TRD LSD... Mechanical Vs helical

[Stealer Of Souls]

Hi.

TRD lists for the AE92 a Mechanical LSD and a Helical LSD.
In simple terms, what are the differences?
Is one better than the other?

My friend is interested in one and has asked my opinion... And frankly I don't know the difference...

[pc]

I like my TRD clutch pack LSD, have been driving it for about 1/2 year and it's good.

http://forums.toyspeed.org.nz/viewtopic.php?t=37945

[Stealer Of Souls]

Anyone suggest an LSDs 101 for me... Even after reading that thread I still don't really understand most of it...

The decision was easy for my AE86 diff... 2 way TRD, that was really the best cheapest option for me... (Won't hear that often, TRD cheapest option!!!)

[Mr Revhead]

first up...
C or E series? i assume C series as there is no listing for helical for the E, but pays to check!

and use of the car? ie racing? road? and be honest! dont say racing if its only 2 street drags a year!

[AceSniper]

plate type is best if you are racing on a track alot, the down side is at slow speeds its noisey when and the clutch plates wear, but if one wheel lifts from the road the other wheel will still have traction on the grounded wheel while a Helical will turn into a open diff.

Helical is more of a street lsd using gears to lock the wheels meaning no servicing needed (not clutch plates to wear) same as a torsen asfar as I know??? which is the lsd found in some c series box's factory.

dono if that helps just my.. blah blah

[gurutasker]

If you wish to know a few in's and outs on how they work.. I suggest reading here:

http://auto.howstuffworks.com/differential.htm

(On the 2nd page they start getting into LSD's)

But the advice you will get from people on here is equally as good.

[trdfxgt]

iv been using a plate lsd in my race car i honestly think you could use it in a road car mines 1.5 way trd

[AceSniper]

Im about to fit a c56 with route6 gearset an kaaz lsd will be used on the road dont think it will be an issue... if it is... its more driving style and learning how to handle it and if not... Ill live

[flygt4]

plate lsd ftw. right up until the plates are toast anyway , then they suck

they have the best grip , but also require a degree of mechanical sympathy. no full throttle full lock turns , you just have to tease the clutch as you do a tight turn. also means a wheel tends to skip when you do this too.

[Stealer Of Souls]

first up...
C or E series? i assume C series as there is no listing for helical for the E, but pays to check!
and use of the car? ie racing? road? and be honest! dont say racing if its only 2 street drags a year!

He's bought it as a track toy. And his intention is to get to a good three or four track days a year, motorkhana, autocross (maybe) and see how it goes. If he's really liking it I can see him trying out other stuff too.
But really I just wanna be able to give him a nice informed choice, outline the major differences, reasonings and a my thoughts.

The car is MadFX (he doesn't actually own it yet, he's just negotiating the price...), so it has a C box with LSD. But the current box is smush, and he was considering going TRD.

Is there even any point? Or is the factory LSD good?
In any event, I'd still like the info for future reference.

Oh yeah. The how stuff works wasn't quite what I was looking for... Although good info..

[AceSniper]

depends what lsd is in the box atm, as some aw11's have trd type plate lsds that have found there way to fwd's (I had one) or a torsen type found in some c56's an so-on... at a guess if its lsd its prolly a plate one, might be worn tho could be rebuilt
and if its just the gearbox is fkd put it into another box

[flygt4]

i scored one of those aw11 trd mechanical lsd's, only issues is they are a bit too tight for a fwd setup

[AceSniper]

Thought tight was a good sign




TRD list the same part numbers for all c series box, fwd and aw11 guess it could be adjusted if you new what todo, partly the reason I sold the one I had and the fwd lsd box I found... has a kaaz plate type an some other good bits

[TRD Man]

Generally, (and it is very general) a helical is better for the hard surface - more forgiving on the other equipment - and a mechanical, or plate type, is better for loose.
That's the theory.
In practice, I'd go for the mechanical in all motorsport applications.

A couple of points.

If anyone is running a TRD LSD in a FWD in 1.5 way I'd suggest they remove it and turn the ramps to the 2 way setting.
Likewise, have your installer do this before fitting a new one. Otherwise it may break.

At the same time I'd get them to shim it up a little. As they are out of the box they're not tight enough to provide drive if you lose all drive to one wheel i.e broken axle etc...

In our rally car our TRD LSD was shimmed up to the point of being unbreakable on the bench - almost, but not quite, locked. I don't recommend you go this far, just a couple of shims.

[Mr Revhead]

imo for a FWD

plate type for competiton

helical for road.

[sergei]

You will find that helical LSD is very nice on tarmac, it changes the whole feel how car drives, for example before my AE101 used to understeer like a pig (due to lack of traction on the inside), now it is way more balanced...
Helical is very smooth, you don't get jerks like with plate LSD...

[trdfxgt]

A couple of points.

If anyone is running a TRD LSD in a FWD in 1.5 way I'd suggest they remove it and turn the ramps to the 2 way setting.
Likewise, have your installer do this before fitting a new one. Otherwise it may break.

At the same time I'd get them to shim it up a little. As they are out of the box they're not tight enough to provide drive if you lose all drive to one wheel i.e broken axle etc...

In our rally car our TRD LSD was shimmed up to the point of being unbreakable on the bench - almost, but not quite, locked. I don't recommend you go this far, just a couple of shims.


ok i am runnig this please tell more ? why not use as 1.5 way ?

[TRD Man]

I am runnig this please tell more ? why not use as 1.5 way ?

We sold several hundred of these over the years & we heard of very few breakages - about 5 in total.
All, though, had suffered from the same problem. That is the ramps had been broken in units used in motorsport applications. We had one car that had destroyed 2 LSD's in a very short time. One came in the car ex-Japan and another new LSD that we had supplied.

We asked TRD to consider the matter but they were unable to determine the fault. They did, however, supply a box of casings to repair the damaged LSD's.

So we set about looking into the breakages ourselves by reviewing photographs & broken parts with some of our most trusted gearbox & motorsport gurus.
We knew that the LSDs were all set up in the 1.5 way mode and the nature of the damage was consistent with an object hitting the ramp with force not unlike a hammer hitting a nail.
In the 1.5 way mode there is an allowance of movement to produce a lesser effect under deceleration.
In the 2 way mode there is no such movement.
When we installed the new parts into the new unit that had failed in the rally car which had broken 2 LSDs we installed it in the 2 way position. The problem didn't re-occur.
From that day on we advised all FWD LSD buyers to install these in 2 way mode, when using in competition, and we had no further issues.

It certainly wasn't the most scientific investigation by any means. Indeed it could well have just been a bad batch of parts. Or another explanation. But the bits aren't available separately so I've advised buyers to switch them to 2 way mode ever since.

[neo]

Just for gravel applications or for tarmac too?

[TRD Man]

As far as we knew the cars in question were rally cars used principally on gravel. I don't know that the surface would make any difference but if it did I would have thought seal use would be harsher than gravel.