01-25-2005, 09:57 PM
Join Date: May 2003
I bought a version 1.1 pro4 kit a while ago from Hong Kong and it seems to have a dud rear differential.
I built the diff exactly how the manual says except i used ceramic balls. When i was finished I rotated the two outdrives in opposite directions and it wasn't smoothe like you would expect. It had a high spot where the action would be tight then you would pass it and it would be loose. Basically it had inconsistent action. At that time I just ran it hoping that it would get better but it didn't.
The ceramic bearings eventually wore out and the diff clicked so i changed to the standard diff balls. There was no more clicking but the action still had hard spots every revolution. This is not the drivetrain action binding but occurs when the diff is out and you just turn the outdrives.
The car has been handling badly for a while and i think the diff may have some part to play in this.
I got annoyed at the car and decided to rebuild it. This time i tried many things to try to fix the diff.
At first i thought it was the spring and screw so i changed them to tamiya ones but he action was the same. Then i changed the gear itself, but again it was the same. Then i thought it may be dodgey outdrives. So i bought some more carbon one and a delrin set.
I was wrong, even with the delrin outdrives the diff still had the same problem. I changed every other part of the diff such as the bearings and nut etc. The last thing to change was the diff plates.
I put in new plates but yet again the problem was not solved. I was talking with my dad and he looked at the plates to find that they were warped, on a flat table they could be rocked. This must be the problem. I checked my other 3 spare plates and found that they were warped also and as expected they all made the diff bad.
Has anyone else come across this problem and found a solution? At this point i will have to buy a whole new diff and hope it works.
The other problem i had was the diff coming loose all the time, i read about it on this forum but have only tried to replace the nut without much luck. Something interesting i found was that my rear right universal was very warn on the end of the T section where the diff outdrive is. This is an unusual place for wear and none of the other universals had even a scratch near that area (the very end). My therory is that the universal was rubbing against the diff screw and undoing it (its the right direction). What i have just done is cut the end off the crew enough so that it still sticks out of the nut but hardly as far. Im hoping this will fix the problem, i will find out friday.
Can someone else please check their universal to see if they have the same problem, as this may be the reason for the undoing of the diff.
I also found another problem lol, when i put a HPI spool diff into the front the wheels vibrated badly when at full steering lock. On the track it made the car spin out all the time and very hard to drive. I put lots of grease like the manual says but still have the problem, my friends also does the same thing. But my other friends with the Titanium racing spool didn't. Could this be the delrin outdrives fixing the binding problem?
sorry for the long post but thanks for your time.