Ball Diff problem

[Mike01]

Hi all,

I'm having a problem with the rear ball diff in my Pro 4. It loosens up after every run...I tighten it and it's fine, nice and smooth, but then I run and bam! It's loose...really loose.

I took it apart, but everything looks fine. Any ideas on what it could be?

[racer234]

It might be in backwards. If it's a belt drive car (I think it is :confused: ) then if it is in backwards it will loosen itself. Pop the diff out, and reinstall it the other direction. Hope this is it.

[RCHavok797]

The first thing that came to mind is that you put the diff in backwards as previously mentioned. Check the manual to see if you have it installed the correct way.

[losi racer13]

its backwords. my diff did the same thing im my xxx-t its funny how it happens

[Mike01]

It's a shaft drive Pro 4...there's only one way to put the diff in...if you put it in backwards, the wheels turn the other direction.

Any other ideas? :)

[gizmoguy303]

Try replacing the diff nut that the diff screw threads into. You may just need a new one. Good luck!

[racer234]

I have a T4 (with three gear tranny, so theres no belt) and you can put the diff in anyway you want, and it will still go forward. I'm not sure how they build the Pro 4, but if I were you I'd just double check your diff.

[ITurnLeft]

gizmoguy got it. I bet your diffnut is stripped, or at least getting there.

[resonantfreq]

loctite the thrust bolt, I had to do the same thing on my electric truck...

[RH Customs]

I'd agree sounds like the diff nut is worn out. This is common in TC3/TC4 diff when thery where out but I have yet had this problem with my TC4. If the kit is not to used you might have broken the plastic in the nut by overtighning it. Make sure to check everything.

[yellow15]

it's a common problem for Pro4. some people (including me) replace it with the TC3 T-nuts/bolt and problem fixed.

the pro4 diff screw snaps easily too. me and my friend has snapped 5-6 in 1 months time before switch to the TC3 one. And since then we never have any problems.

I'm not sure if it's okie to mention here but check the pro4 forum at rctech and there are heaps on ppl talking about this problem/solutions.

[Mike01]

Thanks all. I appreciate the advice.

I've ordered a bunch of diff nuts, so I'll just swap 'em out as needed.

This is the first problem I've ever had with my Pro 4, and this is my second season racing it.