CSG and RCE tag-team suspension Q&A thread! Ask us anything!

[BishamontenZC6]

Question about the infamous conical washer on KW based coils. Why exactly and technically some people recommend it and what problems could occur if it’s not installed between spring perch and Group N top hats ?

Also, why KW and ST installation manuals don’t mention it, only RCE does ?

[fminicooper]

Hi,
I’ve had a failure on the shock absorber rod.

Setup: FRs 2016, NA engine, Bilstein B6 dampers, Pedders top hats, Eibach springs, –3° camber. About 30,000 miles total, including several aggressive track days.

Has anyone experienced a similar issue?

[Scargod]

Breaking at that spot is common, if it's going to break. Were you banging curbs?
I don't know Pedders top hats, or the Bilstein's, but if that's a 12mm shaft then that may be your answer. Most front, high-end racing dampers are a minimum of 14mm diameter.

[Racecomp Engineering]

Originally Posted by Scargod

Breaking at that spot is common, if it's going to break. Were you banging curbs?
I don't know Pedders top hats, or the Bilstein's, but if that's a 12mm shaft then that may be your answer. Most front, high-end racing dampers are a minimum of 14mm diameter.

That's not the damper shaft since it's an inverted strut. The damper shaft is inside the body and at the bottom.

The breakage could be from a variety of things, most commonly in my experience from from a bit too much torque on the top nut. It happens. I'd just have Bilstein rebuild the dampers.

- Andrew

[Scargod]

You got me there. I wasn't paying attention. Still, couldn't it be small for hard racing?
You rightly corrected me, yet I've had no response for the question I asked...

[Racecomp Engineering]

Originally Posted by Scargod

You got me there. I wasn't paying attention. Still, couldn't it be small for hard racing?
You rightly corrected me, yet I've had no response for the question I asked...

It's just hard to tell the cause in this case. There are tons of 12mm top nut struts out there doing just fine. An improperly torqued top nut could certainly push it over the edge. Or a materials defect, or a massive impact that also would wreck a 14mm top nut, etc...

- Andrew

[J95]

Originally Posted by Scargod

So, the alignment people are not moving the collards (sic) at all? No corner balancing? In your case, you are expressing ride height in distances from the fender to hub. This is not helpful to a lot of people who cannot go with dimensions off their modified fenders. Measuring off the pinch welded sheet metal seam on each underside of the car is more universally accepted, even though tire diameters comes into play and tire pressure to a small degree. This is how 949 Racing suggests we measure ride height...
If you notice, the seam of metal that forms a rib is quite straight till you get to about a foot from the front, where (on my car) there is a slight upward taper of perhaps 1.5 to two mm's. So I suggest that everyone measure well back from the front jacking point on the pinch weld area.
I'm at around 5" in the front and 5-1/4" in the rear with 24.5" diameter tires.
For the 2022+ Subaru BRZ and Toyota GR86 (Premium/Limited trims) equipped with factory 18-inch wheels, and tires that are 24.8" in diameter, the standard pinch-weld height is approximately:155.6mm or 6.125” front and 158.8mm or 6.25 rear.

As to your camber, I believe we need to know all of what you've done to the car's suspension. You mention rear LCA's. And, if you go over an inch lower you really need to correct the geometry with aftermarket parts.
Somewhere in this discussion I read an opinion that a lot of camber doesn't have a lot of affect on tire wear while driving on the street. It does if you go straight a lot. It does when you brake. It does adversely affect handling in the wet. It reduces traction when driving slowly on the street.
On the track, which is all I do now with my BRZ, I run -4° or more camber and over -3° in the rear. A one degree difference from front to rear is very common.
Note that I'm all in on mods to my suspension and I have significant aero. I have custom, lowering subframes (as noted in my post above). I have gutted my car to where, with a roll cage my car is 2,600 pounds. I run sub 200 TW tires in 255 X 17. I sometimes run Hoosier 245 R7's (24.3" tall). I'm waiting on a set of 245/40R17x 24.7" diameter, Vitour Tempesta Sonic tires to try.
If we don't speak a common language, with full disclosure, it's difficult to have a meaningful discussion where we can help each other.

Not moving the collars, no corner balancing

Next time I will measure the metal sheet as well. What I can tell you is how much was the drop (from OEM), approx.: 1.7'' front / 1.8'' rear. My target is ~1.1-1.2'' drop, no more than that


About the suspension changes to the car, not that much:
- Front whiteline KCA416 camber bolts (they are maxed out, the shop did not touch them)
- KW w3 with front KW Clubsport top mounts, they touched
- rear adjustable Whiteline LCA, they touched
- Wheels 17x9, 235/40

With this set up, adding -1° camber has lowered ride height by 10-15mm