I just don't get it

[grand_wag_85]

Just rebuilt the quadra-trac in my Cherokee. All went well, new chain, good differential but only 90 miles down the road the chain slips, there's a grinding noise from the low range unit and the diff is acting like an open differential instead of limited slip.

There's plenty of fluid and I know I did everything right but I just don't get it. I've rebuilt nearly a dozen of these things.

[Gambler68]

Just rebuilt the quadra-trac in my Cherokee. All went well, new chain, good differential but only 90 miles down the road the chain slips, there's a grinding noise from the low range unit and the diff is acting like an open differential instead of limited slip.

There's plenty of fluid and I know I did everything right but I just don't get it. I've rebuilt nearly a dozen of these things.

Bad angle in the mounting somewhere perhaps? Broken bolt or something? If you're that confident in your QT rebuilding skills, maybe look at other factors.

Right before we went to Moab last spring, I noticed some oddness and Flint crawled under there..I was missing bolts in the mounts, half the QT->Th400 bolts were loose/finger tight..etc. Bad stuff :(

[grand_wag_85]

Will check that, thanks Ryan.

[Headhoncho]

That stinks. I hope it's not a total loss for you.

I'm sticking with my gear drive 205 all the way.


JR

[FSJ Guy]

How is it acting like an open diff? Do you mean it's acting like a slipping transmission??

The only way the diff could fail is if the splines on the side gears were bad. Remember, the splines on the cones only enable the limited slip portion of the diff. The diff will still function if the cones' splines are bad.

Noise from the low range unit is bad. If that goes out, you have NO power transfer from the transmission to the transfer case. You didn't by chance install that bad one, did you? :eek:

What was the chain slack when you tested it?

[grand_wag_85]

Ethan-
The low range and case I've been running in 2 different Jeeps since July and I've had no problems until now. The chain was brand new, and the diff is acting like a slipping trans. The diff was one of the ones I got from you, looked good and worked good right after it went in.

I'm just stumped because I've never seen or heard of anything like this happening so quickly. I know these things pretty well but still...

[grand_wag_85]

Just tore the case down and found something scary. Everything looked burnt. The fluid was still somewhat clear but the differential looked like it had been thrown into a fire and it took a prybar to free it from the front output shaft splines.

One other thing, don't know if it's related. This transfer case has always gone into neutral when you really nail the gas, on the trip this morning it kept going into neutral if barely any gas was applied:confused:

[fulsizjeep]

I am just throwing out some thoughts here Sean...

Are all your tires the same size? Same brand? Your front axle has been engaged right? Like manual hubs not locked or one locked and the other not? Did you get roughly 2 or more quarts of fluid when you drained it? Sounds like the LSD was worked to a point of overheating.

The neutral thing... We had an occasion where the tranny mount was flattened out and basically worthless. In the Wagoneer, the fuel tank would get tapped by the QT linkage and throw it in neutral when you hammer the throttle. Other than that, sounds like something worn out in the low range unit.

[grand_wag_85]

Yup, all 4 tires are 31x10,5's. No locking hubs and got 2ish quarts of fluid drained out.

The planetary gear thing for the low range unit seems to be the culprit, one gear is completely shaved and the rest are worn down. The output shaft bearings look like they seized and melted all to one piece. Definately wierd whatever the heck happened.

Oh well.

[janie]

Just tore the case down and found something scary. Everything looked burnt.


Sean, just a female's point of view, but when things seize up and look burnt, I automatically think "no dayum fluid"

Sure not trying to say you missed anything, because it definitely sounds like you covered your bases. Usually when I screw up (which happens more than I like) it's normally because I've forgotten the most simplest/obvious things.

I'll keep my fingers crossed you wake up tomorrow morning and say "dadgummit I forgot to....... and you'll have your answer.

Keep us posted.

[J4GRAND]

The planetary gear thing for the low range unit seems to be the culprit, one gear is completely shaved and the rest are worn down. The output shaft bearings look like they seized and melted all to one piece. Definitely weird whatever the heck happened.

You did fill the low range with about a 1/2 quart of fluid then the main unit? It sounds as if there was a lack of fluid (for whatever reason) to the low range.

[FSJ Guy]

I'd replace that low range unit. I bet your diff is fine.

And yes, I know that's easier said than done with the gas tank in the way of the low range unit!

[grand_wag_85]

I filled the low range unit before I installed it but I *think* I just solved the mystery. There's a rubber ring that seals the low range unit, part of the ring had pulled out of the groove towards the top and I didn't realize this. The low range unit went on a bit crooked and was fine for about 40 miles. This caused the 'C' clip for the planetary gears to fail and the ring that they sit in rubbed against the lower part of the case. All of this caused heat& vibes that loosened the bolts for the low range unit. From there it's anybody's guess.

Awesome 4WD just a b**** to work on:banghead:

[fulsizjeep]

OH ***, the **** thing lunched itself floating in the narrow ****ing gap. Since the tranny drives the Jeep through that union, much torque wiggle could result. Ouch ****it. :(

[grand_wag_85]

Eh, when you play with fire sooner or later you're gonna get burnt up.;)

[FSJ Guy]

Ouch. Yup, that low range unit has to be installed straight. BTW, fill the low range unit AFTER you install it on the t-case. Otherwise, all the fluid will just pour out when you "turn it sideways" to install it. Once you get the planetary gears to align, it should slide ALL the way on very smoothly without any resistance.