Help! Bad Vibrations/shaking

1985taylor1925 said:
Agreed. Check out the link I just posted. Its the most detailed discription Ive found. In fact a higher front lift would create more positive caster, which would actually help stabalize the front tires according to that article. Hence the reason they increase caster on race cars. So if the lift is the cause of vibrations, then like you said its due to the angle of the cv's. And the steering rack would affect foot and toe, not caster
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The more you lift the front end, the more your caster nears 0 or negative. Because the upper control arm is attached to the mount at an angle, as it travels down, it tilts the knuckle towards the front of the vehicle. As this happens, you decrease your caster angle. Reducing caster angle does not induce vibrations, it enhances any that are currently going on. It makes the steering more sensitive to anything going on in the front end.

Think of your caster angle as 0 if the arm of the knuckle with the UBJ in it is perpendicular to the ground. Tilting towards the rear is positive caster, tilting towards the front is negative caster. As the front suspensions resting point is pushed down, you loose caster angle, not increase it.
 
CoMarc said:
So, how do we decrease the angle of the CVs to get rid of the vibration without loosing our lift? I figured that's what the Diff drop was supposed to do.
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IF your vibrations are originating from your half shafts, its because one of them is worn out. The angles induced from lifting the front end are not enough to create vibrations from the driveline.

Unless its a crazy amount of lift. I have 3" on mine and through getting everything replaced was able to turn down the vibes coming from the front end. But I still have the original half shafts. Best place to start is wheels and tires. Swap the fronts for the rear, get them balanced a couple times. You can even throw in some Dyan Beads after the shop balances them for a little dynamic balancing. The caster being so close to 0 will enhance anything else being off in the front end.
 
opie74 said:
The more you lift the front end, the more your caster nears 0 or negative. Because the upper control arm is attached to the mount at an angle, as it travels down, it tilts the knuckle towards the front of the vehicle. As this happens, you decrease your caster angle. Reducing caster angle does not induce vibrations, it enhances any that are currently going on. It makes the steering more sensitive to anything going on in the front end.

Think of your caster angle as 0 if the arm of the knuckle with the UBJ in it is perpendicular to the ground. Tilting towards the rear is positive caster, tilting towards the front is negative caster. As the front suspensions resting point is pushed down, you loose caster angle, not increase it.
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If thats the case then the knuckle must not be positioned in the same relative spot on the upper and lower control arms. Cause if it was the caster would remain the same throughout the suspension travel. I'll take a look at it today. But that seems like a strange design. Or I guess just a design that wasnt intended for a lift.

But still its like you said, caster (especially the relatively small amount youre adjusting it with a lift) isnt the direct cause of the vibration. Im lifted 2" in the front so Im really not that worried about it. Im fairly certain that my vibration is still a balance issue.
 
Balanced at Discount Tire... Bought my tires from them and lifetime free balance so I did it there.

Its funny because I had done my ball joints and tie rods, lifted the front end up a few turns, and rotated the tires so I wasn't really sure what the vibe was from. Luckily it was the easy thing and the tires.
 
Baja Runner said:
Balanced at Discount Tire... Bought my tires from them and lifetime free balance so I did it there.

Its funny because I had done my ball joints and tie rods, lifted the front end up a few turns, and rotated the tires so I wasn't really sure what the vibe was from. Luckily it was the easy thing and the tires.
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They did a good job when they balanced my tires too. But now that I have wheel spacers on they wont balance due to liability issues, which is stupid. All they need to do is write a note that they didnt install the spacers and are not liable for them. Thats what Toyota did. But Toyota cant get my balance right. I have a lifetime balance with discount tires as well and cant even use it! I could just take them off and bring them in seperately, but discount is an hour for me and I dont have another vehicle to haul them in.
 
1985taylor1925 said:
They did a good job when they balanced my tires too. But now that I have wheel spacers on they wont balance due to liability issues, which is stupid. All they need to do is write a note that they didnt install the spacers and are not liable for them. Thats what Toyota did. But Toyota cant get my balance right. I have a lifetime balance with discount tires as well and cant even use it! I could just take them off and bring them in seperately, but discount is an hour for me and I dont have another vehicle to haul them in.
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Jitters, yes, I have wheel spacers too, but they do it anyways. My real good friend is a manager at one of the stores and he's actually the only one that gave me crap about them. He actually told me he wouldn't mount my new tires because I had wheel spacers on. ;)

But yesterday the discount guys didnt say anything about it. I guess they just turn a blind eye on it.
 
Baja Runner said:
Jitters, yes, I have wheel spacers too, but they do it anyways. My real good friend is a manager at one of the stores and he's actually the only one that gave me crap about them. He actually told me he wouldn't mount my new tires because I had wheel spacers on. ;)

But yesterday the discount guys didnt say anything about it. I guess they just turn a blind eye on it.
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Man, thats no fair. I actually just called the local discount tire a second time and tried to convince them. I told them to just make liability note before doing any work, I'll even sign it. They still wont do it. They told me its a black and white rule at every location nation wide.
 
UPDATE:

I went and got my tires balanced and rotated. Guy said each tire was off 0.5-1.0 ounces. After that, however, I haven't had any vibration/shaking issues at all! I have no idea how it was going so smooth with the tires like that before the front "up-lift", but eh.. It's working now!
 
My update.....Installed new ITRE's, OTRE's, and LBJ's (OEM) and had another alignment done. No change.

So Monday I lowered the my Bilstein's one perch and while that helped, I still have a slight vibration at 60mph. I'd already had my tires re-balanced by the installer (prior to all this work) and they said the rears were out , but the fronts were fine. I'm know if I go back again they're going to tell me they can't get a true balance because I asked them to use "sticky weights" on the inside of the rims. I wouldn't mind paying someone else to balance them one more time, if I knew that this would take care of the problem. Just frustrated at this point.
 
Has anyone else had problems with this? I just got my tires balanced and still bad vibrations above 60 mph, it's only when my foot is on the gas though. I haven't tried an alignment yet because I'm saving for some coilovers and figured I'd do the alignment after that. Any help?
 
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