Non-Ford gear/rear end trouble question

[Breadfan]

My dad has a '99 Camaro SS and recently he found the rearend was leaking. By that time he had driven a fair amount with very low fluid. I helped him fill it up, it was down atleast a quart.

Now the rear is making noise when driving. I haven't heard it yet, but my dad said he put some higher weight oil in that quieted it down.

He's well aware that this will probably require a rebuild. I also let him know he's running the risk of having the rear end lock up on him which could cause even more damage. He understand and is planning on having the car repaired but it'd be cool to let him know what might be wrong.

So what's the typical problem when a diff looses fluid and starts making noise? Will it just require new gears or will the entire rearend require a rebuild? He has over 150,000 miles and the car has not had a single problem since new, so he's not upset...anyway the rear end wasn't hte problem, it was a $3 gasket that leaked. :)

Also gotta find a good shop in the Northern VA area that does Chevy's...

[fastblackmerc]

My dad has a '99 Camaro SS and recently he found the rearend was leaking. By that time he had driven a fair amount with very low fluid. I helped him fill it up, it was down atleast a quart.

Now the rear is making noise when driving. I haven't heard it yet, but my dad said he put some higher weight oil in that quieted it down.

He's well aware that this will probably require a rebuild. I also let him know he's running the risk of having the rear end lock up on him which could cause even more damage. He understand and is planning on having the car repaired but it'd be cool to let him know what might be wrong.

So what's the typical problem when a diff looses fluid and starts making noise? Will it just require new gears or will the entire rearend require a rebuild? He has over 150,000 miles and the car has not had a single problem since new, so he's not upset...anyway the rear end wasn't hte problem, it was a $3 gasket that leaked. :)

Also gotta find a good shop in the Northern VA area that does Chevy's...
Could mean a rebuild. Did you replace the fluid with the correct type fluid? Is it a rear end like our MM's? If so you just can't add "regular" rear end fluid, need the "special" fluid or an addititave to make the "regular" fluid "special" fluid.

[Tinaree]

The noise may be coming from the bearings, not the gears.

adding 140wt oil is a stopgap, but shouldn't hurt. I have used it for racing and others insist on it. In the old days, people would put sawdust in the gearboxes to quiet them down (non-helical gears). But I bet the gears and the pinion bearings are fine.

He will probably be alright for a long time. I assume its a Dana 60. It works pretty much like the Ford 8.8" and should cost about the same to fix. You might try replacing just the axle bearings, because low fluid affects those first. You will need to remove the axles to replace them and the seals, but it shouldn't affect any of the gear setup, and isn't overly expensive.

Friction modifier is really a solvent, and it keeps varnish from building up on positrack clutches. You can get by without it if you use full synthetic gear oil, but that means you have to have a perfectly clean unit from the outset. You can always add some later, it isn't going to blow up if there isn't any in it.

[Breadfan]

At first we filled it with the regular fluid, second time it was down a bit and he filled it with heavier fluid. No friction modifier and I'm not sure if the chevy units need it. Honestly we didn't look into it.

I'll let him know, maybe we'll just pop the cover, put heavier oil and modifier (if necessary) in and inspect things. If the bearings are just bad he'll probably just have a shop do it.

That'd be cool to not require a rebuild, it'll probably need one eventually and I don't think he'll get rid of that car anytime soon if ever.

[RoyLPita]

I thought F-body GM cars come with the Austrailian 10 bolt rear?

[Breadfan]

Well I called the chevy dealer, they have the GM friction modifier for about 7 bucks. Will grab that and a gasket and some 140wt oil. LS1.com is down and that was a good source for Camaro info. I did a google search and did see mention of people using 75/140 gear oil, but it was on a Holden site...*sigh* (Holden = GTO)

Anyway...will just ask the guy at the parts counter what oil to get and get a higher weight. It's my dad's car so I don't have a manual handy...

Will probably do this Saturday afternoon for him.

[Tinaree]

There is basically 90wt and 140wt. It is the bearings that determine what is best, and 140 is probably fine.

[BillyGman]

I'm not so sure that it's a good practice to be mixing two gear fluids that have different viscosities like he has done. I did that one time, and as soon as I did, the rear end began to make noise two days later, and I kept driving it until it got louder and louder, and one day while traveling at about 40 MPH, the car came coasting to a stop. I then got out, and saw that there was a puddle of gear oil underneath the car, and literally a trail of pieces of the rear end housing along the road behind the car. The ring & pinion gears broke apart, and completely crunched the entire housing to bits. I saw a monsterous hole punched in the side of the housing!!!

[Tinaree]

I may have misunderstood or just assumed something, but didn't he have the rear cover off to fix the leak? That would have required a light cleanup job, I would think. I thought he was just asking about the 140wt he put into it afterwards??

But good point. I wonder what did that? When it started the noise did you go over it closely? Why did you add oil in the first place, was it leaking? That might explain some things, LOL! I assume it was one of those headscratchers that leaves you wondering in the end.

[BillyGman]

At first we filled it with the regular fluid, second time it was down a bit and he filled it with heavier fluid. .This^quote above is why I have the impression that he mixed two different viscosities together. Hopefully "Breadfan" will correct me if I have the wrong impression.:) And BTW that incident that I described with the rerar end housing on my car being destroyed was my 1985 Mazda RX7, and that happened about 6 years ago. Live and learn. I didn't care much about the car anyway since I had already got much more than my money's worth out of it. I bought it for $4,500 with 41,000 miles on it, and that happened when it had 105,000 miles on it. So I just had it towed away to the scrap yard.

[Tinaree]

Good catch. I missed that.