Just got a 84113 ball diff for my scorcher. Problem.. (loosening)

[Antmax]

As the title says, I just got a new ball diff and installed it this afternoon. the problem is that it keeps coming loose. I've worn it in gently and just ran it around the house but it slowly loosens till the spur starts slipping on it's own.

Only thing that isn't normal is the 5000mah lipo battery which does give it quite a bit of punch. Having said that, there isn't enough room indoors to use it so I'm surprised it's coming loose so easily.

Do you think I built it wrong? Anyone else have this problem. I've tightened it up several times, even right up to the point where the diff is almost locked and it still happens.

It does turn much better, it's actually quite fun indoors but doesn't grip as well off road. I like to use it as a trail car at slow speeds around the garden and it's not as good at climbing the obstacles as it used to be. So I may end up switching back again eventually. Would be nice to play with it for more than 5 minutes without it coming loose and the spur spinning though.

Thanks...

[Grastens]

I had this problem as well with my Buggy Champ, but retightening the diff has not really been a problem since I realized I could just remove one grub screw from the left/right universal joint (I can never remember which) to get to the hex-shaped recess on the one axle. It does need to be done up fairly tightly in order to remain together while still giving some differential action, though every few runs I would end up tightening it again.

For climbing obstacles, the non-differential setup is of course much better.

This is an issue with the Tamiya Hop-Up ball diff, however, as many have reported its difficulty to keep adjusted! It is part of the reason the vintage Thorp hop-up differential is so highly sought-after...

[Antmax]

Ah, ok! so it isn't just me. It's true that it's pretty quick and easy to adjust. Just need it to stay tight long enough to enjoy running it. I'll give it another shot tomorrow.

I don't suppose thread lock on the adjustment bolt would help? Might try that if all else fails. The tamiya threadlock Gel that comes with the kit isn't that tough to overcome.

Thanks for sharing your experiences Grastens. Glad I got it fairly cheap, They recently released a new batch so I snapped one up for $32. 4 months ago they were selling on ebay for $100+ would have been sorely disappointed at that price.

[bromvw]

IMO the tamiya SRB ball diff is just a piece of junk -end of .I bought one 14 months ago and its nothing but hassel -total waste money .

[Grastens]

I don't suppose thread lock on the adjustment bolt would help? Might try that if all else fails. The tamiya threadlock Gel that comes with the kit isn't that tough to overcome.

It could help. I have not run my Buggy Champ in a while but can get a chance to do so when I return home for the holiday break. I remember first noticing improvement in cornering when I installed the ball diff for the first time, but now I figure the stock rear camber setup on my car is not really doing the differential any favours, i.e.: reducing the contact patch on the rear tires to the point that grip is negligible, and therefore the effect a differential would have is as well.

All of that will be cleared up in that fateful drive, however!

[matman]

Oh !! Great news to read . I have just build the diff etc for my SS . So this may not be the best thing to use ?.

I will have too look into it when i get mine going , in the next few weeks .

They do only go one way in , in the instructions . I mad sure i had put it in the right way .

I may have too put some thread lock on it as well , but will run it 1st .

Thanks for the info .....

[Percymon]

Does it work - yes

Is it a pain to constantly set-up - yes

If you want to run on sand or loose dirt then don't bother, its really only any benefit on hard ground - and then it could be argued it takes away some of the classis handling traits

a bit of thread lock is really the only way forward with these units

[bromvw]

Does it work - yes

Is it a pain to constantly set-up - yes

If you want to run on sand or loose dirt then don't bother, its really only any benefit on hard ground - and then it could be argued it takes away some of the classis handling traits

a bit of thread lock is really the only way forward with these units

Dave all i can say is that when i find a thorp vintage item the tamiya one is going one place - in the Bin .

[Badboy]

Mine works perfect!!!

Never had any problems with it!

Badboy

[OldSchoolRunner]

Thread lock!

[Antmax]

I haven't taken it apart again to threadlock the adjustment screw but have been driving it some more. The turn radius with my more direct steering mod is noticeably tighter. Between 2 and 3 feet in the forwards direction and it's generally much more composed and predictable. But I'm not sure it's really more fun. It's WAY better on the street, off road in the rough it gets stuck a lot easier when climbing over tree roots etc. There just isn't enough torque in one wheel to get it over obstacles so it gets caught up easier and you loose the spirited pug like unpredictability of the original setup.

I can see myself reverting back to the stock gearbox later since I already have an axial exo for speed and sharp handling and the Scorcher has lost some of it's nostalgic vintage character with the ball diff.

[THEWILD1]

I just got one for my SS' now I'm nervous' though I only intend running it on dry sand do I realy need one?

[Antmax]

I tried the Tamiya threadlock gel that came with the kit but it only stopped it from coming loose for a short time. In the end I decided to go back to the stock gearbox which turns poorly but climbs a lot better and makes for a better trail runner which is what I mostly use it for. If I want a sharp turn I'll just have to stab the throttle and put it into a spin and hope I can catch it hehe.

[Percymon]

I just got one for my SS' now I'm nervous' though I only intend running it on dry sand do I realy need one?

Unless you want to run on hard packed soil /clay or tarmac then don't bother - you are far better off with the kit set up on loose surfaces

[Antmax]

I don't regret buying it since I got it for a good price. I'm sure with a better threadlock or some kind of glue you could get the tightening bolt to bind permanently. The ball diff has a habit of going out of circulation and then the prices rocket up to $100+ just like almost the whole of last year. I have one if I want one

[OldSchoolRunner]

I tried the Tamiya threadlock gel that came with the kit but it only stopped it from coming loose for a short time. In the end I decided to go back to the stock gearbox which turns poorly but climbs a lot better and makes for a better trail runner which is what I mostly use it for. If I want a sharp turn I'll just have to stab the throttle and put it into a spin and hope I can catch it hehe.

Stronger Thread Lock!

OSR