LSD set up

[antno]

Recently bought a tt6 and the rear end was solid. No slip in the diff what so ever. I thought it could of been welded up as the car could possibly have been drifted back in Japan.

 

Anyway pulled the diff housing out n popped the back off and I think it's a carbonetic diff but il find out more when I get it to work and have a look at the plate pack.

 

What I want to know is how much preload do you normally run? I'm a novice driver so I suspect something quite low 50nm or something. I'm going to use it for trackdays n just general road use so I want it to go round bends.

Also the ramp angle seem to be about 30/30 which would be nice and progressive. Has any one tested different angle for braking and acceleration?

 

Cheers antno

[dude]

Sounds like a 2 way of some sort, horrible for the road but great for drifting or drag racing, you need to find out the make to get the set up info, also remember its not like the Toyota diff so you cant run ordinary fluid in it.

[antno]

The preload is just too high unless the diffs broken. Some one has put extra bevel washer in or increased the number of friction faces to the maximum or they have increased the plate pack height. I can reduce the friction faces by putting the outer spined plates together. We use kaaz diffs at work so Ive got plenty of oil to throw at it. Another question. Has any one had a carbonetic diff apart? Do they usually have a choice of ramp angles?

Cheers antno

[antno]

Actually if it is a carbon plated diff will the oil differ from the steel plated kaaz diffs?

[antno]

so i stripped the diff and found nothing wrong with the internals. think the diff is actually a kaaz as its very similar. i think it could have possably have had the wrong oil in. the preload on the bench when cold was only 50nm but i think that when the oil gets hot it goes too thin and the preload goes much higher, which is whats causing the solid rear axle. the diff was set to its full friction face setting of 16ff. i rebuilt the diff with kaaz oil to the same set up as it came out of the car and got 110nm of preload so i think it was set up for drifting or drag racing or possibly a competent driver. ive decided to run it at 8ff with a preload of 60nm(second photo in) so its a bit more progressive and better around bends.

 

if anyone thinks its another diff please let me know

 

figures i got with kazz oil

 

16ff 110nm

12ff 85nm

8ff 60nm

4ff 35nm

 

Edited December 13, 2011 by antno (see edit history)

[Chris Wilson]

It's a 2 way diff and not adjustable (some types have a body section you can turn though about 30 degrees and bring a none equal set of ramp angles into play, to give "1.5 way". Using decent oil will help, best oil is the OS Giken stuff, or Neo, but both are *WHOA, how much....????!!!!" expensive. Next best is Castrol LSD oil with Chrylser Cherokee Jeep friction modifier added, the modifier is available from any Chrylsler dealer in small bottles. The Castrol oil I think is still available from Demon Tweeks, from memory it's 737 or 747 type. I can check, there's a gallon in the workshop for older cars. Put two or three bottles of the additive in. Very best is bin it an fit a Giken LSD section It'll be awful on a track with those ramp angles.

Edited December 13, 2011 by Chris Wilson (see edit history)

[antno]

It's a 2 way diff and not adjustable (some types have a body section you can turn though about 30 degrees and bring a none equal set of ramp angles into play, to give "1.5 way". Using decent oil will help, best oil is the OS Giken stuff, or Neo, but both are *WHOA, how much....????!!!!" expensive. Next best is Castrol LSD oil with Chrylser Cherokee Jeep friction modifier added, the modifier is available from any Chrylsler dealer in small bottles. The Castrol oil I think is still available from Demon Tweeks, from memory it's 737 or 747 type. I can check, there's a gallon in the workshop for older cars. Put two or three bottles of the additive in. Very best is bin it an fit a Giken LSD section It'll be awful on a track with those ramp angles.

 

I have a fair understanding off setting up diffs was just wondering on the preload on the plate pack that's all.

I work for a small rally team and do the odd race car. I mainly build engines but the other guy in the gearbox shop has been building compotition boxes for years. Started at prodrive on the wrc legaceys then the imprezas. So he's always there to help but he's never had anything to do with supras

 

We do porsches and we run a kaaz diff with 40nm of preload on the pack and 60/45 ramp angles. 60 under acceleration and 45 under breaking.

This is quite soft and progressive but it is for gravel and rear engine and rear wheels drive so can't really use anything we've learnt testing that on the supras as it's not ending up in the forest. For road/trackday novice drivers we halve the preload again so it's even less grabby. Some factory race cars used to use spools instead. Possible due to the diffs shearing I don't know.

 

We found the kaaz diff doesnt need massive preload well not for a Porsche.

 

Also have you tested with the kaaz oil?

We couldn't as our diffs are in the gearbox so we have to use an oil compatable with syncros.

 

Do you think the 30/30 ramp angles are a bit too flat?

Would you stay 2 way with 45/45 or 1.5 way and run a 60/45 or something?

Also what way would you have the ramp angles flatter under breaking or acceleration?

 

Cheers for your time

antno