Installing solid pinion spacer today in stock 1995 Z28 3.42 10-Bolt, M6. Axle shop said set backlash tight, at .004. Reusing original gears/bearings. New seals of course.

A half hour of searching turned up a lot of recommendations ranging from .005 to .008. Car sees long highway cruises as well as strip use. So, is .004 too tight considering the heat generated during highway driving? What is ideal?

Thanks!

 

If you are reusing the gears that are currently installed, I would match the backlash, contact pattern and torque to rotate to what it was before removing the gears. You will want the gears mating after the install just like they were before. If not, you could run into some noise and longevity issues.

The OEM spec is usually between 0.006 and 0.008 AFAIK on GM gears.

 

Thanks MAtLT1.

The axle guy seemed to think .004 would help prevent gear frags, and sets them up that tight. Barring further input, I'll set it to .006.

Anybody tried .004?

 

I read your post a little further, realizing that you were reusing the gears and not installing a new set. If you are reusing an old set, it is best to match the current backlash, TTR etc as close as possible. Were this a new set, it wouldn't matter as much.



Do you have a picture of this spacer by chance? If it is the part I am thinking of you may get lucky and not have to change any of the shims.

 

http://store.summitracing.com/partde...5&autoview=sku

If this is the part you are talking about; IMO you should check the specs before tearing the rear apart (back lash, ttr, and contact pattern). Know what shims went where, because you will want to put those back in the same place they came from intially. Reinstall everything and see how the specs compare. If everything matches, I would call it a day. If it doesn't, then you may have to start shimming

 

I failed to check the runout before disassembly, so I already goofed that up. But I will reuse all the original shims for initial assembly. I was just a little concerned that if I didn't get the bearing preload exactly as it was before, I might alter the backlash too. I'm going out to start assembly now, and I'll check the pattern and backlash when I'm done.

It is the Ratech. Here's the pic from Shoebox, just like mine:



Here is the link to Shoebo's EXCELLENT homepage.

http://shbox.com/1/4th_gen_tech1.html

Hope he doesn't mind me linking his image above. I have donated to his site, so I'll feel justified in using a LITTLE bandwidth now and then unless asked not to (thank you shoebox!):

 

Yeah, as long as your pinion depth doesn't change the backlash won't. But just to be on the safe side it doesn't hurt to check everything.

 

OK. backlash is at .0075. High end of spec, but due to all shims same, if the pattern is good I'll leave it as is.

 

Pattern OK I think. A little deep but oval. Sorry no pic, camera in car with wife.

Thanks for the help.