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

dakattack7 · 04-23-2018, 01:17 AM

Hello all, trying to set up this 9.5 14 bolt for my 96 K1500.

I got a junkyard diff, it has 300k+ but the ring and pinion looked good to me not being too shiny or sharp, machining marks still there..

So I installed all new bearings, and figured I could use the stock shims since I only replaced bearings.

Now, with the stock big carrier shim, there was zero backlash. None at all. With this shim the pattern showed to need more backlash like you'd expect, but it would at least obviously mark the ring gear.

I used install kit shims to get the backlash to .008, spec being .006-.010.
Doing this leaves me with this pattern, that I can't really interpret as it doesn't look like any I've seen. It barely marks the ring gear, no matter what I do. Spinning the ring gear, spinning pinion pressing against the ring gear, spinning the pinion with a drill..

So, I tried to go from the .023 pinion shim to a smaller one, .020 then .018ish because it looks like the most definite mark it's leaving is pretty low. Neither had any effect nor made it mark definitely, real similar to what you see here.

So, what do we think is going on here? I'm stumped, not that I have much experience as this is my first rear but this doesn't make much sense.. I would just throw all the stock shims in and run it, but like I said that ends with zero backlash..

Maybe this pattern is okay? The coast side looks okay I think, and you go off of that using used gears?

**truckdude239** · 04-23-2018, 04:27 AM

Please upload your photos here to the site and no photo bucket wr can not see ur pictures

**PGSigns** · 04-23-2018, 07:08 AM

Used gears can be hard at times. They will wear till they have a full contact like you are seeing and be just fine. On a used set I measure pinion depth and reset it back to that and set the backlash on the looser side of the spec and call it good. Has worked so far.
Jimmy

**kwmech** · 04-23-2018, 11:50 AM

You cannot set up used gears per-se......especially since they have 300+ on them. Put the original shims back in and set the back lash. Any changes you make can make those gears howl or sing. After 300 thousand miles they are going to have their own pattern

**Ironangel** · 04-24-2018, 07:17 AM

OEM shim thickness for 10.5 14-bolt is .017"...Stick the 0.18" in there and button it up. Backlash should be 6-10 thousandths...

04-23-2018, 01:17 AM	#1
dakattack7 Registered User Join Date: Feb 2013 Location: az Posts: 177	Gear Pattern Help Hello all, trying to set up this 9.5 14 bolt for my 96 K1500. I got a junkyard diff, it has 300k+ but the ring and pinion looked good to me not being too shiny or sharp, machining marks still there.. So I installed all new bearings, and figured I could use the stock shims since I only replaced bearings. Now, with the stock big carrier shim, there was zero backlash. None at all. With this shim the pattern showed to need more backlash like you'd expect, but it would at least obviously mark the ring gear. I used install kit shims to get the backlash to .008, spec being .006-.010. Doing this leaves me with this pattern, that I can't really interpret as it doesn't look like any I've seen. It barely marks the ring gear, no matter what I do. Spinning the ring gear, spinning pinion pressing against the ring gear, spinning the pinion with a drill.. So, I tried to go from the .023 pinion shim to a smaller one, .020 then .018ish because it looks like the most definite mark it's leaving is pretty low. Neither had any effect nor made it mark definitely, real similar to what you see here. So, what do we think is going on here? I'm stumped, not that I have much experience as this is my first rear but this doesn't make much sense.. I would just throw all the stock shims in and run it, but like I said that ends with zero backlash.. Maybe this pattern is okay? The coast side looks okay I think, and you go off of that using used gears?

04-23-2018, 04:27 AM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,217	Re: Gear Pattern Help Please upload your photos here to the site and no photo bucket wr can not see ur pictures __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

04-23-2018, 07:08 AM	#3
PGSigns Senior Member Join Date: Jan 2011 Location: Hayes Va Posts: 4,569	Re: Gear Pattern Help Used gears can be hard at times. They will wear till they have a full contact like you are seeing and be just fine. On a used set I measure pinion depth and reset it back to that and set the backlash on the looser side of the spec and call it good. Has worked so far. Jimmy __________________ 60 to 66 Chevy and GMC window decals http://67-72chevytrucks.com/vboard/s...d.php?t=661131 Good friends, good food and a hotrod what else do you need? 1966 BBW long fleet Daily driver 1965 BBW short fleet Sold and going to a good home 1965 Suburban 2003 3500 Duramax 2005 Ultra Classic

04-23-2018, 11:50 AM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,388	Re: Gear Pattern Help You cannot set up used gears per-se......especially since they have 300+ on them. Put the original shims back in and set the back lash. Any changes you make can make those gears howl or sing. After 300 thousand miles they are going to have their own pattern

04-24-2018, 07:17 AM	#5
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: Gear Pattern Help OEM shim thickness for 10.5 14-bolt is .017"...Stick the 0.18" in there and button it up. Backlash should be 6-10 thousandths... __________________ 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"



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