smgbad

iTrader: (1)

I just had a 3:73 (GM used... looked fairly new though) installed in my 99 T/A. I also had my shop replace the shims and bearings and seals and all while they were in there along with 2 quarts of Royal Purple. This is coming from being a stock 3.23 (WU5). Now it whines fairly frequntly through all stages of deceleration and whenever i put my foot on or take my foot off the accelerator. Honestly it just sounds plain annoying. The shop knows it's whining but said that's the problem with buying used (matched) gears and rings, and that it may just be setting a new wear pattern which will make it go away. Is this correct? They haven't steered me wrong before, but I spent about $500 on this project and am going to end up hating driving my car because of it... Which sux b/c I love my car... Any input would be greatly appreciated. Thx

9000th01ss

iTrader: (10)

Depends on how loud. I've put many used ring and pinions in and they always seem more quiet than new aftermarket.

Usually if you read backlash before taking the gears out of the original rear, and setting the new one up exactly the same it won't make any noise at all.

Another problem I hear of often is how people think the original GM pinion shim is close enough. I read that a lot when people put in new aftermarket gears, many recommend starting with the original shim. They come in a variety of thicknesses for a reason.

The shim matches the rear housing and pinion both. Not one or the other. The factory selects the shim based on case intolerances and pinion machining indifferences. Change only one and that shim is useless, and you changed both by putting a different pinion in a different case.

And there is no way to set up a used gear set with any special tool, all you need is marking compound and a shim kit, it's trial and error until the pattern is right.
If it's not dead on it's going to make noise, gears don't break in again. You don't set a new wear pattern on gears twice.

Sounds like they got the pattern close enough, and used a tried a true excuse.

DaddySS

When you say "GM" - do you mean original AAM three cut gears? The set up and swipe pattern are different than 5 cut gears.

smgbad

iTrader: (1)

Dunno if I should try to take it back to them and ask that they try to check the setup again for peace of mind, but most likely I'll get charged $250 again.... hope not... They had said the gears looked nice before they installed them, but cited it was probably the used gears causing the whining. Or should I just let it be?

9000th01ss

iTrader: (10)

Yea, have him print this out and give it to the shop thats doing the work, they'll look at it say you got this one, throw the paper in the trash.

Where does the GM Phoenix cut fit in? What cut is that? The Phoenix cut is the one with the different pattern.

9000th01ss

iTrader: (10)

When you put "used" parts in anything, they are always to blame. They're going to continue to use that excuse until you give in and buy new gears and they hit you for another about $500.

smgbad

iTrader: (1)

They say they'll look at it again for me... which would include draining the housing, painting it again, and double- checking the pattern. The guy on online I got thegear from says that the gear was very quiet in the S-10 it came out of, and that's pretty much all he sells is gears.. he seems to think they put the wrong shims in I suppose.