I gots the shakes

[biohazardbill]

Also the rear seal on the trans appears to be shot now due to the vibration... tranny fluid on bloth mufflers.

[biohazardbill]

Another thing...

its hard to tell but it looks as though the rear pinion maybe be higher than the trans yoke by about 1/2"

So i guess a simple solution might be to just change ride height to be an inch or so higher lol... but what fun is that...

[CC69Rat]

I'm confused. .. but I think the problem is in the angles, they just need to cancel each other out. I usually run mine at 1-2 deg pinion down at ride height. 1/2 deg of shim for every 1 in of drop. 6" drop = 3 deg shim at ride height. (minimum) I may even do 4 deg on a 6 drop. With bags, I'd say 4 deg shims would sit it about right.

Just reading through your post again, I'd put the trans mount about 1/2-3/4" up higher than where it was originally and shim the axle about 3-4 degrees. Here's a picture of mine with a 6" drop spring and 1" blocks. This is a 3 degree shim.

(I know the Ubolts are too long, I'm waiting until I get the bed back on, I may do 2" blocks)

[biohazardbill]

Where did you get your shims?

[biohazardbill]

Also are you running a 2 piece or a 1 piece drive shaft?

[CC69Rat]

http://www.stockcarproducts.com/cont...ion-angle-shim

I have their lowering blocks too, but they're kinda pricey. Honestly I don't like them that much. There is a forum member 'way2lo2' that might be able to get them for you cheaper. His name is Boris. Cool dude man ..

I'd do the 4 degree ones.. just me.

Oh, one piece custom cut driveshaft. Mike Hudlow here in Chattanooga set it up for me. Hudlow Axle if you're into Jeeps and stuff. He's around the Rossville area.

[biohazardbill]

From my understanding the angles need to be within 3 degrees of one another...

So based on these figures:

rear is 6 degrees up


front is 7 degrees down

If I put a 4 degree shim in the rear it would lower the pinion a bit to 2 degrees up.

That would be a difference of 5 degrees. So I would also have to try and shim up the trans another 1/4 inch or so which will raise the trans and reduce the degrees down.

Correct?

That being the case I should probably go ahead and see if I can get the trans up that extra 1/4 and see how much that changes the degree on the front. Then match that on the rear.

[Bigdav160]

I'm not sure I'm following. Ideally the working angles should be the same at the front of the driveshaft as the rear. Most specs are less than one degree difference from front to rear..



Working angles of less than four increase the life of the u-joints and increase the "critial speed" of the shaft

[CC69Rat]

^ I think I need to see where you're measuring from Bio. Lets use the picture he posted. Can you take it into paint or something and mark where you're measuring from? Can you take some pictures and post them up?

[davepl]

I assume everything is laterally centered, but as referred to above the angles must be:

EQUAL AND OPPOSITE

In this case it's because as the cap on a U-joint swings past it's most extended point it speeds up/slows down the entire shaft. If that angle is out of whack with the other end, not perfectly offsetting it, it will be tring to slow down/speed up the shaft by a DIFFERENT amount.

That difference will cause vibration. Just want to be clear that it doesn't matter (except in drag cars) really what the angles are, so long as the perfectly cancel each other out in the opposite direction.

And that, folks, is why they had to invent Constant Velocity (CV) joints, because the front wheels turn and mess up the opposing angles. A CV joint is basically two U joints back to back so they solve the problem internally.

[biohazardbill]

To measure I removed the driveshaft

For point A I put in a yoke that was not attached to a driveshaft. I pointed the holes for the u-joins straight up and down and placed the angle finder on the outer most points of where the u joint would have been.

Point C I rotated the wheel til the rear yoke was straight up and down and the magnet held it to the flange.

[biohazardbill]

Ok so I took my driveshaft to a reputable place this morning in ATL. He is familiar with the shop that originally did it. He says he has fixed many things from them in the past.

He GUARANTEES it wasnt balanced. Also upon inspecting the shaft he pointed out a couple other things that I missed. The rear joint somewhat bound up and was hard to manually move, he also said it was a ujoint that was cheap like somone else in this thread suggested. I asked him if the binding was possibly due to the fact I drove on it a couple times he said no and he showed me where it appeared the prior shop heated one of the ears and bent it.

They were going to go from behind the front ujoint back... I asked him if the front joint was also cheap, he said yeah.

He thinks with the binding of the rear joint and bent ear coupled with lack of balancing would cause a ton of the issues. He is pretty sure a new shaft will solve the problems but cant be 100% positive.

So they are replacing everything except my slip yoke and using spicer ujoints. I already got new rear trans seal and strap kit. I pick up the shaft this afternoon.

[biohazardbill]

Guy called said shaft is ready for pick up.

He said he threw my old shaft on the balancer for giggles.

He said their machine each end should be within .01

One side of my shaft was .053, the other was .057 so he said it was vibrating like a *****.

[biohazardbill]

Well new drive shaft is in, vibration is better. Got up to 100 on the freeway before letting off. Now that I know the driveshaft is fine I will start messing around with the pinion angles.

[CC69Rat]

At 100mph, I'd say a little shaking is acceptable

Glad its working out for you .. sucks about the first drive shaft tgough . Lesson learned I guess.
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[Bigdav160]

IIRC, .025 is the limit on driveshaft runout. Sounds like the original shop got it wrong.

[brad_man_72]

We build our shafts within .010" also .002 for slip and stub and carrier bearings.
Many factory shafts don't meet these specs.
Its possible to ballance a shaft that's Bent it just takes more weight.

Glad I talked you into having your new shaft checked. Not all driveline shops are created equal.
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[C10_ustacould]

Driving these trucks is like pushing a brick through the wind, just a "little" vibration at 100mph is a blessing.

[Codez67Chevy]

I'd say go to another tire shop and make sure your tires are balanced. Cuz if they are off just a little you'll get the shakes. At least that has been a problem for me and it fixed it.

[brad_man_72]

Originally Posted by Codez67Chevy

I'd say go to another tire shop and make sure your tires are balanced. Cuz if they are off just a little you'll get the shakes. At least that has been a problem for me and it fixed it.

It doesn't hurt to watch them. Told the tire guy I had a vibration on a used car. He didn't notice the wheel was bent half an inch, he told me it was out of ballance and asked me if I wanted him to ballance it. I had to lol.
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