So I was digging through the garage today when I came across a set of 4.10 gears that came out of my 96 Z28. I totally forgot that I even owned them! But then I remembered why they were in a box and not in the car when I sold it:

They were LOUD! Very loud! I got them used on ebay a long time ago with a Mac dif cover for about $100. They had some low miles and I thought that it would be fine. Well, i get them and the wear patern looked normal (or at least the mechanic said it was normal), but on the top side of about five or six teeth it looks like someone took a grinder to the inside portion of them. Not inside and inbetween the teeth, but like you laid the ring gear down and then set your hand ontop of a few teeth. I might need to get some pictures of them so that everyone knows what I'm talking about.

My question: Does Richmond ever remove part of the gears or teeth to balance them in any way?

I also remember taking them out of the car not because of the noise, but because when you would drive it on the interstate (in high gear M6) it would vibrate at only one spot... Not when you were maintaining speed and not when you were decelerating, but a spot right inbetween where it was like all the pressure was off of the gears. As I recall if you were to put it in neutral and let the clutch out on the interstate it would vibrate too. It felt like a driveshaft vibration. Any clue what this was? I used a solid pinion spacer then too. I had the driveshaft checked and it turned out okay.

Well, I was thinking about throwing these things in my 98Z M6 for a little while before I get a Moser rear. It would be the motivator to tear into the rear end to replace all kinds of howling bearings anyway, and I know that I will replace the 10bolt with either a 12 or a 9". I would go ahead and buy the moser now but I am about 6 months from graduating from college. In the mean time, however, I know that my bearings in my rear are giving me a fit! And if I want to continue to think of this car in anyway as being reliable I need to tear into the rear and start fixing problems.

Would anyone hesitate to install these gears? I mean, there already paid for, lol. Or should I just buy some new Motive gears?

 

if they were in a car with a torsen prior to your car someone may have ground a few of the teeth to remove the thrust block or "paddle"

 

You know I didnt think about that. It wasnt much griding at all though.

 

they are probably fine, just as long as the ground down portion does not come close to the contact pattern on either the drive or coast side of the tooth you should be golden

 

I think I am going to take a picture of them later so that I can show what I'm talking about, but that does sound like a likely scenario.

Like I said earlier though, these gears just have to last me until I can afford a Moser 9 or 12. I do a LOT of highway traveling though, and noise doesnt bother me much, its the reliablilty. Luckily for my 10 bolt, I've never been to the track, I dont take off hard from a stop, no burn outs, and I try to RPM match shift.

 

When I re-gear 8.8s I have to grind down a couple teeth to get the cross-pin back in (open rear). Its very little and its on the inside of the ring gear. I always polish the ground area so its as smooth as possible to avoid any noise or issues..

Sounds like what everyone else is saying...post up a pic or two though for confirmation.

J.

 

Here we go. After examining them I realized that the mark goes ALL the way around the gear, plus down inside the gear there is an inconsistent grinding that goes around the outside edge between the teeth.





Now what's everyone think? Throw em in? Besides exploding from launching, is there any chance that these things wouldnt last 20k miles in the car just highway cruizing and the occasional stepping on it thru 3 or 4 gears?

This last picture shows the outside grinding in the bottom right hand side.

 

t t t

 

Any thoughts?

 

Nobody?

 

The only reason we would ever cut back the teeth was to help with getting the cross shaft back into a carrier when using certain ratio's (4.10's and above).

I kinda dont think that this is the reason for your peticular set... as we only did a tooth or two... not a swept area like what is shown in your picture.

I say run 'em. As I doubt you will even notice an out of balance issue with the slower speed and small diameter of the differential assembly.

 

I remember some vibration on the interstate in neutral or in a sweet spot between decell and cruizing...it really didnt bother me, I just took them out because no person that wasnt up to speed on car mods would think that a vibrating and really noisy rear end is a "bad car" to buy. I am a little concerned because I dont remember the edge that goes around the outside of the gear. The last pic shows that pretty well. It looks like they've been ground down a little at the edge of each tooth. But then again, they could have come like that.

I just want to make sure that they're not going to self-destruct or something. If I could get maybe another 20k or 30k Interstate miles out of them then I'm all about it! Whats everyone think?

 

You wont feel any vibration from a perpendicular axis... that being from the differential carrier or otherwise. The vibration you felt was somewhere else in the drivetrain... and most likely the driveshaft or a worn transmission output bearing where the yoke slips into on the end of the outputshaft.

The pictures that you have provided show me nothing that would catastrophically fail from its intended use. I have seen gear sets with much, much more missing (intentionally) and live up to endurance racing abuse.

No worries man !! I say run it.

 

Sweet! Thanks everyone.