Mark B's Build Thread

Mark B.

Bronze Supporter
#41
Thanks guys! Yes, I'll definitely need new rear springs. I had to screw the adjusters all the way down just to get it up to 4.5" ride height in the rear!
I also had the AC charged while I was there. After replacing one torn o-ring it held vacuum/pressure and I have cold AC! (just no passenger compartment :) )
 

Mesa

Active Member
#43
Congrats Mark!
What spring rate is currently in the rear? It looks like the suspension push rods are near the shorter end of the adjustment. If you have the preload screwed way tight to get desired ride height, you may want to adjust the ride height via the pushrods instead.

Like that intake manifold!
 

Mark B.

Bronze Supporter
#45
Congrats Mark!
What spring rate is currently in the rear? It looks like the suspension push rods are near the shorter end of the adjustment. If you have the preload screwed way tight to get desired ride height, you may want to adjust the ride height via the pushrods instead.

Like that intake manifold!
Thanks guys!

Mesa, they are 7" x 650 springs on the rear (and yes, the preload is very tight :( ). I have about 3/8 of thread showing on the push rod heim joints so I can definitely go more on those. I'm assuming I'll need to get stronger springs -- maybe 750 or 800, but wanted to wait to buy them until I get the body on and see how much more spring I need.
 

Mesa

Active Member
#46
I have and like 850 rears, but have more weight than most with a Ricardo, two full size radiators and a blower causing additional rear weight bias. Regardless, there is plenty of unused rod adjustment on your car. Probably a good idea to explore that option in the meantime.
 

Cam

Active Member
#47
FYI - the new standard rear springs are 850. I’ve got a Graz and my battery is located a bit forward of the rear wheels. There’s still a good bit of adjustment left at static ride height.

If you’re going to track the car heavily you may want to go even stiffer, from what I hear.
 

Mark B.

Bronze Supporter
#52
Hi Howard, I don't have any pics on my machine right now, but it's a K&N RF-1024
Air Filter Length (in): 10.00 in.
Inlet Flange Inside Diameter (in): 4.500 in.
Air Filter Top Measurement: 7.000 in. L x 4.500 in. W
Air Filter Bottom Measurement: 9.250 in. L x 6.250 in. W
 
#53
Mark,

I have been through a number of sets of springs. I just double checked and the car currently has:

7" x 2.5" Hypercoil Springs (7B0900) 900lbs Rear
4" x 2.25" Hypercoil Springs (4A0800) 800lbs Front (with rams and helper springs)

Ride around town is a bit harsh. It's fine on smooth roads at 100mph (typical track speeds). Is too soft at 150+ (COTA/ORR speeds).

At 160 the dropped seat pans will peel the reflectors off the road if you have the CF wing.

Car has a high speed push which I am assuming is aero. Is reasonably balanced at moderate speeds (say 100).

I'll be going to 950 rears for my next outing.

Take all that with a grain of salt and compare with how you plan to use your car. Good news is springs are not that expensive so you are not stuck with your first choice.
 

Mark B.

Bronze Supporter
#54
Thanks Frank! I went with 850's in the rear at least for now. I'm not planning any additional aero since it will just be occasional track use. Like you said, though: springs are cheap :)
 

Cam

Active Member
#55
Mark - my car has 850/standard length springs in the back and my coilovers are at max extension. I'm planning to leave it like this till I can tune the suspension more but a longer spring is in my future, at a minimum.
 
#56
Thanks Mark for the air filter number. Frank, springs, I am going to use 950R and move the 850's to the front. You're right about high speed aero imbalance. I was getting a strange brake balance feel at the end of the back straight/first 1/3 of brake zone at COTA (+150mph). The car would seam to pitch from rear bias to front bias, but it was delayed as if the rear of the car was overcoming a lower than usual ride height at high speed before it could load the front of the car. It also felt a bit twitchy as I applied the brakes hard but only at that point on the track. Kind of like the toe was going neutral or a bit more positive at the front. But it didn't do that on the front straight brake zone. Maybe the uphill and slightly slower speed made a difference.

At least that's all I could come up with. I tried to re bias towards the front but that just screwed up the rest of the track. My car really likes a 1/2 inch rake with the front lower and if the rear is getting pushed to a rearward rake from aero loading then that would be a possible

I am looking forward to getting back to COTA and doing a back to back spring change from 750F 850R to 850F and 950R.
 
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