Question about suspension - Tilted Forum Project Discussion Community

DiffEng · 09-15-2003, 09:40 AM

I've got a 93 Jeep XJ Sport with the 4.0L inline 6.

Recently, it has developed a serious case of rear axle hop. I'll drive over a bump and the rear axle will hop for several seconds afterwards. Not just a minor hop, I'm talking about a hop that makes the whole vehicle shake and vibrate. It's quite scary.

I'm thinking it could be worn out shocks. I've had ths thing for 5 years and have put 140000km on it since I bought it, and I haven't done any suspension repairs other than adding a leaf when I bought it.

Any other thoughts or suggestions?

Mill · 09-15-2003, 10:06 AM

Sounds very much like worn shocks. If you leave it too long it will cause a cuping wear patern on your tires and wear them out fast.

Crawl under and look for worn bushings, rusted or leaky shocks, broken leafs, missing spring clamps.

Moonduck · 09-15-2003, 11:22 AM

You can also try a simple test. Put your foot on the rear bumper and shove down hard and let it bounce up. If it comes up quickly and rebounds at the top stroke, it is very likely worn.

Frankly speaking though, if you have that many miles on the vehicle and have never replaced your rear shocks, it's a good time to do it regardless.

DiffEng · 09-15-2003, 11:56 AM

Yeah, that's why I didn't get too excited about the idea of having to replace them. It's high mileage (282,000km total), so I figured the shocks were probably in need of replacement anyway.

I'm not too familiar with the mechanics of solid rear axles, so I wasn't sure if there could be something else that might be causing the hopping.

Thanks for confirming things for me.

I've looked underneath, and there's nothing obviously wrong. The leafs are good, shocks aren;t leaking, bushings still look good.

Peryn · 09-15-2003, 12:07 PM

heh, my 87 cherokees got 252k miles (not km) and never replaced any suspension parts. You can tell by the sloppy ride and major body roll, but no axle hop.

On the plus side, if it is the shocks or something, with a solid rear axle, it will be relatively easy to get to and work on.

DiffEng · 09-15-2003, 01:27 PM

Sloppy ride and body roll is part of the XJ's mystique! I can get used to those, but the axle hop can be frickin' scary!

I plan on doing the shocks myself. I hate paying for labour.

Peryn · 09-15-2003, 08:16 PM

well, Not sure what axle hop feels like on the road, but im startin to get some crazy clutch chatter starting out in first gear. Thats pretty freaky when it gets bad. Good luck with teh suspension and if it fixes it, let me know what you put in and how much of a difference it makes. Once i get some money its time to start fixin it up.

Sion · 09-16-2003, 04:00 AM

just to be on the safe side, have the ride height checked too, that will confirm whether the springs need replacing as well. take it to any shop that does alignments, they will have the specification and can measure it in about 2 mins, probably wont even charge you.

DiffEng · 09-16-2003, 09:17 AM

I thought about that possibility too, but the factory height specs won't work, as I had an add-a-leaf done shortly after I bought it. Of course, the add-a-leaf was suppossed to add 1.5" of height in the back. So I guess factory specs, plus an inch or so would be a good indication.

09-15-2003, 09:40 AM	#1 (permalink)
DiffEng Tilted Location: Canada Eh!	Question about suspension I've got a 93 Jeep XJ Sport with the 4.0L inline 6. Recently, it has developed a serious case of rear axle hop. I'll drive over a bump and the rear axle will hop for several seconds afterwards. Not just a minor hop, I'm talking about a hop that makes the whole vehicle shake and vibrate. It's quite scary. I'm thinking it could be worn out shocks. I've had ths thing for 5 years and have put 140000km on it since I bought it, and I haven't done any suspension repairs other than adding a leaf when I bought it. Any other thoughts or suggestions? __________________ Plan for today: 1. Contemplate end of world 2. Build fort out of sofa

09-15-2003, 11:56 AM	#4 (permalink)
DiffEng Tilted Location: Canada Eh!	Yeah, that's why I didn't get too excited about the idea of having to replace them. It's high mileage (282,000km total), so I figured the shocks were probably in need of replacement anyway. I'm not too familiar with the mechanics of solid rear axles, so I wasn't sure if there could be something else that might be causing the hopping. Thanks for confirming things for me. I've looked underneath, and there's nothing obviously wrong. The leafs are good, shocks aren;t leaking, bushings still look good. __________________ Plan for today: 1. Contemplate end of world 2. Build fort out of sofa

09-15-2003, 12:07 PM	#5 (permalink)
Peryn Junkie Location: San Diego, CA.	heh, my 87 cherokees got 252k miles (not km) and never replaced any suspension parts. You can tell by the sloppy ride and major body roll, but no axle hop. On the plus side, if it is the shocks or something, with a solid rear axle, it will be relatively easy to get to and work on. __________________ Dont cry kid, It's not your fault you suck.

09-15-2003, 01:27 PM	#6 (permalink)
DiffEng Tilted Location: Canada Eh!	Sloppy ride and body roll is part of the XJ's mystique! I can get used to those, but the axle hop can be frickin' scary! I plan on doing the shocks myself. I hate paying for labour. __________________ Plan for today: 1. Contemplate end of world 2. Build fort out of sofa

09-15-2003, 08:16 PM	#7 (permalink)
Peryn Junkie Location: San Diego, CA.	well, Not sure what axle hop feels like on the road, but im startin to get some crazy clutch chatter starting out in first gear. Thats pretty freaky when it gets bad. Good luck with teh suspension and if it fixes it, let me know what you put in and how much of a difference it makes. Once i get some money its time to start fixin it up. __________________ Dont cry kid, It's not your fault you suck.

09-15-2003, 10:06 AM	#2 (permalink)
Mill Psycho Location: Center of the Universe	Sounds very much like worn shocks. If you leave it too long it will cause a cuping wear patern on your tires and wear them out fast. Crawl under and look for worn bushings, rusted or leaky shocks, broken leafs, missing spring clamps.

09-15-2003, 11:22 AM	#3 (permalink)
Moonduck Junkie Location: SE USA	You can also try a simple test. Put your foot on the rear bumper and shove down hard and let it bounce up. If it comes up quickly and rebounds at the top stroke, it is very likely worn. Frankly speaking though, if you have that many miles on the vehicle and have never replaced your rear shocks, it's a good time to do it regardless.

09-16-2003, 04:00 AM	#8 (permalink)
Sion Dumb all over...a little ugly on the side Location: In the room where the giant fire puffer works, and the torture never stops.	just to be on the safe side, have the ride height checked too, that will confirm whether the springs need replacing as well. take it to any shop that does alignments, they will have the specification and can measure it in about 2 mins, probably wont even charge you. __________________ He's the best, of course, of all the worst. Some wrong been done, he done it first. -fz I jus' want ta thank you...falettinme...be mice elf...agin...

09-16-2003, 09:17 AM	#9 (permalink)
DiffEng Tilted Location: Canada Eh!	I thought about that possibility too, but the factory height specs won't work, as I had an add-a-leaf done shortly after I bought it. Of course, the add-a-leaf was suppossed to add 1.5" of height in the back. So I guess factory specs, plus an inch or so would be a good indication. __________________ Plan for today: 1. Contemplate end of world 2. Build fort out of sofa