STX 550 rear diff

[Cowboy550]

Hello All
I would like to modify the rear diff, I would like to achieve deactivation of the brake actuated LSD, I think it’s dangerous on the road and useless everywhere else, unpredictable and not much fun.
years ago Arb said a rear locker was the answer to all my problems ( circle work ) barrel racing, wheels and burnouts... because both rear wheels spin the same the brake lsd won’t engage, but then I was told that you can’t leave it engaged All the time.
I just read a post here about trutrac, which must be like a Detroit locker ? had one of them behind a V8 351 with a 9in, wow that was fun
also I have read about an Elocker.

you can switch everything off except for the rear diff Brake LSD
I’m leaning back towards the ARB air operated diff lock, I can use on board air for lots of stuff

would love to hear from The brain trust before I make a decision, all information is greatly appreciated
Thank you

 

[Old.Tony]

It should be possible to pull the LSD stuff out of the diff. I only know this because stupid me had my diff rebuilt - because it had a small leak in a seal, and they said it had a copper crush washer which needed to be replaced, and then the gears had some problem ... $2800 later I was handed a diff without LSD any more. That's ok, I don't miss it, I only miss the cash ...

 

[Cowboy550]

Hello Old Tony thank you for the reply, I think I may have explained it wrong.
the diff is factory and uses the brakes to simulate LSD,
im looking to upgrade to either real LSD or locked.
I read the trend about trutrac... sounds very good.
just wondering which way to go

 

[Old.Tony]

If it was my truck, I probably wouldn't worry about it - I've no interest in going too far off-road any more, limiting my non-sealed journeys to forest trails and some desert graded roads at the most.

I don't know how to modify the diff you have. The manual is no help there, I didn't see anything that you could modify to change the diff operation (in fact it looked like a normal open diff).

An ARB locker should replace the innards, as would a Harrop e-Locker should you wish to go the electric route rather than air.

Hopefully some of the more adventurous members here will have some other ideas.

 

[GunMentalGrey]

If it’s braking the spinning wheel it’s more like traction control or VDC (vehicle dynamic control) or whatever it’s called. That’ll all be controlled by the computer and not related to the diff - which may have an LSD centre.

Our pathfinder has a VDC off button to disable it, but you need to activate it every time you jump in the car. I’ve turned it off a few times on the beach but otherwise it doesn’t seem to do much on the roads unless you are being really silly with the right boot in the wet. It’s probanly different in a V6 ute though. I know my D40 loves letting go at the back in the wet and traction control would be kicking in every other time I take of when it rains.

 

[Cowboy550]

Yes GMG thank you for your input, it’s a fine line between brave and silly hehehe.
On the Stx550 you can turn everything off except the diff braking
one day I disconected the wire to the rear diff which brought two lights up on the dash that disconnected the diff braking (Awesome) but it wouldn’t go into 4wd.
The diff isn’t full LSD, with VCD on traction control cuts in ... with it turned off both wheels spin in a straight line most of the time, but if I corner and one wheel spins the diff brakes that wheel tranfering it to the other wheel, imagine how unpredictable that is...

 

[Horatius]

The diff isn’t full LSD, with VCD on traction control cuts in ... with it turned off both wheels spin in a straight line most of the time, but if I corner and one wheel spins the diff brakes that wheel tranfering it to the other wheel, imagine how unpredictable that is...

Sounds like it would be very helpful off road, far better idea than LSD. Some of the newer vehicles seem very good at what they can accomplish without lockers. Although nothing beats having actual lockers off road, wouldn't be much chop on the highway though lol. Have heard people who swear by Detroit lockers as a on/off road compromise.

Which type of conditions do you want it for? Worth noting that any type of genuine locker can only be used at low speeds on soft surfaces. Otherwise you'll go through tyres and eventually stuff the drive train.

 

[Cowboy550]

Thank you for the reply Horatius, I would like to do circle work, barrel racing in the paddock and be able to predict the outcome on tar, I love the Detroit locker idea ... which is locked under acceleration, I think trutrac might function the same way ?
You are right Horatius a fully locked diff adds lots of wear and tear,
and active diff braking LSD is becoming more common.

 

[landmannnn]

Just to be clear, the differential is the component in the middle of the axle. It has no wires going to it and it a purely mechanical device to split the torque to the rear wheels.

The V9x uses the abs rings on the axle ends to sense when a wheel is spinning, and applies the brake on that side. Simple and effective.

Your options to improve the Dana differential are fairly wide as this unit is used in many vehicles including Jeeps (although not identical).

An air or electronic actuated diff lock is ideal off road as it can be turned on when the going gets tough.

There are various mechanical locking diffs around which lock up when one wheel spins. A bit crude, either on or off, ideally suited for off road again. Often used in the front to complement a locker in the rear.

Finally proper limited slip diffs are available. Various technologies, most can be set up for the user to adjust when the come in. There are even electronic versions which take it a stage further. It sounds like this is what you need.

 

[GunMentalGrey]

Now I’m wondering again what you hope to achieve.

A locking diff, like air-locker or e-locker is driver selectable and would it be locked in sealed roads, so on tar would be an open diff, still at the mercy of the electronics, perhaps moreso than the LSD.

The auto locker style, such as Detroit, will work differently and may behave weirdly on the roads too. they are typically locked until power is applied and the wheels are determined to need different speeds. As above they are on or off and also may be at mercy of the electronics. (Don’t quite know how they work, nor how to explain it)

I’m still leaning toward the problem being something to do with stability control that you don’t like. I’m not a fan of it when I want to ‘have fun’, but see the advantage for everyday driving or for ‘less skilled’ drivers. As mentioned above trying to drift on the beach was impossible with it turned on, but had fun with it off not that a 2.2tonne 4wd wagon is good at drifting either.

Having said that, I haven’t experienced stability control in a ute so don’t know how aggressive it is at trying to correct such a tail happy vehicle.

 

[Been a while]

It should be possible to pull the LSD stuff out of the diff. I only know this because stupid me had my diff rebuilt - because it had a small leak in a seal, and they said it had a copper crush washer which needed to be replaced, and then the gears had some problem ... $2800 later I was handed a diff without LSD any more. That's ok, I don't miss it, I only miss the cash ...

Oh Mannn, seriously! Some mechanics! Who was that?

 

[Old.Tony]

A well-known (and I should add, highly regarded or so I was told) Gearbox and Diff company in Newcastle.

That's also a clue to its name.

 

[Cowboy550]

Thank you all for the insight, Im heading towards a Detroit trutrac LSD center... I’m not doing any serious 4 wheel driving just the odd stunt every now and then... circle work, towing and road use with some fun is what I really use it for. going to chat with Harrop tomorrow to find out what to expect.
VCD and traction control will still work but ABLSD hopefully will be doing nothing as both wheels will spin simultaneously.
The 550 really needs traction control in the wet because its catches me out Drifting unexpectedly.
Thank you Landman for your time and great information, not sure if UK is different but here the rear diff is assumed as a complete rear diff, a diff center is a diff center, housing, axles and hubs all make it up. I think you are Right a proper LSD center is the answer to all my problems and the best possible solution for my application.
Thank you everyone for your input I have learned a lot and feel I am make a much better decision, I nearly ordered an ARB locker but I think a proper LSD is the way to go

 

[landmannnn]

I wasn't aware that Australians use the term "diff" to describe the differential, axles, half shafts etc.

 

[Horatius]

^ Nor was I. The diff is the part between axles and the tail shaft, as far as I knew.

 

[GunMentalGrey]

I’ve heard plenty of people refer to the diff including the whole rear assembly for a solid axle diff. They say diff, and include everything you would remove if you took the diff housing off, so includes axles, hubs and brakes.

Anything with independent suspension doesn’t include axles etc. so the diff would only be the housing bit.

 

[Horatius]

So a diff rebuild would mean new axles wheel bearings and brakes? Why not throw in wheels and tyres as well lol?

Not saying you are wrong, but have only heard "diff" referring to the pinion, ring and planetary gears that transfer drive from the tail shaft to the axles (which are separate components). Though if you needed a diff housing it would have axle tubes necessarily, as they're joined. Always been my understanding.

 

[Horatius]

^Have heard people referring to the front diff as the diff itself complete with half shafts and crossmembers. Though I think this is for expedience as no one is going to remove them to sell the diff itself. Then again when I put my locker in, I had to remove these parts to get at the "diff" lol.

 

[GunMentalGrey]

So a diff rebuild would mean new axles wheel bearings and brakes? Why not throw in wheels and tyres as well lol?

Well you might do new axle and bearings with a diff rebuild, not brakes though.

It’s just shorthand, us Aussies love shortening stuff.

 

[Cowboy550]

If you ring and said I’m looking for a diff for a ford AU ... they would give you a price on a complete diff from brake to brake. If you rang and asked for a diff center then you would be talking about the diff center only... that’s how I have always understood it.... not to say it’s right or wrong everyone has there own interpretations
Wow got some great learning out of this thank you all