Cure for diff problems?

[nicefrog]

I'm having a lot of problems with the diffs in the pro truck and the pro buggy. Oddly the madrat stayed with a non slipping diff for much longer, but both these were slipping beyond being able to be tightened in about 5-6 packs. I haven't pulled them apart yet but I'm sure others must have had the same problem. So I thought I'll start off on my mission to make them better by asking what is the main problem? the balls or the plates? and does anyone know if the kyosho plates are a direct fit? I know the b4 ones need machining the inside to fit. I also know I can get the B fast diff kit and be done with my problems, but I was wondering where the problem is so I can maybe fix it in the mean time. I'll give you an idea how loose the diffs are, the only way I can get the diff to not slip is have the slipper so loose that the car hardly moves and that's with an allen bolt in the diff and done up as tight as it will go.

Now that I have good hex heads right through the cars the diffs are about my only problem, I've not had any plastic parts break despite lots of big crashes apart from breaking that part 2015 when I hit the wheelbarrow at full speed in the truck but that was to be expected

[kedal]

Weird...
I dont have had any problem with my diff, but a normal wear, after many, many pack and 2 races.

I'm sure you built them correctly, I'm sure you set them up correctly, so... I don't know where is the problem, but the first thing I'll change for my next diff will be the grease. I don't know how bad is the stock grease, but I'm pretty sure that any other brand (AE, Shum) grease are better.

If you can't fix the problem, try to flip out the ring, make attention about the thrust and try to rebuilt your diff with a good diff grease and a good thrust grease.

Or, as you say, buy the b fast kit diff, with a set of lub

[nicefrog]

It's weird my madrats diff still works, but 2 out of 3 don't I'll pull the one out of the truck tomorrow and see if I can find out what's worn

[Battle_axe]

i would expect you will find that your thrust bearing is dead the balls will have cracked and be split in half

1.put a new thrust bearing in it use AE black grease and put it on the screw

2.then take the plates and some 800 grit wet and dry paper and sand them till smooth on a flat surface using one of the out-drives to hold the ring.

3.clean all the parts in motor cleaner then put a tiny bit of the black grease on the out-drive where the ring sits. place the ring on top of this.

4.using eather ae stealth lube or the kit diff lube place it onto the diff ring quite thick.

5.then place the diff gear on top of this and put the balls into the holes.

6.repeat steps 3 and 4

7.put more diff lube onto the balls

8.place the other out-drive and diff ring on top

9. put in the spring, screw and nut and tighten till you cant turn the gear with the out-drives held still.

10. hold the one out-drive in a vice and get a dremmel on a low speed with the cotton cone shaped polishing bit in it press this into the other out-drive for 20 seconds turn the diff over and repeat.

11. tighten the screw 1/8th of a turn

12.repeat steps 10 and 11 once more

13 install diff in the car

14. ENJOY

i have been doing this for years it works great i would however recommend some new balls and plates before starting this too

[nicefrog]

That's an awesome post, I wish I had of read that before I built the cars . As of now if the bearings are cracked it's going to end up more sensible to order B fast diff kits with hardened parts and carbide balls. But first I'll see what is broken tomorrow

[nicefrog]

It was the thrust bearings that were smashed, I've ordered 2 of the complete B-fast kit. I guess in a week or so I'll see how that goes