violent shaking.................

question......

my 47 when driving down the road starting at about 45 mph has a very bad vibration...the faster you go the harder it gets...but when you let off the gas the vibration stops....................

any ideas?

 

...oh... that's whats shakin'..... u-joint maybe???

 

Hey are ya running radial tires??? Dont think it would be a u-joint, give us a little more info and we will figure it out with ys.
Cheers
Chico

 

could also be motor/tranny mounts... my Fleetline had a horrific vibration the first few times I drove it..... turns out, I never put new tranny mounts in when I put it together.....

 

Nope dont think it would be motor or tranny mount as it would shake from the start,but ya never know he needs to give us some more info just not enough to make a suggestion.
Chico

 

And Im sure the Hangover had NOTHING to do with it?

 

Maybe some 'prankster' taped a quarter to your driveshaft??? Glad you got home ok though. I felt 'baby-fresh' all the way home... Spar/"DUSTY"

 

u joint.

 

need more info...

In no particular order,

1, Bent drive-shaft
2, dead u-joint
3, bent axle
4, bent wheel
5, blown belt in tire
6, blown diff

There are many things that would cause this sort of vibration but I would start looking at the easy stuff first.

 

I'd check my wheel bearings...........they shake like a mutha.

Then they go out.

Then you have to replace them and whatever they took out.

So then you bend over and grab your ankles.

xxx
Brandy

 

45 too 55 is a tire balance problem

 

my chevy JUST started shaking badly this past summer..but mine does it at 65mph and up..i checked all the tires and lugs and they're all aired up and on tight..i'm gonna have a front end alignment done (when i find someone to do it!) and i THINK my doors might be sagging or something because they seem to be doing the bulk of the shaking.
creepy

 

What do you know about the clutch?

 

Did ya figure it out yet?

 

Yup, check that first.

L

 

We had an old Super Duty at work that would shake bad enough at 40+ to flap the fenders if it hit a bump. You would have to bring it to a stop and go again. I would guess spindle slop.

 

i gotta think dry/worn u-joint... letting up on the throttle and the vibe goes away just screams driveshaft to me

 

hmm, did you lower this car?

Did you yank a bunch of leafs out of the rear end?

You are most likely experiencing axle wrap up. The spring leaves are no longer capable of locating the axle properly and allowing the pinion to climb under load. When you decelerate or coast the pinion drops back into alignment an the vibration goes away.

Solution is to either use some sort of traction device or to replace the springs and have them de-arched to achieve the same ride height.

 

Whoa...this sounds dead on to what is up with my Galaxie right here. Excellent idea. I know my radials are in good balance and I just had the driveline redone and balanced, but I have the same bad vibration at about 70mph that nearly goes away when you let off the gas. Yea, and mine is riding on worn out leafs in the back with 2" lowering blocks..sounds dead on to me.

 

Normally I'd say a vibration that occurs at a certain speed (tire rpm) would be tire related. If I read your question right letting up on the load, but still at the same 45 mph speed stops the vibration, that would eliminate the tires.(they are still spinning at the same RPM) If you can make it start and stop vibrating with just the gas pedal, then I'd say it has to be in the drive line somewhere. Trans, driveshaft or rear. That's where I'd look anyway.

 

Lowering blocks give the axle leverage against the already weak springs exaggerating the problem. Pinion wedges will help to point the pinion down (racer trick for better bite) but can cause other problems. www.iedls.com has some great links concerning driveline angles, you should read the articles before making any changes.

The solution to the problems is better leaf springs or traction control devices. this is also why four link systems have become popular, good ride and good axle control for lowered cars.

To throw a "tradional" twist into the solution how about pulling something right out of the 1930's to assist in axle control! Large luxury cars with parallel rear leafs had an extra spring pack sort of like an overload. It was quarter eliptic mounted under the axle pad like a lowering block with the leafs pointed forward. The spring eye had a shackle that extended under the main leaf but had slack. When the axle rotated under load this shackle would engage the main pack and add the quarter eliptics spring stiffness to the front half of the main pack just as slapper bars or Cal-Tracs would.

I tried to find a picture online but came up empty.

 

thx guys .im pulling the motor and tranny out tom. to get it ready for the body shop so ill check everything out...........im thinking its in the driveshaft...........

 

need more information. Is the shaking accompanied by any sort of noise, does it change if braking without deceleration? Wheel bearing or tire out of balance or pinon bearing or tranny output bearing or loose motor mounts or what did I miss?

 

ok i figured it out..........................

the hard way..................lol......


as i left the house this morning on my way to the shop,i got about a block and a half away and out came the rear u joint...........so there is the problem.......i guess i can turn the rear end up some to compinsate from lowering the rear end,to get it at more of the angle as the front one..............

 

Ya' mean ya' didn' even look fer the loose thingie before askin' us whut it wuz?

 

I've had U-Joints look fine before to me, no slop, no visual defects at all and then *BAM* have them give out short time later. I had a rear u-joint go out on a truck a few years back. Had a mechanic look at it 10 minutes before it happened and he was driving when it happened, surprised us both.

 

No no, it still made a huge rumble and racket on the road, but when you looked at the joint, it looked fine. You could pull and push on the shaft with no play at all. It physically looked like a fine u-joint at the time right before it went out. It really baffled us both. We were trying to establish if it was the joint, the ringset chewing itself apart or pinion bearing. Turned out to be the joint.

 

I'm thinking that driveshaft might be way out of balance or something? That might account for the violent shaking before the joint went. Anyhow, I'm sure you've thought of that. Just speculating. Good luck.