So now that the car is moving, and I have things moving in the straight and narrow. I have been driving the car more, and working out heating bugs, tuning bugs, and I had a vibration, well still do. I bought a new driveshaft because the one in there was a homemade cobbled up shaft. The engine was balenced with damper, flywheel, but not clutch. I have an 833 that was well used. At higher speeds I get a pretty bad vibration, I mean verry noticable speed related vibration. Driveshaft is new, gears are new 3:91s. I balenced the wheels/tires 1.5 years ago when boughten. What could be the problem guys. I know I have been on here a lot lately, but you guys have been pretty spot on on everything so here is another one for ya.

Kasey

I had the same type of problem on my Challenger, replaced all I could and it was still there.. Pulled the tranny and had it gone through and found the the input shaft bearing was toast, along a few others in the tranny.. I have the tranny checked next as long as you ruled out all other causes..

I just built the tranny with new bearings, and all new syncros, and output shaft bushing.

Kasey

Hmmmmmmm then not sure what to say.. are the tired okay.. balance and or good shape. how new is the clutch.. how bout the rear end.. axle bearings carrier bearings.. Oh and don't over look stupid stuff like mounts..

I had the same problem on my 340 Swinger, ended up being the back u-joint which was almost new. Like to have never figured it out. Good Luck! Ronnie in Okla.

How's the drive shaft turn by hand? My 833 started to shake , it was a bent main shaft. Drive shaft would turn free then bind some. Did your car set on those tires that long with out moving?Could be the tires.

If you changed anything in the rear suspension recheck your pinion angle. 25+ years ago I put super stock springs on the rear of my 72 duster. I had a high speed vibration and went crazy trying to find it till I read about pinion angle. When I changed the springs my pinion angle ended up at 5-10 degrees nose up. I lowered the pinion back where it should be and the vibration was gone.

check anything that rotates. Did the tires flat spot from sitting?
I had a incompentent shop that turned some brake drums for me, one was out by 32thousands and the other out 10 it was one of the last things that i checked.
what about the driveshaft yolk that goes into thte rear of the trans, is it loose?

good luck
scott

pinion angle

Ok, the rear end has everything new. I rebuilt the center, and it has green bearings. The Tires are definatly not flat in spots, I make sure if it does set its off the ground. The only thing Im thinking is the rearend is out of a truck, and I cut and moved the pads 10 years ago before I even knew what a pinion angle it. I know I measured before and after when putting them back on, but I was 16 years old ish when I did it. Im going to check that first. Then I might take my wheels in and ballence them again. It definatly rear oriented.

Also I just got done putting a new yoke in the rear from Mancini, its the nice billet steel one. Sooooooo, new shaft, rebuilt tranny, new gears, new rear bearings, new u joints, new output bushing, new front yoke, new 11" rear drums, new green axle bearings, and I did exactly what mopar told me on measuring my shaft. I had vehicle weight on cal, measured from 1 inch from bottoming out in tail shaft, and to the center of the rear yole. Center to center was 49 3/8 ish.

Im hopeing on the pinion angle...
Thanks guys

Kasey

checking pinion angle is free ask me if ive checked mine and i know i have to ...

too much reading on this stupid board , i have the vibration toooo..

http://www.moparts.org/Tech/Archive/axle/8.html

Well, after going in the garage and just eyeballing the drive shaft angle, it is almost straight with the rearend, the shaft comes out of the trans, goes into the rearend in a straight line. I need to take the rear nose down a few degrees I think. Its way confusing, and Im getting a headache...

I need to put some wedges in the rearend.

Kasey

So if my angle now os nose up, I need to put the wedge in backwards thisk side rear to bring my nose down correct??

Kasey

Yep thick part towards the rear of the vehicle...

If the nose of the 3rd member is up you put the shim in with the fattest part at the rear of the car. That will tip the nose of the 3rd member down.

Raul

Now I need some wedges

Kasey

Wedgies!!! Go to any grade school,we used to give those out for FREE.

so my pinion angle is 0, maybe 1 posotive, my floor is reading 0, my rearend reads the same at my pinion flange. thats bad, and probably my vibration, or what my dad calls knuckle knock.

kasey

Jack the car up and put it on four jackstands so the car is as near to level as it is on the road, run it up slowly in gear and identify what RPM and or speed the vibration is at. Remove the wheels and tires (make sure to either remove the brake drums and don't touch the brake pedal whie thier off ) and check it again. If the vibrations are still there look at the driveshaft, pinion angle and so on let us know what you find. BTW, Make sure the jack stands are under the rear end housing to test, not under the frame with the rear end hanging down on the springs and shackles

I know the pinion is the problem, I just said the floor, and my pinion are equal as a referance. The shaft basically is dead straight from trans to punkin. Its not good, and I know I need it corrected. Ill be busy in the morning, but I got to get it to Kearney for Reed Koeppe's flat landers fling this weekend.

Kasey

Well, I set my pinion angle 4* down from where it was, and I checked the ballance on the rear wheels, They were off by 2+ oz each. Still vibrates like crazy, I dont feel safe trying to make a maiden voyage down the strip with nast bad vibrations under power at high speeds, so Im just gonna trailer my car to Kearney to check out the cool Old scool cars there, and enjoy a stress free weekend.

Im starting to think I might have something in the tranny causing greef and racket, but I wont dig into that till I pull the engine for the stroker.

Thanks guys for all the sugestions, and help.

Kasey

OK, now Im just PIZZED beyond belief...

I just spent over 350 bucks, 370 after freight on a new ballenced drive shaft, and after pulling my hair out trying to find the vibration, I checked mounts, set pinion angle, ballenced wheels, checked brake drums, free revved the engine to 3800, you name it, I finally said to myself, I better check the only thing different. The driveshaft I just bought. ITS FREEKING WELDED 3/16 OUT OF ROUND ON THE FRONT YOKE!!!

Needless to say I wont be racing at all this weekend. I guess thats what I get when I order a shaft from a dirt track company who specialise in chevy style shafts.

When I got the thing, the front yoke felt funny, and had a catch in it. I noticed one of the caps wasnt pushed all the way in. I saw one of the snap rings was over the cap, not in the groove. Chevys are outside snap ring style, so If this guy is use to building these, I can see the possibility of it being wacko. But anyhow, I now know what happened. He probably had the yoke, and the ujoints together, WRONG, then tacked them up, but probably spun up the shaft before welding solid, and since one cap wasnt in correctly he compensated fo this by offsetting his yoke into the tube. If I wouldnt have inspected it, and ran it it wouls have been ok untill the u-joint flew appart.

I understand SH*T happens, but I really wanted to run my car this weekend...

Oh well.....

I can cruise for a bit, I still have heating issues to deal with too.

Kasey

Sorry the way things turned out for you this weekend. I wish you lived closer as I have several shafts laying around. Post the length you need and maybe someone can help out.

My shaft is 49.5", maybee couldnt hurt to be a snippy shorter, but I have 49.5 ". It has 7290 joints in it.

Kasey

Thanks!!!!

they did a good job balancing the driveshaft after building it

i would put it thru their front window

TRUST ME,,, Id love to.

Well I got the Demon up on the hoist today, got out my dial indicator and spin wheel tip, measured the tranny end. Its over .075" out of round. Thats terrible, and I can not believe this passed any quality control at all!!

Im very upset, and I really dont know If Im gonna have them build me a new one, or get my $$$ back and go strange, or mark williams.

Kasey

whered the shaft come from ?

Its a "FAST SHAFT" from a shop in Iowa. They are well known in the dirt car world, and my buddy has been flogging on one for years, and The race shop I bought mine from highly recomended mine. I on the other hand do not... I realize sh#t happens, but why me???

Kasey

Is it the drive shaft or the trans main out put shaft? u-joint? Hate to see you trashing somebody's product if it's not the problem. I had two out put shafts bent on two different transmissions. Could be that I drop the clutch at to low of rpm's

dennys is a better place to get one ..

Got my shaft back, Its only got the typical "im going 110mph in a 1971 model mopar" vibration now, but is smooth as silk at 60 through 80 on my speedo which is not accurate I have found out via state patrol.

The guys at Fast shafts were good to me, and said "sorry for the F up" and have a nice day. It still had anout .010 of run out in it, but That coud be a number of things with an old 833.

Kasey