I am currently running a stock 87 rear driveshaft and I intalled a new transmission mount, I have a terrible vibration at high speeds, would a double u joint driveshaft fix this problem? I currently have one but dont know if it will fit, just want some info on the topic! thanks.

 

Have you checked your u-joints ?, if there bad you could get a vibration.

 

^^^ bingo....

Put some grease in the u-joints. If you still feel a vibration after that, pull the driveshaft down and rotate the u-joints in every direction. If they feel smooth, look into tire balance or other. If any feel stiff, it is seizing up.

Other would be the slip joint/spline shafts on the driveline. They need grease, too. But, if you have any up and down play (with the driveshaft in place), this could be the problem.

Check said items and report back.

 

I've considered that as well, but i've been under my truck looking for play in the shaft and there isnt any...although this can't always confirm they are not bad, If they are bad i'd rather swap to the split shaft to avoid further vibrating comlications since i already have the shaft and u joints are a bitch to swap especially when they are the originials!

 

oh i've greased the bitches to death! haha. have yet to drop the shaft tho, tire balance is fine theres no vibration in the steering wheel, so i know its in the rear end. I will check others and will get back! thanks!

 

Yeah, I keep telling people you really have to drop the DS to see if one is seizing. They'll feel solid.....or can, rather... while the DS is in place. But, while rotating you'll notice it's stiff whereas it should be smooth and easy to manipulate.

 

If you find the u-joints to be ok then it could be the axle bearings in the rear end, i had to replace the rear axle bearings on my 86 4Runner a while back because they were so worn out that you could wiggle them back and forth about an 1/8'' of an inch, the new bearings made a huge difference.

 

did you line up the u-joints on both ends. they need to be orriented the same with each other, as close as you can. they might have gotten turned if you pulled both ends of the driveline apart.

 

^+1 - if the joints are tight, there's a chance they're not timed properly if the slip yoke came out

 

Like said you have to pull the shaft to inspect the joints properly.

 

Did you install the driveshaft at the same time as the new tranny mount ?

Did you install a poly, instead of rubber, transmission mount ?
If so, that's most likely a large part of the problem.
Poly has no place in engine mounts nor in suspension components.





Fred

 

Care to elaborate, Fred?

 

hey guys, my truck is at the muffler shop getting a new exhaust! Havent had time to check, but my mount is rubber, and I've never dropped the shaft so I couldnt have let anything fall out of place, I'm thinking i'm going to swap shafts with an early 90's pickup as they are split and that will solve my problem if my tranny isnt completely lined up with my shaft. (which i think is the problem)

 

Okay. Good luck.

 

Well then you would have done something to make the lineup not be correct.
Did you change anything lately, such as lift height ?




Fred

 

I had front end damage a few years ago that might be the root of the problem, I think my tranny is thrown to the side a tiny tiny bit, not serious as it doesnt vibrate until 100km/h or so. thats why I am going with the split shaft idea as it will cure the off kilter engine mount(from accident) which leads to the tranny..... I haven't lifted it.......YET!