Caster....

Some time ago, I got around to finally putting on a fresh left upper control arm, and new upper inner bushings, the car has had a very slight pull to the right....

the caster is set with upper joint behind lower joint, per stock spec....I think that is positive, as I recall, like a motor bike....

so because it pulled to the right, I figgered the more caster the better, I pulled the left arm loose and switched some shims around, putting about 1/16 or less in the front, and adding same to the back...all I really did was swap shims so to leave camber alone.....

NOW, it pulls much MORE to the right.....WTF???

:bonkers:

obviously I need go back and then proceed from there.....but I figgered it would pull to the side with MORE caster, not less....

:bonkers::goodnight:

Gene,

I wouldn't play around with it. Get it aligned.

Yves

Belgian1979vette said:

Gene,

I wouldn't play around with it. Get it aligned.

Yves

Click to expand...

I used to, up north, but there are NO competant alignment shops here near me....they all give the the 'hustle' and so I get pissed and leave....

honestly, today not one of them knows how to do more than set the toe...

show them a shim upper arm and they do nutz....

If after increasing the positive caster to the left the car pull more to right..... is because you have some toe out.
With more caster at the left wheel, that wheel will try to stay stright with more force that the right one..... if you have some toe out, the result will be the right wheel pointing to the right side.

Basically the caster must be the same in both wheels, otherwise the car will pull to left or right in relaction to the toe you have.
Of course..... unless you have zero toe...... in this case you will notice more effort steering in one direction than the other, but the car will stay in the line.

I hope my hugly english is enough to explane the concept!

exactly, caster adds straight line stability because any steering input will have to pull the spindle upright (towards vertical). You can see this on a lot of cars when parking, with full steering lock you can see one side of the suspension pushing the car up, it's the result of the kingpin angle and caster.

I see cars coming from the US w/ a lot more cater on the pass side than on the drivers side (mcpherson strut cars commonly w/ 4 dr and 5.5 pass side) to get straight line stability and compensate for road crown.

As a result if your car pulls and most roads are crowned it may not be a bad idea to add some more caster on that side.

Twin_Turbo said:

exactly, caster adds straight line stability because any steering input will have to pull the spindle upright (towards vertical). You can see this on a lot of cars when parking, with full steering lock you can see one side of the suspension pushing the car up, it's the result of the kingpin angle and caster.

I see cars coming from the US w/ a lot more cater on the pass side than on the drivers side (mcpherson strut cars commonly w/ 4 dr and 5.5 pass side) to get straight line stability and compensate for road crown.

As a result if your car pulls and most roads are crowned it may not be a bad idea to add some more caster on that side.

Click to expand...

So if it pulls right, on a level pavement ADD more caster to the RIGHT??

:flash::bonkers:

No, get the toe setting right first, Then if your roads have a crown and it pulls even if toe is set correct, THEN add a bit more caster to the side it's pulling towards

Alignment shops... don't get me started..... :lol:

Maybe not all of them but most cannot do anything but turn the tie rod until the green light on the alignment rack comes on... many have no clue what they're doing and when you ask about the angles the answer is always "set to factory specs"....

MYBAD79 said:

Alignment shops... don't get me started..... :lol:

Maybe not all of them but most cannot do anything but turn the tie rod until the green light on the alignment rack comes on... many have no clue what they're doing and when you ask about the angles the answer is always "set to factory specs"....

Click to expand...

Karsten, my issue also, down here, I dearly miss D&L brakes and alignment in Kensington Maryland....

:crutches::flash:

Twin_Turbo said:

No, get the toe setting right first, Then if your roads have a crown and it pulls even if toe is set correct, THEN add a bit more caster to the side it's pulling towards

Click to expand...

the car pulls to the right IF I let go the wheel on level pavement, the road crown is not that large a issue....as it's the same on either side of the crown...

so the car goes straight IF I hold the wheel straight...not a issue...toe in looks great....just that slight pull to the right....

so you are saying ADD CASTER to the right, on other words add a shim to the REAR of the RIGHT upper arm.....??

I can't understand that, but that's what I doing in the AM.....

among 100000000 other things...but number ONE is my coffee.....


:clap:

No, I say get the toe right first. Just eyeballing is not good enough you need it on an alignment setup to adjust it correctly. I agree about most shops only setting toe, that's what the jerks here do too. A shop did the 88 camaro a couple of weeks ago, explicitly told to remove the 5.5 caster from the pass side and put it to 4.5 like the other side and adjsut toe because one tie rod was set longer than the other. Sure enough all they did was the toe setting.....sons of biotches.

That's the reason why I have a (actually 2 ) alignment setups, I'm going to set the smaller sun one up soon and do it all myself. Can't trust anyone anymore these days.