Losi XXX-CR Diff

Wacker 2 · #1 10-07-2010

I've not long changed from associated B4 conversion kits to running a AC CR2 conversion kit... much much better performance and far happier with the CR2 kit but I've come to realise that the Losi diffs are pants!

Does anybody have any handy tips on how to make a losi XXX-CR diff feel smooth and work well???

I've tried new losi diff balls, new losi diff plates, new losi diff gear and new losi thrust race bearing... all in the hope that it will make the diff feel as good as the B4 ones did. But, to no success!

I am running schumacher diff grease for the main bearing and am using associated black grease for the thrust race.

Can anybody suggest any better greases to use that works well with the Losi diff???

Once built, it didn't feel too bad to start with (not a patch on the B4 diff tho) but after only 1 run it felt really notchy and gritty!

I also have quite a lot of float side to side when the diff is assembled into the gear box... approx 1-2mm... is this normal? are there any diff spacers that I can use to pack out this slop and stop the side to side movement once in the car?

Are there solutions to these problems... or do I just have to put up with it in order to have a great car to run?!

Any help would be grately appreciated

Thanks, Jon!

Stu · #2 10-07-2010

Losi diffs are very very good.

It maybe just be dirt in the thrust race, clean & re-assemble.

You can shim the diff but a little side-to-side movement will not casuse any problems.

mace · #3 10-07-2010

The XXXCR Losi diff works very well if you tighten it up until it gets a little bit scratchy and then you have to loose it a little bit until it works smooth again, usually I use Asso Stealth Diff Grease and Asso Black Grease.

"I also have quite a lot of float side to side when the diff is assembled into the gear box... approx 1-2mm... is this normal?"

No, are there copper shims behind the drive rings or shims behind the big bearings?

Greets mace

V-Rossi · #4 10-07-2010

I like Losi diffs a gazillion times more than AE diffs. Both are smooth when building them, but the Losi ones just keep on running smoothly. Maybe I'll post a diff building guide on here, but a lot of the 'tricks' I use are summed up in in the topic Lee Martin made: http://www.trfracing.co.uk/page_1265187551237.html

A few things are very important:

- Sand your diff rings, I use #700 for it
- Use enough diff grease*
- Use the right grease: Schumacher or Much More for diff balls, AE Black Grease for thrust bearing
- When having a bad diff, check your thrust bearing first. Often the diff balls or plates aren't the problem.
- Adjust it by hand until it doesn't slip, then tighten it just a tiny bit more. Run it for 3-4 minutes and check it again. You may want to tighten it a bit more.
- Set up your slipper properly. Seems obvious, but a lot of people don't know the difference in sound between a slipping diff and a slipping slipper.

*Unlike some people say, An offroad diff really benefits from using a good amount of it. Only when you gearbox isn't sealed right, you are running a belt car or a 12th car you need to put a thin layer on the diff balls. I do it like this: take a small sack (like the ones spare parts come in), then put a lot of diff grease and the diff balls in it. Keep moving them through the grease until they all have a nice layer on them. Smear some extra grease in the diff ball holes, put the diff balls in and you are ready to go

It was pretty hard to avoid writing things like "smear the grease on your balls" etc.

Wacker 2 · #5 11-07-2010

Quote:

Originally Posted by V-Rossi

It was pretty hard to avoid writing things like "smear the grease on your balls" etc.

Lol... good call! thanks very much guys for all you advice... good things for me to try but doesn't sound too much different from what I am already doing! I dont spend any time running in tho so I shall see if that makes any difference!

Cheers, Jon!