trf511 diff slipping problem

[m1buc]

hi guys could do with a bit of help.

my rear diff on my 511 continues to give me problems, slipping under acceleration.
I have fitted new tamiya diff plates, ceramic diff balls and new white pulley.also fitted a new thrust race and nut and bolt. This time I also bought tamiya VG diff plate grease part no 42170.

I have built many ball diffs in the years i have been racing but not come across this problem as bad.

As I understand that the diff plate grease goes only on the side of the diff plates that sit on the outdrives? this is to stop slippage? and normal diff ball grease on the balls and otherside of plates.?

I also have trimmed the diff pulley high spots off( which sit next to the diff ball holes) in attempt to get the diff plates to sit tighter against the balls. this has not seemed to work either.
Am i doing something wrong.?

to try and solve the problem I going to buy new diff outdrive part no 51286. but can not find a shop with them in stock.

does anybody have any spare ones for sale or know where i can get them?

thanks mike

[Lee Martin]

tighten it!

[Jan Larsen]

Odd, it shouldnt do that. Tighten it so you cant turn the pulley by hand after sliding two allen keys in the outdrive slots, but nothing more. I'm using geardiffs with great satisfaction (I hate rebuildings diffs all the time), but the standard ones should work just fine. They wont last long though, especially on high grip surfaces.

[GRIFF55]

You can get these so tight as they will not work as a diff.... Is your slipper adjusted ok, not too tight as to make the diffs slip?

[Rich D]

Yeah what Griff says, occasionally i have to retighten my rear diff too. To check your slipper tension, hold onto left rear wheel, hold spur with thumb then try and turn the right rear wheel forward. You should see the slipper plate spinning when you apply moderate force. If it isnt then your diff isnt tight enough. Or your slipper is set too tight. Tighten the diff 1/4 turn, back the slipper off 1/4 turn and retry. When its set right the rear diff should still feel smooth. I then set my front diff a touch tighter than the rear. Dialed !

[DaveG28]

Alternatively do what I do and "warm up" the diffs before races

I wouldn't recommend it, but with the diffs set how I like them I often get slip, I do some hard starts on high grip bits of the track before the race starts and that seems to sort it! Plus it freaks Northy out...

Your right on the grease by the way, the plate grease only goes outdrive side!

[DCM]

When you assemble the diff's, it helps to bed them in, I use a cordless drill, with one outdrive in the drill, hold the other and run the drill slowly for 10-15 seconds, then flip the diff, reset.

Otherwise, you just need to nip it up a little!

[Mr. Red]

Dont feel like this is a typical 511 issue but with all balldiffs. I find the 511 diff to be the easiest to get right.

[muratti]

Originally Posted by DaveG28

Your right on the grease by the way, the plate grease only goes outdrive side!

What should be the benefit of that grease? The Diff plates shouldn´t slide on the Outdrives anyway, isn´t the force applied throught the spring with the screw enough to keep the plates from sliding?
I already wondered what this grease should be for but i couldn´t believe it´s for the Outdrive side of the diff plates.

[DaveG28]

Originally Posted by muratti

What should be the benefit of that grease? The Diff plates shouldn´t slide on the Outdrives anyway, isn´t the force applied throught the spring with the screw enough to keep the plates from sliding?
I already wondered what this grease should be for but i couldn´t believe it´s for the Outdrive side of the diff plates.

Don't really know tbh, but it is much thicker and stickier than normal ball diff grease!

[Rich D]

ive been using a tiny smear of the HARD friction damper grease on my diff plates ( outdrive to plate side of course ) This is how Jilles Groskamp builds his touring car diffs.

[Fredrik Emilsson]

Lee has written a guide on trfracing.co.uk

I use the new plate grease between diff plates and outdrives, think it is great. It is very sticky.

[m1buc]

thanks lads.

i have the slipper set up just right as described in one of the post.

i have tighten the diff up bit by bit after running the diff in. to stop the slip, the screw was so tight it stripped on the nut ?


just not sure what is going on. thats why want to try new outdrives and build a complete new diff asnd see how that goes.
does any one know where i can get the outdrives?

[Jan Larsen]

Dumb question maybe, but are you sure you're assemblying the diff correctly? Not inserting the diff screw into the wrong outdrive? I've seen it before.

[m1buc]

good point but no all checked and double checked as per manual.

[Belsten]

you sure the plates are seated correctly on the outdrive when assembling & tightening ? And that you have the adjusting screw on the correct side when installing the diff in to the car ?

[Welshy40]

Maybe you need the nuclear rc diff covers once youve sorted your diff out. Me i just tightend it up and used a kyosho screw and nut as its stronger.

[Belsten]

and greases

[m1buc]

thanks for all advice its all good, learnt a few things about bedding the diff in. so going to rebuild once more and follow all your advice.

just one quick question. i just want to make extra sure.

the diff screw and thrust race should go in to the female shorter outdrive and the spring and nut should fit in to the longer male out drive. is this correct?

thanks once again for all your help lad.

[DCM]

Spring and nut in the long side, screw and thrust race in the short side.