traction enhancement

[JimCT]

Detroit locker

I installed a Detroit locker in the Salisbury rear axle of our ambulance and it is the best mod I have done to the beast. No quirks on the road, just a rare pop when it releases. Also have GB Aussie upgraded axles and axle drive flange after breaking a Salisbury axle. Bullet proof so far, and we are not that easy on the ambulance.

[AU_88]

I do not understand the need for a transfer case locker, what does that change? is there a slip between front and rear wheels with standard transefer box.

An open transfer case is like an open diff, an open diff will allow most of the power to go to the wheel with the least amount of resistance, a locker will send the same amount of power to each wheel no matter the resistance, the same is true for the transfer case, if one axle has less resistance, most of the power will go to that axle, but with a locked TC it sends relatively equal power to both axles.

[TeriAnn]

An open transfer case is like an open diff, an open diff will allow most of the power to go to the wheel with the least amount of resistance, a locker will send the same amount of power to each wheel no matter the resistance, the same is true for the transfer case, if one axle has less resistance, most of the power will go to that axle, but with a locked TC it sends relatively equal power to both axles.

Time for a comment or three:

1. The full time 4WD Rovers have transfer case that is like a center differential that can vary the power sent to the front and rear depending upon need. These transfercases need to be locked to provide equal power front and back. The series transfercase is part time 4WD. When it is in 4WD it is always locked, providing equal power to the front and rear.

2. A Detroit locker is an automatic locking diff and applies equal power to both axles when it is locked and works like an open diff when it is not locked.

Personally I don't like the Detroit locker because I would have no control of when it decides to lock and when it decides to unlock. I much prefer a manual locker so I decide when I want to to challenge an obstical with an open diff or want to get serious with a locked diff. I have an ARB in the rear. My personal preference.

2. The Salisbury is a Dana 60 made under license in the UK. It has a beefier carrier and ring and pinion gears and is 24 spline. Detroit carriers designed for the old style Dana 60 fit. The Salisbury was standard fitment on the rear of SIII 109s only. It is a bolt on swap with the earlier 109s. You just need to uses the stock SIII 109 rear propshaft. The Salisbury requires moving the spring perches inboard and for the already short rear propshaft to be shortened even more if you try to fit one to an 88. An 88 is better off keeping the Rover axle housing and converting the guts to 24 spline.

A Salisbury front diff was standard fitment to the SIII One Ton model and can be moved over to the 109 as well but they are hard to come by.

3. A Detroit Trutrac is a limited slip carrier that never truly locks. As long as both tyres have some traction the trutrac will send power to both axles. If one axle is in the air or on slick ice where there is no traction it acts like an open diff and there is no power to either axle. Like an open diff the Trutrac needs resistance on both axles to work. The way to cheat is to lightly ride the brakes to simulate traction on both axles when one tyre is in the air.

4. Lockers on the front axle are superior to limited slips as long as you are driving in a straight line. However, try to work the tyres for increased traction on the tyre edges or turn and you put a lot of stress on the front axles. A limited slip lets you work the tyres and turn the wheel as you climb or descend without nearly as much axle stress. Which is why most people go for a limited slip on the front and a locker on the rear. The stock Rover carrier is a week 2 pin design and you are MUCH better off with any of the aftermarket or the Salisbury carrier.

5. The Rover 4.7:1 R&P gears are thin and not known for its strength. When used with any of the lockers you need to use a spacer with it to make the combination thicker. The Salisbury 4.7:1 is a beefy gear set. There is an aftermarket 4.75:1 R&P that is as thick as the Salisbury R&P and has a lot of meat on the gears making it a lot stronger than the Rover R&P. It is a recommended R&P upgrade when going to a limited slip or locker in a Rover diff.

4.75 Ring gear on left mounted to a TruTrac carrier.
Rover 4.7:1 ring gear sitting on a spacer plate on right mounted to a Quaife limited slip carrier.

While I'm at it:

24 spline axles net to a 10 spline axle



Below 24 spline front axle vs 10 spline front axle:

I any one is interested, my 109 has a Ford 5.0L V8, NP435 close ratio gearbox, Series transfercase with Ashcroft high ratio kit, rear Salisbury with ARB, and hardened Great Basin rear axles. The front is a 24 spline Trutrac, 4.75 R&P and Seriestrac 24 spline front axles. It has been a trouble free combination for me that I'm real happy with. The combination gives me 50:1 low range first at the axle (stock LR is 40:1) and with 33 inch dia tyres 65MPH is at 2650 RPM.

[JimCT]

Detroit vs ARB

I had intended to install an ARB locker in our ambulance, but the one time we laid it over on it's side I could have driven out of the situation if i had a locker, but i would never have had time to engage the ARB. It was a side hill and as soon as both high side wheels left the ground I lost forward motion, if I had the Detroit I could have driven it down the grade abit and saved it. And I have to say at least in the ambulance the Detroit locker is a joy. just something else to think about.

[AU_88]

I had intended to install an ARB locker in our ambulance, but the one time we laid it over on it's side I could have driven out of the situation if i had a locker, but i would never have had time to engage the ARB. It was a side hill and as soon as both high side wheels left the ground I lost forward motion, if I had the Detroit I could have driven it down the grade abit and saved it. And I have to say at least in the ambulance the Detroit locker is a joy. just something else to think about.

I generally turn on my rear locker when I see something that may give me trouble. If I cant get past it with the rear locked, then I reach up and flip the front switch.... No biggy.

[lrdukdog]

lockers

This seems to be a "to each their own" as to which is better.
Jim Wolf

[AU_88]

This seems to be a "to each their own" as to which is better.
Jim Wolf

Agreed.

[TedW]

Question: How common is it to break a front 10-spline axle?

I lean towards taking TerriAnn's advice and switching my rear end to 24-spline, and adding a truetrac. However, I also lean towards leaving the front end as is (10-spline).

[mongoswede]

a general way to think about this is: a locker will only be activated when you engage it. So you only use it when needed. A limited slip will be working all the time whether you want it to or not. It takes a little getting used to the feel of a limited slip in your drive train.

[I Leak Oil]

a general way to think about this is: a locker will only be activated when you engage it. So you only use it when needed. A limited slip will be working all the time whether you want it to or not. It takes a little getting used to the feel of a limited slip in your drive train.

Depends on which locking Diff you get....

[NickDawson]

I liked the idea of replacing my stock diff with a truetrack until I looked at the cost of moving to 24 splines* - not sure I do enough off roading to justify it...

How risky are they with 10 spline axels? Is it a guaranteed matter of time before they snap?

*also need to check my frankenrover as it may likely have a 109 rear and/or 24 spline axels - any quick way to check?

[mongoswede]

Depends on which locking Diff you get....

I guess when I think of lockers I think of air or electric engagement that are pretty much on off. Everything else I consider a limited slip.

[I Leak Oil]

I guess when I think of lockers I think of air or electric engagement that are pretty much on off. Everything else I consider a limited slip.

So you consider a detroit locking diff a limited slip because of it's lack of driver control? What about a spool? No switches there. A detroit is every bit a viable locking diff as an ARB or an e-locker. Just not selectable. Do you have any personal experience with a detroit? I do. I currently have ARB's but that's for my own reasons, not because a detroit is any less effective, just different. It's certainly not a limited slip....

[I Leak Oil]

I liked the idea of replacing my stock diff with a truetrack until I looked at the cost of moving to 24 splines* - not sure I do enough off roading to justify it...

How risky are they with 10 spline axels? Is it a guaranteed matter of time before they snap?

*also need to check my frankenrover as it may likely have a 109 rear and/or 24 spline axels - any quick way to check?

10 splines are guaranteed to snap with a stock carrier nevermind a ltd slip or locking diff. To check your spline count....pull the axle shaft. 6 bolts is all it takes.

[JimCT]

Detroit Locker

Not sure where you are getting your info but there is no slip in the Detroit Locker. It works great.