gear swap in an 8.5

BillySS

Frequent Racer
Dec 13, 2009
433
0
0
Matawan,NJ
How hard is it? Im thinking of doing it myself. In Need of pointers please
 

t5montecarlo

MalibuRacing Junkie
Oct 21, 2007
4,633
31
48
Lederach, PA
garage-scene.com
Read, read, read, and lots of patience. You will be installing and removing parts several times to ensure the wear pattern is correct.

I replaced an open carrier with an Eaton in my wagon and it came out right with no noise. Since I was reusing the original gears, I did not need to calculate the pinion shim thickness.

I recommend a carrier shim kit that comes with an inner/outer piece for the shim pack. I bought a kit from Tom's Differentials (think it was called a Super Pack). I remember that one part was like an open top hat.

I made a large lever to bolt to the pinion flange to help with removing the pinion nut and for tightening it. In my case, the case was on jack stands, so I didn't have the car mass to help me.

You will need an inch-pound torque wrench to set the pinion bearing preload.
You will need a dial indicator to set the backlash.
You will need a tool to determine the pinion depth (there are different types of tools available).

MonzaZ may be able to help.
 

BillySS

Frequent Racer
Thread starter
Dec 13, 2009
433
0
0
Matawan,NJ
I found one tool on Summit website for $38 and another kit for $480. Huge difference.
I have dial indicators and magnetic mount. I have to locate a press for the pinion bearing.
I watched the video from Richmond. Seems simple enough. But constantly pressing on the bearing will be a problem if the shims aren't right.
 

BillySS

Frequent Racer
Thread starter
Dec 13, 2009
433
0
0
Matawan,NJ
Yes I saw that one. Even used it goes for hundreds. Crazy to pay that for one time deal.
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
It's best to buy or make a set of Checking Bearings. You can use a Flapper Wheel & Die Grinder to sand the I.D. so they just slip on/off, then when you get the Shims/clearance correct put the new Bearing set on for the final install.
 

StreetBu

MalibuRacing Junkie
Mar 21, 2004
4,158
3
38
Upstate NY
Had an old mechanic give me the best tip ever. The main reason the rear end needs to be shimmed is because the cast housing shifts as it cools. If you simply unbolt the old gears, swap new pinion in using old shim pack and keep the carrier shim packs in the same location. You'll either be dead on or only have to make very slight adjustments. Basically your compensating for the housing not the gears or carrier. When I swapped my open carrier for a Tru-Trac, I didn't have to change a single shim.
 

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