What is the best limited slip rear diff for the current model F150 assuming 90% street driving?

 

I'm a little confused about your question. Ford only offered one type of limited slip diff as far as I know, but they do offer it in a few gear ratios. Or are you asking about an aftermarket LSD to add to a truck that currently runs an open diff?

More details please, and I'm sure someone can help you out.

 

Eaton "Detroit" TrueTrac is the best. It doesn't have clutches to wear out like the facrory limited slip.

 

I'm in construction and I just purchased a 2014 that had everything I wanted except a limited slip or locking diff so rather than order one I bought this one and am now looking for an aftermarket unit.

 

x2

Tough to beat this choice. Good on the street and useful in the slick stuff.

 

Anybody you would recommend to install it I'm in Houston?

 

I had a good old Eaton Posi installed in my '02 E150 when it was new. It has served me well for way over 100k miles. The clutches on it are carbon and will theoretically wear out, but if you don't spend a lot of time off roading it, it will last a long time. Both the Eaton Posi and the Ford Trac Lock are rebuildable, and the Posi has different springs available for more lockup potential.

I put an Auburn posi into my old '86 GMC van way back in 1990 and that was a nice smooth unit but the case itself wears out over time on those. The Tru Trac is not supposed to wear out, but the way it works, the helical gears are pushed against the case itself so it seems to me that it could, in the long run, wear out as well. I know that it's a really smooth diff.

Good luck; see if you can find a 4WD club or some drag racers and ask them who does their axle work for them at a good price. I got a discount coupon for my posi at the Detroit Autorama (custom/race car show) from the booth of the place that did the install for me, and I got the Eaton for the same price as a Ford Trac Loc would have been. (And I have had old GM muscle cars and Vettes with the same Eaton Posi so I am fond of them.)

Good luck,
George

 

What the hell is a good limited slip in a truck? Never heard of one

 

Another vote for Eaton TrueTrac. I had this installed on my previous truck (04' F-350) and ran it for about 4 years. 75% on-road, 25% off-road. I didn't baby it. It acted the same as my stock open carrier when cornering.....I'd say that aside from when my rear tires lost traction you wouldn't even know it was in there.

 

I have a Detroit Truetrac in my 92 Bronco and in my 2011 FX4.

 

Picked up the new truck today and was told by the accessory sales babe not to install an aftermarket LS because it could void the warranty. Is there a hot line number I could about this?

 

Any aftermarket part could void your warranty if it can he proved that, that part caused a failure you need fixed. If you blew you rear end and you had a aftermarket ls then I could see them not covering that but I can't think of many other things it could effect.

 

When I had my Eaton posi installed in my brand new van, I made the assumption that if the rear axle bearings, ring and pinion, etc. ever failed, that I might have to deal with it on my own dime. However, if you find a good rear axle shop to do the work, chances are that the clearances, etc. will be set better than on the stock truck.

Otherwise, what effect could a limited slip unit have on any other part of the truck? How would the dealer ever know what's inside the rear axle if you need to have a power window motor replaced?

I'd go talk to the service manager at the dealer or someone with authority if you really have any concern, but why mention it at all?

George

 

I'm not a mechanic but, I'm of the thinking that a high quality aftermarket ring and pinion set isn't going to cause any driveline issues up stream.

The unit that you want will be warranted by the company, the rest of the axle may be on your dime. How many axles have you had to repair between the brakes and the ring gear? I've never so much as had to pull an axle seal let alone a shaft in less than 250K miles.

I'd get it and drive happy.

 

What sort of differential does your new truck have? Open, factory LS, or the e-locker?

The only warranty issue you could have would be if something related to the differential itself failed. An aftermarket limited slip unit replaces the factory carrier, and so any issues with pinion depth, backlash, or carrier bearings would be denied warranty coverage should you have a problem. In addition if you had a problem with a leaky axle shaft seal they could blame the shop for damaging them when they removed the shaft.

Yeah, there's no way anyone could credibly argue that an aftermarket LSD caused powertrain issues not related to the rear axle.

I wouldn't mess up a good thing. My truck needed a new ring and pinion at 11,000 miles because of an improper setup from the factory. The brand new set started whining within a couple hundred miles of installation because the tech screwed it up. They took a month fixing it because they were waiting for a special tool, and once fixed there was still some whine from the improper break-in of the new gears. Had I not sold the truck they would be putting a second ring and pinion in.

I've seen a few threads over the year of rear end shops botching the job and finding various ways to get out of replacing improperly worn gears. Some even say "it's normal". I'm sure most shops get it right, but I wouldn't want anyone but a Ford dealer messing with my differential.