Kirkham suspension aligment specs.
 

David or Thomas,

Do you have any specs., toe, camber, castor, ride hight, measuring points for track and wheel base for these cars? Do you have original specs for the AC cars for a guideline?
I went to drive my car on the east coast last week after assemlby and it isn't quite there yet.
It wants to turn right with any amount of throttle applied in any gear.
The car wants to go straight when turning the steering wheel and kisks back violently which tells me the front castor, camber is not right.
I have driven real Cobras before many times and this one isn't there yet.

Anybody from around Seattle or the Olympic Penninsula know of a race shop with the right equipment to align this car??

Bruce Robles

It's on thier website

http://www.km289.com/information/alignment.html

Check this out

http://www.gasholes.com/smf/index.php?topic=3232.0

Randy

The alignment stuff is towards the end. Unbelievable what Morris is doing.

Why does Tom's Motorsports say you can't use the string method? Morris does...

HRJ,

Tom takes all measurements from the center of the chassis. Some people run a string around the car and measure from that, and that is not 100% accurate.

When measuring from the center of the chassis that insures each wheel is in the same relation to the chassis as the other.

**)

Kris

We do everything from the Centerline of the chassis.... infact we even show folks how to make sure the chassis is square....

Once we know the chassis is square then you can set up your strings from the chassis tubes.....

The way you are talking about is only after you have set the car up the way I have .......then you can make some tubes that attach to the car that go around the car to do some chassis adjustments at the track....

My next efforts will be using Laser Levels instead of string...

Bruce has a problem with Bump Steer and he would do himself a favor and go read my latest issue on how to do Bump Steer and get the car working the way it's suppose to...

Morris

This link will take you to the beginning of Morris' "chapter" on Bump Steer.

Thanks for the clarification, Special K. All of this discussion and Morris in particular have inspired me to at least attempt to align my car by myself...:) We'll see!

Morris,

A BIG thanks for posting that information. We are always tinkering with the car to make it better and it is outstanding to have customers who care about their car and are willing to teach us how to make things better and show us area where we could improve.

Morris has send us NUMEROUS emails on how to improve the car and we have already started to implement his suggestions--starting with the wiring. (the original cars looked like the proverbial "bundle of snakes." Morris was also very instrumental in helping us to fine tune our suspension parts to refine the geometry.

Like Morris says, the string method of alignment is quite acceptable if it is done correctly like Morris has shown.

One thing Morris did tell me when he was here was that street alignment and race alignement are not the same. Could you please explain that a little bit more Morris?

David :):):)

Along those same lines I have a question about spring rates.
The Kirkham alignment specs show 600# rear and 450# front springs.
Info that I have seem from Tom indicates a 450# rear and 600# front spring.
Both were for FE powered cars.

Any thoughts on this??

Good question Xlr8or !

I'm scheduled to have Tom set up my suspension and this is an item that I need addressed on kmp253.

thanks

Scott

p.s. kudos to Professor Morris for his passsion on kmp259 and his generosity in sharing information -- Morris, you Da Man... thanks

xl,

Spring rates are not important, wheel rates are important. The spring works with whatever geometry the suspension has giving you X wheel rate. Our suspension geometry is a little different than anyone else's so you can't exactly compare us to anyone else. (But, that doen't mean we have found the most perfect soloution there is to find.)

We arrived at our spring rates through Dave Dralle, and through many, many, many test miles. Of course, the tester was probably biased, (my brother and I). I, personally, do not like the weak springs in the rear as I don't like the rear end swaying around that much. Others, undoubtedly smart, choose different rates because of different preferences.

Also, driving on the street and driving on a track are different animals. Pure track cars are terrible to run on the street--of course, some people don't mind, though. I tend to set things up more for street use than track use. Most customers are happy with our set up, but there are a few, like Morris, that blow everyone away and not only raise the bar, but set a completely new one. We would be dumb not to listen to him.

I have heard lots of good things about Tom's Motorsports as well. I would love to hear his comments, and complaints, and incorporate what we can into our production as well.

Keep the ideas coming!

David

The info I have from Tom's was for a Kirkham car.
I prefer the improved handling of a semi-track setup over a cushier street setup when driving on the street. Of course a pure track setup would have differences in camber/castor/toe to help turn in and throttle steer exiting that may not be desired on a street car because of excessive tire wear. I want to find a happy medium. A friend of mine has an alignment rack I can use to get the basic alignment done and make it drivable when the time comes, but I was planning on making a trip to Tom to get it dialed in by someone familiar with Cobras.

I have spoken with Tom at Tom's motorsports several times. He has built and seviced some very fast spec racers. They are running 600 pound front springs a speedway engineering 1 1/4 front bar, 400 pound rear springs and a 5/8 rear bar. I am running a hi-tech with the same front set up and coleman spindles. In the rear, I am running an 800 pound rear spring and no bar. Harrison autoworks set my cobra up and has also set up bob bacon's hi-tech. Bacon's hi-tech has an aero package and is probably the fastest cobra in the country. Chris Harrison does not run a rear bar on a cobra because he says that traction suffers off the corner. Also, you get a bunch of camber and toe change in the rear with the original design so stiffer springs is better. The stiffer I have gone in front, the more rear traction that I have picked up. I would be interested to here Morris's comments on no rear bar? Scott

I can't wait to hear what Tom has to say after seeing one of our latest cars. I am sure he will have some good ideas on how to make the cars better--which is what we all want! Please keep us informed. 2 heads are better than 1.

David

Thanks Guys For the baseline alignment Specs.

Morris, I to have spent many years in racing going from a BP Shelby GT 350R SCCA Club Racing in the '60's and on to TRANS-AM, FORMULA 5000, CAM-AM and Champ Cars in the '70's, GTU, GTO, GTP in the '80's and CART thru the mid '90's.

I think it's great Tom and David have finally found someone with the expertise and the time to do what you have done with web pages that were related to me.
I find your comments concerning the roll resistance and the need for a stiffer bar on the Cobras spot on.

My car has the billet upper and lower control arms with rod ends every where. Your car has a fixed lower control arm which, whether good or bad, gives a base to start from. With the infannant adjustment on my car, unless the rod ends are installed at KMS on a fixture that was built with consideration to length for the proper track, wheel base etc. the job of doing the alignment is monumental.

As mentioned you can't do this at your local tire store. You graffic explainations and pictures are terriffic, and there are those of us out here who have experience in doing many of the things you have touched on. However many of the people who purchase these cars don't have the knowledge, or didn't until your post, how to, or where to get this type of work accomplished.

I have spoken to Thomas about building fixtures to assemble the A-arms in in order to get the Rod Ends screwed in the proper length so the car is square upon delivery. This would require removing the suspension from a car that has been properly aligned and using the A-arms as models to build the fixtures from, for all four corners, upper and lower. Or they could use the original Cobra non adjustable A-arms as a reference. Perhaps while you are around thier shop you can get this in the works. It would save a ton of time in the end, and some guy who buys a car and just wants to drive it can, with some degree of safety. I have friend down in LA who took his car to a guy I know down there, ( I just moved to Washington and don't have my shop set up yet) and it took 3 10 hour days to get it right, ride heigth, track, wheel base, bump steer and corner weight. It cost a fair amount too.

I realize that this won't cure bumpsteer problems and there will need to be some fine tuning, especially for track use, but at least there would be a known base to start from.

Since I have been relocating, I had a shop in the Atlanta area install the engine and get it running and drivable. They did a nice job with the install and paid close attention to detail except they aren't suspension minded. They set the front toe and that's about it.

Since the car is being shipped soon, and I'm 6 mos. from my shop being done, I was wondering if anyone knew of someone in the Pacific Northwest who has a place to do what Morris has described?

Thanx.

Bruce,

We too are glad Morris came along and posted all of this for everyone. You should see his wiring harness if you really want to see something cool--inspired us to change ours completely. No one likes the Prince of Darkness and electrical gremlins.

We found exactly the same problem you are describing with all of the rod ends everywhere in the suspension--people were taking too much time to set everything up. Our latest version of the suspension has fixed bearings on front lower control arm inners and on the rear lower control arm inner.

I don't know of anyone in your area, but I will check to see if we can find someone.

David

See Morris...everybody wuvs you!:LOL:

Guy's

I'm not sure where to start.... you caught me on the road with out any of my notes.....but we'll try to answer some questions that have been posed on this forum.....

The first thing we have to do when we start with a chassis is make sure the Chassis is square..... and we do that by dropping a string from 4 points on the chassis that are the same point on each side..... the idea is to find Centerline of the chassis and see if the chassis is square......that is the starting point of the chassis work......

I like to find the Centerline and then once I know where the center line is ...... measure to my chassis frame or tubes to see if they are straight with the Centerline...... this will make measurments easier at a later point..... if they are not straight then you'll have to use the Centerline to make all of the measurments....

Once we know the chassis is straight and square and know where centerline is....then we have a reference point .... the outside of the frame rail...... on our car the frame rail or 4" tube frame rail became our reference for toe or for location of suspension points.....

So what we do first is measure Castor..... Castor has many good things going for it..... in the sense that it will make the car track straight.... but you may need Mark McGuires Forarms to turn the steering wheel..... on the street we will run 3*to 4*degrees of Castor.... on the track we will kick the Castor up to 5*- 7*degrees and this will help the steering wheel return when in a loose turn ........ you can't respond fast enough with your hands.... many times I would just let the steering wheel rotate in my hands and the front end would correct for itself..... but again on the street you will have a hard time turning the steering wheel with 5-7degrees of Castor.... BTW Castor won't have anything to do with the turn ability of the car...... just tracking down the track....

Then we set Camber ..... leaning in of the wheels..... on the street we will set the camber from -.7 degrees to -1 negative degree of camber..... on a track we'll set the camber based on the tire temps..... usually a static setting will be from -1.5* to -3*Negative degrees.....again the tire temps will tell you where to set the tires camber....

Toe is set for the street at 1/16 on each front wheel.... and usually an 1/16" to 1/8" on each wheel..... depending on what type of suspension you have and what your bump steer tell you.... That is why Bump Steer is so important.....

Once we do this we go back and make some measurements..... like we drop lines of string or clamp right angle straight edges on the rotor..... this is when we will measure where the wheel or rotor is from the chassis..... or better yet measure from the frame rail to the lower ball joint to know the track is going to be the same.....on both the front wheels as well as the rear wheels.....

After we know where the wheels are located ...then we get into Bump Steer.....

Everybody has their own way of doing this....and there's no set way to accompolish this

But Bump Steer has to be done.....an I believe not many cars have had it done....so I wrote the issue in Gasholes to help folks to learn how to do this stuff....