Measuring Chassis Height & Shock Adjustment

Pat Mical recommends, if I recall correctly, aboout 1/2" to 1" downward rake forward in order to reduce high speed front-end lift.

Jim,

adjust the rears to make the lower rear control arms parallel to the garage floor. You can measure between the floor & control arm near the pivot & out near the carrier, adjust until the measurements are the same.

Then lower the front end until the door sills are level. If you want to give the car a nose down attitude as Peter mentions, pick some point between the chassis & floor just in front of the front tires & lower the front end another 1/2" beyond level. This is a touchy adjustment, so don't go too far. You are sacrificing positive caster & straight ahead stability in favor of a lower cg and aerodynamics. You are also putting that fiberglass air dam lower to the ground and more likely to scrape on driveways, etc. I believe lowering the nose is more beneficial to the Ford era Panteras that don't have that big air dam like your beautiful GT5 does.

Of course, after you've done all that, you really need to take the car to somebody who has the scales to do a 4 corner weighting.

your amigo

Coz,

ditto what George said about teh 4 corner weighting. I had that done to my car this past summer. They do the alignment and balancing in 1 session. I was very pleased.

Your car looks great by the way....wanna trade?

John

I like Tracy's black GT5S rake (photo below), with the nose about an inch off the ground. Has air bags, and he says it can ride at various heights, however I am sure there is a ride limit. In the near future I hope to have an article with his car and my GT5S and I will inquire more about the air bag thing.

Thanks Peter, George and John...

That's pretty much what I did George. I got the rear level using the lower control arms as my ground up measuring reference and kept it just high enough to clear the fenders at the top of the fender wells tire wise.The rears actually tunk under just a little. Height looks good there.

Going to check where the the bottom of the door sills in the morning and see how level they are. From there I am going to lower the front end the 1/2" rake. Eye balling it, I think I'm pretty close.

Monday It's going to my alignment shop for the 4 wheel alignment and balancing of all 4 corners.

Thanks guys. Will post a picture after it's done on Monday.

Coz:

If you're playing with your ride height, I'm told it can affect your bump steer. Therefore, you may want the shop to have a look at your bump steer while they're at it. When I had my alignment/ride height/bump steer tuning/corner weighting done recently, it took them over ten hours to do the whole job; whenever they changed one parameter it changed another. Don't ask what the bill was...

Great idea Peter.
Thanks for the reminder. I have an appointment in the morning at 10 AM to get everything done.

I read a couple different write ups about setting up a car for a track. Both write ups said there are a lot of guys at the track that really don't know what they are doing and use 4-corner scales to even out the weight on each wheel. With long explanations they described how this can really de-tune a suspension and make it worse. They had a whole series of procedures to getting a suspension tuned which may be worth looking into. It's more deep then what I have gotten and can't provide much useful other then they both made it very clear 4 corner weighing is a good way to mess things up.

Gary

Gary I agree .. you can measure the wieght of the car on 4 corners .. but its what you do with those weights is what counts ... you dont want all 4 corners the same weight.

I can say what the weights should be but .one thing I do know .. you need to know exactly what the use of the car will be .. street or road race ... then all 4 corners will be a different wieght. I know the focus will be on the front left and right rear. its all about wieght transfer and which way the car twists under acceleration.

I dont claim to be an expert .. but thru experience in drag racing .. most of the time its exactly the opposite of what makes logical sence.

Ron

From what I have read things like slight differences in springs, slight twist in body, un-even spring rates, etc. all combined make the 4-corner weighing a crap shoot. Could be a thread all on it's own.

Yea ,,, I dont think its rocket science ... and I dont think any one car reacts the same way. I do feel the Pantera has a lot of room for adjustment.. The shocks assemblys you can buy adjustable. The ride height is adjsutable ... spring rates you can get advise from a vendor ... the suspension with a little welding experience can be altered to have adjustments.

Then its a matter of trial and error.

One thing I learned is HARD adjustments on shocks almost sent me into the guard rail at about 140mph a few times... not a good place to start on the hardest settings .. LOL SOFT is a good place to start and guarrenteed you'll end up back there .. the problem is a lot of people start there because of tire clearence issues .. it prevents rubbing.

Ron

Alignment is done for now.
GT-5, running 275x40x17 front and 335x35x17 rears.
Caster Angle: Front Wheel: 3 degrees
King Pin, Front Wheel: 8 degrees
Front Camber: 3/64
Front Toe In: 3/64
Rear Wheel Camber, Negative: 5/64
Rear Wheel Toe In: 5/64
Raked front angle: 1"
Damping: 16 settings. All shocks set on 7.
We used this as a starting point, once I drive it for awhile, I see how it handles and we'll fine tune it from here to suit my style of driving it.

When Balancing the weight in a race car, it involves more than having a set of four corner scales. Last year I took my race car to a guy whose specialty is suspensions, shocks, and Racing, and when done right it will make a difference! It brought my lap times down almost 1.6 seconds per lap, and this was the only change on the car (and yes I run very consistant times at the tracks that I run regularly). This guy races BMW's in the Grand Am series, and he talked the team owner to let him set up the car's suspension and corner weight balance, and the next thing his and his co drivers car is out performing the other three team cars. He now does all the teams cars. So it really boils down to having the right person do the work.

Coz
How much shim did you have left in the lower control arms at that setting? Do you have adjustable uppers? I had a customer lower his car so the rear arms were parallel and we could not get the rear camber to come in. With no shims in the lowers the car still has a noticeable negative camber in the rear. We toyed with raising the car just one inch while it was on the alighnment rack and the camber came in perfect but the customer didn't think the car looked as cool so we left it. I guess negative rear camber looks cool? Anyway, I am curious as to your rear arm set up.

Brook,
We actually used 1 to 2 shims on the lower a-arms on each side, front & rear to get the toe where we wanted it. My lower A Arms have extra long studs on the lower a-arms that pass through the frame rails. Still could have added more if we needed them, we had more than enough room.

I have adjustable Heim joints on the upper A-Arms so the Camber is very adjustable. We also had plenty of room to go positive or negative from where it's at now.

The Heim joints are the only way to go to be able to really zero in on the camber getting the rear tires firmly planted level across if you want it lower.

I will take a picture of the car tomorrow and post it from the side and rear so you can see the rake and foot print from the rear.

What coating did you use on the lower suspension arm?

Hubs painted?

Sure is pretty isn't it?

It's Shiny Silver powder coating.
The uppers, sway bar & brackets are done the same way.

The uprights/hubs were jet hot coated as were the headers and mufflers.

That is piece of art Coz! Just beautiful. I could look at it all night.

So what were you saying about trailer queens? I can't believe that you're gonna drive in the dirt and the rain and not pull the wheels off just to clean every inch of that suspension.

And with that polished ZF, where does it end? What about your half shafts - are they chromed?

It's hard to believe, Coz - Mr. Daily Driver - with a toothbrush in hand getting every grain of greasy sand off those shiny zerks.

Man, you're scaring me.

Naw brother....It's always going to be my daily driver. To me, trailer and garage queens are worthless, but that just my personal feelings, to each his own.... If I wanted something to just look at, I'd buy a poster and put it on my wall. It would be a lot easier and a hell of a lot cheaper.

I did this to actually help in the cleaning and not so much the show of it. But it did come out good. Now I can spray everything down with an Orange cleaner, let it set for 10 minutes and then just wash everything away with water. Towel dry it and it's back to looking like it was just done.

I stripped the 1/2 shafts and clear coated them. They look ok....Thought about powder coating them too but them but decided not to.

Tooth brush ???? Not a chance

It has always been and will always be a driver to me. The day I stop driving it is the day I sold it.

Thanks Deeb.

Here is a pic of the car I am talking about. I had him call Pantera Performance to see about getting adjustable arms but he decided they were too much money. I guess tires are cheaper?
You can see the footprint definately runs to the inside.

I guess it really depends on how much you drive the car. At 400+ a tire, I think the heim joints would be cheaper in the long run....

quote:

Originally posted by Pittcrew:
Here is a pic of the car I am talking about. I had him call Pantera Performance to see about getting adjustable arms but he decided they were too much money. I guess tires are cheaper?
You can see the footprint definately runs to the inside.

I can only share my experience in the alignment and corner balance of my 911SC track car. My Pantera hasn't been done yet.

They put the car on the pads of the scales. The ground or the rack has to be perfectly level. The car will have half a tank of gas and they place the weight of the driver in the drivers seat.

They then look at the weight of each corner. Each corner will be different.Race teams etc will go to great lengths to get the 4 corners the same in the shift of fuel tanks, battery relocation or ballast if the rules allow so.They then take a corner say the right front and then look at the left rear. They then start adjusting the ride heights. The car is really sensitive to this. For example raise the passenger front you now raise the passenger rear.You also upset the other 2 corners.Its sort of taking a sheet of square wood and placing a ball in the center. Drawing a X to all 4 corners. Each car has its own weight bias characteristic or weight bias distribution. For instance in the 911 case its more 60/40 because the engine is in the rear.In the Pantera's case I think its 50/40 because its mid engine design.

So they are adjusting ride heights, trying to get the weight bias of the car correct and doing an alignment all at the same time.It really is half rocket science and black art. Not so easy. It takes an experienced person to do this. As Rapid pointed out, get it right and seconds come off your lap times.Get it wrong and your car has a pull to the right or the left that can be mistaken for a bad alignment.The car will also develope a front end skip during really hard corning.You'll be fighting a bad corner balance the whole way through a turn.All this is done for the car not the drivers style of driving.Thats why they have sway bars for fine tuning.

This is just for a roadracing circuit. Circle track or oval track racing opens up a whole another can of worms and experience.Its really important you don't take your car down to Rayco's for this procedure.You can but you'd never fully exploit the true handling of the Pantera at speed.

As I mentioned, it is a mechanical science to it.Its why they charge so much money for it to be done correctly. I've only explained in what little I know.They have books of explanations and theories of this stuff.

As far as the Pantera I payed Pat Michals a lot of money up front. He refabricated all four corners of my upper control arms so I have as much room possible in setting up the suspension without bind.George is right when he says don't lower the rear of the car past the level of the lower control arms. If you do, You've used up most of the travel of your shocks. You end up with a bucking bronco.Having extended upper rear control arms is a cheap advantage in setting of the rear for the correct castor.

Dan