True Trac or Detroit Locker

Printable View

Show 40 post(s) from this thread on one page

21st August 2012, 07:14 PM
djam1

The Detroit is about 6 years old and if you have a look at the design you will ALWAYS get more backlash than a standard diff centre, all in a driveline that already has too much.

This is a quote from the Detroit Manual

"Backlash or slack between the driving and driven clutch teeth is an inherent part of the NoSPIN and necessary to permit automatic operation when driving in forward and reverse. The total backlash in the driveline is increased by the amount of the reduction between the ring gear and pinion. If the ring gear pinion ration is 5 to 1, the total backlash in the drivetrain with the NoSPIN would be about 30° . This in turn is increased by clearances between planetary gear, sliding splines, and the ring and pinion gear. We feel that the total driveline slack can amount to as much as 1/4th turn of the driveline without being abnormal, but if it exceeds ¼ turn, other parts in the drivetrain could be checked. Further clarification of operational and performance characteristics is available through Technical Bulliten No. 81-1044. A copy is available by writing to our marketing department."

That said my LT95 is due for a reshim so its probably more noticeable.
Where is Wagoo he knows more about these things than most?

Quote:

Originally Posted by ugu80

How old is your Detroit? I have the latest model and it is almost unnoticeable in operation. I had it fitted the at a LR specialist who commented that he could see the internal differences from the older models to quieten and smooth its operation. However, even the new ones will have a lot of backlash if not properly shimmed, which is why I got a LR specialist to fit it.
21st August 2012, 07:45 PM
Iain_B

I just bought an Ashcroft ATB from LRA ( and another one coming over for the front) for my Defender ( adding some Maxidrive axles and flange for the rear since I have gone through one set already under warranty)

I have Trutracks both front and rear on my Discovery, and they are great - really transformed the off road ability.

The traction control on the Defender works well, but I found going up a few steep creek exits last year on the OTT was more difficult than I found doing worse and slipperier slopes than in the Discovery.

This years trip has the potential to be in some loose and slippery conditions, so the Ashcrofts are an insurance policy, and at $777 including shipping and the adaptor plate for the diff, I think it's good value. You may get them cheaper direct from Ashcroft, but they were out of stock.
21st August 2012, 08:30 PM
101 Ron

I am a great fan of the detroit.
You must up grade rear drive flanges and axles.
I have been running the detroit in the back of my 101 for many years now and also have a ARB in the front.
The 101 Landies wheel base is 101 inches verses 127 inches of the defender both running a salisbury.
The 101 has no power steering with that shorter wheel base and the 101 will tow/carry a heavier load off road.
I run 36 inch simex.
Both vehicles are constant 4WD.

What I am getting to is if a vehicle is going to feel any bad effects between the two vehicles with a detroit in the back it will be the 101.
To date the detroit has been barely noticeable except for extra traction.
The detroit doesnt dig holes in the sand or cause the vehicle to slip side ways on a slope........why would it as it is locked just the same as a manual locker when off road.
Any effects of digging in or going side ways is way beyond the point of where you would go with open diffs and is the same effect of a vehicle at its limits with a ARB/TJM locker ect.
I regularly tow heavy loads though round abouts and up camberwarra MT hair pins on the stubbie 101 with not problems or ill effects.
Constant 4WD system is the key on road as the drive of the front diff hides any presence of the detroit in the rear.
Most people who knock the detroit have had early versions and in part time 4WD systems......ie series 3 landy not so good.
Defender with saisbury......perfect.
The detroit is a easy fit in the salisbury.
Ron
Ps
Yes there is some extra back lash put in the system, but not a great deal and not worth worrying about.
No difference to tyre wear or anything like that, but rear tyre pressures will need to be kept equal as they should be any how or the vehicle may want to pull to one side in the steering on a tarred road.......good tyre pressures and no issuses.
22nd August 2012, 07:29 AM
ugu80

Quote:

Originally Posted by djam1

The Detroit is about 6 years old and if you have a look at the design you will ALWAYS get more backlash than a standard diff centre, all in a driveline that already has too much.

I did qualify my statement with an 'almost'.
22nd August 2012, 08:37 AM
vnx205

Quote:

Originally Posted by djam1

The Detroit is a pain on side slopes and introduces a lot of backlash into the drive train.

Quote:

Originally Posted by 101 Ron

The detroit doesnt dig holes in the sand or cause the vehicle to slip side ways on a slope........why would it as it is locked just the same as a manual locker when off road.

Can someone explain exactly why some LSDs and/or lockers cause problems on slippery side slopes? Which types are worse and why?

I am not questioning whether it happens or how much it happens. I just want to try to understand why.
22nd August 2012, 08:41 AM
clubagreenie

Quote:

Originally Posted by JC Rover

I've heard the true trac works very well with traction control. I'm about to get one for the rear Sals on the defender. Most of my off road driving is on sand. Where is the best place to get one? USA?

Jono

I have an Ashcroft ATB in the Rear of my D2 with TC and it's seamless, quiet and have never noticed TC operation on road even while u-turning it tightly. You can feel it working off road where there will be a slight pause in momentum until it sorts itself out and thing start moving again (esp with the auto) but I'd add one to the front as soon as I have the budget.
22nd August 2012, 09:24 AM
isuzutoo-eh

Quote:

Originally Posted by vnx205

Can someone explain exactly why some LSDs and/or lockers cause problems on slippery side slopes? Which types are worse and why?

I am not questioning whether it happens or how much it happens. I just want to try to understand why.

Lockers make the wheels turn at the same speed regardless of traction or speed. When the ground is slippery, this can mean both wheels are slipping even at idle speeds. Add a side slope to the slipperiness, and both wheels will be slipping in the direction of rotation AND down the slope parallel to the axle. With open diffs, the torque goes to the wheel with less traction so it slips while the other wheel stays still meaning no slip in any direction.
LSDs don't tend to display the side slope slipping unless they are particularly aggressive, so a tightly adjusted clutch type LSD or a spool that locks up might display the characteristic when it activates, while a geared LSD such as Trutracs or ATBs which don't lock up at all will require a lot more throttle to get enough torque to both wheels for the same result.

Any locker be it automatic such as Detroits or selectable such as ARB, MaxiDrive, Jacmac will show the same characteristic, but selectable lockers can be turned off in these situations.

You can also see locked vehicles crabbing across rock steps as the wheels spin trying to find traction whilst unlocked vehicles will sit on the spot with one rear wheel spinning.
22nd August 2012, 09:38 AM
vnx205

Thanks. It seems so obvious once it is explained. :)

I suppose one way of looking at it is you have a choice between both wheels spinning and slipping sideways or one wheel spinning and the other one just sitting there and while it might not help you to go forward, at least by sitting still it reduces the tendency to go sideways.
22nd August 2012, 10:00 AM
isuzutoo-eh

Quote:

Originally Posted by vnx205

Thanks. It seems so obvious once it is explained. :)

I suppose one way of looking at it is you have a choice between both wheels spinning and slipping sideways or one wheel spinning and the other one just sitting there and while it might not help you to go forward, at least by sitting still it reduces the tendency to go sideways.

Exactly :)
22nd August 2012, 10:05 AM
goingbush

Quote:

Originally Posted by butundede

I have also heard the same, but has someone out there got one in the back of there traction control equipped defender?

Cheers Bob.

Hey Bob

Human nature what it is everyone will tell you the setup they have works great.

Different strokes for different folks. Whats good for one truck or driving style, or environment might be totally wrong for another.

Its like art, very subjective. So its very hard to make a decision based on that.

if its got Traction Control the answer is easy Detroit / Eaton Truetracs or Ashcroft ATB (both work the same way) compliments Traction Control & vice versa

Yes fitting a Detroit Locker in a Salisbury is the cheapest & easiest option but you must install heavy duty axles. And rather than working with the Traction Control it will make it redundant.

In my case, for what its worth, I don't do much mountain work anymore (exept for testing) mostly outback touring towing a Caravan & if need be dump the caravan & go for daytrips / prospecting etc, a bit of sandy stuff but never any beach driving ( I hate salt water corrosion). I'm not really in a demographic that usually needs Difflock or LSD but I like to know the traction is there when / if I need it.

I opted for a Eaton Truetrac from Great Basin Rovers in Utah for the Salisbury in the rear of my 04 Td5 (which has Traction Control & yes it is a Salisbury).

The difference was instant & immediate, No difference noticed on road but the car is transformed off road, so much more capable and quieter. Made all the difference between even ripping the wet lawn up maneuveriung the caravan and not making a mark now.

So happy infact that I got another truetrac for the front, and that has absolutely transformed the 110 into the most capable 4x4 I've had, on my local mountain test track its even better than my dual maxidrive diff locked V8 90 was. (not forgetting what I said in the first line at the top of the post)

Where the rear TrueTrac made no change on road, you can definetly feel the front is there, Under hard driving there is some power on/off oversteer/understeer , but no more that you'd be used to if you drive a normal front wheel drive sedan, off road there is no tendancy to bulldoze straight ahead at all like there is with a full diff lock.

Best thing about it, its all zero maintenance, no thought req, it just works when it needs to. and its actually a lot easier on your axles and driveline components that an open diff / full difflock / or open diff with Traction Control.

( If my Defender did not have traction control I'd have fitted Detroit Locker / HD axles in the rear and a Truetrac in the front. )

good luck with your decision

Show 40 post(s) from this thread on one page