Setting Backlash

[89GTpwr]

Hello,

Okay i have measured the two factory shims that came in it when i took it out and got .275 on the left and .270 on the right and my question is.. does that have to be maintained the same so - 275 + 270 =545, so in the end do i have to end up with 0.545 thou in total? because as of now it is really really tight to install the carrier with that amount of thinkness and really hard to remove, so now i am just wondering if i am able to take any thinckness away to make it a bit easier? or i have heard that you take 6 thou away from each side and then when you have your backlash set up within spec you put the .006 shims back in on each side, will this work? I am just getting really frustrated trying to remove it and install it several time to acheive the right backlash as it is Tight.

One more quik question is that i have bought the ford racing gears 3.73's and was told that in most cases the factory shim on the pinion can be used or the fordracing gear is at least really close to stock pinion depth, but any ways i ended up measuring both of the pinion head thicknesses with a vernier and ended up putting only a .010" shim on the ford racing gear instead of the 0.034" shim that came on the stock head, .... does this sound right, or should it be closer to the stock head i have yet to check it with gear marking compound because i havent got my backlash set yet.

 

[Bullitt347]

If you are using the same carrier and carrier bearings, then the shim load should stay the same as that is what sets the pre-load on the carrier bearings. 9 times out of 10 you can use the same shims and the back-lash and gear pattern will look good. If you have to little backlash then you would take .005-.006 out of the left (drivers) side and add it to the right (passenger) side to keep the proper preload on the carrier bearings. Once the backlash is correct (.004-.012) then you can worry about pinion depth if the pattern is out of wack. Putting more shim under the pinion bearing will put the pinion gear further into the ring gear and likewise taking shim out will pull the pinion further out of the ring gear. You want the pattern to be in the middle of the gear, not out on the edge and not bottoming out either. Check coast side pattern as well as that can have an effect of off throttle gear noise/whine.

 

[dtlionsfan]

Don't worry about backlash,worry about gear pattern.I just installed a 3.55 ford gear and used the same shims on pinion and carrier from the 2.73.Perfect pattern and dead quiet at all speeds.

 

[battyice]

It is always recommended to start with the factory pinion shim(s), especially if you are installing OEM gears. The resistance you've noticed while installing/removing the carrier is normal, if it didn't go in hard you wouldn't have any carrier bearing preload.

As for the recommendation that you don't worry about the backlash, that is simply not good advice. You might get lucky if you are installing OEM gears, but try that with an aftermarket set and you'll likely end up with a howling differential.

Take the time and do it right. In addition to the contact pattern and backlash, pinion bearing preload is very important, as well as proper torque and locktite on the ring gear bolts and pinion nut.

 

[rd]

It will be hard to get the diff out or in with the proper amount of side shimsl, as they provide preload on the bearings.

The factory proceedure has a tool that bolts to the main cap bolts and spreads the case to ease removal and reinstallation.

I made one, and it helps. Otherwise, with care, it can be done with a hammer.