Caster question

[nitrofarm]

My Aspire was in a wreck from PO. The left side has a Festy axle & the engine mount is custom. I had to relocate the engine about 3/4" @ the RH mount.(In order to get the motor "squared")The entire front end is basically new excluding the rack. I'm still getting a LH vibration into the steering wheel. It never happens on smooth pavemant. Only occurs going up or down a grade. It comes in @ 65-75 and will stay till you slow down past 65. Im running @ 1/32" of total toe out,measured via my Red Neck gauge. Also tried new tires,it helped but didnt cure. My real reason for telling you all this... If my LH knuckle has NEG Camber.Instead of POS Camber.Could this be the cause of the vibration? Like perhaps the Caster is pushed back to zero.And the tire is "Fluttering"? Thx-

[georgeb]

Get another body! Until then you can check the camber with a carpenter's square on the floor of a level garage touching the tire and measuring to the rim (don't use the tire because it bulges). Don't know how to measure caster but it can be tweaked by shimming torsion bar to control arm attachment.

[Movin]

Castor will cause a pull. Likely something has a little play that will not show up
with the car jacked up. Upper bearing plates , steering rack bushings..(not the
steering rack mount bushings) worn out struts..Ball joints and tierod ends are
pretty easy to pry around with the car on the ground. Things like those first
two get overlooked a lot though.

I see why you ask this, you have seen the front of a grocery cart castor wheel
vibrating like crazy and that is what you feel. We call that the "death wobble"

It happens because tires are never perfect and something is loose.

[nitrofarm]

Get another body! Until then you can check the camber with a carpenter's square on the floor of a level garage touching the tire and measuring to the rim (don't use the tire because it bulges). Don't know how to measure caster but it can be tweaked by shimming torsion bar to control arm attachment.

Castor will cause a pull. Likely something has a little play that will not show up
with the car jacked up. Upper bearing plates , steering rack bushings..(not the
steering rack mount bushings) worn out struts..Ball joints and tierod ends are
pretty easy to pry around with the car on the ground. Things like those first
two get overlooked a lot though.

I see why you ask this, you have seen the front of a grocery cart castor wheel
vibrating like crazy and that is what you feel. We call that the "death wobble"

It happens because tires are never perfect and something is loose.

Everything is very very new except the Rack. All the way from the Bearings,Tie Rods Ball Joints bushings.The Steering Seems very tight. I can drive @ 75 in the rain no problem. Its just this dang vib through the front end. Oh well, I'll keep digging. Im gonna try to get some idea of my Caster with a bubble protractor. I'll buy one @ the store.And try to compare Left & Right. If I dont measure anything to funky I'll try moving the tranny around a bit.Maybe that axle is being stretched to much? Thx-

[Movin]

Some of the auto cars have a problem with the passenger side CV being crowded
by the transmission location and you will feel the inner cv tapping the end of the
bore. This usually happens when the suspension is above or below center, not
cruise, Acceleration or deceleration.

Some basics...You have wheels that center up on the aspire hub..not some aftermarket
ones that may even have the wrong lug taper and hole size.
You have a light car, the tires have to be balanced far more accurately than big
heavy beasts like Subaru's . Good tire stores will have a balancer that can balance
tp 1/10 ounce, far more accurate than the normal machines do. I have to cut weights
using these fine machines to achieve vibration free high speeds. This kind of problem
is not the death wobble but is irritating, and bad enough can make doors and windows
shake as well.

[nitrofarm]

Thanks movin-We've logged 50k on this chassis since I titiled it last July. I've been fighting this vib for 50kdrool It got soooo much better with the shorter axle. Just hit a doe on the way home for work this am. And we got front eneded by a 18yr old texting about a month ago.I'm ready to retire this chassis.Just thought it would nice to figure out where its coming from.The good news is taught me a lot of patience. :cry_smile: PS anyone put 50k on their car in 11 months? We drive the crap out of these cars.

[Movin]

If shorter is better you can shorten the axle a little more..
With the car jacked up can you wiggle the axle back and
forth a little on both sides? It needs this clearance.

[nitrofarm]

Got it,smooth like a baby's bottom.Put some new tires on the rear.The last of the vibration was coming from a wear pattern in the rear tires.I can cruise all the way up to 85 without anything abNORMAL I'm still going to try and check the Caster with a Digital Protractor called the "Cube" Thanks to recomendations from Charlie aka Advancedynamix. Also tightened the rear bearings while I was back there.The car is super tight now,almost hate to call it a parts car now.

[blkfordsedan]

I'm confused....is your issue the caster or camber? Usually, caster has no effect on anything except for "self centering" after a turn. My Festy has + caster on one side and - on the other. It drives great, no pulling, but won't self-center. As long as its within a few degrees from side to side, its usually within spec.

[nitrofarm]

I'm confused....is your issue the caster or camber? Usually, caster has no effect on anything except for "self centering" after a turn. My Festy has + caster on one side and - on the other. It drives great, no pulling, but won't self-center. As long as its within a few degrees from side to side, its usually within spec.

I was having a vib and it felt like it was coming from the front.But in actuality it was coming through the chassis.Traced it down to the tires in the rear.Buuuut I stll need to try and check the caster. The Festy axle fits perfect so that shows you how much the LH side got pushed in.Now I need to see if the strut tower got pushed back as well.

[Movin]

Axle pushed in is camber, from the side.
from the front, tire pushed to the back of
the tire well in the fender, so it is not centered
with the wheels straight ahead would be negative
camber.

[nitrofarm]

Well I finally got a chance to use my new digital "Angle Cube".Thanks to Advancedynamics for the suggestion! Its the best $30 I've spent in a while.It is a great tool for checking caster,camber etc. I was really surprised to find that L & R caster were both about 1.5 deg.I was expecting to see the L side really wacked out.The vib is almost non existant now.So I'm going to look at my eng/tran alignmant. Maybe the L axle is just too straight and needs a little angle.Someone IDRC mentioned that you dont want your axles perfectly straight to the hub.Because you can get a harmonic vib. Thats exactly what I feel ever so slightly. Your thoughts are always welcome & appreciated-