Anyone out there running front & rear LSDs? (1 Viewer)

[SkyMall]

I know selectable lockers are generally considered the way to go, followed by a rear auto locker of some sort, but I am fascinated by the idea of running front and rear LSDs. I know the only option for the rear is the Auburn and the front is either an Auburn or a TrueTrac. As I understand it the Auburn has a higher bias than the TrueTrac, so it seems to me that the preferred set up would be the TrueTrac in the front and the Auburn in the rear.

Anyone doing/done this?

Thoughts on pros and cons?

I think I mentioned this in another thread, but I thought I'd start a separate conversation about it.

 

[math]

I don't have a recommendation for you, but I'm interested as to why you want an LSD front and rear instead of lockers? I'm not criticizing your choice, just curious.

 

[SkyMall]

A valid question, for sure.

I like the idea of a completely passive system that requires no user input - an extension of the AWD concept rather than a step toward more traditional 4WD. Fully mechanical traction control, if you will.

 

[math]

A valid question, for sure.

I like the idea of a completely passive system that requires no user input - an extension of the AWD concept rather than a step toward more traditional 4WD. Fully mechanical traction control, if you will.

Do you still have your viscous coupler in? Because you're 1/3rd of the way there if so!

 

[45Kevin]

Since LSDs "engage" when there is a difference in the rotational velocity of each wheel, they would "engage" every time you turned the steering wheel. Not a good idea to have one in the front in my opinion.

 

[math]

Since LSDs "engage" when there is a difference in the rotational velocity of each wheel, they would "engage" every time you turned the steering wheel. Not a good idea to have one in the front in my opinion.

I figured there would be some way to tune them such that a very large difference in rotational velocity was required in front. Is that the case?

 

[45Kevin]

I'm not sure what the difference needs to be to engage a LSD, but think of the difference in rotational velocity between the front wheels when you turn. The sharper the turn the greater the difference. I don't know how you would tune a LSD, but would you only want it work when the wheels are cranked?

 

[SkyMall]

I've got a 1994, so I don't think I've got the viscous coupler.

From what I've researched, friction type (cone or clutch) LSDs do have some ability to tune the torque bias. With the torsen type (TrueTrac) I don't think it's adjustable.

 

[SkyMall]

If I recall, I believe some of the older AWD cars had a 3-way LSD setup. That's where I came up with the idea. When I searched around the net, I found quite a few Jeep guys running F/R LSDs and while they tend to be outliers in the community, they also tend to be happy with the setup. I was curious if anyone in our community has any experience with this set up.

 

[ppc]

93 and up have viscous couplers.

 

[LXDOC]

I have aTrue-Trac in front and Auburn Pro-series in back on a 97 LX with the supercharger. I like them. Be sure and use Ford friction modifier in the Auburn Pro-series equipped diff. It will shudder on sharp turns if you don't. Some synthetic diff oils say they have modifier in them but the Auburn still needs the Ford friction modifier. More importantly, Auburn does not recommend synthetic diff oil.

 

[SkyMall]

93 and up have viscous couplers.

Got it. I couldn't remember what year that was. I had 1995 in my head.

 

[SkyMall]

I have aTrue-Trac in front and Auburn Pro-series in back on a 97 LX with the supercharger. I like them. Be sure and use Ford friction modifier in the Auburn Pro-series equipped diff. It will shudder on sharp turns if you don't. Some synthetic diff oils say they have modifier in them but the Auburn still needs the Ford friction modifier. More importantly, Auburn does not recommend synthetic diff oil.

Thanks! That's the type of info I was looking for.

Why did you pick this set up?

Why type of wheeling do you do?

Other than the friction modifier shudder issue, any other cons? How does it drive in various daily driving conditions? (Dry pavement, wet pavement, snow/slush/ice)?

Do you find that it does 90% of what a locker set up would give you, without having to engage/disengage anything? That's kinda the impression I got from the Jeep guys.

 

[Notch]

I'm not sure what the difference needs to be to engage a LSD, but think of the difference in rotational velocity between the front wheels when you turn. The sharper the turn the greater the difference. I don't know how you would tune a LSD, but would you only want it work when the wheels are cranked?

The difference in wheel speed while turning is minor compared to when one loses traction.

 

[normiex]

My brother put a LSD in the front of his Hilux and it is great on the sand. LSD diffs distribute torque not speed, as soon as you have a wheel in the air the LSD acts like an open centre with a small amount of resistance (applying the brakes actually helps get drive), so it should be alright in the front end and works great offroading as long as both wheels of the axle have some grip. I have done tests with a near new work car with a LSD and as soon as a wheel was off the ground you get no drive at all.

The front diff in a 80 series is the same diff centre (different crownwheel and pinion) in a Toyota Hilux of a similar year so that's another option for you.

 

[b16]

I'm not sure what the difference needs to be to engage a LSD, but think of the difference in rotational velocity between the front wheels when you turn. The sharper the turn the greater the difference. I don't know how you would tune a LSD, but would you only want it work when the wheels are cranked?

Depends on the LSD. Clutch type you add shims to change the engagement. Most cars that come with front LSD's will be helical to allow front wheels to turn without issue. My old Evo 8 had center and rear clutch type LSD's with a front helical LSD. It was fantastic.

 

[thetoyotaman]

If your not doing a lot of tire lifting they are a great option. I originally tried them for my wife driving on ice as she was having trouble with the locker in the rear of the 82. I had tru tracs front and rear in my 82 mini truck and they worked great. I also have Japanese clutch pack type front and rear in my Isuzu Trooper and they also worked great. On the Trooper I have to run Red Line LS oil to stop shudder. Not sure on an 80 how the viscous coupler would change things.

 

[LXDOC]

My driving conditions are mainly mud/ wet sand in north central Texas and trips to high country of northern New Mexico. No rock crawling (daily driver). Simplicity of install (no pump, lines, actuator, diff drilling required) and ease of maintenance were important. They are unobtrusive in a daily driver.

 

[thetoyotaman]

I agree and also work great and in snow and ice. And the wife likes it as well.

 

[SkyMall]

This is a really great discussion. I have to be honest, I thought I'd get a lot of flaming. Haha!