97 ZJ vibration on braking

All of a sudden my 97 ZJ 5.2 Up-Country with not quite 90K miles has started shaking during braking at around 50 MPH. At 65 no vibration, at

30 no vibration, but if I hit the brakes at 65 it goes through a period of vibration around 50 mph (that number's not exact) and then stops vibrating as it slows. Does not seem to be specific to or alleviated by turning.

It's had the brake rotor recall. Had new pads and rear rotors a year ago and no problem since until just now. Front CV joints need replacement (boots gone on both) but that's been so for some time (noticed it when I changed the pads but haven't had a chance to do it yet). Put new shocks in a week ago and the vibration seems to have started then. I have a new steering damper in the box in the garage--was going to change it with the shocks but life intervened.

Seems to me that the procedure to follow is replace the steering damper, since the part is paid for already, then the CV joints since they need it anyway, and then go on from there.

That said, do the symptoms described suggest any specific problem to anybody? Or something else I should do on general principle while replacing the steering damper and CV joints?

Thanks.

Reply to
J. Clarke
Loading thread data ...

CV joints can cause vibrations but usually they just pop as you turn a corner. Clean them out, check for wear, and you might not need to do anything more than put new grease and a new boot over them.

With the age of your vehicle I'd be checking the lower control arm bushings for wear. The main wear point is the front.

formatting link
While it's possible to replace bushings only it's FAR easier to simply buy and install newer lower control arms. This is something you will need to do on a lift because those bolts get torqued to 130 ft.lbs and that needs leverage. (or air tools)

Reply to
DougW

Do not torque bolts with airtools!!!!

Let me repeat that

DO NOT TORQUE BOLTS WITH AIRTOOLS!!!!!!!!

Airtools ( impact wrenches) are inconsistent and usually over torque a fastener .... and who wants a bolt snapping while rolling along at 70 mph? I had to replace 5 lug bolts on an RV (Dana 70 dual tire axle) because of some idiot with an impact gun if you don't think they can be over tightened... and those were 5/8" studs compared to your Jeep's roughly 1/2" studs.

Personally, I prefer a flex beam or dial indicator type torque wrenches, but in tight spots a click type is acceptable.

Btw, for a 130 ft/lb torque, use a long 3/4" drive torque wrench for reducing the pull on your muscles and for accuracy.

Reply to
C.L. "Budd" Cochran

Just adding my experience with a somewhat related vibration problem. '00 XJ front end started shaking at around 50 mph and I had to brake immediately to slow down and stop the shaking. It was ok below 50 and ok above. Had an alignment done and rotated the tires and it got worse! Replaced the steering damper and balanced the tires. Problem solved. I am now looking to replace the Mickey Thompson Baja's with a more road friendly tire. Looking at the Michelin M/S2

Steve

Reply to
Steve

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.