axisT6

iTrader: (3)

Did you do the initial break-in correctly? If not, then it is possible to wear through the hardness. I had this exact thing happen to a set of gears I installed for a guy. I stressed the importance of the initial break-in because the gears get HOT the first few miles. I tell people with fresh gears to drive the truck for 30 minutes (no heavy hauling/towing/acceleration, speeds under 60) and then park it till the diff cover is not so hot that you can't hold your hand on it. If the gears do not get the initial work hardening, then you run the risk of the metal softening and the teeth deforming.

If you can, get pics of the pattern on the coast side of the gear teeth and post them up.

Gilbert@Ace Racing

Honestly, In my opinion that "break in" period is the responsibility of the installer. Bottom line in my opinion is that if a guy pays me to set up any gears in any axle, I expect him to be able to knock the hell out of it leaving my shop without recourse or fear of failure. I do not use mfgrs suggested backlash numbers, they will bite you in the *** every time.

I have set gears up in 3k H/P Outlaw 10.5 cars at 3,240# and factory stock cars for Chrysler Dealerships for over 15 years... and I very much understand the difference between what the mfgr says vs. what the real world proves.

There is a reason I do not install Moser gears.

g

smokeshow

iTrader: (16)

What backlash numbers do you use then?

Gilbert@Ace Racing

It's relative to the gears, the mfgr, the axle in question and the type of use it'll see.... typically if it's a street deal I don't let 'em see much over .006" - .008". If it's a soft race gear set on a 9" or bigger I set 'em up at .011".

g

SmokinHot98

iTrader: (20)

I already shipped off the gears to Summit, but the pattern looked damn near like the stock 3.73's that came out. I took it easy for 400miles, but it did see a lot of highway use during that time bc that's how I go to work. This next go round will be different bc it wont see the highway for awhile, I'll just the little Accent for work duty

I miss it already, driving a car w/138hp just isn't as fun as 400hp lol

14psisupra

iTrader: (1)

I believe my new OEM gears are now set up between 3-6 thousands. Did about 50 miles of easy driving which was a few heat cycles. Quiet as stock

axisT6

iTrader: (3)

I see your point. Most of the people I have installed new gears for have been able to successfully break them in with no issue. There have been a few times where they asked for me to do the initial break-in due to the fact they were tied up and would have to drive a long distance once the truck was picked up. Also I need to clarify, the individual I mentioned that had the early failure, his gears were initially installed by a reputable shop. I put his originals back in.

So you do the initial break-in on new gears and then tell your customers to have at it right out of your shop?

As for backlash, most of the gears I set up call for 0.006" - 0.010". My target is like you stated, 0.006" - 0.008". The exception is new AAM gears in GMs which call for 0.003" - 0.006". I aim for 0.004" or 0.005" with those gears.