antman89iroc

What is the affect of ring gear run out and how much is really too much?

I've read where some recommend <.002 and others say .005 is the max. Mine measures .0045 run out at the differential flange and the back of the ring gear. I believe the differential is the problem.

This directly relates to my other issue which is backlash variation. Again, how much is too much and what is the affect of running at the limit?

I am currently building a 9 inch for my IROC with a Yukon case and trac-loc, new gears, bearings etc. Setup went fine but backlash varies about .005 total. From .008 at the tightest to .013 at the loosest. A tech at Quick Performance as well as a tech at Richmond told me it's high end but ok and I shouldn't notice any noise due to it. The pattern looks good but as you would expect shows indications of tight and loose spots as it gets in those areas. I have settled on the backlash range that gives the best compromise between those two locations and looks super in between.

The gears I am running are "white box" no brand gears from Quick Performance. The Yukon spec sheet provided says to keep the backlash .006-.010 but the Richmond tech suggested to open it up some since normally you would target the center of the range and that should be the tightest spot. I have setup a dozen or so gears over the years and have never had this much variation. I don't really know if I am making a mountain out of a mole hill or if this is something I will regret running as is. Suggestions?

sofakingdom

iTrader: (1)

Pop it off of the carrier, turn it 180°, and see what happens.

antman89iroc

Thanks for the reply, I did that & no change. While I had the RG off I installed the Trac-loc only with a few bolts keeping the halves tight and the run out was still there. That's why I believe it is mostly the TL and not the RG.

big gear head

If this differential is new I would return it to Yukon. They shouldn't let anything out of their factory with that much run out.

If this is a Yukon Duragrip be sue that you use hardened washers on the ring gear bolts. For some strange reason they drill the bolt holes for 1/2 inch bolts when they should be drilled for 7/16 bolts. The large holes allows the ring gear bolts to back out after being used for a while if you don't use good washers on the bolts.

antman89iroc

Yes, it is new and does have the 1/2" holes, but no washers were supplied. I agree that it seems like too much run out. More than I've ever seen but is it too much and what kind of problem would it create to run it?

big gear head

That differential should have never left the factory with more than .0025 run out. I would send it back. NASCAR teams scrap them if they have .003 run out. It might not cause any problems on an average street car, but I wouldn't want to start out with one that already has that much run out.

Did you have to grind a bunch of material out of the case to get it to clear the left side? Don't install this without some good hard washers on the bolts.

antman89iroc

I agree is seems excessive and I am in contact with the supplier to see if I can get it swapped out.

I did not have to grind out behind the ring gear to clear the posi "hat" but did need to take a little off near the pinion bearing to gain a bit more clearance for the ring gear teeth. It didn't hit but had ~.020 and I got it closer to ~.100. This is a 3.50 ratio so the clearance isn't real bad.

Yes, it's a street car, frequent driver but I do occasionally take it to the strip for a little tuning. I want it to last and be as quiet as possible.

Thanks for the input.

antman89iroc

FYI the vendor, Quick Performance, responded promptly and offered to pick up the third member, have it checked & corrected and return it to me at their expense. I think this is generous since I purchased all the components separately. I'll let you know what happens from here.

big gear head

It's good to see customer service like that. I've had no problems with QP.