I had a pinion bearing failure and took the opportunity to upgrade my stock rear-end. I was looking for decent street traction with onroad manners being a top priority. I also wanted something solid and reliable that would do well off-road, yet didn't want to mess with selectable lockers with pumps or cables. I've had a Detroit auto-locker in a prior rig and although a full locker is superior off-road, it really sucked driving it on road. All that throttle steering and clicking & banging isn't where I want to go with my Bronco. So I installed a built third-member with all new gears, bearings, seals, and a Detroit Truetrac mechanical LSD. I also swapped in a set of 31 spline axles and rear disc brakes while I was at it.
The Truetrac is definitely a different animal. Inspecting the unit, it has a surprisingly small housing with a contained box of gears inside where the traction magic happens. Also unlike a conventional clutch based LSD which is more like an open diff with ability to lock-up, the Truetrac seems to be more locked with an ability to slip instead. On the jack stands, both wheels would turn in the same direction, and turning by hand I could not invoke a slip of the LSD.
On the road the interference from this LSD is entirely unnoticeable. There are no impacts with normal turning and powering in/out of curves, no obnoxious noise from the rear-end, and no noticeable transfer of power between the rear drive wheels. Only in a parking lot doing slow doughnuts at full steer-stop, only then did I get a little bit of a chip from the inner tire trying to lock up. The traction add on the road is significantly improved. As hard as I tried, I could not spin the inner tire. Instead, when you mash on the throttle accelerating out of a turn, you're quickly launched forward without the slightest hint of lost traction where you would have otherwise broke loose. With meaty 33x12.5 tires, it's almost scary how much traction is available. By all accounts this LSD is very well equipped for on-road use and I couldn't be happier with the performance on the street.
For off-road impressions, I headed up to my favorite drainage ditch up the road. It's just deep enough that when you hit it at an angle and wedge the Bronco in there, you'll end up with 1 rear tire and the opposite front tire in the air. Granted not a true off-road test but definitely good for evaluating traction when you have an open wheel. Obviously with an open rear diff, as soon at that tire leaves the ground you're done and have zero traction. With the Truetrac things work a bit differently. The LSD is designed to transfer power to the wheel with slip assuming that wheel has "some amount of resistance (traction)". In an open wheel situation where there is zero resistance, the LSD did what it could and the wheel with traction was grumbling, chirping, and flinging dirt but simply wasn't receiving enough percentage of power to clear the ditch. It wasn't until I depressed the brake enough to slow the open wheel that forced the transfer of power to the wheel with traction and let me crawl out of the ditch in 2wd. For off-road it's definitely a different driving style and from what I understand falls in-line with conventional LSD behavior (brake manipulation). I would say the LSD is likely best for snow, mud, or general slippery conditions. For rock-crawling where you end up with flexed out open-wheels, skip the LSD and go straight to a full locker.
Overall I'm really pleased by the Truetrac. Onroad the LSD adds some sport and performance with the noticeable improvement in traction with little to no side-affects. Off-road the LSD works well (certainly better then open) but falls short of a full locker counterpart. Personally I think I'm going to use a full auto-locker in the front to help compliment the LSD in the rear.
And some pics....
The Truetrac is definitely a different animal. Inspecting the unit, it has a surprisingly small housing with a contained box of gears inside where the traction magic happens. Also unlike a conventional clutch based LSD which is more like an open diff with ability to lock-up, the Truetrac seems to be more locked with an ability to slip instead. On the jack stands, both wheels would turn in the same direction, and turning by hand I could not invoke a slip of the LSD.
On the road the interference from this LSD is entirely unnoticeable. There are no impacts with normal turning and powering in/out of curves, no obnoxious noise from the rear-end, and no noticeable transfer of power between the rear drive wheels. Only in a parking lot doing slow doughnuts at full steer-stop, only then did I get a little bit of a chip from the inner tire trying to lock up. The traction add on the road is significantly improved. As hard as I tried, I could not spin the inner tire. Instead, when you mash on the throttle accelerating out of a turn, you're quickly launched forward without the slightest hint of lost traction where you would have otherwise broke loose. With meaty 33x12.5 tires, it's almost scary how much traction is available. By all accounts this LSD is very well equipped for on-road use and I couldn't be happier with the performance on the street.
For off-road impressions, I headed up to my favorite drainage ditch up the road. It's just deep enough that when you hit it at an angle and wedge the Bronco in there, you'll end up with 1 rear tire and the opposite front tire in the air. Granted not a true off-road test but definitely good for evaluating traction when you have an open wheel. Obviously with an open rear diff, as soon at that tire leaves the ground you're done and have zero traction. With the Truetrac things work a bit differently. The LSD is designed to transfer power to the wheel with slip assuming that wheel has "some amount of resistance (traction)". In an open wheel situation where there is zero resistance, the LSD did what it could and the wheel with traction was grumbling, chirping, and flinging dirt but simply wasn't receiving enough percentage of power to clear the ditch. It wasn't until I depressed the brake enough to slow the open wheel that forced the transfer of power to the wheel with traction and let me crawl out of the ditch in 2wd. For off-road it's definitely a different driving style and from what I understand falls in-line with conventional LSD behavior (brake manipulation). I would say the LSD is likely best for snow, mud, or general slippery conditions. For rock-crawling where you end up with flexed out open-wheels, skip the LSD and go straight to a full locker.
Overall I'm really pleased by the Truetrac. Onroad the LSD adds some sport and performance with the noticeable improvement in traction with little to no side-affects. Off-road the LSD works well (certainly better then open) but falls short of a full locker counterpart. Personally I think I'm going to use a full auto-locker in the front to help compliment the LSD in the rear.
And some pics....
