

ChadW · 09-25-2022, 08:30 PM

Quote:

Originally Posted by Ironangel

The first and third pic dont look bad, the second pic (drive side) looks like a well worn gear set. Was that thing whining before the you installed the posi? I think your close enough considering that is a high mileage gear set... Scroll down to the bottom of page 8 of this link, it indicates that a used set of gears only the coast side of the gears should be read... I think your good to go

https://www.randysworldwide.com/impo...PDATED2021.pdf

Tks for the link...I agree...I think ill just run it and see how it does...
Posted via Mobile Device

**kwmech** · 09-26-2022, 12:13 PM

If you are just installing a posi and using the gears over, do not change the pinion depth. A back lash reading should have been taken prior to. If that is correct, .007 may be too tight on a used gear set and create a whine. Try it but you may have to increase the back lash by a few thou. Could as easy as swapping a .003 shim side to side

ChadW · 09-26-2022, 03:26 PM

Quote:

Originally Posted by kwmech

If you are just installing a posi and using the gears over, do not change the pinion depth. A back lash reading should have been taken prior to. If that is correct, .007 may be too tight on a used gear set and create a whine. Try it but you may have to increase the back lash by a few thou. Could as easy as swapping a .003 shim side to side

It is a 10 bolt that was narrowed and new moser axels were made...I then bought the project...the pinion and carrier were in the rear end but im not sure of their history etc...I pulled the gov loc carrier adn put in a yukon posi...shimmed to .007 and left the pinion alone...so you think i should widen up the backlash a bit?

ChadW · 09-26-2022, 03:53 PM

Quote:

Originally Posted by kwmech

If you are just installing a posi and using the gears over, do not change the pinion depth. A back lash reading should have been taken prior to. If that is correct, .007 may be too tight on a used gear set and create a whine. Try it but you may have to increase the back lash by a few thou. Could as easy as swapping a .003 shim side to side

It is a 10 bolt that was narrowed and new moser axels were made...I then bought the project...the pinion and carrier were in the rear end but im not sure of their history etc...I pulled the gov loc carrier adn put in a yukon posi..The GovLoc was not shimmed correctly i do not beleive as i was able to remove the carrier with little not no effort...pretty much fell out...Installed the Yukon and shimmed to .007 and left the pinion alone...so you think i should widen up the backlash a bit?

**kwmech** · 09-27-2022, 11:56 AM

Looking at the gear without the paste on it, you can tell they are used. It is a crap shoot with a used set especially not knowing the history on the rear end. You can run it and see if it makes noise. More than likely it will. But increasing the BL could also create a noisy rear. Having the carrier fall out due to no preload on the carriers is a little wondering. If it were me while this is apart. I'd spring for a new set of gears and bearings and not worry about it--OR run it and see what you've got. It may be fine. How's that for being non-comittal?

09-24-2022, 05:17 PM	#1
ChadW Registered User Join Date: Jan 2018 Location: Danville, IL Posts: 160	Pattern check Put a yukon posi in my 10 bolt. First time messing with diffs. Got backlash to .007 and ran a pattern. Can anyone tell me what this pattern is saying? Good or bad? Posted via Mobile Device Attached Images

09-24-2022, 08:12 PM	#2
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,582	Re: Pattern check Looks pretty good to me... I've never seen a contact patch that wide as in 2nd pic though __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

09-25-2022, 11:13 AM	#3
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: Pattern check The first and third pic dont look bad, the second pic (drive side) looks like a well worn gear set. Was that thing whining before the you installed the posi? I think your close enough considering that is a high mileage gear set... Scroll down to the bottom of page 8 of this link, it indicates that a used set of gears only the coast side of the gears should be read... I think your good to go https://www.randysworldwide.com/impo...PDATED2021.pdf __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American" Last edited by Ironangel; 09-25-2022 at 12:22 PM.

09-26-2022, 12:13 PM	#5
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,389	Re: Pattern check If you are just installing a posi and using the gears over, do not change the pinion depth. A back lash reading should have been taken prior to. If that is correct, .007 may be too tight on a used gear set and create a whine. Try it but you may have to increase the back lash by a few thou. Could as easy as swapping a .003 shim side to side

09-27-2022, 11:56 AM	#8
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,389	Re: Pattern check Looking at the gear without the paste on it, you can tell they are used. It is a crap shoot with a used set especially not knowing the history on the rear end. You can run it and see if it makes noise. More than likely it will. But increasing the BL could also create a noisy rear. Having the carrier fall out due to no preload on the carriers is a little wondering. If it were me while this is apart. I'd spring for a new set of gears and bearings and not worry about it--OR run it and see what you've got. It may be fine. How's that for being non-comittal?



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.