Is front differential bad?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
R

RenoReno

Active Member
Messages
37
Reaction score
0
Hey guys. I picked up a Rampage MT off of ebay for a great price, with very little run time on it. There might be an issue with the front diff though and I'm wondering if someone can shed some light on it for me. The seller has turned out to be a d bag and is no help. He won't even send me the charger for the receiver battery pack. No worries there, another is on order with an additional battery pack. Here's the real dilemma.


With the car sitting on blocks, the left front wheel free spins. All the other wheels when turned, give a little resistance and move the center drive shaft. Spinning the left front wheel results in no movement of the driveshaft at all and there's no resistance. There is also a little lube leaking from the left side of the front diff and the diff cups are not tight against the diff housing. Bad front diff? That's what I'm thinking.


What's the best option for fixing it? Just purchase a whole new front diff of rebuilt it with components off of ebay or from the redcat site.


Thanks in advance for any insight and advice.
 
If you spin the wheel that "turns freely" and that diff cup spins, but the other 2 on that diff do not, then you are going to need to open up the diff.

This is rare, the MT diffs are pretty tough.
 
I've searched around some more and it seems like it might be the diff cup. They have a pin through the narrow portion of the shaft that's inside the diff and apparently the hole through the shaft creates a weak point. I saw a youtube video where someone did a homemade tempering of the diff cup shaft end with a torch and air cooling it. Supposedly strengthens it a bit. I ordered a set of diff cups. Once they come in, I'll tear it down. I've got to get a better set of better allen drivers than the ones I've got. I'll keep posting here.
 
Last edited by a moderator:
Ludabud said:
Go with dog bones and axles. Much better and less moving parts to fail. Just my two cents :)
Click to expand...
Yeah, I've heard they're more durable than CVD's. It's got dog bones and cups at the diff side. CVD's on the side where the wheels are. I wouldn't know where to begin on changing them. I'm really starting to think it's the retaining pins, or where they go through the cup shaft, inside of the diff, because the diff cup moves in and out on the diff, on the side that free spins. It doesn't move in and out on the side that moves the rest of the drive train when turned.
 
Differential was fine. It was the diff cup shaft where the pin goes through it. Bit of a pain changing it. Hope I don't have to do it again. If I do it's getting hardened diff cups.
 
Back
Top