marks_lude

Shock builders....

I am refreshing a set of Moton Club Sports, with some help from AST. I've received their instructions, and completed 1 shock. I'm waiting for a follow up to a few questions, but thought someone here might know.

I swapped for fresh oil and did the procedure to purge air from the canister and position the floating piston. Next is putting the shaft back in, topping off the oil, and screwing the top cap on. I do not see any formal procedure for purging air out of the shock body when you put the top cap on. It is as if they are not concerned with air trapped here.

Maybe it pushes past the shaft seal over time once the nitrogen pressure is added and the shaft moves from use? Anyone have input on this?

macr88

You'll want to get as much air bled out of the piston as possible by pushing it into the oil then waiting for the bubbles to rise then pulling it up and back down again until the bubbles are gone. You really want to try to get all the air out that you can.
Note: this is only from my limited experience with my Bilstein dampers.

Random1

The procedure for Penskes is in their adjustable shock manual which can be down loaded from their web page in the down load section. The procedure is similar to what Mac88 mentioned. A couple of additional things...

- be sure the canister is pressurized to 150 psi. This will keep everything in place for the next step.
- use a soft blow hammer to tap the piston shaft into the oil. Make sure the top pin is installed so you are not hitting the rebound adjuster. As you tap the shaft you will see air bubbles get released from the piston. When you pull the shaft/piston back up don't let the bleed holes go above the top of the oil. Repeat this until the air bubbles stop.
- once done release the canister pressure. top off with oil and screw the shaft bearing into place.
- pressurize the canisters to the desired pressure.

WebMasterP

This is just a general question and not meant to poke or stab at anyone's setups (especially since I'm currently running a similar setup to what I'm questioning). I'm wondering why when I calculate rates on the car to match theoretical "good race" frequencies (like 2.0 Hz Front and 2.1 Hz rear) you get numbers that show one should run 100lbs softer springs in the front than in the rear, but then everyone runs 100+ lbs in the front than in the rear in practice. Does this have to do with the stock rear bar? Or is math/theory wrong about this car?

chino101

I've been wondering the same thing my self. According to some independent research performed by another forum member, most non-CR S2000 were equipped with stiffer springs in the rear, relative to the fronts. (http://www.mccanless.net/Characteriz...rings_rev1.pdf) So your math may not be too far off. But my question is, why does a race car need the front and rear ride rates need to be around 2.0Hz and 2.1Hz respectively? For a road going passenger car, the ride frequency stagger is to done for ride comfort. The higher ride rate at the rear axle is intended to mitigate, the pitching motion that a car may experience when hitting a bump.

josh7owens

I think it has to do with the non-stagger wheels and tires. It seems when you add the etra front tire it's really hard to make the rear stick as well as the front. So maybe we all do it to unstick the front alittle or transfer weight to the rear on corner exit quicker. I'm running a 2.6-7 HZ front and like 2.5-6 rear. 900F/800R seems to work ok for me but I'm not exactly the fast guy either. 800/700 seems like a good rate to go with if I was to change mine.

I'll let the pros chime in...

oinojo

Real world testing vs. Theoretical mathematical observation. I haven't tried softer front springs than rear so I can't say whether one is better than the other. I run a 200 lbs split and the car works well for me.

pinkertonpunk

I know of two people that've tried it and one switched back right away. The other I think is selling the car.

Random1

I've been running a 200 lb difference, front 200 lb greater than rear, for a few events now and really like it.

marcrx5

I tried 100lbs siffer rear in an attempt to remove the rear bar and still keep a similar balance to my setup with the miata rear bar. I had to keep softening the front bar to get it to rotate to m liking, to the point where the front felt sluggish and overall roll stiffness was down a fair amount. I'm back to a 100lb stiffer front setup because I wasn't seeing the results I hoped for.

I might try it again with a heavier stagger. For reference, I did also run it with the miata rear bar and I didnt have enough front bar to make the back end stick.