montanaman

I did a post on limited slip in the front - it's an awesome mod.

The engineers at Eaton & Torsen took the timee to talk to me on the phone, and the one to have is from the '13 raptor.

https://www.f150forum.com/f38/limite...-front-377699/

Apples

I tested the live-axle/rear axle open-diff version of this on my truck three weeks ago, but only on loose, flat ground. I'd like to try it again with one rear wheel in the air. My open diff'd truck made two rooster tails on a desert dirt road. Unlike a locker or limited, though, power is sent to one wheel OR the other, but not both at the same time. This is how an open diff works when one wheel is restrained from rotation.

This is why I labor under the impression that this "simulated" limited-slip via AdvanceTrac software + ABS hardware won't work if one axle is broken. When the spinning wheel is braked by the PCM (perhaps many times per second), the differential spider gears transfer driveshaft torque to the other wheel. I don't see how that can occur if an axle is broken.

I'm not flaming you (on the contrary; I always enjoy your posts, sir), but I don't see how this can work unless both axles/both axle propshafts are intact. Please explain?

montanaman

The TrueTrac isn't going to work, according to the Engineer I talked to in April, when I was doing my front LS. - He told me the TrueTrac, like I have in the back 'punkin, is built to deliver most of it's torque in one direction, and while it'll work in reverse, he wouldn't guarantee how long it would last. - As far as the Torsen/Raptor one, after 3 months I haven't used it a lot, but it's awesome.

PerryB

Thanks for putting up the info and part number for the Raptor/Torsen diff. It's definitely on my to do list in the foreseeable future.

schmeal

I also want to thank montanaman. I read your thread and ordered the raptor torsen for when I had my front regear done. Thanks for doing the research.

montanaman

It's too bad I had to replace the front steering rack because I blew all my mod-money for next year. ~ I was going to do some Fox suspension next.

Eric Kleven

Montanaman, see my response in post #7.


but there's a caveat to doing that: The rear axle 8.8 Tru-Track bias ratio is about 3.5:1. When I was doing these diffs in my '97 Mountaineer, the Torsen front bias ratio was about 2.5:1. The higher bias ratio of the tru-track might make it more of a handful on the steering wheel, and who knows about stresses on front-end parts.
I'm willing to bet the Ford/Torsen unit is also a lower bias ratio.


edit:
Next tab I had up was your Raptor Torsen install, noting comments with your engineer convos. 'Would hate steering that' sounds about right, and the Ford/Torsen definitely sounds like the easy/happy path.

montanaman

I thought it was cool that the engineers I talked to would take time out of their day to talk to me. And I know that we rarely run 4WD, and that 99.9% of people couldn't care less about a front LS, but I think if FOMOCO offered an option of putting in the front LS along with an e-locker or mechanical LS in the back that a lot of people would order them.

STingray1300

That's the funny thing, I'm "old school". I don't freaking know why all this new computer controlled crap works. I almost wish it wouldn't. Give me manual lock-out hubs, a second gear shift for the TC, a TruTrac/Fr and a Detroit locker/Rr and I'm happy. All I know is, that I was able to crawl over Goler Wash and Mengel Pass in Death Valley with a broken CV axle (joint bearing was toast, completely blown apart; as in, the front wheel turned and the CV axle just wobbled and clunked, but didn't turn <engine off>). And there were spots that a 145" w.b. truck should not have been trying to crawl rocks.

Perhaps someone will be able to explain it thoroughly to both of us (?)

montanaman

Not too hard to explain - your truck managed to get by on three legs !