Detroit Locking differential

[The eXpedition]

Hi Guys,
So after several research and development on google, I managed to find out the Detroit locker are the best to perform as locking differentials.

But I do not know which part is the correct one for my 2012 Expedition?

Someone has written in another expedition forum that Detroit locker rear and Detroit Truetrac front is a powerful combination (the best in fact) for the expedition.

Now what is the gear ratio of my expedition, is it 9.75"? or 8.8"?

I want to order those two, so any website to start with is appreciated and what could be my part number?

Secondly I was going to place an order with Auburn locker, it is similar in functionality to the electronic locking differential in the FX4 package, but I was afraid as I read around some people say it never worked as advertised and fail frequently.

Also the warranty is one year only, it looks short looking to how important is something like this...

Anyone had a previous experience with this subject as a third generation owner?

 

[DetroitDarin]

You can't run an e-locker/Air locker WITH a DetroitLocker.

Eaton (who makes the detroit locker and truetrac) show this:

1997 - 2012 Ford 9.75" Detroit Locker part#225C194A TrueTrac part #913A477

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf

Your truck probably has 8.8" in the front and 9.75" in the rear; the gear ratios do not matter in terms of installing lockers.

 

[tonydiv]

If you can find an application for an e-locker or ARB air locker, that would be the way to go. Both of them are selectable lockers that only lock the axles when you want them to. When driving on the street, the truck drives completely normal. A Detroit locker will bang and chirp the inside tire on tight turns. It's really not ideal for a street driven truck.

In addition, the stability control (and traction control) on your truck may not function correctly. That system needs to be able to send braking to individual wheels to work. If the axles are locked together, it really can't do its job.

 

[DetroitDarin]

one point - the lockers - truetrac and detroit - lock up when under power; I suspect it'd be okay on the streets if you adjusted how you drive. I like to power through corners myself

Another side note - and I cannot over-stress this point: There is no "Best" solution to anything. What you do with your truck dictates what you need. Don't spend money on things that may not provide the performance you are looking for, OR spend money on those things but instead give ME the money and I'll send you the parts you "need" based on your planned useage.

 

[The eXpedition]

You can't run an e-locker/Air locker WITH a DetroitLocker.

Eaton (who makes the detroit locker and truetrac) show this:

1997 - 2012 Ford 9.75" Detroit Locker part#225C194A TrueTrac part #913A477

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf

Your truck probably has 8.8" in the front and 9.75" in the rear; the gear ratios do not matter in terms of installing lockers.

The problem with ELockers that they perform open differential when not engaged, that doesn't fit my application. Regarding the detroit locker it disengages automatically when turning provided that you be nice with the throttle.

if both wheels are continously turning together as in the detroit locker case, would that harm my mpg?

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[The eXpedition]

If you can find an application for an e-locker or ARB air locker, that would be the way to go. Both of them are selectable lockers that only lock the axles when you want them to. When driving on the street, the truck drives completely normal. A Detroit locker will bang and chirp the inside tire on tight turns. It's really not ideal for a street driven truck.

In addition, the stability control (and traction control) on your truck may not function correctly. That system needs to be able to send braking to individual wheels to work. If the axles are locked together, it really can't do its job.

There is an application for that I think but just the problem is acting as open differential when not engaged. They only and only Locker that performs best as limited slip when not engaged and locked when engaged is the auburn one. But not a good reviews i seen on the web regarding the performance

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[DetroitDarin]

if both wheels are continously turning together as in the detroit locker case, would that harm my mpg?

Not in the least. Your engine wouldn't know it's turning both rear wheels; it turns only the driveshaft.

Maybe do a detroit in the rear and an e-locker up front? Your truck would behave great! Would be more capable than stock having the detroit in the back - and the 4wd system would work exactly the same off-road - except when you REALLY got stuck, you'd engage the locker


Another thing -

Lockers are to get INTO trouble off road. A winch is to get OUT of trouble

 

[The eXpedition]

Not in the least. Your engine wouldn't know it's turning both rear wheels; it turns only the driveshaft.

Maybe do a detroit in the rear and an e-locker up front? Your truck would behave great! Would be more capable than stock having the detroit in the back - and the 4wd system would work exactly the same off-road - except when you REALLY got stuck, you'd engage the locker


Another thing -

Lockers are to get INTO trouble off road. A winch is to get OUT of trouble

You are absolutely right

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[Shaky]

I have a Detroit in the rear of a 79 Blazer that I use off road. Off road, the Detroit is awesome and very, very strong. On the road, it really affected the driving quality. Long sweeping turns take a LOT of attention. The power to keep highway speeds on long sweeping turns is quite often enough to make the Detroit lock up. That means the truck is going to try to go in a straight line. So you end up steering more into the turn. Then uf you let up on the gas, the locker releases and the truck has a tendency to dive into the turn.

The biggest issue is a technical one. When under power, the Detroit will allow one tire to free wheel faster than the one being driven. So in a turn, the inside tire is doing the majority of the pushing. With an open diff, the power goes to the wheel that spins the easiest, which would be the outside wheel.

Have fun with your truck, I just recommend trying to drive a vehicle on the road that has a Detroit before you install one-if your truck is a daily driver. I love my Detroit off road. I don't like it on the road. And if there is any ice around, just park it. A locker will definitely require you to need a winch if there is ice around.

 

[BIG GREEN FORD]

I'm glade to have limited slip, now that I here shaky I don't want a locker . its really only good for rock climbing. If you lock the rear in the mud and have to turn you will just sink yourself.
I welded the rear diff on my buggy witch is the same as a locker and my expy goes everywhere it does with the limited slip

 

[DetroitDarin]

interesting:

When does a Detroit Locker lock?
The Detroit Locker is locked up 100% in a straight line or if you are spinning. The unit unlocks in a turn for the wheel that is turning the fastest.

FAQ

From the jeep crowd:

I have Truetrac units at both ends and for my use, the beach and winter driving, there is nothing better. It has great road manners and instead of worrying what a locker will do during turns, icy roads and snow, the Truetrac will actually help in those situations. If I was climbing rocks and didn't use the Jeep in the winter, I would have definitely installed a Detroit Locker in the rear.. ..

I love my Truetrac. I had a Detroit in the back of my old YJ. That thing was a billygoat, but it was not good in slippery on-road conditions. I went with the Truetrac in the back of my new TJ because the wife couldn't drive the old one at all. I like it so much that I may put one in the front to match.

If you have a tire in the air and it doesn't split the torque between both of the rear tires (it needs at least a little resistance to work properly) then use your e-brake. That is what I do and it works great for me! Granted, I do almost no hard-core rock crawling. But then again, if I did hard core rock crawling all the time, then I wouldn't be using an '06 TJ daily driver, I would have something else!

I'm running the Truetracs in both axles, too. And pretty much concur with everyone's sentiments which range from "they're great" to "they're not lockers and lockers are better".

The Truetracs are more of a balance, a compromise traction device. They provide a lot more traction than open diffs or typical LSDs. Yet they're not as good as lockers in delivering "ultimate traction." However, you don't have a lot of the on-road / reliability / cost compromises that you have with lockers.

So . . . significant traction improvement, good on-road manners, good slick-road handling, no complicated air compressor or air line set up, no finicky e-locker engagement systems, no clicking, ratcheting or chirping noises on road.

Once they're installed, you can pretty much forget about them.

I would say that if you have a dedicated trail rig, or are playing in rocks (or lifting your tires off the ground a lot) then lockers would be a much better choice.

But for general trail running on forest or mountain roads, or going through muddy sections, and so forth the Truetracs are just fine.

Very occasionally I'll encounter a situation that overcomes the Truetracs. . . it doesn't happen often, but every once in a while and about half those times the guys with lockers are having problems, too. In these situations I bust out my winch and pull me through the 3-5 ft of trail that is causing me problem, then get going on my way again.

Look into TrueTracs - A truetrac in the rear and a electronic locker in the front and I think your truck would be a great compromise of street and off-road. I 'think' that's the route I'd like to go.

 

[DetroitDarin]

Another great post - but jeep-specific. Although it's for jeeps, his comments on traction/strength, etc, are valid across any platform

The one nice thing about the Truetracs using the 27 spline shafts is that upgrading later is pretty easy if money is tight now. Since the gears/TT's are already set up, swapping new axles is a simple matter of draining the diff, taking wheels/brake off, popping out the cross pin in the TT to remove the c-clips and sliding the stock axles out. Reverse installlation with new HD axleshafts. This can be done by any home DIY-er.

Glad people are finding this thread useful but I'd also like to make sure people are clear on things:


Strength of Axle Assembly
While the Truetracs and the HD 27 spline shafts bump up strength, it's still not to the same level as a Super35 or D44. As such I'd probably limit tire size to 33". We are, after all, still talking about our D35's which aren't known for their great stregth and 27 spline shafts are still 27 spline shafts. So, it'd be my recommendation to nix the 35" tire idea.

If someone REALLY wanted 35" meats, or to hammer on their rig offroad, best to go for the Super 35, D44, 8.8 or other serious upgrade. But with some care the D35 and a Truetrac should hold up reasonably well to 33's and a driver respectful of their Jeep. Below is a strength comparison.

Weakest

1. Stock D35 axle (with or without Trac-loc
2. D35 axle with stock shafts + Truetrac LSDs
3.0. D35 w/ HD 27 spline shafts (1541H) + Truetrac LSDs
3.5. D35 w/ HD 27 spline shafts (chromo) + Truetrac LSDs
4. Super35s, D44, 8.8s

Strongest




Strength of Diff Carrier
In a line up of least to strongest (generally speaking) of differential carriers (the part the ring gear bolts to) they fall like this:

Least Strong

1. Stock Open Diff
2. Stock Trac-Loc LSD
3. Lunchbox Locker
4. Truetrac/Detroit/ARB/Other Full-case replacement differentials
5. Spools

Strongest




Traction
As Jerry (and others) mention in these threads the Truetracs are not lockers. they're great, offer lots of tractioin, are certainly better than traditional LSDs, but they aren't lockers. This is fine by me as I appreciate the other benefits the TT's provide and am willing to bust out the winch on rare occasion.

In a Least-to-Most traction line up the field looks like this:

Least Traction

1. Open differential
2. Trac-Loc (or other clutch based LSD)
3. TrueTrac LSD (helical gear based)
4. Locker / Spool

Most Traction


Again, rock crawling or other wheel'n where tires are lifting off the ground often is best left to lockers.

 

[BIG GREEN FORD]

In the mud #3 is going to be a lot better the #4 in are heavy trucks in my opinion

 

[DetroitDarin]

heavy is as heavy does - I'd bet a full locker, even in mud, is the best choice, most of the time.

 

[Bedrck47]

kindly update your signature line with year model and engine information. This can be done in the USER CP section as this information helps others give you replies specific to your expy

 

[DetroitDarin]

^^ He doesn't need year-specific info so much as 'general off-road' performance options info

 

[AggieExpo]

sorry to bring up an old thread, however I'm looking at lockers vs limited slip. I have not heard anyone talk about the OX 8.8 locker for the front and using an ARB locker for the 9.75 rear. For on the road i believe that the open diff is going to be best, but for off-roading a lcoker weather it be a true locker like a spool is best for traction. but i would never get a spool or weld my spider gears to make a spool. I do like limited slip but not all limited slips are created equal. Some have clutch pads which wear out. I think the selectable locker would be best. However the ARB is about 1,200 and the OX is about the same price. So before i spend my hard earned cash i want to know if anyone has run either of these. I'm Fine with a Limited slip like the 8.8 true trac up front but would really like a locker in both the front back. And i also need to regear for 37" tires. and all this at the same time of installing my lift. My offroading is mainly muddy trails and getting to and fro the job site and the deer blinds. I hardly have to worry about ice or snow "except this Novemeber" becasue it never gets that cold around here. but heavy rain and mud are something i deal with all the time.

 

[Shaky]

AggieExpo, I like how you are thinking. Based on my off road experience, I've seen the Truetrac be very effective off-road when used up front. However, everyone that used it had the ability to unlock their front hubs for on-road use. The marketing says it is fine for a AWD vehicle on dry roads. I wouldn't do it because it will effect driving manners and cause higher tire wear. I understand that they are expensive, but for a vehicle regularly driven on the road, I'll always recommend a fully selectable locker in the front. The exception would be where the front hubs can be unlocked.

I've never seen a Truetrac used in the rear, so I can't speak to that. After using a Detroit in the rear while on-road, I've become a fan of selectable lockers to be able to turn them off.

I wish you the best in your decision making.

 

[AggieExpo]

I decided to get an ox selectable locker for the front. And for the rear I'm still undecided. I would like a selectable locker but I'm not a fan of the ARB. I don't want to worry about airlines or seals leaking. I think I'll wait until ox makes a locker for the rear. I think I'm going to stick with the limited slip in the rear and just pray that ox makes a locker sooner than later.

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[The eXpedition]

interesting, I am planning to get ARB for the front axle 8.8", the rear one is undecided due to the fact I do not want to lose the limited slip functionality by adding a locker that acts as an open diff when not engaged, otherwise Detroit locker is excellent except for the daily On-Road drive like I do.

I really don't want to get a rear auburn locker although it acts as a limited slip when not engaged for the simple fact that I would end up have two air compressors based lockers in my 2012 Expedition.

I hope the industry does improve in this sector.