yokomo mr4 bc
 

I have a yokomo mr4bc and I can not keep the ball diff tight .I have used lock tight on the diff bolts . They stay tight for 3 or 4 min then they get lose . What am I doning wrong? Can any one help

I used to find that they would come loose if there was too much silicone grease on the main balls, just use a smear of it. Also make sure the thrust bearing is well packed with black grease. Try replacing the screw instead of just re-applying loctite.

Apart from that, your car probably doesn't have a slipper (a very rare option part) so that puts extra load on the diff.

I had mr4bc and really liked it. I would rebuild the diff using a new thrust bearing and make sure you don't over tighten the diff to avoid flat spotting the halls. Also, use a new spring.

New thrust race, spring and screw. As said previously, make sure the thrust race has a decent amount of black grease on it.

did you using the right diff screw?the yokomo's diff screw at the end have a little bent.

Not all of them have the bend, most of the ones I have had came with blue threadlock paint on the thread. Some have a full thread and some have a shoulder. In theory the shouldered screw should be more reliable, but they key is patience when you build it to make sure everything is well lubricated and not overtightened.