Gear Install Question

I need an opinion from the experts. I am installing 4:56's in my Dana 30 and have every thing set perfect except my pattern is very strange. It is centered between the root and the top, it is also centered between the heel and the toe but is very skinny and only covers about a third of the face of the drive side face. Has anyone seen this before?? This is my first install on a reverse rotation and I was wondering if this was normal. Thanks

Pics...

Did you wrap a shop rag around the yoke nice and tight before checking the pattern?

Sorry no pics. No I did not wrap a rag around the yoke. I usually set the pinion preload to around 20 in/pds, set the backlash to the center of the range with plenty of carrier preload than turn the ring gear with a wrench. Generally this anal, time consuming method gives wonderful wipes on the ring gear however I have never seen a skinny pattern like this.

Why aren't you turning the pinion and holding the ring gear with the palm of your hand to produce drag on it.

EDIT: you sure you are talking drive side? Reverse rotation is reverse rotation afterall.

You can also put drag on it by shoving a pry bar or screwdriver under the carrier and jam it against the backside of the ring gear. Drag is drag though, no matter how you apply it.

RWS: So your pattern is centered root/top & heel/toe but is skinny? Is it still oval shaped?

When I did mine it seemed proportianate to the teeth size (compared to the 8.25). It seems like the only thing that would affect the 'skinny-ness' of your pattern would have to be backlash, right? But if your backlash is incorrect then your pattern is going to move in/out of the top/root plane. (sorry, thinking aloud).

I would say as long as the contact pattern is where it is supposed to be you will be fine.

Whose gearset is it? It could just be how they were cut...
Mitch

It is damn near impossible for other to evaluate your pattern without pics.

Every Ring & Pinion manufacturer, every service manual, and even the FSM state that you must generate turning resistance when checking the contact pattern. Increased rotating torque isn't the same thing. Simulating a load on the yoke is the right way to check the pattern.

Frank,
I disagree that placing resistance on the ring gear isn't going give you a good pattern. The net result is going to be the same.
I know this because I used to check it both ways, placing resistance on the yoke, and then placing resistance on the ring gear. Guess what? Results were always identical.
You have to figure that if you are placing load on the ring gear and turning the yoke, your net result is the same. Increased rotating torque is still going to give you the contact you want between the pinion teeth and the ring gear teeth.
Your gears can only make contact one way....

I think the only reason the FSM, and Ring and Pinion literature tell you to do it by holding the yoke with a rag is so you get a 'clearer' pattern. But regardless of how you place drag, it's the same result...