View Full Version : New ring and pinion installed: are thise contact patterns ok?

01-01-2006, 02:00 PM
This is a 3.42 Yukon ring and pinion set.
It's a thick ring for a series 2 carrier (10 bolts).
I ended up with this drive contact pattern: does it look OK?
So far I hear no new noises, but our roads are wet in this period and I have snow tires so it's hard to say.
How can I find out if I screw up? Noise? Temperature increase?
Other pics here
The last two pics are how I left it.

Thank you!


01-01-2006, 02:21 PM
Im no expert, but it looks good since the pinion looks to be contacting in the center of the teeth.

J&J Speed Shop
01-01-2006, 03:12 PM
Looks pretty good it is better to have more contact toward the root than the heel, and you are slightly toward the root which is good. The pattern looks good so as long as your backlash is good I think you are golden

01-01-2006, 06:08 PM
Pinion shim is too thick, drive looks deep and your coast is close, what is your backlash set to?

01-01-2006, 07:21 PM
Backslash is 0.25 mm or 0.010 inches.
There was a "BS 0.008" on the ring and I was told from the seller to set it 0.008 - 0.010.

Here a picture of the pattern with the original shim (0.032 in).
I then added a 0.004 in shim what caused the pattern I posted at the beginning of this thread.

Under the car it was looking better with the additional shim, but now when I look at the pictures I don't know...

Assuming the pinion shim is too thick what will happen? A noisy rear? Or will it brake soon?

PLS don't tell me I have to take it apart again! :bang:

01-01-2006, 09:19 PM
Your drive opened up more and your coast is good. I would leave it there and put oil in it. Who's the manufacture of that gear set? What is your backlash at with that pattern? If it's .010 then tighten it up a little, the coast might look better.

01-02-2006, 01:00 PM
Your drive opened up more and your coast is good. I would leave it there and put oil in it. Who's the manufacture of that gear set? What is your backlash at with that pattern? If it's .010 then tighten it up a little, the coast might look better.

The manufacturer is Yukon Gears. Backslash is 0.010 inches.

Unfortunately that was the first contact pattern I had, then I added a shim and it made the pattern I posted at the beginning of the thread :( :( :(
Under the car it was difficult to see what it was better and I noticed the difference only later on, when everything was already assembled and filled :bang:

Under 60 mph there is no noise at all, but between 65 and 80 I can hear it. Not loud: I have to pay attention.
What happens if I leave it like that? will it get better or worst?
Should I open it up again and set it as it was in origin = with the better pattern?


01-02-2006, 02:19 PM
Wait until you get your break in done and change the oil. High speed gear noise on or off the throttle?

01-02-2006, 03:37 PM
High speed gear noise on or off the throttle?

With 65 mph and more I hear something while keeping the speed or under slight acceleration.
As soon I go off the trottle it quites down.
Under hard acceleration it seems to quite down.

Looking at the patterns I could say that coast is fine and this explains why there is no noise when off the pedal. Drive: the pinion is too close for low load but OK for high load.
Is that a possible explaination? Of course I have those brilliant ideas AFTER I put everything together...

01-02-2006, 05:34 PM
Well it's an aftetrmarket gear so you can't really can't say thats what is happening. I think you did an excelent job, the aftermarket did not engineer that gear set for your specific axle so keep that in mind.

01-02-2006, 05:57 PM
What would you do in my situation? Give it a chance and remove the additional shim I put? That resulted in the better contact pattern.
But I know: there is no guarantee that it will be better.

The speed limit on out highways is 75 mph and we drive 75 - 85 all the time so it would be nice to have a quite rearend at that speed... :)

01-03-2006, 11:25 AM
I had a "professional" set up my motive gears and they whined like crazy.
I brought it back and he said the pinion nut came loose but it never quieted down. I hated driving it. Gave me head aches :bang: Would only take it to the track. My posi ended up going. I will never swap gears again. Only Rears.
I am looking for a stock rear to get me by while I save up for a 9 inch.

01-03-2006, 12:12 PM
i'd remove the additional shim.

01-03-2006, 01:54 PM
I have to open it up so or so... so I'll remove the shim :(

I'm a dumbass: I used RTV to seal the cover: I made a nice pattern all around it and made circles around the holes... but only the bolts holes!
On the cover you don't see where the 2 lateral holes are and right there I have just a thin line of sealant :bang: :bang: :bang:
It's not leaking too much, but it's leaking and I don't even know how much oil I still have in there :eek2:

Once the car is on the lift and the pumpkin is open why not do it right?
Man! I feel like "what is this? a screwdriver?"
:chuck-bal: :buttkick: :bash:

01-07-2006, 08:27 PM
Allright! I reopened the pumpkin...
After 100 miles the backlash went from 0.010 to 0.011 in, the contact patterns were about the same (see attachment).

I removed the additional 0.004 in pinion shim and adjusted the backlash to 0.008 in (result: see attachment).

Result: no more noise during acceleration or constant speed.
Nothing! from 0 to 90 mph absolutely no gear noise!
Coast: I (think) I hear some very little noise between 50-30 mph, nothing bad. It could also be the snow tires... It's during decelerations so I don't bother.
Looking at the contact pattern I have the feeling that DRIVE became better (bigger contact area) and COAST became worst (smaller contact area). This could explain the quite acceleration and the little noisy deceleration.

I'm happy with the result! This has been the last step to convert my A4 to a M6 :drive:

This is a Yukon thick gear kit 3.42 ratio for a series 2 carrier, I ordered the parts from (part number: YG GM 7.5-342T)
Jason made a grate price and helped me a lot with useful hints. The parts arrived 1 week after I ordered them: what a service! (also considered where I am).

Also thank you guys for your suggestions :)