What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

cv shaft and shackle flip, still vibrates. [Final say]

metalneverdies

metalneverdies

1/2 ton status
 Premium
Joined
Nov 6, 2011
Posts
1,180
Reaction score
154
Location
oklahoma
So I'm at my wits end. I installed the flip and had horrible vibrations. Installed a cv rear shaft and now I have vibrations at 40-45 and horrible vibrations at highway speeds. It mostly goes away or is less noticeable if I am under hard acceleration. Cruising is when it shows up worst.

Am I doing something wrong here? Seems insane to have to order shims with my diy4x 4" flip and 4.5" shackles and a cv drive shaft.
 
Last edited:
What's the angle of the output shaft on your tranny/t-case and what's the angle of the pinion?
 
It's all about the angles. You probably need to turn the rear pinion up to point at the rear driveshaft.
 
With a shackle flip, your pinon is probably pointed to far up, not down. I have this same problem with my Suburban right now. My pinon is almost pointed to the floorboards.
 
On my slightly sloped down driveway:

Pinoin is at 13*

Drive shaft is 19*

Measured on the bottom of the t-case output shaft housing 4*

20130608_142828.jpg

20130608_142809.jpg
 
Doesn't matter what kind of slope you're on, you just want to know what one angle is relative to the other.
I think the difference between the t-case output shaft and pinion is suppose to be 2* max.
Also, make sure when you do these measurements that you have any weight that'd normally be there in place. Like the spare tire, bumper, and 1/2 tank of gas because that'll change your pinion angle a couple degrees.
 
IIRC, a traditional shaft of one U-joint at each end will need to be within 2* difference -- I think this is to what Rampage refers.

The CV aka "double cardan" that has two U-joints at one end can withstand a greater difference.

Tom Woods' site has a coupla good pages about this:

http://www.4xshaft.com/driveline101.asp

http://www.4xshaft.com/selection.asp

It is not unreasonable to have to shim the axle even with a CV shaft. I had to do so as my rear shaft is fairly short -- the joys of a Doubler and a Blazer's short wheelbase. Once shimmed it is well within the limit for my CV and runs happily at any speed the truck can attain.

You might also talk to whoever you got the shaft from, as they'd have more specifics.

-- A
 
dremu said:
IIRC, a traditional shaft of one U-joint at each end will need to be within 2* difference -- I think this is to what Rampage refers.
Click to expand...
Ummm, yes. Details, details :whistle::D
I thought he said he was going to need to buy a CV shaft, but after re-reading the original post I guess he already has one. :dunno:
 
rampage said:
Ummm, yes. Details, details :whistle::D
I thought he said he was going to need to buy a CV shaft, but after re-reading the original post I guess he already has one. :dunno:
Click to expand...

I do in fact have a cv shaft installed.

3/4 tank of gas, full interior.

So what is the max degree difference with a cv then.

Its a high angle drive line shaft I bought used. Joints seem to be in good condition and a brand new rear joint. They are installed correctly.

How big of a shim do I need?
 
You need to shim up your pinion 6 degrees to get it even with the driveshaft angle.

Just to make sure it might not be a bad idea to pull the rear shaft and drive around on the front to see what it does. This will eliminate any other possibility such as out of balance tires, or bad bearings somewhere.

So basically you need a 6 degree shim
 
blazinzuk said:
You need to shim up your pinion 6 degrees to get it even with the driveshaft angle.

Just to make sure it might not be a bad idea to pull the rear shaft and drive around on the front to see what it does. This will eliminate any other possibility such as out of balance tires, or bad bearings somewhere.

So basically you need a 6 degree shim
Click to expand...

If I had some way to keep the transfer case plugged that would be a good idea. As of now I can't install my front shaft without some exhaust rerouting.

So I need to shim the pinion up 6 degrees then?

Ill call kurt on Monday and order some bolt on shims
 
Last edited:
I once made it to the parts store and back in front-wheel-drive with a plastic cup electrical-taped to the output cone of the 208.
 
I'd go with a 4* shim. You don't want the pinion at 0*. That will also prematurely wear out a ujoint. There needs to be a touch of angle so the bearings roll.

Every truck is a little bit different. Next guy might need an 8 and the very next, none at all. And some guys will have angles worse then yours and it won't vibrate at all.

Just out of curiousity, what condition are the ujoints in and is there anyway you can straighten the pinion so you don't have to take the measurement off the corner like that?

Just FYI you have a 15* operating angle on the double cardan joint and a 6* on the pinion u-joint.
 
Last edited:
cybrfire said:
I'd go with a 4* shim. You don't want the pinion at 0*. That will also prematurely wear out a ujoint. There needs to be a touch of angle so the bearings roll.

Every truck is a little bit different. Next guy might need an 8 and the very next, none at all. And some guys will have angles worse then yours and it won't vibrate at all.

Just out of curiousity, what condition are the ujoints in and is there anyway you can straighten the pinion so you don't have to take the measurement off the corner like that?

Just FYI you have a 15* operating angle on the double cardan joint and a 6* on the pinion u-joing.
Click to expand...

I will get a new measurements on all the parts with a flat flange and post up.

The rear u joint has like 30 miles on it. The cv joints have ~10000. All look to be in good condition. I know the tires are good; had them on before the lift.

Kurt: re measured using the flat of the flange.

Pinion = 13*
D-shaft= 19*
T-case= 3*

Posting from phone. Pic is upside down

20130608_193933.jpg
 
Last edited:
No real change on the joint in question. 4* shim is still what i'd recommend.
 
Well, got shim installed still had scary vibrations. I called kurt and we decided that it had to be my drive shaft.

Took my new-used cv shaft out and took it in for a balance check. Guy at Blumenthal's cringed when the cv joints moved. Apparently the cv joint ball socket stud thing as screwed. He pulled it apart for me to see and showed me how scored up everything was. Turns out I bought a bad shaft after being told it was good and had no vibes. :doah: hard to verify over the internet.

So $330, 3 u joints, a cv joint, and a balance later the vibes are a bit better but it still shakes above 45. If I stomp on the gas from a low speed and hold it, the vibration isn't bad / goes away. When I let off and cruise the vibration is back. Its pretty bad still about 60-65 mph. 75 makes me think the u joint will wear out and fall apart.

I'm guessing it still has to be the pinion angle? I'm loosing my mind getting this to work right. :pissed:

20130702_125946.jpg

20130702_125941.jpg
 
That is proper. the angles should be like this.

degreecv.jpg
 
You must log in or register to reply here.

Latest Posts

Top Bottom