Negitive Caster problem - Chevelle Tech
Brakes, Suspension & Steering Conversion questions & more.

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post #1 of 36 (permalink) Old Jun 24th, 19, 4:22 AM Thread Starter
 
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Negitive Caster problem

I just rebuilt the stock front end in my 67 El Camino. new ball joints, control arm bushings, center link, tie rod ends, shocks. converted to a quicker ratio steering box off a low mileage donner car. took it in to be aligned and came back to the shop they said the best they could get the caster was -4.5 on both sides camber is close at o and -0.2 toe was 0,15 on each side or total of 0.30
What in the world could cause so much neg caster. I double checked just to do it that the control arms are on the right side the top control arm shafts are on correct.. I am stumped. only cure I see is global west G plus upper control arm is suppose to add 5.5 degre of caster. but why would I need that?? what is wrong here? I see no damaged parts. I am going for stock appearance but right now it drives BAD especially going into a corner. So I have to do something.


Any Ideas what may be going on?? Thanks Joel
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post #2 of 36 (permalink) Old Jun 24th, 19, 5:50 AM
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Re: Negitive Caster problem

I think your thinking is backwards on caster camber. minus 4.5 is very good caster and usually not obtainable with stock arms. zero camber is about right . now if you got your terms backwards your cross member may have sagged causing the control arm upper mounts to move toward each other which is common. moog makes offset upper shafts to cure this and restore the camber to zero
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post #3 of 36 (permalink) Old Jun 24th, 19, 6:18 AM
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Re: Negitive Caster problem

Quote:
Originally Posted by gnicholson View Post
I think your thinking is backwards on caster camber. minus 4.5 is very good caster and usually not obtainable with stock arms. zero camber is about right . now if you got your terms backwards your cross member may have sagged causing the control arm upper mounts to move toward each other which is common. moog makes offset upper shafts to cure this and restore the camber to zero

No, you want positive caster, and as much of it as you can get in most cases in these cars.
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post #4 of 36 (permalink) Old Jun 24th, 19, 6:20 AM
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Re: Negitive Caster problem

Quote:
Originally Posted by Joel Tobert View Post
I just rebuilt the stock front end in my 67 El Camino. new ball joints, control arm bushings, center link, tie rod ends, shocks. converted to a quicker ratio steering box off a low mileage donner car. took it in to be aligned and came back to the shop they said the best they could get the caster was -4.5 on both sides camber is close at o and -0.2 toe was 0,15 on each side or total of 0.30
What in the world could cause so much neg caster. I double checked just to do it that the control arms are on the right side the top control arm shafts are on correct.. I am stumped. only cure I see is global west G plus upper control arm is suppose to add 5.5 degre of caster. but why would I need that?? what is wrong here? I see no damaged parts. I am going for stock appearance but right now it drives BAD especially going into a corner. So I have to do something.


Any Ideas what may be going on?? Thanks Joel


Can you take a picture of the upper control arm mount at the frame? I'm curious to see the shim arrangement they ended up with. Even a 1/4" of shim on the front stud really moves caster a good amount.

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post #5 of 36 (permalink) Old Jun 24th, 19, 6:23 AM
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Re: Negitive Caster problem

My first place would be to look at one obvious answer - they screwed up.

Take a look at the upper A-arms - how big are the shim packs that they put in on each side?

Quote:
Originally Posted by Joel Tobert View Post
I just rebuilt the stock front end in my 67 El Camino. new ball joints, control arm bushings, center link, tie rod ends, shocks. converted to a quicker ratio steering box off a low mileage donner car. took it in to be aligned and came back to the shop they said the best they could get the caster was -4.5 on both sides camber is close at o and -0.2 toe was 0,15 on each side or total of 0.30
What in the world could cause so much neg caster. I double checked just to do it that the control arms are on the right side the top control arm shafts are on correct.. I am stumped. only cure I see is global west G plus upper control arm is suppose to add 5.5 degre of caster. but why would I need that?? what is wrong here? I see no damaged parts. I am going for stock appearance but right now it drives BAD especially going into a corner. So I have to do something.


Any Ideas what may be going on?? Thanks Joel
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post #6 of 36 (permalink) Old Jun 24th, 19, 8:27 AM
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Re: Negitive Caster problem

How much rake does the car have? If the rear end is lifted it rotates the king pin inclination rearward. The more level it sits the better. Even nose high, from an alignment point of view is better.
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post #7 of 36 (permalink) Old Jun 24th, 19, 9:01 AM
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Re: Negitive Caster problem

Quote:
Originally Posted by Calculated Risk View Post
No, you want positive caster, and as much of it as you can get in most cases in these cars.
that's what i said. if you actually have 4.5 degrees of castor and 0 camber thats great but ive never seen a stock chevelle go more than 2.5 or so. i think you mean you have 4.5 camber and zero caster which is a problem
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post #8 of 36 (permalink) Old Jun 24th, 19, 9:31 AM
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Re: Negitive Caster problem

I would take it to an alignment shop that understands these old cars. Negative 4.5 will make the car drive like KAhKA

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post #9 of 36 (permalink) Old Jun 24th, 19, 12:05 PM
 
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Re: Negitive Caster problem

Aerial view, the upper ball joint should be behind the lower ball joint. If it's forward (as it would be with -4.5 caster) something is amok for sure...
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post #10 of 36 (permalink) Old Jun 24th, 19, 1:43 PM
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Re: Negitive Caster problem

i was thinking for some reason it was 4.5 pos caster so disregard what i wrote before if thats what it actually is
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post #11 of 36 (permalink) Old Jun 24th, 19, 1:50 PM
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Re: Negitive Caster problem

I was able to get about 2-3 degrees of positive caster on the factory control arms, then about 10 years later, it declined to about 1-2 degrees positive. Get as much positive as you can. You might want to find a different shop as not all are willing or able to deviate from the factory specs, which are completely backwards from what is needed and were designed for different tires and at a time when highway driving wasn't as prevalent.

You'll want: Caster: As much positive as possible. Camber: 0 to - 0.5. Toe in: 1/16 to 1/8 total. The more caster you have, the more stable highway driving will be. Negative camber will make cornering better. Toe-in will help straight line tracking.
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post #12 of 36 (permalink) Old Jun 24th, 19, 2:26 PM Thread Starter
 
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Re: Negitive Caster problem

The car is stock height . I will get pictures latter but it has an even number of shims on both studs. pass side has two on each stud and drivers 4 on each stud. the guy at the shop told me he tried to put an extreme amount of shims on one stud. I suppose it would be the back stud, he was talking like an inch of more shims. he said it only brought it in to neg 3.5., not enough. would that mess the camber up? I been thinking of adding 4 shims on the back studs and seeing if it drives better, it would just be a blind shot though , I could always reverse my adjustment. anyway he accused me of having something on wrong but I re checked , compared to other cars... everything appears correct. Thanks for your input.
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post #13 of 36 (permalink) Old Jun 24th, 19, 3:31 PM Thread Starter
 
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Re: Negitive Caster problem

going to try again to upload photos they load to site but wont post to thread
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post #14 of 36 (permalink) Old Jun 24th, 19, 3:35 PM Thread Starter
 
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Re: Negitive Caster problem

you can now see even# of shims- front to back , one side has 2 thick shims and the other 4 thin shims on each side. about same thickness both sides
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post #15 of 36 (permalink) Old Jun 24th, 19, 4:06 PM
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Re: Negitive Caster problem

Try to find an old guy a different alignment shop. Its tricky to get the shims right ...every change affects both caster and camber. All the new stuff uses eccentrics and youngsters don't understand the shim system. Last resort , Moog makes a problem-solver offset upper shaft to add some caster but you will have to remove both upper bushings to install

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