Well, I got the 4.10's in. Damn they're nice. I love them. Unfortunately, they whine a little. I'm pretty sure it's not a normal whine and I need to recheck all of the measurements.

Anyway, before I tear it all down again, I had just a few questions. One, how bad is it to set the blacklash a little off? I set mine at 0.007" and the recommended backlash from the gear manufacturer is 0.008"-0.012". Second, I'm curious as to the cause of the whine. It happens usually only above 60km/h and most noticeably when I'm slowly letting off the throttle or slowing getting onto the throttle. And it doesn't get louder as I go fast, in fact I could barely hear it at 180km/h. I'm assuming it's the pinion depth causing it

Here's a picture of the contact pattern I had:




It looks to me that the pattern is a little off and the pinion is too close. Any second opinions?

 

Transfering to the DriveTrain Forum.
Thanks.

 

Unfortunately (I hate to say this, but) I think you're stuck with noisy gears. I had the same problem last year with a set of Richmond 3.73's I had installed in my car. My Dad did the install for me, and I was right there and checked his measurements (all within spec) and the gears whined REALLY bad. So we pulled it apart and rechecked things.....like I say, everything was close, but we backed the pinion out a little, then tightened up the backlash (to ~.006" I think ) but they whined exactly the same.....didn't matter what we did. Even took it to a gear shop.....they double checked everything, replaced a carrier bearing, but still they whined!

However, this year I've now got 4.10's (Richmond's again) but they are almost as quiet as my factory 2.73's were. Again, my Dad installed them, and I checked his measurements. "Technically" the pinion was not set quite as deep as they called for (it's deeper into the ring gear by a few 1/1000's of an inch) and we left the backlash on the loose side (around ~.012") since I do a bit of highway driving, so the gears will get hot, but still, they're quiet as anything.

I'd say you've just got a noisy set of gears.....it kinda sucks when that happens.

 

Well, I had a friend of mine who does driveline work and he said it looked like the pinion was a little too close to the ring gear, but he said it wasn't by too much. He said that it's not off enough to cause a whine. I'm going to open it up, double check things, and probably move the pinion out a little and loosen up the backlash (it's at 0.006-0.007, and 0.008 is the minimum recommended by the manufacture). After that, if it still whines I'll just drive it like that. Lots of people I have talked to said their gear sets whined for a while until they got some kms on them.

 

It may or it may not help? Hopefully it does. Although, I'm pretty sure Richmond's specs called for .008" backlash, +/- .004", so really, it could be as tight as only .004" backlash, and you should be ok? Try with it a bit looser though.....like I said, my 4.10's have a good ~.012" backlash, but so far they seem to be happy! (which makes me happy! ).

 

Well, I threw the car onto jackstands and the measurements are all different than before. Infact they're perfect now. The backlash is now 0.010". That's what I was going to change it to. The contact pattern now looks like this:

 

Are they quieter now too?

 

Nope, just took the car out for a spin maybe 40 minutes ago. They're a little quieter, but that's probably because I filled with non-synthetic oil this time.

 

Capn pete, 3.73's or 4.10's with a a4, now that you have both whats better for playing in, and do the gears make that much of a differnce over 3.23's

 

Well, I actually had 2.73's before, so compared to them, either 3.73's or 4.10's are a helluva big improvement. BUT, the down-side to either is that off-the-line traction is a little less than desirable, although, as long as you take it easy initially off the line, then you're ok, and yeah.....they haul a$$!!!

3.73 or 4.10? On the highway is where you really notice a big difference, and there's actually not much difference between them (though I'm definitely getting worse mileage now than I was last year even with those 3.73's) but I think my driving habits are just getting worse!!

Once I go to the track, I'll have a better picture of how these gears really work.....I'll give a full update once that happens! As of right now, I say that since both 3.73 and 4.10 are extreme, why not go all the way!!!

 

Hell yes capenpete well said, thats the best way someones said to look at gears so far!!!

 

Hey after weeks I will be able to chime in on this after Friday, Having my 4.10s installed and a new Auburn.

 

Ok maybe I did not see this but are you running Richmond gears? Richmonds in general are typically a little noiser than other gear manufacturers. This is mainly due to the large amount of nickel content in their gears. In the past I was running Strange Gears and the call out for backlash is btw .008-.012, so I set mine to .010. I never had an issue with whine.

 

I sort of got the whine taken care of. A friend of mine came to take a look at the gears and said the contact pattern and backlash looked good. His interpretation of the contact pattern was that the pinion was a little deep, but since I'm dragging the car a fair bit that's it's actually better the way it is. He also mentioned that the pinion depth is close enough to not cause a whine. After telling him exactly what I did installing everything he had me replace the crush sleeve. Apparently, you're not suppose to back off the pinion nut at all, not even the slightest. I did maybe 1/32 of a turn. Anyway, I spent a good day tearing everything down again, replaced the crush sleeve and put everything back together. It fixed a lot of the whine. Now I can only hear it at 70 km/h+ and it's much quieter. For now, I'm fairly confident in concluding that any whine that's still there is something I'm going to have to live with and on this gear set would probably be apparent regardless of who installed it on my car. Spending any more time trying to fix this isn't worth it, with the time I'm saving I could buy a whole new gear set.

I'm going to get some miles on them and hope that it'll reduce the whine even more. Lots of people mention that it took a few hundred miles to totally break in their gears and as they did the whine subsided.