super d

Hey yall I am brand new to this forum and of course I have a question or two. So here we go......

This is my beast at Jackass Meadows CA

its a 97 Grand Cherokee Laredo , 5.2L , quadratec full time 4WD, np249 TC with 148,000 miles. All stock except 30/9.5 tires. I have owned it for 8 years.

Here is the problem which just showed up today, when appling the brakes I here a slight thumping and it feels like slight binding in drivetrain when slowing to a stop. I think it is in the back end or the transfer case and the wife thinks its up front, very hard to tell .

It happens in drive and when the trans is in neutral and the tranfer case is in 4 hi and 4 lo. The thump thump seems to happen with every revolution of the wheels and is more pronouced right before I reach a full stop, but only when on the brakes not under power or coasting . All of the u joints and CV's seem ok to me. It does not matter if I am going straight or turning. There is no pulsing at the steering wheel and does not pull to either side . Otherwise the jeep operates fine with no other problems.

This last weekend I put new tires on it , new rear rotors and pads (I dont think the rear brakes were even working before I did that) ,bled all 4 brakes, oil change, new alternator, new idler and tension pulleys as well as a new belt.

Both front half shafts I replaced over a year ago.

I am a decent home mechanic but have never had any diff or TC experience.

Is the transfer case or something else about to explode? Or could this be a weird brake problem ?

Any help is greatly appreciated !

Thanks

D

Bustedback

Make sure the caliper bolts are tight and that the calipers are seated correctly, other than that it's hard to tell over the net.

4.3L XJ

Do you feel any of it in the brake pedal?

super d

I will check the calipers tonite when I get home, although they looked fine thru the wheels last night . I am also thinkin about measuring the rotors I got from autozone to check for warpage.



Nope I feel nothing strange in the pedal/steering wheel when its happening.

retread

it's most like;y not a wierd brake problem but a relatively common one. likely a warped rotor

tiwvr1

backing plate rubbing the rotor maybe? for checking u joints, and this works for bushings also, look for powdered rust around the joint, if it looks like a orange powder, then its bad. Means metal on metal with no lube. Not sure if thats your problem or not, but good info for the future.

super d

Thanks for the replies .

ok so i got home and took both rear calipers and rotors off and everything was ok. I took it for another test drive and found that it only seems to be noticable under med-hard to hard braking but not close to locking up.

I forgot to measure the rotors for warping but I saw no hotspots or anything out of the ordinary and they are brand new rotors and pads(rears).

possible points of interest

1. the brakes have sucked for years, the R/R rotor was extremly groved for along time. the R/Lft looked ok.

2. since my new rear brake job and bleed this weekend, it stops remarkably better. So maybe I never noticed it before.

3. I had a brain fart taking the first (R/R) rotor off this weekend,the bad one, I thought it was seized on because I couldnt get it off. I tried prying lightly which progressed into beating the crap out of it with a 5 LB hammer with no luck and then I realesed the E-brake!!!!! and it came off easily . I know what a dumb ***. Maybe I damaged the ABS sensor? I doubt it.

4. when jacking it up today I could actually see the lower arm rear bushings move around quite abit. I know all the bushings are shot but keep convincing myself to wait till I get the 3.5 to 4 inch lift to do bushings and ball joints. Shocks are toast and it steers like a boat .

5. the ABS light has been on since I got it 8 or so years ago, but the ABS seems to work .

6. thumping/slight binding presents itself only under hard but not full braking.

7. I think I can feel it with my hand on TC shifter but not 100% sure.

8. I think I hear it in the R/R wheel and Trans/TC area.

My next plan of attack is to strap my helmet cam under the back to see if the bad bushings are causing the the rear axle to rotate back and forth, and look for the red rust on the joints.

AAARRRGGGGHHHH!! so frustrated cause I was nice to it and dumped 1300 bucks into it this weekend and some other problem shows up wtf !!

beers and wrenching makes for a long-winded ,TMI post.

Thanks again for your suggestions and help.

super d

I didnt see a pic forum so ...

tiwvr1

Hmm, forgot bout the ebrake shoes. Pull the rotors off again and check the ebrake shoes good. I have seen those shoes seperate and cause all sorts of wierd noises. Also adjust the shoes so they arent as close to the inside of the rotor hat. and make sure the very inside of the hat of the rotor isnt hitting the rusted metal backing plate.

super d

yep the e-brake pads are toast, very thin on material and whats left is cracking. replacing them this weekend.

I believe I have found the problem.......really really worn bushings on the control arms. , with the e-brake on I put my had on the top of the rear tire and try to rotate the wheel and I can see the whole axle twist enuff to see the pinion move 1 1/2 inches up and down, it looks no bueno.

so now I have to decide weather to save for the lift or just start replacing bushings one by one.

still gonna try the camera deal to see if I can see it happen when under hard braking.

thanks yall

biggene

I would be willing to bet that right there is going to be your main issue. My wife's 99 GC was making a clunking noise when you backed up and stopped, then switched into drive, and I could have sworn it was coming from the driver's rear. Turned out to be the passenger front upper ball joint, lol.