Vibration after TT/Shackle lift

[mjs]

Last weekend, I installed the Warrior shackles and did the tortion twist on my wife's 01 Sport. Install was a breeze and it looks very good. However, I now have a vibration while accelerating from around 20-35 mph. I'm positve it is a pinion angle issue. How do I go about measuring the angles? Has anyone else had a problem with this using the shackles. I gained 1.5" and am kind of surprised that I have an issue with this. Where is the best place to get some shims?

MJS

01 Explorer Sport , TT/Shackle lift, 265 BFG ATs
02 F350 SC V10
68 Bronco

 

[Alec]

Did you get an alignment?

 

[mjs]

I have not done an alignment yet. I am getting that done on Monday. This vibration is not an alignment issue. I'm relatively sure that is a driveshaft angle issue. When I lifted my 2000 F250, I had to shim the carrier bearing down due to the same type of vibration/shudder.


MJS

 

[JDraper]

I have the tt/shackles on my '01 and have no vibration issues. The change in pinion angle is very small with the tt/shackles, and should not cause a problem. I did need an alignment, and that can sometimes cause vibration issues depending upon how far out it is and the type of tire on the vehicle.

 

[Alec]

The driveline angles do not change much with the TT/War lift.

See what happens after the alignment. Be aware that after driving on those tires with bad alignment for a few days your tires may vibrate after getting it done until they even out again.

If you do think it is a driveline issue, maybe the CVs?

 

[Hartman]

Originally posted by Alec
If you do think it is a driveline issue, maybe the CVs?

That's what I first thought when I read the thread.

 

[Stic-o]

it's your cv angle

same happend to me. So bad that when they went to align it you could not spin one wheel at all by hand! It shoud vibrate at high speeds too right? say over 65 and hit a bump at that speed. your gonna have crank them back down a little. I also found mine walked by themselfs UP a extra inch too after cranking and then drivng a for few weeks. same thing again when i lowered it back down.

 

[mjs]

Thanks for the great input. I will try cranking the torsion bars down a little tonight. I had gone up 6 turns which equaled about 1.5". It does not vibrate at high speeds. Only which accelerating and between 20 and 30 MPH.


MJS

 

[mjs]

I cranked my torsion bars all the way back down to where I started and the vibration is still there. That rules out cv joint and alignment. Looks like I am back to a pinion angle issue. Anyone else have suggestions?

MJS
01 X Sport TT/Warrior shackles, 265 BFGs
02 F350 SC 10
68 Bronco

 

[becker69]

MJS; How long have you had the BFG 265's on there? If they are a new addition w/ the TT/shackles.... then it may be the tires. I know BFG are a high quality make; but I have one of my AT/KO's that is bad (unfortunately I bought the tires with a few thousand miles on them so I don't have the option of a BFG warranty. But anyhow one of the tires is so bad I have 6.5 ozs of weight on it to take away some of the vibration And that was after I had it remounted several times. Good luck; just an idea.

 

[mjs]

The tires have been on there for about 6 months. The vibration started with the shackles.

MJS

 

[JDraper]

I'd check to make sure all the bolts are tight and there is no side to side play in the shackles.

Another thought, is it possible one of your wheels threw a weight and is out of balance?? I've had that happen before.

I would be very surprised if it was a pinion angle problem. If your driveshaft is 36" long (guess on my part, I'm not sure of the exact length) and you have a zero pinion angle to start, lifting it 2" will give you a 4.4° pinion angle. If you start with a 4.4° pinion angle with no lift and add a 2" lift, the change in angle is less than 2°. Formula for the Angle=arcsine (driveshaft drop/driveshaft length) if you assume that the pinion shaft is parallel to the ground.

 

[Stic-o]

where?

can u tell where the vibe is coming from? Front/Back. Check the weights on the tires. And as for tires? they should be fine. After about 40k or so depending how u treat them is when they start getting ruff. They just start coming apart on the inside, it's just a BFG thing u get use to it after a few sets.

 

[mjs]

I'm sure this is not tire related. I've run BFGs on all my trucks for about the last 15 years. These only have a few thousand miles on them. I will check the side to side play tonight. The strange thing is that this vibration happens "while accelerating" and around 20-30 mph. Definately from the rear of the vehicle. Coasting through that speed does not result in the vibration/shudder. Almost seems like I may be on the edge of an accessive pinion angle then the extra axle wrap on acceleration causes the angle to be even greater?

MJS

 

[Alec]

What's your differential gear ratio?

 

[mjs]

4:10

MJS

 

[Alec]

Have you rechecked all the bolts back there? Shackles, Ubolts, front spring hangers?

Could just be a bad Ujoint also.

 

[taxx]

all I can say is hehe...

Just kidding I know how you feel. I fought that for a long time. Pinion angle is not probable with that little bit of lift, I had driveline guys look at mine and they said it was fine.

Have you considered that maybe it was like this before and you are just now noticing it cause you fiddled with it and now you are over sensative?

 

[mjs]

I'm sure that it was not like that before I started and somehow it is directly related to the shackles. Although, yes, I am oversensitve to those type of things anyway. Of course it is just my luck that most everyone else does this mod with no issues and I have to be the guy that has the issues.
I have always lifted my trucks and have run into this type of thing before too. Sometimes it takes some troubleshooting, but there is always an answer. This sure would be alot tougher without forums like this though.

MJS

 

[LowdPypes]

You're not going to like this but I had the same problem. Check your upper and lower ball joints, I bet they're shot... (they can align it all day and it won't fix this)

(not sure how much you know about cars, but to do this, jack up one side on the front end just until the tire comes off the ground about an inch. Then put a pry bar under the tire and lift up. If your tire rocks back and forth and you can see play in the ball joints then there is your problem. If the vibration is more on acceleration then it may be your uppers and if it more when you slow down then it may be your lowers. The uppers are a breeze, the lowers will have to be pressed in and out. With the right tools, it's not too complicated but without, you are going to have to take it too a shop. ALSO, I found the parts to be cheaper directly from Ford than from an auto parts store. If you replace the uppers, go ahead and replace the whole arm with the ball joint already pressed in it. Lastly, while you are doing this, if you ever plan on going with larger tires, you might want to put a new alignment kit (camber/casters) on there cause the stock ones won't allow for a true alignment. After ALL this, go get an alignment.)