FLcracker9

I just finished installing my ring and pinion this morning, and the only thing that bothers me a little was my final backlash reading. Spec is .008 - .010, with a max of .015. My final reading was .007, no matter where I read it on the ring gear. This is my first attempt at installing one in a daily driver, though I have installed several on off road vehicles without any failures. Is .007 too tight, or am I worried about nothing?. My pattern looks good, andonce it's broken in (500 miles of short trips allowing it to cool between), I plan to drain the fluid and check backlash again. I drove it a short distance ealier today, and it made no unusual noises (howling). I'm bettingmy second reading will net me more backlash. Looking for opinions?

mjr46

you should be fine once it all settles in it'll go up a hair....safe spec is .008 to .012..it shouldn't hurt it as long as it makes no noise.....what brand gears did you choose??

silver91gt

that should be fine.

FLcracker9

These wereYukon Gears (went from 3.55s to 4.88s in my Son's F150 with an 8.8, yes I know it's not a mustang). It took me 3 tries to get the pattern correct, and I had to add quite a bit over the stock pinion shim to get the pinion depth correct. The stock shim was .031, and I ended up with a total of .067 to get the pattern correct. Next weekend I'll be doing my 89 Hatchback, but Ibought a set of Ford Racing gears for that (4.10). I don't expect as much trouble with the mustang, as I did using the Yukon gears in the truck. I'm going from the stock 3.25 to 4.10 in the stang.

mjr46

wow that's an awful lot of pinion shim......generally most 8.8 take a .022 to .035 pinion shim depth setting to obtain correct depth......but if that's what it took to get the correct pattern so beit.......ford racing ones should be easier but be careful...you might wanna talk to steve at ford racing and get the low down on setting up the 4.10's cause they are actually motive gears and I just did a 3.73 set up and the motive 4.10's he said require a slightly different way of setting them up so no noise is heard......you'll have to get past the lacky techs to talk to him which was no problem for me cause I immediately started to throw out all the technical jargin and terms and methods and the kid I was talking with said ....wow wow wow!!! hold on your over my head let me have you talk to Steve ..who was an actual ford tech for years so he has a lot of experience setting rears up