Upgrade Differential?

SBosco · **Posted:** Thu Sep 30, 2010 12:40 pm

I had to replace my rear brake pads at less than 40,000 miles. I found that odd (especially because I am used to the fronts going first), but figured the cause might be because the traction control uses the rear brakes? I can imagine the large low-end torque production is one of the culprits of the traction problem (aside from my addiction to it :BANANA:

). I have since been turning off the traction control and driving as I normally do to see how frequently the tires would break traction otherwise. I have noticed it happens pretty frequently with my driving style. :roll:

Most of my traction problems stem from accelerating from a stop or at low speeds around turns. I have found it to be really quite easy to lose traction from the rear tire(s), in the rain it's pretty pitiful actually (and these tires have more grip than the OE tires did). When I do break traction, only 1 tire spins so I was thinking maybe the solution to my problem would be to upgrade to a better differential. I have no real need for a locker, but maybe a really good limited slip/posi-traction/etc.

Does anybody have any experience with effective differential upgrades? Any info/recommendations/thoughts/etc. would be greatly appreciated.

LibertyCRD · **Posted:** Thu Sep 30, 2010 1:54 pm

I find it very difficult to spin the tires. So you must have a lead foot, or bald tires, or really slick pavement up there.

I have found NO limited slip units that I have ever liked. They don't seem to work well in my opinion. What I do think is awesome is the Powertraxx "No-Slip" unit made by Richmond Gear. It's a true locker, but it behaves like a limited slip on the road. So it's smooth, but will ensure that both tires are pushing the Jeep at ALL times. During curves and turns you don't notice any harshness either really. It's just a really nice unit and I'd love to get another one.

tjkj2002 · **Posted:** Thu Sep 30, 2010 2:27 pm

Stay away from a lunchbox locker,powertrash and aussie,as they are not very strong and the variances in the 8.25(more so for the '05 and '06 models years) can trash one in short order.You will need to change your driving habits,they will be noisy,wear tires out faster,and are fairly weak as they only replace the spider gears in the OEM carrier,all fact no matter what anyone tells you.

The best LSD on the market is the Detroit TruTrac,works very well and is 100% street friendly and ice friendly,though better in a front application then the rear.The Detroit locker is very good but if you see snow a auto locker is not a good choice(same as a lunchbox locker) and you will have to change your driving habits and will trash your rear tires faster(even with rotations).The last option and the most expensive is the ARB air locker,100% invisible on the street and with a flip of a switch your are fully locked in the rear.

Then don't forget axles,Yukon makes HD axles for the 8.25,can not be used for '06's though as they changed the axles to have tone rings on them for ESP.

LibertyCRD · **Posted:** Thu Sep 30, 2010 2:59 pm

If the Powertraxx No-Slip unit can handle my 5,600 lb. quad cab Ram 1500 offroad... I think it can handle a Jeep Liberty. :mrgreen:

I've run that unit as well as the Aussie Lockers and I have NEVER had a single issue with any of them. They work well and save a ton of time and money. I twisted up my ZJ pretty good on the trail and the Aussie locker never let me down. My Ram pushed the Powertraxx pretty hard and it never let me down. It was also VERY quiet... I didn't even know it was back there. And it did not wear my tires at all, since it's designed to let the outer tire freespin around turns.

We must have had different "lunchbox" lockers.

CATCRD · **Posted:** Thu Sep 30, 2010 3:49 pm

SBosco wrote:

Does anybody have any experience with effective differential upgrades? Any info/recommendations/thoughts/etc. would be greatly appreciated.

I upgraded to the Detroit Truetrac from the factory LSD and it's way better. When you goose it from a turn you may get one slight chirp from the inside tire and then the diff just grabs tight and you're off like a bullet. I can even make the back end drift out on dry pavement. It's totally transparent on the street - no clicking or jerking, and it really hooks up off road. Most of us do 98% of our miles on the street, whether we like to admit it or not, so a full locker in the rear just did not make sense to me, given the reviews on this site about driveability.

DarbyWalters · **Posted:** Thu Sep 30, 2010 4:18 pm

The DTT in the rear would be a great choice. If you put one in the front, it will cause your steering feel to be extremely heavy when in Full Time. The rear one would be a no brainer...wroks great.

ATXKJ · **Posted:** Thu Sep 30, 2010 7:43 pm

I've got DTT's front and rear - front is awesome in the snow
(not much around here but we find Colorado occasionally)

rear has the same concern I think the lockers have - if you break the tire loose on one side - the torque transfers and odds are you'll spin both - especially an issue if the turbo boost is kicking in.......

SBosco · **Posted:** Thu Sep 30, 2010 9:42 pm

Excellent feedback everybody!!! :pepper:

It's great to hear everybody has had favorable results with the Eaton Detroit TrueTrac. That was the one I was leaning towards anyway...I liked the traits of smooth and automatic engagement, with no clutches to wear out, or special additives.

I have no doubt that a locker is superior in certain ways, but It's a little overkill than I think I need for my purposes.

The cheapest I have found the TrueTrac for is about $500 shipped.

http://c-comp.com/product_info.php?products_id=238

But I don't have much experience with internal work on rear ends, so I'm not too sure exactly what I would need parts-wise. I can't think of anything besides just the differential itself, and a shim kit. I have enough AMSoil Severe Gear oil for one more fill on each axle, and have the lubelocker gasket which is allegedly reuseable.

Does anybody know if the TrueTrac will interfere with the traction control/ESP?

tjkj2002 · **Posted:** Thu Sep 30, 2010 10:32 pm

SBosco wrote:

Excellent feedback everybody!!! :pepper:

It's great to hear everybody has had favorable results with the Eaton Detroit TrueTrac. That was the one I was leaning towards anyway...I liked the traits of smooth and automatic engagement, with no clutches to wear out, or special additives.

I have no doubt that a locker is superior in certain ways, but It's a little overkill than I think I need for my purposes.

The cheapest I have found the TrueTrac for is about $500 shipped.

http://c-comp.com/product_info.php?products_id=238

But I don't have much experience with internal work on rear ends, so I'm not too sure exactly what I would need parts-wise. I can't think of anything besides just the differential itself, and a shim kit. I have enough AMSoil Severe Gear oil for one more fill on each axle, and have the lubelocker gasket which is allegedly reuseable.

Does anybody know if the TrueTrac will interfere with the traction control/ESP?

The DTT works better with dino gear oil,actually Eaton highly discourages synthetic oil use with any of there LSD's/lockers for proper operation.

MOSFET · **Joined:** Sat Feb 25, 2006 11:40 pm **Posts:** 295

I have the Powertrax no-slip in a Dodge Ram, and it has worked great. However, you will get some chirping around tight corners if you step on it. I have learned to be easy on the gas around tight corners.

Traction has improved 100%.

LibertyCRD · **Posted:** Fri Oct 01, 2010 2:44 pm

And not only is the Powertraxx cheaper to purchase, but it also cuts your cost significantly if you are planning to have a shop do the install... because with the Powertrax, you don't have to remove the carrier and reset all your specs. Just pop the spider gears out, and pop the Powertrax in. So basically, the Powertraxx for most people will cost 100-110% less money and will work just as well.

SBosco · **Posted:** Fri Oct 01, 2010 2:56 pm

Thanks for the advice, but I am planning to do the installation myself. So, I'm not as concerned with the complexity of the install as much as I am with the end resut and material costs.

CATCRD · **Posted:** Fri Oct 01, 2010 5:26 pm

SBosco wrote:

Thanks for the advice, but I am planning to do the installation myself. So, I'm not as concerned with the complexity of the install as much as I am with the end resut and material costs.

Do you know how to set gear backlash and preload? If not, I would not want to learn on my daily driven diff. Budget for a new set of carrier bearings (~$100) if you want a refresh, or don't want to pull the old ones off the old diff. I'm a total DIY guy, but I took mine to a shop.

DGM635csi · **Posted:** Fri Oct 01, 2010 7:03 pm

I have experience with the Detroit true trac. I had one for 3 years in my old cherokee and its far superior to a clutch type limited slip IMO. It worked flawlessly and quietly, and the performance never degraded over time. I used is heavily off road, and abused it on pavement with no Ill effects. The only disadvantage is if you get one tire completely off the ground, there is no internal load in the differential, and it wont want to lock up. You can fool it pretty easily by lightly applying the brakes while applying throttle. This usually made it lock up enough to get over the obstacle.

I have also had experience with the powertrax units in other peoples rigs. They are quick cheap fix for having no traction device, but you get what you pay for. They are noisy, clunky, and very jerky on the road. As soon as you apply a moderate load, they lock up 100% so its like driving around corners with no differential at all, and your inside tire is chirping while your whole rig fights its way around the corners. If I drove on dirt %100 of the time, this might be OK, but not for the street. They are also very hard on your factory carrier and bearings. I will also note that they acted very unpredictably, almost dangerously in slippery conditions (ice + snow). I am a fan of oversteer, but not when I cant control it.

I am also a total DIY guy, but i did have somebody with far more differential experience than me install the differential in order to make sure that the gears were lashed correctly. It kind of an art, and I sure wouldnt want to risk destroying a set of gears by doing it myself on the garage floor.

After I installed the DTT with new gears and new bearings, I broke the diff and gears in with 75w90 dino gear oil for 5000 miles. Then I switched back to Redline synthetic 75w90. The differentials performance was the same with the synthetic fluid, but my mileage went up about 5-7% during the winter. Personally, the anti - synthetic gear oil "movement" is a bunch of BS. Synthetic oils are far superior to mineral oils in every way. The science behind synthetics has been tested and validated for more than 70 years, and if somebody had gear or bearing failure when using synthetic oil, there's a 99% chance that it was attributed to something else other than the fact that they were using synthetic oil. HAving saif that, do not use synthetic oil for break in, and remember that a much thinner synthetic oil can be used to achieve the same level of protection as a much heavier non-synthetic. Using an oil that is too thick for your application can cause premature component failure. This applies to synthetics especially since they dont thin out as they heat up, and oil that is too thick will not lubricate properly.

tjkj2002 · **Posted:** Fri Oct 01, 2010 8:52 pm

DGM635csi wrote:

After I installed the DTT with new gears and new bearings, I broke the diff and gears in with 75w90 dino gear oil for 5000 miles. Then I switched back to Redline synthetic 75w90. The differentials performance was the same with the synthetic fluid, but my mileage went up about 5-7% during the winter. Personally, the anti - synthetic gear oil "movement" is a bunch of BS. Synthetic oils are far superior to mineral oils in every way. The science behind synthetics has been tested and validated for more than 70 years, and if somebody had gear or bearing failure when using synthetic oil, there's a 99% chance that it was attributed to something else other than the fact that they were using synthetic oil. HAving saif that, do not use synthetic oil for break in, and remember that a much thinner synthetic oil can be used to achieve the same level of protection as a much heavier non-synthetic. Using an oil that is too thick for your application can cause premature component failure. This applies to synthetics especially since they dont thin out as they heat up, and oil that is too thick will not lubricate properly.

Right from the experts.............

Quote:

What kind of oil should I use? Can I use synthetic? Do I need friction additive/modifier?
A quality petroleum/mineral based oil works best in the Truetrac units. We do not recommend synthetic oil. Friction additive/modifier is not required.

http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Differentials/FAQ/index.htm

Synthetic gear oil is subpar to dino gear oil as most major aftermarket diff companies and even Eaton/Detroit discourages synthetic gear oil use.There are reasons for synthetic gear oil use,and that is mpg's and that is it.

SBosco · **Posted:** Fri Oct 01, 2010 11:07 pm

CATCRD wrote:

Do you know how to set gear backlash and preload? If not, I would not want to learn on my daily driven diff. Budget for a new set of carrier bearings (~$100) if you want a refresh, or don't want to pull the old ones off the old diff. I'm a total DIY guy, but I took mine to a shop.

CATCRD wrote:

I am also a total DIY guy, but i did have somebody with far more differential experience than me install the differential in order to make sure that the gears were lashed correctly. It kind of an art, and I sure wouldnt want to risk destroying a set of gears by doing it myself on the garage floor.

I would certainly not attempt it if I wasn't confident that I could handle it...I considered the HUGE screw up possibility for a daily driver. This is why I am recruiting the help of 2 old friends who have plenty of experience with chevy 10 and 12-bolts and ford 9-inchers. They were both on different drag racing teams back in the 60's and worked predominantly on camaros, chevelles, etc.

However if anybody here would like to participate and/or be an audience to the procedure then, by all means, you're welcome to stop by and I'll even supply some "beverages" and snacks. :5SHOTS:

CATCRD · **Posted:** Sat Oct 02, 2010 12:07 am

Sounds like you've got it covered. Enjoy the DTT!

MustangPunk · **Joined:** Sat Oct 02, 2010 2:44 pm **Posts:** 11

SBosco wrote:

Does anybody know if the TrueTrac will interfere with the traction control/ESP?

Yeah, a locker or limited slip I would think will mess with the ESP somewhat, could be a waste to install being ESP/TCS is supposed transfer torque to the wheels with the most traction anyways. Not saying they won't work, but ESP/TCS, will apply braking to one side of the axle(spinning), and power will then be sent to the opposite wheel(with traction, hopfully lol) because of the open diff's spider gears. If a locker or limited slip is installed and engaged, both axles spinning together, with ESP working it may apply brakes to both axles, that being said though, I'm not sure if it's 3 channel or 4. So it maybe braking both axles already anyways. I thought I read somewhere, even with the ESP off on the steering column, it still functions, just not as much. Pretty much I don't see my CRD doing massive posi burnouts, anytime soon.

lol

tjkj2002 · **Posted:** Sat Oct 02, 2010 8:04 pm

A good LSD like the DTT or a locker(when locked) will actually lessen the activation of ESP and the traction control in a good way.No harm will be done by adding one with ESP or traction control.

spymoto · **Posted:** Mon Dec 06, 2010 12:26 am

I just installed my Powertrax, No-Slip in my Kj and it works great and NO noise at all! I used synthetic 75w140 oil in the rear diff, so that could possibly be why. I love it! I would recomend it.

Upgrade Differential?

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