I am entertaining the thought of changing from an open to a posi on my 98 F150. Is it worth the trouble?

I'm on the hard surface most the time, just want the extra push since it is only a 2 wheel drive.

Which is the best posi?

 

Hello Valk1500,

A limited slip differential is one of the best upgrades you can make to improve your traction. I've put one on every truck I've ever owned. Auburn Gear and the Eaton POSI are the only after market limited slip differentials available for your 9.75 rear axle.

The Eaton POSI unit is less aggressive and offers smoother on-road performance but, they recommend using a non-synthetic gear oil in your rear differential or you can get gear chatter from their product. Ford recommends a 75-140 full synthetic oil in your rear axle, so you could run into warranty issues. But you would probably be OK with a 80-140 non-synthetic oil if you changed it about every 30k miles or so.

The Auburn unit is more aggressive and offers more traction with better off-road performance and it works fine with synthetic oil.

http://www.auburngear.com

http://www.torquecontrol.eaton.com

 

This is kinda the question I was asking in another thread (see Detroit EZ-Locker). I want to change my open to an LSD. I considered the Detroit (and similar PowerTrax products) because of the price, I can do it in the driveway in an afternoon, and you don't have to mess with the ring and pinion gears. But now I'm having questions about these products.

From what I've been reading, they are great for off-road use. But on-road not so fun. Things like noise, lurching, stress on parts, and especially a required change of driving style caught my attention. There is one, the PowerTrax limited slip, that I'm still considering. It's supposed to be more streetable, but I haven't found much info on reviews or personal experices with it yet.

I don't have 4x4 and all I want is something to provide plenty of traction to get up a wet boat ramp with a big boat in tow. And, I need to try to do it in an affordable way.

I am still wondering how difficult it would be to pull the guts out of a diff of a truck at a salvage yard and rebuilding them to stick in mine. But with this option, I'm assuming I would need to get a shop involved.

I'd like to hear what others have done.

 

Hello Fishbrains,

I would not personally recommend a Powertrax system. It is not a new differential, but uses your existing differential housing and basically replaces some of the guts. Your OEM differential is not strong enough stand up to the stress the Powertrax no-slip traction system will put on it, and it won't last very long. If possible, spend a little extra money and get a complete differential replacement like an Auburn Gear and the Eaton POSI, and you will be much better off in the long run.

 

rkjerue,

Thanks for the input. I'll stay away from the lockers. I'm looking for low maint. and durability.

Can the Auburn or Eaton install be done in the driveway or should it be performed by a shop?

Thanks,
Fishbrains

 

It needs to be done by a shop.

 

I wanted to put in a good word FOR the powertrax. I have the no-slip in my '97 and in normal everyday driving I rarely notice it. Occasionaly it will 'clunk' but its usually in a slow, turning situation like a parking lot or something. Nothing bad! I would say that if I took you for a ride and didn't tell you I had one installed you would never notice it in normal driving. And yes, it works as advertised. You can stop with one wheel on the pavement and one wheel in the weeds and it will leave a nice stripe on the pavement (4.6 willing that is!!) when you punch it. As far as added stress on the factory parts I'm not sure I would agree as it is more or less an open diff in a turn so it isn't torquing the diff or anything. It seems to lock and unlock very smoothly so it doesn't seem like it would be that hard on the system. No harder than when a useless open diff spins the right tire endlessly and then suddenly hooks... Of course it has the ability to put all the power to one wheel so in the wrong circumstance that could be stressful I guess. I didn't buy mine for heavy off-road use I bought it because it was the only affordable option to get rid of the open diff some idiot (not me) ordered my 4x4 with. And to that end it has performed admirably. After I put it in I was able to drive up a steep gravel road, with turns, in 2wd that had always required 4wd in the past. To date it hasn't done anything unexpected, like ratcheting at the wrong time and throwing the truck in a ditch or any of the other horror stories I have heard about in the past. And yes, I have had it in snow and it is fine.

I've had it installed for nearly 2 years. I did have a problem early on but powertrax took care of it. Apparently when they were still powertrax there were some vendor machining issues on earlier units and I was lucky enough to receive on of the faulty units. They are now owned by Richmond Gear and they have supposedly returned most machining to in-house instead of outsourcing it. They have also supposedly redesigned a few parts here and there.

fwiw,

philip