limited slip diffs

[jamhow79]

My uk 2004 2.5 doesnt appear to have one as the inside wheel likes to smoke itself silly out of tight bends. Cannot find one on flea bay and a quick net search only brought up new quaife ones for more cash than I wanted to spend.

1) Any suggestions on where I may find one or anyone out there with one to sell ?

2) Are they actually worth fitting to a car with such limited power anyway ?

+++ Ive heard stories that the std mazda helical ones are pretty much worthless after about 80k anyway so am I running the risk of replacing a std open diff with whats likely to be a tired or back to being open used one anyway?

[snotrag]

I think theres better places where you could spend the money.

Really - is it such a common occurence?

Off the top of my head, a number of other things that could go someway to solving the problem -

- change of spring/damper settings
- Change of ARB setup
- Change in Chassis Geometry
- Better tyres
- Change in driving style

[jamhow79]

Only owned it for a week so maybe its just me being a bit ham fisted with my throttle applications !!!

Longer term I intend to be visiting as many track days as possible and I do enjoy as much sideways action as possible.

I was under the impression fitting one would be of benefit for low speed grip and more control once ive stepped well over the limit on track ?? (or a greasy roundabout!!)

[snotrag]

dont get me wrong - it does have its benefits!

But I'm jsut saying its probably not the first thing that should be on oyur upgrade list.


If you've just bought it - then getting the chassis aligned and setup is definitely the first thing to do.

I bet on a car that age its never been done since the factory, could be miles out.

[jamhow79]

Yeah I keep hearing how much difference it can make. Seems to drive ok but its the only mk2 / mk2.5 ive driven so will definately have it checked. Being as it has just passed the 100k mark I am thinking some poly bushes and new or uprated suspension will no doubt tighten everything up as well.

+++ I know, I know - I REALLY should have driven a few before I bought the one I have but I work at a car dealership and the option of a uk 2004 registration with full history for just a sniggle over 3k was too good to miss !!!!

[Herman Toothrot]

jamhow79 said:

+++ I know, I know - I REALLY should have driven a few before I bought the one I have but I work at a car dealership and the option of a uk 2004 registration with full history for just a sniggle over 3k was too good to miss !!!!

Great deal!

The 1.8 LSD's came in 2 sort or Torsen, type 1 and 2 type 1 was on the early mk1 imports and locked up better than the later post '96 mk2's and mk2s. Good news is an 1.8 LSD from '94 on will fit your car and they do appear on the owners clubs and ebay regularly and are not that expensive £350 ish I seem to really them normally fetching.

I'm assuming yours is a 1.8 not the 1.6? The 1.6 only ever had the diffs that wear out and revert to acting as open and then only on imports.

Edited by Herman Toothrot on Friday 18th December 18:59

[itiejim]

My car (a '94 1800 Eunos) has a type 1 torsen. I must say that it works very effectively and really stops you spinning power out of the inside wheel. Could be handy in the snow too

[I Am Milk]

Herman Toothrot said:

The 1.6 only ever had the diffs that wear out and revert to acting as open and then only on imports.

That's me.

Anyway to make it lock once again?

[Gizmo!]

I'm not sure what the point is.
I have a standard 1.8 UK model - no LSD, goes sideways perfectly happily.

[OnlyMX5ives]

I love my Torsen but agree that on a std power car its not essential but it does make them more fun / tricky in the wet and slippery conditions.

As above you want a Torsen or Fuji LSD and they go for around £350.

I've sold loads over the yrs but haven't got any in at the minute.

Just wait on Ebay / forums they come up pretty regularly.

[maz8062]

The Torsen is NOT a LSD, it's a mechanical diff. It does not limit slip, it simply transfers torque to the wheel with more grip (when it detects slip) As Mark pointed out they're great in the dry, but very tricky in the wet/slippery conditions. When there is no grip for either rear wheels it will act like an open diff and spin both wheels.

[Munter]

maz8062 said:

The Torsen is NOT a LSD, it's a mechanical diff. It does not limit slip, it simply transfers torque to the wheel with more grip (when it detects slip) As Mark pointed out they're great in the dry, but very tricky in the wet/slippery conditions. When there is no grip for either rear wheels it will act like an open diff and spin both wheels.

I have never ever in my life seen an open diff spin both wheels. One only at a time. Because the grip for both wheels is never identical. And once one starts to spin...it's away until you back off the power. (An experience I'm all too familiar with).

[maz8062]

Munter said:

maz8062 said:

The Torsen is NOT a LSD, it's a mechanical diff. It does not limit slip, it simply transfers torque to the wheel with more grip (when it detects slip) As Mark pointed out they're great in the dry, but very tricky in the wet/slippery conditions. When there is no grip for either rear wheels it will act like an open diff and spin both wheels.

I have never ever in my life seen an open diff spin both wheels. One only at a time. Because the grip for both wheels is never identical. And once one starts to spin...it's away until you back off the power. (An experience I'm all too familiar with).

You are right of course. The Open diff will spin one wheel leaving the other to do nothing, nada, zilch. The Torsen will react in the same way but only if there is no grip for either of the rear wheels.

[MX-5 Lazza]

maz8062 said:

When there is no grip for either rear wheels it will act like an open diff and spin both wheels.

Torsen is a torque multiplier. When it detects slip in one wheel it applies the available torque of the spinning wheel multiplied by a set figure (e.g. 3x) to the wheel with more grip. When there is NO grip on ONE wheel (i.e. a wheel is off the ground) the it sends zero torque multiplied 3x to the other wheel i.e. zero torque. You can combat this by applying the handbrake

Surely if neither wheel has any grip you ain't going anywhere regardless of what the differential does

[jamhow79]

Lots of useful info again guys and gals thanks.

Unless ive misunderstood then a torsen diff will revert to behaving like an open diff if both wheels loose traction ? whats the point in that ? I am correct in thinking that a conventional lsd would apply power to both wheels if they have both lost traction am I not ? I thought that was the hole point - power gets transmitted to both wheels to stop the inside wheel spinning it all away and keep my drift going that little bit further down the exit ramp

Am I right with all of this or have a got the wrong end of the stick in my hand ?? (again)

[snotrag]

Your correct, kind of.

Pull out of a T-junction. Weight on outside wheel.

Open diff - inside wheel ihas less weight on it, spins up, wasting power.


Torsen - inside wheel spins. However - it is not spinning 'free', there is still some resistance (that is unless your such a hooligan or have such badly setup suspension that the wheel is dangling in mid air).

As Lazza said, the TORque SENsing diff picks this up and sends the torque to the opposite wheel.


If you jack a car up with a Torsen then I beleive it will act in the same way as an open diff - if one wheel cna spin freely while the other does nothing.


And yes - if you get stuck, the handbrake is the key to getting out.

[gdaybruce]

MX-5 Lazza said:

Torsen is a torque multiplier. When it detects slip in one wheel it applies the available torque of the spinning wheel multiplied by a set figure (e.g. 3x) to the wheel with more grip. When there is NO grip on ONE wheel (i.e. a wheel is off the ground) the it sends zero torque multiplied 3x to the other wheel i.e. zero torque. You can combat this by applying the handbrake

That's interesting - I hadn't realised that that was the principle on which the Torsen worked and in this weather the handbrake tip could prove very useful.

My Eunos has 125,000 hard driven miles behind it and by most accounts the diff should no longer limit the slip. In practice, however, it does. You can certainly provoke inside wheelspin by, for example, booting it out of a T junction but pushing hard on a track day I found nothing but traction.

Incidentally, with both wheels jacked up, turning one by hand makes the other turn in the same direction, which I always understood to be the sign of a LSD.

[maz8062]

http://www.youtube.com/watch?v=osKLMzYxyyw

[MX-5 Lazza]

The Mk1 1.6 viscous LSD is supposed to wear out and become more or less an open dif but the Torsen doesn't.

Driving on snow & ice with a Torsen shouldn't be a problem. As long as there is some resistance then it will be able to channel power to the tyre with the most grip. Only if there is no grip at all to one wheel 9i.e. wheel off the floor) will it fail to give any propulsion.