kbeam418

My xj has an odd quiet thump when on bumpy roads. I've checked every single suspension component front and rear everything is tight (all the control arms are new lucky me!). The only thing I think it could be is the back seat or bad shocks. Does the back seat normally make noise? I don't think it's shocks because none of the corners bounce more than once when I push down on each corner but they are rusty and the bushings look cracked.

fb97xj1

Is the backseat locked down? Could be barely holding and rattling a little? If the factory jack is still under the back seat, check that. Check the exhaust hanger next to the gas tank. If the hanger rots off and the pipe is too close to the leafspring, youll hear it. The bar pins in the upper shock mounts can shift if the bushings are shot. Check the rear sway bar if you have one. Not all XJ have one. Just start grabbing stuff and see if it moves. Wear safety glasses. All it takes is one piece of dirt to send you to the ER.

kbeam418

It's the shocks I got the old ones out I'll upload some pics of the old ones they were trashed. I'll be putting some nice new Gabriel Ultras on tomorrow would've got it down today but I got too short of bolts for the upper mounts. 1/4x1-1/2 grade 8 bolts should work I'm thinking. Drilling those old bolts out was fun took me 30 minutes per side.

Tbone289

It's a little too late now, but the typical fix for the rear mounts is to knock out the weld nuts in the rear with a punch and replace them with a bolt down from the top or flag nuts like this made specifically for the purpose:

http://www.roughcountry.com/jeep-xj-...-nut-1082.html

I just wanted to mention this for anyone who reads this in the future with the same issue that most of us have to eventually deal with...

kbeam418

Yep I used one inch (grade 8) bolts going from the TOP. I tried taping a nut to a wrench going through the "access hole" now I've got a stuck bolt to get out.

Are quarter inch bolts strong enough?

Tbone289

I just bought the largest bolt that would fit through the upper shock mount, and I'm pretty sure they were the same size as the OEM ones that were rusted in there. I don't remember what size it was, but I haven't had any issues.

fb97xj1

Bolts were 5/16 x 18 on my 97. I think 3/4" long.

kbeam418

Picture as promised;

kbeam418

New shocks are in! I used 1/4 grade 8 bolts, tied some safety wire to them and pulled them through worked like a charm! I used two grade 8 nuts (didn't have any lock washers) on the ends, used a 3/8 ratchet to tighten them up. The result is the car rides a lot better the Gabriel Ultra shocks are just perfect imo in terms of ride quality. They're stiff but not bone rattling. That annoying thump over every bump and dip on a road is completely gone also.

Tbone289

Yeah, I'd say those shocks were due to be replaced.

I used nuts to secure the bolts in place, then sandwiched the bar pin with washers on each side between that nut and a locknut. That way the bolt is locked in place and doesn't rotate when changing the shocks.

fb97xj1

Those shocks are done. Check the front shocks if you havent already as they probably arent that far behind. Mine didnt look much better, and replaced front and rear at the same time for an even ride. I doubt they were ever replaced as they still wore the Pentastar logo, and the odometer read 234k miles. They had no rebound left in them. Doublecheck your bumpstops, too. I didnt realize i was missing a front stop until i started pulling the shocks.

kbeam418

The front rides okay, it's not as stiff as the rear is but they're not horrible. Front bump stops are still in place, rear I'm not sure about but this thing isn't seeing a trail anytime soon so I'm not worried about it. The rear was oe on mine and they had almost no damping my dad was complaining about how bouncy it was in the rear lol.