Orthonormal

The prime feature of the Penske 8100 shocks is the wide range of adjustment for low-speed rebound. The compression adjusters honestly don't do a lot judging by the dyno plots. So if you are not planning on spending the money on the 8660 cannisters then you might just want to save a little more and get the single adjustable version.

If the problem is happening on street tires, it is sounding more and more like a swaybar problem, or a siezed rear shock. Make sure to check the brackets that hold the swaybar bushings to the frame. Those bolts tend to loosen and fall out, and they can be hard to see.

glagola1

I've found that by increasing the compression of the front shocks, the wheel spin goes away. I'm also running my comptech on full stiff + an extra bolt and 225 v710s on all corners.

And Steve W., to point out that the few national trophy positions that were on Penskes this year doesn't really mean anything. Nobody fast was on Motons, unlike years prior.

Moton clubsports retail for 3600 fwiw. You can get them for slightly less if you try.

Naka

Although I don't have adjustable shocks in my car yet, I would bet money that's very true. In fact, that would be my very first initial adjustment (instead of softening the rear).

[QUOTE]Moton clubsports retail for 3600 fwiw.

glagola1

I drive the motons daily and they are very livable. The are valved so that you get a bit of NVH over small bumps but even the konis are that way. The clubsports valving is great for auto-x and the range of adjustment is so large that I couldn't see why you'd need to get them revalved.

You can buy Motons from Jason Saini, or you can find dealers by searching moton's site. You could also call Lex Carlson at Moton USA and have him recomend a dealer that's close to you.

I don't know the weight difference but I'm pretty sure it's negligable. The bodies on the MCS are aluminum, not steel like people have suggested.

Orthonormal

See my original post...

Naka

I see. Thank you guys. Great info.

I didn't know Jason Saini sold Motons. How do I get a hold of him? Does he have a shop? He's from Chicago, right?

Also, how often do you need to "revalve" these high-end shocks?

BKR

You have been given a whole lot of good advice, but somehow, everyone has failed to mentioned the most obvious cause of the problem. Odds are, the Comptech bar is broken. Based on replacement cost, I'm sure you didn't want to hear that, but check it first.

Disconnect one downlink, and try to move that arm of the swaybar. It might be that the crossbolt hole is just egged out badly, but more likely the bar is fractured.

Windscreen

Point taken, and, while I'm not trying to turn this into a pissing match:

-it does say something that the "fast" people chose Penske over Moton

-I believe firmly that Moton is not the best choice for a stock class car. They are better suited for cars with aero where that big diameter shaft will displace lots of oil for smaller shaft movements. Moton cannot create as digressive a valving curve as Penske can, so I fail to see any fundamental design benefits in Moton vs. Penske.

Back on topic: what BKR said. Look for a broken front bar. For some reason when I originally read this post I thought Saner and not Comptech.

Steve

Naka

[QUOTE=Windscreen,Oct 24 2006, 03:25 PM]They are better suited for cars with aero where that big diameter shaft will displace lots of oil for smaller shaft movements.

Orthonormal

First, digressive valving:

The ideal damper that you learn about in basic physics and engineering classes has a linear force vs velocity relationship. If you plot the piston speed on the X axis and resisting force on the Y axis, you get a straight line.

A digressive damping relationship is one where the slope of the damping curve decreases for higher piston speeds. So in effect, below a certain speed you have a high damping rate, and above that speed you have a lower damping rate. Why would you want that? Low speed mostly controls the motion of the body of the car (roll, dive) and how it responds over slowly undulating pavement. High speed mostly determines how the suspension responds to sharp bumps. On bumpy pavement, it is useful to dissociate those two behaviors. You want to control body lean, but you want to be able to absorb bumps without bouncing your wheels up into the air. With a linear valving you can have one or the other, but with a digressive valving you can come a lot closer to doing both.

As for the shaft diameter, I don't think I understand either. In my mind, the shaft diameter is related to compression of the gas charge, resulting in a static force and a weak spring response. The piston head diameter would be what determines the volume of oil that must be displaced. It seems to me that a larger piston head would give better fine control at high damping rates, while a smaller piston head would give better fine control at lower damping rates. I guess that it all depends on what the flow vs pressure relationship is for the apertures & shim stack (the "valving") looks like. That's not my area of expertise.