Mark Anderson

Dennis how much does your car weigh? I'm at about 2650 at the moment so that may be part of it. I have tried many spring rates with as high as 1600 lbs up front. At Willow the track times were always about the same but the car was alot more difficult to drive with the stiffer rate. I had Craig Stanton drive my car once and he was the one who recomended a softer rate. He said he wanted the car to roll over more. I tried it and never went back. I feel I can put the car anywhere with more comfort which in racing conditions is awesome. I might be able to get a slightly faster lap time with a stiffer spring but the car would be on the ragged edge. Ok for time trialing and maybe qualifing but not good for racing. I've also changed some geometry on my car which was a big change. The stock configuaration would loose effective spring rate as the suspension went closer to end of travel. Not good.
If you ever want some help in making some changes give me a call.

mark kibort

I know your car configurations better than you do!

remember your famed massive passing day at road america? i think it was back in 2000 , you still had your GTS wing, 2.2 rear end and 420rwhp. at sears in 2000, you ran on BFG R1s and ran a 1:51.3. We didnt run the hard compound tire until sears in 2001, which was my first Speed GT race. (those tires really sucked, but it was good practice!)
so, 1:51.xx was your first time at sears on R1 DOT slicks, but it was your first time. a year later ,you ran 1:52-3 on the real street tire , (i was 1:56 in that speed gt event) and then when you went back with PCA on real slicks and huge tires up front in '02, new intake, big wings, changed geometry, 550hp, you ran 1:43/4...

You also ran in 1999 on those same BFG R1s, 1:40.xx which has been my best time since 2002 on Dot slicks. later, with more HP, and other changes, you dropped down to 1:35s in speed GT on DOT RA1s. even though recently, you have posted 2:18 at Road America, 1:30.8 at laguna and 1:39.9 at Sears. (hows that!!!!??)

So, the point of this was, my car in its stock shape is handling pretty darn good if i can run as fast as you ran with 100 more hp on a new track for you ( in your old car's configuratoion, on same type of DOT slicks ). The only think i had working for me was the handling. so, if 750/450 springs works for my car at some varied tracks in california, i dont think its a stretch to say that its a good starting point. (for weights of 3000lbs to 2800lbs car empty)

Now, my big question is the effects of pinning the rear weisach. both you and Joseph have pinned them by the geometry changes back there, right? if so, i wonder if now, its hurting my car with the fact that the big GT3 wing i have has planted the rear of the car, but the weisach wont let the car rotate!

thoughts??

MK

SwayBar

Witness!

Mark did some great driving that 2003 weekend doing a best-of 2:18.2, and Kevin Buckler 2:16.5, both during qualifying:

http://www.pca.org/clubrace/2003_res...a/red_qual.htm

Another fun weekend at Road America.

In 2004, Mark K did a best-of 2:34.9: (..no burnout icon)

http://www.pca.org/clubrace/2004_res...SprintRace.htm

BC

How has this helped in reality? I have seen you speak about the changes generally, and seen some pictures.

drnick

mark, im interested in what you are experiencing with handling at the moment since adding the wing. are you saying the handling has changed substantialy?

ive been driving the nurburgring lately in addition to terrorising the uk motorways (currently sitting on 12 points - i thought the object was to get more ) my car is in a streetable condition and runs on street tyres along with 650/ 425 springs. the car is really forgiving with late braking into turns and fluffed gear changes rarely inducing oversteer, the back hardly ever steps out but the front gets pushed.. so ive increased the front tyre size - that helped. and now ive added the rear swaybar from carl and that has reduced understeer and made the car more sensitive to weight transfer (read oversteer!)...

anyway i was interested to know how the wing was affecting the handling, is it inducing more understeer?

Dennis K

Thanks for the info, Mark. I'm at 3250 lb full tank. 800 lb/in springs on the front, 550 lb/in springs on the rear, rear swaybar disconnected, so setup-wise it's pretty close to yours.

Curious about your geometry change though. I remember seeing pics of your lower A-arm modified w/ a different pivot point for the shock. Has shock mounting been moved outboard? And do you know by how much? I guess your wheel rate is higher even though our spring rates are the same.

Mark Anderson

I don't have all the numbers at my disposal but the problem with the front end geometery was that as you got closer to the end of travel the the effective spring rate got much lower. The harder you pushed the car the softer it got. Kind of oppoisite of what you might want. By alterning the mounting locations we were able to minimize that effect.

BC

It looks as though:

You welded TWO shock brackets together to put on the A-arm which allowed you to not move the pickup point for the sway bar, but also move the shock out on the arm. The holes in the Arm that you use for the brackets do not look to have been changed.

Secondly, and more obviously, the upper a-arm ball joint area seems to have been move outboard of the original position. Maybe the two halves of the spindle were taken apart and you had the extra metal welded on? And it hasn't failed or bent, which means someone did it right.

BTW - did you ever seam weld the chassis?

Mark Anderson

So you are still almost 500lbs heavier than me. Couple that with my effective front wheel rate and it is a fairly big difference. I'd try 1000 front springs and reconnect your rear bar. You might find a good balance there.

Mark Anderson

I did not modify the upper arm ball joint or spindle. Here is a picture of the upper shock mount. I did have the front end seam welded as well as add the extra bracing.

BC

Ah, I see. You have mostly removed any rubber from the shock movement. The lower a-arm still has its rubber, but that is hard to justify removing ( I did, but I'm not sure it was a good idea).

I wonder how much weight your tub dipping removed. Do you were ear plugs during the races?

Mark Anderson

My lower a arms do not have any rubber. Years ago I had some custom arms made for myself and Bob Devore. It was no easy project.
I do not know how much weight was lost in the chassie stripping as the same place blasted it and powder coated it. I estimate about 50-75 lbs. I do not wear ear plugs but I recently added a muffler because the noise was getting to me. I just hated to add the weight.

BC

Great info Mark. In the above pic I thought I saw rubber on the lower arm. That "project" doesn't sound like it was one of the fun ones.

Mark Anderson

It's possible that we were using a stock arm to mock up but I stil think what you see is the dark grey grease on the bushing surface. To make that lower arm they had to machine off the rubber and the barbed surface on the casting so a machined sleeve could be installed.

mark kibort

Yes, i was running bonified 3 second a lap slower tires (at laguna and road amercia) with some real hard hooseirs that i was in denial about. (ruined several races before i figured it out!)
With the 90 degree day and high humidity, Anderson could only muster a 2:21.xx that day, 3+ seconds off his best. Joe was 1.5 second faster than me with the same kind of car (Ron's) but with new and larger hoosiers!

Do i get a burn out happy face for 1:39 at laguna for the last two 4 races? !(on my used Toyo RA1s which i only run now!)

tough crowd

MK




poin