Help!!! Front end binding up

Hillbillyd · 08-13-2006, 11:37 AM

Hey guys, I haven't posted much here but have read quite a bit. I have a problem that is driving me crazy. In January, I started to take my 1995 Grand Cherokee to Minnesota to pick up a motorcycle. I didn't make it 3 miles on the interstate before I felt MAJOR thumping in the Jeep and pulled over thinking I had a flat tire. Nope. I started on the road again, just a mile or two and same thing happened so I turned around and eased it home. I can pull over, stop, and take off again without the thumping for just a minute, then it starts all over again. I replaced the u-joints in the rear driveshaft thinking that may be it. Nope. Next I removed the front driveshaft and drove it for a couple of months with no thumping. I have replaced the front axles as well. Took it to a shop that suggested changing the front driveshaft. That did not fix it either. With the driveshaft in, it makes the thumping noise and feels like the front end is trying to bind up. You can faintly hear the tires squalling on the highway as well. I can shift the transmission and transfer case into neutral and it does not stop until the vehicle stops. My latest attempt at fixing it was changing out the spider gears on the front end since they looked kind of rough. The bearings looked ok on the carrier so I did not replace them. It did not fix it and I am now completely stumped. What could be causing this problem?

Thanks in advance, any advice is welcome!

**Woody** · 08-13-2006, 11:44 AM

I'd take the DS to another shop and have them check it's balance. That's usually the case when it's doing what you describe.

jeep946 · 08-13-2006, 11:53 AM

something to check... is the pinion gear loose. i had the same type of noise. withe drive shaft in try to move the pinion around if it move just tighten the nut up and see if that helps. you might need to replace the outer pinion bearing as well.

97JeepZJ · 08-13-2006, 12:34 PM

my ZJ did the same thing, pull the FT cover and check the ring gear my was doing that and when i pulled the cover the ring gear was missing some teeth so i put new r/p in and its been fine just make sure you clean out the pumkin really good so you dont leave any chunks of metal behind. good luck

Hillbillyd · 08-13-2006, 01:20 PM

Thanks for the replies. Ring and pinion looked good, I'll check pinion nut to see if it's loose.

Hillbillyd · 08-13-2006, 05:56 PM

Pinion nut is fine. I removed the front driveshaft for now. Works ok like that for some reason. I removed both driveshafts for a test though. Started the Jeep and put it in drive and ran it up to 70mph or so for extended time. Never made the thumping, but then I simulated a load by letting the rpms drop then nailing the gas over and over. It made a knocking sound in the transfer case every time I did this, but I'm not sure if that's normal or not. The transfer case sounds pretty noisy to me (kinda like rough bearings) but since it is a chain driven transfer case, I'm not sure how much noise is normal.

Anyone else got any input?

Thanks

**Woody** · 08-13-2006, 06:03 PM

That's not something you should do to your T-case. It's really hard on it.

You never said which type of T-case you have. If you have a NP249 (quadra trac) you probably have a burned up viscous coupler. It's cheaper to put a NP231 or NP242 in place of the 249 than it is to get a new viscous coupler.

If you have a NP242 (select trac) or a NP231 (command trac) you probably need a new chain. I just did mine and it doesn't take long and is fairly inexpensive. You'll probably find that with that you'll loose some clunking, but if you still have a thumping, your DS is out of balance or a joint is binding.

Hillbillyd · 08-13-2006, 06:43 PM

Quote:

Originally Posted by Woody

That's not something you should do to your T-case. It's really hard on it.

You never said which type of T-case you have. If you have a NP249 (quadra trac) you probably have a burned up viscous coupler. It's cheaper to put a NP231 or NP242 in place of the 249 than it is to get a new viscous coupler.

If you have a NP242 (select trac) or a NP231 (command trac) you probably need a new chain. I just did mine and it doesn't take long and is fairly inexpensive. You'll probably find that with that you'll loose some clunking, but if you still have a thumping, your DS is out of balance or a joint is binding.

Thanks for the info. I have the NP249, so I guess I should assume it is the viscous coupler you mentioned. Guess it's time to trade the old bird off, I don't want to sink any more money in it. I need a truck anyway.

08-13-2006, 11:53 AM	#3
jeep946 Registered User Join Date: Feb 2006 Location: Indianapolis, Indiana Posts: 466 Profile Gallery Classifieds My Jeeps	something to check... is the pinion gear loose. i had the same type of noise. withe drive shaft in try to move the pinion around if it move just tighten the nut up and see if that helps. you might need to replace the outer pinion bearing as well. __________________ 94 Grand Cherokee, 4.6 stroker, 7 inch custom long arm kit, 33x12.50x15 Firestone destinations m/ts, flow-master 40 series, magnaflow high flow cat, locked front and rear, super axle kits front and rear, pioneer head unit, CB on channel 10, and a B&M built transmission, switched from a 231 to a 242, 2000 Grand Cherokee steering and knuckles and brakes, no abs, wildwood adjustable proportioning valve, and lots more

08-13-2006, 12:34 PM	#4
97JeepZJ Registered User Join Date: Aug 2006 Location: Syracuse, NY Posts: 45 Profile Gallery Classifieds My Jeeps	my ZJ did the same thing, pull the FT cover and check the ring gear my was doing that and when i pulled the cover the ring gear was missing some teeth so i put new r/p in and its been fine just make sure you clean out the pumkin really good so you dont leave any chunks of metal behind. good luck __________________ 97 ZJ V8, 9" longarms, 35" MTR`s, ARB ft bumper, TR rear bumper, Arb lockers, supper 30 kit with lockouts in the ft. ( the ZJ was 2wd when i started ) and a lot more !!!! ( MY JEEP HAS A MONEY PROBLEM )