Vibration @ High Speeds

Recently I've developed a vibration @ higher speeds - 60 plus...

This vibration sort of feels like I've got a wheel or two out of balance, but I was wondering...what other things might make it vibrate?

Thinking through changes/upgrades that might contribute to this I'm thinking it started back when I installed the re-built tranny...been putting up with it for a while.

I've also put new shackles and bushings on it...now I wouldn't expect these shackles and bushings to have caused it but I do remember that when I finished, my steering wheel (which was slightly rotated) was now sitting correctly. Apparently the shackles corrected an alignment problem, or maybe they worsened it....

 

Is the vibration at tire speed or driveshaft speed? Should be able to tell if it's tire related or driveshaft related that way. Does it change when you let off the gas slightly?

 

Driveshaft out of balance?

Does it get worse the faster you go?

 

Three votes for drive shaft....what would have caused that? I mean it was riding fine before with the same drive shaft.

It does get worse the faster I go but it doesn't start till around 55 or 60, and really won't let me go much faster...it's just too much vibration.

Come to think of it...I started noticing it soon after the tranny was replaced...think maybe I caused a u-joint failure by taking it loose from the t-case then rebolting it?

Oh yeah Lynn, these shackles were supposed to be stock lenght but they are 1/2" longer than the factory ones...from hole to hole that is..Seems like that's 3" as opossed to 2-1/2"

 

Try checking the u-joint condition. Release parking brake, grab driveshaft and try to move it around at each end. If a u-joint strap is loose or the bearings are shot you'll know right away. Just a suggestion... that's how I found my bad u-joint.

 

Thanks Chris and others...Sounds like u-joint is the #1 culprit. I might just go ahead and pick up new ones and swap all of them out.

 

You've probabally checked this but make sure the slider is timed correctly on the drive shaft. Caused the same trouble for me once.

JB

 

I have no idea what a slider is on the driveshaft??? what is that and how is it timed?

Oh...BTW....I just ordered 4 u-joints from Krage. Didn't know that the front one was different from the rest but according to Krage it is. Said that from '66 - 71 the front joint was different. Would that have anything to do with the V6? cause he mentioned the V6 in our conversation. Also.. he said that the front u-joint wasn't available from Spicer like the other three were.

 

John here is a pic of the diffo front yoke sizes. Top one is from my '71 w/ V6, the bottom one is from 4-cyl (I think). 4WD Hardware has recently added the smaller ujoint to their inventory in case you can't find them elsewhere.

 

Thanks Alan, but Krage had the u-joints so I've already ordered them and had the fight with my wife about it...so I'm good to go.

Hey that may be a good cliche...BTDT and had the fight with my wife about it.

 

The slip yoke end of the drive shaft is removable from the splined half of the driveshaft.........the yokes on both ends of the driveshaft need to be in the same plane. If the two halvrs of the driveshaft have been apart, they need to be put back together correctly, or "in time".

Jef

 

sounds like a wieght feel off of either the wheels (would be gradually worsen than improve) of drive shaft (noticed at all speeds).

 

Really need more info. Can you feel the vibe more from the steering wheel, or in the floor board? We can all keep guessing but need to know where the vibe comes from to pin point the problem and make good recommendations.

 

mud in the wheels??

 

I recommend you check your tire ballance first. Had an old ford truck a few years ago that I transplanted an updated transmission into. It would develope a vibration at about 50 that would go away if I white knuckled it up to 70. sometimes it would be so slight you could barely feel others I would slow back down and come up on 50 again so I wouldn't hurt it. went through everything, reballanced driveshaft, renewed clutch, new ujoints etc. not saying they didn't need it but didn't fix problem. just before I sold the truck I had the wheels reballanced and it stopped. check the easy stuff first...02 Randy

 

Check the easy stuff first??? now who would do such a thing?

Actually I do think it's the tires....but I want to swap out the u-joints. I think I can do that and I've not wrenched on it since the Pertronix upgrade.

On the drive shaft how do I know if it's misaligned or "timed wrong"? Are there marks that will realign it for me? I'm not sure if the mechanic who installed the tranny pulled the d-shaft apart or not...I didn't when I did it the first time.

 

Yeah...now I get it...I would have never known it mattered...heck I could probably check that myself and see if it's right or not....thanks a million Boyink.

 

OK went for a test drive last night...there's no vibration in the steering wheel. It vibrates all the way from the front axle to the rear.

I climbed under it to check the drive shaft and sure enough both of the drive shafts are out of alignment. And...low and behold I ran into the mechanic who installed my tranny this morning on the way to work. Of course he couldn't remember whether or not he separated the shafts when he did the tranny swap, but he said he'd help me fix it.

I know it's really no big deal, but still,...if he's the one who screwed it up, then he ought to fix it.

Plus, I've got new u-joints coming so I can kill two birds with one stone.