16 replies to this topic

[uc79]

Hi all . I have recently got a 10bolt salisbury diff cut down and coverted to disc brakes for my UC Torana and I'm trying to work out what to run a LSD center or for bit extra coin do I just go an Eaton Trutrac center ? Any info would be great cheers.

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[Bigfella237]

The Eaton / Detroit TrueTrac I believe is rated around 500HP, they have a better locking action than a traditional LSD but suffer a flaw in absolute zero-traction situations (such as on ice) where they just freewheel one axle.

 

Harrop redesigned and released their own version of the TrueTrac to handle almost 50% more power than the original, but it costs 50% more as well and apparently still has the same flaw under zero-traction conditions.

 

Then another company (Autotech Drivelines I think it is) redesigned it yet again and released what they call the "WaveTrac", which costs about the same as the Harrop version, doesn't handle quite as much power, but doesn't suffer the same free-wheeling flaw.

 

Then you've got some more 'specialised' centres like e-Lockers and spools, but they're not really designed for on-road use.

 

I guess it comes down to your application and usage, if you only have a mild V8 and only ever drive on the street, then I'd say spend the money on something else, if you plan on "chuckin skids" at every set of lights (not that I'm suggesting you do of course) then go the TrueTrac? I suppose it also depends on the condition of the LSD centre and whether you have to spend money getting that rebuilt too, Salisbury LSDs are cones from memory aren't they, not clutches?

[axistr]

I have a Eaton TruTrac in the hatch 9" 500 hp very predictable and nice and quiet. They don't need special oil and mine has 100% lock up on wet grass. Doesn't snow around here but if it handles wet soggy grass I would have thought to some extent it would have handled ice. Its the gears pocketing in the hemisphere that limits the slip. The more slip you get on one axle the more it tries to limit the slip. Anyway very happy with mine and only cost me $680 new.    

[Bigfella237]

This video demonstrates the flaw well, with one wheel jacked up there is only drive to one side, he has to put his foot on the brake to load the diff and get it to lock up...

 

[ozyozyozy]

If only intending street maybe performance street they are fine and the odd strip work.
If your going to lean on the car lots(if you like the corners) they DO spin the inside tyre, i know of 3(including my own) in 9 inch diffs that do this.
Know of 1 car that has started having similar issues with a wavetrac aswell, this has been in the car about 12 months.

Best lsd to use is ramp and plate, these are not always available for all types of diffs and they can come with a hefty cost for some.

[RallyRed]

2  cents worth

 

I have these  types -

 

LSD - quiet, only limit the slip, and not much more than that, wear parts need replacing from time to time. OK for street and long flowing tracks.

Harrop Tru Track - silent operation, on the street and flowing tracks they are great. No wear parts, However if you kick a wheel up in the air...its just like a single legger.

Detroit Locker - noisey, rought as guts in operation, zero slip once locked, regardless of wheel off the road etc. Great on tracks, a little rough for street

 

Dont know anything about drags, wavetracks or spools.

 

Hope that helps

[ozyozyozy]

Rallyred
Most LSD's(factory fitted) are built to a cost not quality.
Good ones are available but cost puts them out of reach for most people, have seen prices of $3500 plus for competition 9 inch LSD's.

True tracs can open on long corners too, they require suspension setup that loads both rear wheels evenly.

[gtrboyy]

I've used rebuilt factory lsd centres for most of my street cars & they've all held up fine although if planning burnouts or abuse yeah get something better.

 

My sle has spool...it's not so bad with massive tyres but silly screech & bounce at roundabouts annoy me.

 

Biggest downside is truetrac are $650 for 9" yet quite a bit more for everything else

[uc79]

Wow thanks guys for all the info . I guess i have alot to consider as i do have a bit of a lead foot sometimes .

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[uc79]

Oh yeah firgot to mention it in furst post . Its for a LS1 conversion . Diff also has 28spline axles in it

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[76lxhatch]

I highly doubt the Harrop version is any better, they just make a new carrier (using the same Eaton internals) to suit the diff housing since Eaton doesn't make one.

 

The Trutrac actually gives quite predictable drive out of the corners allowing you to accelerate earlier, and isn't as susceptible to power oversteer as various lockers are. As with any "limited slip" diff the action requires one wheel to spin in order to transfer torque to the other, you still get a lot of forward drive with one wheel spinning rather than losing all traction and swapping ends.

 

Its an expensive item that can be difficult to justify, but probably not something you'd regret buying once you have one.

[RallyRed]

Agree...lockers can be oversteery

 

Happy to be corrected....but my experience with Tru Tracs ( as stated earlier) is that once a wheel comes off the ground ( i.e. hillclimb, ripple strip etc ) then there is very little  drive. They feel  no better  than a normal LSD in that particular situation. 

Like I said, depends on your application...for spirited road use they are great, long flowing tracks they are great, tight lefty righty tracks with lots of ripple strips etc.........so so.

[ozyozyozy]

A proper LSD(clutch) does not work anything like a truetrac.
As load is applied the spider gears push out againest clutch packs tightening the centre.
The competition LSD's also have a ramp angle that the shaft of the spiders gears work on, changing the degree of the angle speeds up or slows down the locking, this also works on over run, to provide locking on braking.
Truetracs are torque biasing, they are suppose to deliver power to the wheel with the most grip.

Comes down to the old question what do you want to do with the car, this dictates everything

[76lxhatch]

A proper LSD(clutch) does not work anything like a truetrac.

On the inside no, but from the outside operation is very similar in that the torque transfer cannot work without the movement of the low traction wheel turning at a higher speed. Unless you have something externally controlled (e.g. viscous coupling with PCM control from ABS sensors or the like) then the only inputs any diff has are the driveshaft and the two wheels.

[Heath]

Too much rear swaybar and you will have single wheeling issues with a TrueTrac when you throw the car hard laterally.

All choices in this area have compromises. I think the TrueTrac is still about the nicest thing available for a street car. Throw it in and forget about it. You can reliably lay two lines, it's good on the dirt/grass, there's no clunking or wheel skipping...

But when I've drifted with Torsens I do find that you do end up getting decent wheel speed differences from inside to outside, particularly at moderate to high speeds. And even initiating a donut or similar on a skidpad can get you into a situation where the drive all goes to the inside wheel. Let's be honest, that ain't very graceful or enjoyable.

Edited by Heath, 23 September 2017 - 11:28 AM.

[Racehatch]

I agree these things seem better for street driving, not so good for circuit application - I went from a spool to a trutrac and like how it helped the turn in, not so much the off throttle on corner entry and they way it locks under accel at high speed through corners. 

[rexy]

I think for the average street car with a nine inch a LSD centre is the best all rounder. Reasonably cheap and plenty of grip.
As for this bloke and his 10 bolt? Probably the same answer.