Does any one have any input or thoughts on the auburn pro series LS's im thinking about puting this on my truck

 

Look at some other posts Jcaz07, there's a bunch of related info. I prefer the eaton/detroit true track but the limited slips are OK. Just remember that you'll be replacing clutches at some time. Hope this helps.

 

Thanks for reply. I did look at some other posts in here but i couldnt find anything current the shop that i deal with recomends the auburn pro series for the f150's i had detroit lockers on my previous truck and had no complaints

 

I have both an Eaton Truetrac and an Auburn High Performance in my two trucks.

I love the Truetrac in the F-250. It's smooth but very positive when it needs to be. Because it's a gear drive, it should retain it's performance just about forever. I've used the unit for about five years and am TOTALLY satisfied. My unit has about a 3.5:1 bias ratio but, typical of gear units, you don't feel it much on the highway (because they don't have preload to break past). They are also very good in ice and snow... very predicable and easy to control. Top-notch product in all respects.

I got the Auburn for the F-150 because there were very few other choices for my axle (the 10.25 semi-float that comes in the 8200 GVW trucks). At first, I felt like I "settled" for it. I definitely wanted something more positive than the factory LS. That said, I'm kinda surprised to be this happy with the Auburn. I have heard that the cone clutch design is very smooth compared to plate clutches. Cone types are reputed to be more civilized with more bias than plate clutches. I would have to say that is proven true for me.

The HP series Auburn has a 2.5:1 bias ratio where the Pro has 3.5:1. The only real difference in the units are the preload springs, so you can retune whatever you buy. I have driven trucks with the Pro and they will bark tires a fair bit around turns, even if you try hard not to (unless you have a load in the bed). The HP is pretty smooth and you only feel it if you power hard around a corner. The Pro would be pretty hard NOT to bark tires in just about any circumstance, except with a full load. I've been running the HP for about three months in ice, snow and mud, not to mention TWO TIRE burnouts (for a change ( : <). Would have to give it a thumbs up in terms of performance. My truck is not a hard core off-roader, so I'm not going in those tires-in-the-air situations that defeat limited slips and dictate a true locker.

I guess I can't comment about longevity for a long time yet. The upside is that, according to most sources, the Auburn cones retain their bias longer than a plate style, but the downside is that they are not rebuildable once they totally wear out. You MIGHT be able to rebuild a plate type, once, though many of the plate type units I've seen that were used hard will show case wear in various places that may make then non-rebuildable too. In my experience, you can usually count on being able replace the plates once for normal wear. The second time, you may find so much case wear that you shouldn't rebuild it, or at least expect good performance if you do. How much longer can the cones go? I have hearsd some numbers in the realm of 30-40 percent longer effective life.

FYI, the factor Traction-Lok has a bias of under 2:1 (typicaly about 1.8:1), so you don't often feel it at all... even when you want to!

 

Thank you for the information Jim im leaning towards the auburn pro series myself

 

Thats some interesting info. Never took the ratio's into consideration. Didn't know you couldn't rebuild auburn LS.

 

Hi, I found this thread really helpfull, but can someone explain the bias ratio to me?

It seems like you would want a 2:1 (if that equals 50% sending each tire equal torque)

 

First, remember the absolute rule: The average speed of both axles will always equal the speed of the ring gear. Going straight down the road, if the ring gear turning 100 rpm, so is each axle (100+100/2=100). If you are stuck, with one tire spinning and one stationary, the same thing applies. If ring gear speed is 100 in that circumstance, then the spinning tire is turning 200 rpm if the stationary tire is 0 (200+0/2=100).

OK, so you’re stuck with an open diff, one wheel on a high traction surface and the other on ice. One wheel spins madly and the other is stationary. If you apply the brakes on that spinning wheel and slow it down, a percentage of the torque will be transferred to the side with traction. That’s exactly what a limited slip differential (LSD) does. There are many mechanical ways to achieve that, from clutches to gears, but the amount of “braking” in a limited slip is measured by the torque bias ratio, or simply bias ratio. Many limited slips use the same types of pinion and side gears as an open diff, with clutches outboard of the side gears to apply braking. Gear separation forces, generated by torque, compress the clutch pack and deliver braking, but there has to be some grip on the loose tire for that to work well. FOr that reason most plate type clutches are preloaded with springs, so there is some "braking" available from the get-go. How much preload usually dictates the bias ratio.

The torque bias ratio is a reflection of the amount of torque that can be transferred from the low traction side to the high traction side. If the low traction tire can support 100 pounds-feet of traction torque (whatever grip the tire has plus any "braking" built into the limited slip) and it's designed with a 3:1 bias ratio, that means 300 pounds-feet of torque can be delivered to the opposite tire.

Factory LSD are usually low bias units, from about 1.6:1 to 2:1. That ensures no obnoxious drivability issues, such as chattering, tire barking in turns, etc. Aftermarket buyers usually want more traction and are willing to put up with more symptoms, so bias ratios usually start a little above 2:1 and go up to about 4:1. Some LSD can be tuned to go higher but at that point, it’s practically like a spool and an automatic locker will probably be closer to being transparent. At 2:1 the symptoms are minimal. They start being very noticeable at around 3:1. Overall, light rigs may exhibit symptoms sooner than large, heavy rigs, given equal bias ratios. Gear type LSD can usually get by with higher bias ratio without adverse symptoms than can a clutch style because they are not usually preloaded. An open diff, incidentally, has close to a 1:1 bias ratio. Not quite 1:1 because there is some built in friction.

 

great explination! So would a clutch type be marginally more beneficial when a wheel can't hold any torque? i suppose that it still wouldnt be enough to get you moving though.

another thought is, does anyone ever install line locks so that you can set brake pressure on a single wheel if you do get in the case where it cant hold any torque? that is probably taking it too far lol

 

You mean over a gear type? Yes, in that regard, the gear types need a little more help, but they are a LOT smoother on the street.. With any LSD, brake pedal modulation (light brake application) adds to the effect. Even lightly applying the parking brake (if it applies on the rear wheels) will help (on an open diff too) by transferring torque from the low to the high traction side.

Dune biggies have used them forever! As above, lightly applying the parking brake really helps transfer torque... more so with a preloaded limited slip.

 

yeah, the clutch type over the gear type. (i am trying to decde between an auburn an the true tac)
so dune buggies run the gear type or did you mean they work the parking break? whatever a dune buggy uses would be agressive enough for me!

 

also, would the true trac, gear type, be ok on the front for daily driving in 2 wheel mode, or would this be functioning, ie fighting the steering, when in 2 wheel? I'm not sure how that works.

 

Dune buggies have a hand brake lever for each rear wheel, in addition toteh foot brake. They using it as much for turning as anything, but it works as a poor-man's locker too.

If money is no object, the TrueTrac is the better unit IMHO (I have one of each), but you won't be disappointed by the Auburn. The TrueTrac can be used up front in many cases. If your truck has the IWE setup, no problem. If it has a center disconnect, the TrueTrac will cause the driveshaft to spin. Short term that can deliver a vibration. In other rigs with a similar setup, that's been known to eat up the front output bearing in the t-case over a long period... but I don't have any "case histories" of this in Ford IFS. If your truck is an '01, then it will have a center disconnect. Overall, the best choice up front would be an electric locker, like the Eaton E-Locker, or an ARB Air Locker that go totally open when unlocked.

 

yeah it is an 01, so its the center disconnect as you put it. i know i am asking a thousand questions here, but can you tell how/where the front disconnect works. i see the cv shafts spinning, so i would assume the driveshaft doesn', so so how could that feed back with the tan lsd?

 

The center disconnect disengages one axle from the differential via a splined, sliding coupler and a vacuum motor. Both outer shafts (CVs axles) turn but only one side is actually connected to the differential. It's driving the side and spider gears, but because there is no connection on the other side, it's not driving the diff case or the ring gear (much... in cold weather, there actually may be enough fluid friction from the thick, cold oil that it will for a while).

With the LSD, the unit will think one side is spinning, lock up and drive the case.. and the ring gear, pinion and drive shaft. A locker or preloaded plate type LSD would be worse than a TrueTrac that doesn't have any preload, but it will too. The are some conditions where it won't, much, but I won't go into another technical diatribe. If you were insistent on a limited slip up front, the TrueTrac would be the best choice. You'd still be dealing with some adverse symptoms possibly.

Te IWE trucks ('04-up) have disconnects at each wheel, so none of the front drive components are spinning.