Jlam

iTrader: (2)

Thanks!

C_alan

So I picked up a used B74.1 last week. This car is the first one I have had that used the oil filled differentials. How concerned should I be that the center diff spur gear appears to be oily. There was just a touch of liquid on it (not enough to drip). I have not run the car yet, and am wondering if I should go through the car and replace the o-rings on the diff outdrives? Or is it normal for there to be small leaks from the diffs?

cartmen34

iTrader: (2)

I had the same problem with my b74 center diff. It wasn't leaking badly enough to drip, but it was obvious fluid was coming out from around the cup gasket. I tried new seals, gaskets, new case, and even a new diff cap. Nothing worked. Then I tried one of these with a fresh gasket and haven't had a hint of fluid leaking since.

Alexv2024

iTrader: (2)

I haven't had an overly leaky diff yet and Ive built a 74, 74.1 and 74.2. You might be over or under torqueing the screws. Also take black grease and coat both sides of the gasket, that'll help a lot.

Other than that try putting on new O rings, also coated in lots of black grease.

C_alan

That looks like it would work because it would give a more rigid surface for the gasket to mate to, but does it weigh more than the stock case? I don't think adding more mass to the drive train would be desirable.

Alexv2024

iTrader: (2)

Considering how the vast majority of people don't have issues with leaking stock/plastic diffs, its not the rigid surface thats the issue. If you had a TLR 22x4 I know they sand their diff cases to get them to seal better. Their mold actually has imperfections in the sealing surface that buyers have to fix. Most of us b74 guys don't have issues, but bad parts do happen or people ignore worn/bad parts and have issues. But its much more rare. I have seen 1 person at a racetrack that uses the aluminum diff housings in all the races I've been at all over the east coast.

However, if you are having a repeat issue with a new diff case, and most parts replaced on the same diff then its the part you haven't replaced, or you're screwing it together wrong. If you've replaced everything in the center diff except the aluminum cap/spur gear mount then its either that part is warped or has a imperfection causing a leak or you over or under tighten screws.

What I do with new diff housings is get a screw and screw it in and out with some black grease on it, and go as deep as I can without the cap/ring gear on and without distorting the top. That way when you put on the cap/ring gear you can tell when the tension goes up from compressing the gasket. If you dont pre form the threads you are fighting new plastic and the gasket so you might under tighten it.

C_alan

Well the leak appeared to be very slight, so I decided to go ahead and run the car yesterday at my local track during open practice.

Holy crap, this car is fun to drive. Having spent the last two months trying to get a setup that works for my two whee drive car, the way this 4 wheeler hooked up with out hardly changing anything was impressive. The car cleared our triple jump with no issue, and did pretty well in the sweepers. I loved having so much on throttle steering.

We had a light crowd for our Friday night club race yesterday, So the race director let me run the car in 4 wheel sportsman (I was one of three in the class). I didn't do so bad, and finished second, but I was a lap back.

So this week I will replace the diff seals, and hopefully have another fun time with car next Friday.