Can anybody tell me is 6 thou backlash would be ok. auburn 7.5 pro series posi W/410 gears street/strip use, thanks len

 

I think it is suppose to be from .004 to .008 but I am not 100% certain. Someone else should be able to confirm/correct this.

 

It depends on the gears you are using. Each company uses their own specs. Look at the instructions or manufacturer's website to see what they recommend.

 

Richmond, for example, says aim for .008", +/- .004". So you can run from .004" to .012" and that's acceptable. They even say for oval track racing, run as loose as ~.020" I believe? (been a while since I read the specs). I think we set my 4.10's on the slightly looser side, but I still do quite a bit of highway driving with my car . They've been perfectly quiet though since day 1 .

Common knowledge / practice, and what's typically recommended by the manufacturers is that the less backlash, the better, for drag racing purposes (basically, so the gears are almost always in full contact, or really close to being in contact). Having an automatic, when I drag race, usually I'll have my feet on both pedals, and I'll pre-load the drivetrain before launching, so even with more backlash, the slack gets taken up.

But anyway, I think .006" is just fine .

 

It's ok, might actually make for a stronger install. Gears seperate a bit under power, but tighter usually means noisier.