Wheel Alignment Question

I did the alignment on my car and was able to get 3 degrees caster. Did you notice if the bushings had different thicknesses on the flange/face. Mine were 2 differnet thicknesses and I was able to move the lower control arm foward and the upper reward to give me more caster.

This has long been a problem on the Pantera, not enough caster. I took advise some time ago from my friend Pat Mical. He told me to move the top ball joint back by 3/4" (19mm) by widening the top arm. I did this and found the car much nicer to drive as it no longer darts around at high speed. This mod also dialled in some much needed self centring.
I have not yet got around to checking it with a caster gauge, so I cant tell you the exact specs. All I know is it makes the car feel much safer at speed. With the ball joint moved back 3/4," this leaves a big gap in front of it. I made a 3/4" aluminium spacer to go with the original shims to fill this.
I am going to shim my steering rack over the winter, in a bid to remove as much bump steer as possible. I will check the caster at the same time.

When I modified my top arms, I made a rather crude fixture for holding them during the welding process. I have since made a very sturdy and accurate fixture that makes the whole job a lot easier. I also weld in an adjustable camber lock. This stops the top ball joint getting knocked back in it's slots.
I have done 5 pairs of arms now, and have had lots of positive feedback.

The ride height of your car will not affect the caster. Providing you lower the front and rear the same amount. That's a very nice looking 72 by the way. You could lower it more if you want to. My car rides with the rear A arms straight.

Johnny

I can also attest to Pat's fix which now delivers at least 3 degrees of caster. I sent him my front a-arms and my car is a flat as can be - no wandering and no more high speed white knuckle moments.

He also recommends doing the rears too.

UFO,

If you lower the front relative to the rear, you will indeed alter the caster in the wrong direction, if you lower the car the same amount at all four corners the caster will not be affected.

Normal practice on most sports cars is to set the caster from 3 to 6 degrees, it will vary from chassis to chassis, you want enough to stabilize the car at speed and no more.

your friend on the DTIC

I am running 4.5 degrees caster with Pat Mical's modified control arms. If I wanted, I could get more.

The more + caster you have, the more difficult it is to steer around turns.
Cars with power steering can take a little more but the wheel will still fight you.
+ caster makes the car want to go straight.
You need to find a compromise.
2-1/2 to 3 + seems to be approximately it.
Less will make the car much more squirly. More and you can't turn the wheel quick enough to steer around tight turns. 3+ would be good for a drag race car to keep it going down the track.

The profile of the steering tire effects this tremendously. Also the suspension can be tuned largely with air pressure. The difference between 30 pounds and 40 pounds is night and day.
It depends as much on the wall stiffness of the tires as anything.
These cars were not designed for 35, 40 or even 50 profile tires.
Round shoulder front tires like Pirelli CN36 make driving more civil but the car won't generate big G numbers, but that's how the suspension was concieved of.
The square edges of those low profile tires can create instant, violent oversteer, and they also enhance bump steer to a lethal level.
P7 Pirellis are a hybrid tire between a stiff wall and a bias ply tire like the Arriva.
The car is easier to tune and more predictable.

I don't know how the wide body cars are tuned but considering what I have experienced driving you are going to have to prove it to me that they are not death traps on NY roads.

...let the games begin...step right up and whip up on me...pain and degredation is what I'm all about.

Doug ,

Have you found any one with a brain in the NY area that can help me align or check 9138 ... I made 2 apointments locally and they both cancelled stating their machine will not do a Pantera ... its the same as an old vette ... but having a problem finding a shop to do it.

I have to say 9138 was suprisingly very well behaved on the track in 2 different tracks .. one big oval and one short turn.

Ron

I would like to help but I can't make a recommendation.
There seems to be some kind of issue with the Pantera and the current computerized equipment. Don't ask me what. I don't know.
It probably needs to be aligned on an older machine. More likely it needs to be aligned by an older technician.

One of the Westchester Street Rodders had a shop and could do them but I don't know where he is at right now.
I'll try to track him down but don't hold out too much hope. I think he retired and moved to NC.
(This didn't come from me but, if you have a good interior shop with a nice level floor, you can do it "manually" right on the floor).
Toe in is always considered an approximation of +/- 1/16". The camber can actually be done with an accurate level (plumb) a calculator and an accurate measuring device (dial indicator).
The castor can be done with a castor bubble level.
The car does not have to be set to an accuracy of .001 degree like the "computerized system" does.
An accuracy of plus or minus 1/10 of a degree you can get right on the floor, just like in the old days, no BFD.
Since you will want to try different settings you may as well learn how to do it yourself. Most of the roadracers do already.
Because someone has a $150,000 machine, it won't make the setup any better, it will just calculate the value of pie to the last diget. We don't really need that.
No technician can pull a number out of a book or database and tell you it is the right setting. You need to try various settings based upon the factory as a starting point.
This is the problem of the technowizard world we live in now. No one can balance thier check book without a "scientific" calculator.
Unfortunately one needs to take thier own lives in thier own hands. (Nothing personally intended).

Panteradoug:

My car is a wide body so that is why I am running 4.5 degrees caster. I would never recommend that much caster for an early model Pantera on taller, narrower tires. However, with the 285/40-15 tires on the front of my car, the extra caster is simply a matter of survival.

If you think your roads are rough in NY, try coming to Canada with our winter-ravaged highways. Before Pat Mical modified my control arms for additional caster, the car would dart left and right unpredictably with every pavement imperfection. Not only was that stressful, it was dangerous.

My GT5 will never be a Lotus Elise in terms of lightning fast reflexes, and yes I have some extra steering effort, but this is mostly noticeable at lower speeds. Since my car is seldom driven in the city, it doesn’t bother me. Or even my wife, for that matter.

My wife only ever complains about the clutch effort and the stiff throttle pedal. Interestingly, she just went out and spent a few thousand dollars on some super high tech elliptical random orbital etc etc exercise machine. Is it just me or does something not add up here…?

- Peter

Thanks to everyone for your replies.... After utilizing every bit of my free time for the past 9 months doing the restoration on my P-car, I couldn't wait any longer to see how good the engine came out, so I took the car out with the caster angle being a little shy of where it needed to be. It was definitely squirrelly at high speed so I took George's advice and lowered the rear another 1 1/4" which seems to have stabilized the steering. I don't know how much more caster I gained since I haven't measured it yet, but this definitely helped the car's handling. However, I would still like to get just a little bit more caster. For this, I would like to get some more information from Johnny on how he is modifying the upper A-arms. I have an extra set of a-arm so I can modify a set to gain more adjustability. Johnny, assuming that the a-arms consist of a forward arm and rearward arm attached by a plate welded across each, where are you cutting the plate to allow you to move the rearward arm? At the original weld or in the center? Are you bending an offset into the rear arm or just spreading the opening? What is your preferred welding method for re-attachment (Arc, MIG, or TIG)? Thanks for the help.....
P.S. The engine came out awesome......

Panteraufo,
I have another set of arms to modify next week. I will take step by step pictures, and post them here.

Johnny

Thanks Johnny.... As aways, I really appreciated the information and learning experience....

I have my A-arms modified like Johnny's and am very pleased with them. I don't know what the caster angle is but the steering effort is acceptable. Tracking is great.
Mark

Ok some very basic questions if I may :

The caster is the angle the front spindles lean backwards at the top in relationship to the lower control ball joint ?? correct ... what we are saying here is the Pantera as set up stock doesnt allow enough adjsutment to get enough caster ... for what type of driving ?? street ? what about racing would I want more caster ?

The camber is the amount the front tires lean inward at the top in relationship to the bottom ball joint ?? correct ? with wide modern tires what would we want that to be in degrees ?? The pantera does allow for some adjust ment on top but is it enough to use modern wide radials ?? The name of the support sold I guess holds that adjustemnt in place and from changing with the modern roads ( which are worse then 30 years ago ) is that piece worth using ?

Ron

quote:

Originally posted by accobra:
Ok some very basic questions if I may :

The caster is the angle the front spindles lean backwards at the top in relationship to the lower control ball joint ?? correct ...

Yes

what we are saying here is the Pantera as set up stock doesnt allow enough adjsutment to get enough caster ...

Why not? 2-1/2 to 3 degrees is a lot.

for what type of driving ?? street ? what about racing would I want more caster ?

You might want more for a Champ car or Indy Car. Probably to run the Silver State if you are going 200+ to keep the car going straight.
Wide body Panteras may feel more stable with more caster. More caster will numb out some of the dartiness the monster tires cause.

The camber is the amount the front tires lean inward at the top in relationship to the bottom ball joint ?? correct ?

Yes. Pantera specs are 0 degrees in front, -1/2 rear. My 67 & 68 Shelbys would want -1/2 to -3/4 on the street. On the track as much as 2-1/2 to 3 negative. The rear will have -1/2 already built into the stock 9" rear.


with wide modern tires what would we want that to be in degrees ?? The pantera does allow for some adjust ment on top but is it enough to use modern wide radials ??

My car is a stock fender car. 8"/10 Camis. 225-50-15 P7's. For that set up there is plenty of adjustment available.


The name of the support sold I guess holds that adjustemnt in place and from changing with the modern roads ( which are worse then 30 years ago ) is that piece worth using ?

It's a camber lock. I have one but it is as the English say, "redundent".

Ron

quote:

......My 67 & 68 Shelbys would want -1/2 to -3/4 on the street. On the track as much as 2-1/2 to 3 negative. The rear will have -1/2 already built into the stock 9" rear.

How do you achieve camber on a straight axle?

Play in the bearing and the centerline of the pumpkin and the centeline of the outer bearing are offset to create it.

Thanks Doug ...

Ron