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pinion gear assembly (how to shim)

17K views 39 replies 8 participants last post by  bugget_jr 
#1 ·
Hi, I got a pontiac 8,2" 10-bolt b-o-p axle in my firebird-67, and I bought a differential, ring gear and pinion gear. The ring and pinion gear have not the original ratio so I have to "re-shim" those when assembling the axle.

But I kind of got stuck at the beginning thus I don�t know the proper way to shim out the pinion gear. The inner bearing of the pinion gear is really hard to assemble, It�s requires tapping on the bearing, but if I do this it will be really hard to assemble more shims if it�s required.

So the question is: How do I assemble shims and bearings in a proper way (Observe that I gonna have to assemble more shims later, so it�s not the final assemble)?

Grateful for all help I can get :)
 
#28 ·
thanks for all help, understood it wasn´t easy to see the last pictures but my brothers cellphone camera was much better so here´s an update:

coast side:


drive side:


Here´s some of my thoughts: What´s most important, a soft pattern or an centered?

If I have less pinion shims doesn´t that equal to more backlash (and too far up on the top) and if I decrease the BL that´s equal to make the pattern to far down to the toe side on both side? (you guys is probably right, I´m just trying to figure out where I thinking wrong)

really appreciate all the help :)
 
#29 ·
The most important thing is to get the pattern centered between the root and face. Right now your pattern is too far to the root, which means that you pinion is still too deep. Moving the pinion depth will change the root to face pattern. Backlash controlls the heel to toe pattern after the pinion depth is set correctly. Look at the pattern that you have now. Don't pay any attention to where it is located heel to toe, only look at root to face. Keep reducing the pinion shim until the pattern is centered between the root and face of the tooth. The pattern should get wider as it moves away from the root. Each time you change the pinion depth you will have to reset the backlash. Keep the backlash at about .007 to .009 until you get the pinion depth correct. Then you can make slight changes to the backlash to fine tune the pattern.
 
#30 ·
alright, so I changed the pinion a bunch of times and with a 0.026" shim gives the widest pattern I think, also the 0.02 shim makes a wide pattern. I took some photos on a bunch of shims, because I´ve tried all possible shim combinations now and it won´t get centered.

0.026 shims with good BL gives:



0.02 shim with good BL gives:



0.017 shim with good BL gives:



Is the 0.026" shim good?
 
#32 ·
I´m not sure what the shim thickness was in the previous post but I think it was 0.037". Ok, i´m going to try out the 0.03 shim. Should the gears make noise with this setup? What should I prefer, a setup too close to the root or a setup close at the toe as this setup?
 
#36 ·
I'm going to assume that you are turning this with the pinion gear because the pattern is not clear with defined edges. I recommend sticking an axle in and use the axle to turn it several times in both directions to get a more clear pattern. Also be sure that the pinion bearing preload is set correctly every time.

The .026 pattern looks pretty good. The .030 pattern looks pretty good on the drive side, but the coast side is a little too much on the root. Go back to the .026 and make some adjustments to the backlash to see if the coast pattern will move toward the heel some. Use the axle to turn it.
 
#37 ·
ok, so I got a nice pattern so I began to install the pinion for the final time. I installed a new seal and a new crush sleeve but I got really worried when I started to screw the pinion nut. I was told that I should screw until I feel the crush sleeve crushes (it would rotate easier) and that it would take a lot of wrench torque until it crushes. So I started to screw the nut (really hard) but not until it crushed because the pinion got stuck (I couldn´t rotate the pinion). Is this normal and will the pressure release when it crushes?
 
#40 ·
anybody knows how to do a proper assembly of the inner retainer of the drive shaft? should I heat the inner retainer so it shrinks or can I just press it on? And how important is it to have new gasket (at the brake backing plate)? because the axles I know have is in bad shape and is going to be replaced when I got new ones (about a mounth from now) and don´t want to spend to much money on something temporarily.
 
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