Procharged GTA

Hi, we are still messing with our ford 9" rearend in a 1986 Trans Am,it is a Moser 9" ford rearend,it has the nodular iron Moser case,Detroit Tru-Trac,and 31 spline axles. I last posted in january about this,and we were running Motive Performance gears,and couldn't get the gears quiet,no matter how we set it up,it howled a certain amount,not extremly bad,but more than it should,so we thought it must be a bad gear set. This time we ordered a new set of US/Strange gears,as they are supposed to be quieter than the Motive's. We just installed them last night,but haven't put the rearend back in yet,because we want some opinions on the contact pattern we are getting,we are tired of taking it in and out,(this is the 3rd or 4th time). The pinion on our new US/Strange gear set,says to set the pinion at a 1.025" pinion depth +/- .002". So we used our T&D Pinion depth checker,and it said that to get it to a 1.025" pinion depth,it had to have .048" shims. I talked to some people on another forum,and they said .048" shims sounded like alot for a 9" ford rearend,and most use around .020" of shims. We have measured and re-measured,and that is what it says it takes to get to 1.025". We even measured it after we put the .048" in it,and it comes out within .001",at a 1.024",so it must have somthing to do with the aftermarket Moser case.

The pictures posted below are with .048" shims and .010" backlash. What do you guys think of these patterns,does it look correct? The first picture is the coast side,i'll have to go get another picture of the drive side,it was to big. Thanks,Brian

Procharged GTA

Here is the "DRIVE" side of the tooth.

Lo-tec

The pattern looks high to me. Here are pics of mine:

Procharged GTA

I don't think your pictures worked,what do you mean when you say it looks high? Thanks

Lo-tec

Pics fixed. The pattern looks too high up the teeth. It should be more or less centered on the tooth both up and down and front to rear.

Are you loading the gears while making the pattern? That will change the way it looks.

I attached your pics:

Procharged GTA

Thanks for attaching the pictures,we are loading it,but don't know how much,we are using a big screw driver with a piece of rubber hose streched over it,and holding it against the ring gear as we turn it. Thanks for your pictures,they are nice and clear. Thanks,Brian

Procharged GTA

also, were do you get the yellow marking compound,and how much is it? What we used was titanium white paint and brushed it on,and looking at your pattern,it doesn't look smeard like ours does,maybe thats throwing somthing off. Also my dad just called me and said he just read in a book,to turn the ring gear,and "not the pinion" when checking contact pattern,we checked it turning the pinion. Thanks

AlkyIROC

When I set mine up, I put a load on the ring gear with a pry bar and turn the pinion by hand. I stick the pry bar on the top or bottom of the ring gear then put pressure on the gear. This gives a more accurate wear pattern. No rubber hose required.

There are plenty of web sites showing gear wear patterns and what to do to correct them. At least with a 9", it's easy to change the pinion depth with shims behind the support. The hard part is determining the proper side bearing preload.

http://www.precisiongear.com/pgtechpatterns.htm

I like to use this one myself
http://www2.dana.com/pdf/5717.PDF

Lo-tec

You can get gear marking compound at any GM dealer. I think I took a big pry-bar and jammed it in the case against the ring gear and then turned the pinion to make the wear pattern. I would add .005" of pinion shim, reset the backlash, and see what it looks like.

Procharged GTA

thanks for the help,i really appreciate it,by chance,do you remember how much shim you have in yours,and what your pinion depth was supposed to set at? Thanks

AlkyIROC

Depends on what gear set and case I use. With my current C7AW-E case and 4.86 gears, I think it has about .040" of shims to get the pattern I wanted. Lots of trial and error to get the best pattern. I think the last time I did it, it took me almost 2 hours but I finally got the pattern I wanted.

I haven't set up my new 4.57 gears in the Moser aluminum case yet.

With the race car, ring and pinion noise isn't an issue. Different gears need different patterns. Some gear manufacturers just happen to have noisy gears no matter what pattern you try.

Procharged GTA

Thanks for all the help guys,we ended up settling on .046" shims,and it seems to be quiet!!

Brian