hey,

im getting a crazy vibration when i excellerate. its like my engine is running through water. everything in the cabb vibrates, its like a sharp vibration too, not side to side, kinda like in an earthquake. what do you think is wrong?  1975 cj5 v8 304

thanx bud

I'm living with a similar problem.  I think I have traced it to a worn drive-shaft u-joint.  From what I understand ... if the u-joint moves when you pull on the shaft, it's bad.

I am going to replace mine this weekend.  Hopefully that will fix it.

Pete  

i've had a problem like that. it turned out to be broken belts in the tires. i took it to a brake/alignment shop. the guy spun my tires and they were kind of egg shaped. i couldn't tell because the tread was still ok. cool mechanic though. he could have easily jammed it to me to the tune of about five bills for ball joints, bushings, rod ends, etc. he just told me to try different tires and come back if i still had the problem. needless to say, i became a customer of his because of his honesty and knowledge.

if it's not the tires being out of balance or messed up some other way, it could be driveline u joints, or driveline angles. if you have a cv or double cardan joint on your driveshaft, the bolts may be coming loose causing the vibration( if you have a double cardan, check the bolts, i hade a driveshaft fall out and it beat the crap out of my tub). most tire shops will check all that stuff for free because they want you to buy your next set of 33's from them. you seem to get treated pretty well when you roll into a tire shop on big mudders. they may even bump you up in front of a couple hondas. 

i just reread your question and by your description about the vibration it also made me think it could be spring wrap. when your tires rotate forward, it makes the rear axle try to rotate up. this loads the leaf springs and turns them into an S shape. then the snap back trying to lift the rear tires off the ground(wheel hop). if you want to know more about any of the stuff i posted, let me know and i'll try to explain it more detailed and tell you how to check.  

i dont think its tire related. its under my cab, its like a grinding vibration. it shifts fine, and accelerates ok, but my 4x4 shifter in the floor is rattling like crazy, like metal a metal rattling.  but it doesnt do it all the time, sometimes it stops. but sometimes its pretty rough, not where it affects driving, but its def. something i need to find out about, i dont want to tear up any major components. thanks for your help so far, hope this helps to locate my problem.

check out your driveline real good. it's probably ujoints. mine used to go out all the time before i got my driveline angle right.  

Check the u-joints from the driveline. They might be cracked. Out of curious, did you put a Suspension Lift recently? if you did, then you ill need a slip yoke eliminator kit.

good luck.

-JIM

i found the problem i believe. i think(well pretty sure) its my cv rear driveshaft. the uv joint in it was broken on one of the ends, and it broke the actually housing(for lack of better desrciption) its in. im sure i need to replace the spacer, but does anyone know what the "housing" is called that attaches to the actual driveshaft, and if so can i buy just that part. i dont want to have to shell out 300$ for the whole damn thing.

thanks guys