Torsen verse clutch pack

[Marcus Miller]

Thoughts?

Dry weather, is a Torsen (say stock Miata, last generation) worth the investment over a tightly packed 1st gen Rx7 LSD? pros/ cons?


thanks!
Marcus

[64oeg]

Well, if the third member in the latest version of the Miata is still aluminium, it'd be lighter. As far as is the Torsen being better or more durable than a clutch pack LSD, I really don't know, as I don't have enough, (ie-barely any) experience with the Torsen.

However, the "stock" LSD in my "black Beastie" racecar was raced for several seasons before I owned it. I did rebuild it about half way through my first season with it. I thought it maight be getting weak going over turn 4 at WHRRI. On hindsite, it might have been wheel spin. So I would say that the durability issue with the "stock" LSD is very high.

George

[Andy Bettencourt]

I believe the Torsen-type diffs to be far and away the most durable of the competitive units. Since there are no clutch-packs to wear out or heat up, the durability is VERY high.

Google Torsen and you will learn a lot.

AB

[Hotshoe]

Originally posted by Andy Bettencourt@Dec 24 2005, 01:59 AM
I believe the Torsen-type diffs to be far and away the most durable of the competitive units.
AB

[snapback]69119[/snapback]

... Andy,

.... Do you have any experience with a torsen in a first gen? Will a torsen still pull if one axle breaks? I know that a LSD won't.

.... I have often wondered if I should build one for my 84 RX7. I have a problem loosing power in the turns if I hop a curb with the inside wheel.

... Rick

[Andy Bettencourt]

Originally posted by Hotshoe@Dec 23 2005, 08:22 PM
... Andy,

.... Do you have any experience with a torsen in a first gen? Will a torsen still pull if one axle breaks? I know that a LSD won't.

.... I have often wondered if I should build one for my 84 RX7. I have a problem loosing power in the turns if I hop a cub with the inside wheel.

... Rick

[snapback]69121[/snapback]

I don't but they do spin if they are airborne.

AB

[seckerich]

Originally posted by Hotshoe@Dec 23 2005, 08:22 PM
... Andy,

.... Do you have any experience with a torsen in a first gen? Will a torsen still pull if one axle breaks? I know that a LSD won't.

.... I have often wondered if I should build one for my 84 RX7. I have a problem loosing power in the turns if I hop a curb with the inside wheel.

... Rick

[snapback]69121[/snapback]

Hi Rick
The torsen will spin if you get a tire light with curb hopping. It needs pressure on the internal gear sets to have any grip. If the clutch unit is slipping you don't have enough preload or the ramps are bad. I use the torsen on the long tracks like Roebling but use the clutch units for VIR and Kershaw. Drop me a line if you need some setup help, I have done a few. :119:

[Bildon]

>> Will a torsen still pull if one axle breaks?

No.
A clutch type will basically "lock" your diff to a degree when torque is applied.

- Bill

[wrankin]

I too am trying to decide between the two - I have found good deals on both a clutch lsd and a torsen and need to make a decision in the next day or so. This is for a 2nd-gen RX-7 that's hopefully heading towards ITS one day.

Has anyone experienced increased understeer from the clutch lsd? I have heard that this can be an issue, but have never seen first-hand examples.

Thanks,

-b

[Eagle7]

I like the torsen, but I've never driven a clutch-type that wasn't worn out.

[Ron Earp]

Don't forget the welded option.

I've been using a Torsen style for the last 1.5 years. As Rickey said and others confirmed, I will occasionally lose forward thrust if lifting a wheel. I experience it most at VIR and CMP.

Since the Dayonta 2008 race I've been running a welded differential because my 3.56 gearset happens to be tied to the welded setup. I'd never driven a welded diff before but I love it. It offers fantastic traction at all times.

It does have downsides though, it will push in corners and you have to drive around that. It is also sapping power. Push one around a paddock and you'll see how much power it saps, all of yours!

But it has fantastic traction and I like it. Not as evil or wicked as folks told me it'd be. I think Steve Parrish set his fastest VIR lap with a welded diff in place and he normally runs a clutch pack.

I'm now having a clutch pak diff built and I understand when properly setup it'll have the traction like the welded but won't have the push.

[Marcus Miller]

Man, old thread!
I've now raced on both the clutch pack and torsen; I like the clutch pack, for the lack of curb hopping issues. I had to deal with that a bunch with the torsen.

Marcus

[wrankin]

Man, old thread!

Yeah, sorry 'bout that - I didn't notice the date until after I had posted (I glanced at the year and read it as an '8' rather than a '5').

I've now raced on both the clutch pack and torsen; I like the clutch pack, for the lack of curb hopping issues. I had to deal with that a bunch with the torsen.

Thanks, it looks like right now I'm gonna pick up an inexpensive clutch-type for my 2nd gen RX-7 and give it a try. If I don't like it, I can try out a Torsen at a later date.

One question - the clutch pumpkin I'm getting is in pieces right now, so I'm going to be doing a reassembly/rebuild. What sort of pre-load range are most people running? I've been doing some poking around miata.net and have seen everything from 90-130+ ft-lbs cold. But a lot of that is from autoX folk who are trying to minimize push on really slow tight corners. What are the thought about proper setup for the track? Say like VIR?

Thanks,

-bill

[seckerich]

There are specs in the Mazda factory manual for the thickness of the floater disks and the clutch disks. If there is wear these can be replaced or shimmed to get your stack height correct. Your preload setting is just the minimum necessary to get the diff to still work while one tire is unloaded. This is more feel and track related than just a base number. The actual locking is based on the ramp angles (45/45 stock) and the number of disks. Get over 75# with oil (they all feel great dry) and you should be OK.