What is everyone doing for rear toe adjustment?
What with notching, aftermarket arms, and replacement bolts being illegal, has anyone produced some offset bushings yet?

 

0 toe in the back for the BSP car.

 

I wasn't particularly happy with Truechoice or Koni when I had my double koni's done (once by each)....call Jeff Wong at ProParts. I heard just dropping Brian Peters' name gets you bumped to the front of the line (kidding!....or maybe not?).

 

ok, but how did you get there?
Clearly with the car lowered, it moves out of spec.
I'm not the freshest on SP rules, but I believe you guys get a few more allowances than we do in ST for making adjustments.

 

Everything is still stock in the back for me, alignment related. At my ride height, I was able to get the rear toe and camber at reasonable settings. I might have a little more camber than I'd like, but it's been good enough.

 

So has anyone ran a spring in the back without the helper and collar mix?

If so, what was the length of the spring?

Glenn, I know you said you couldn't get "much" lowering with a 7-inch spring....how much is "not much"?

I doubt I will even try to go too far past a 1" drop. If I can get an inch and a quarter of drop (max) and simplify the setup, I will probably go that route.

 

You'll end up running a 9-9.5" spring, but DON'T DO IT. There is no reason not to spend the ~$150 and be able to run shorter/narrower spring, along with being able to properly corner balance the car. You can find 2.5" used springs all over the place. You will still only be in about ~$225 for the rear springs/perches.

 

I'm not trying to simplify the rear spring for the sake of saving money. I would actually be willing to spend MORE money on a simpler solution.

1) From the pics, Glenn's highest ride height looks pretty low. I want to be able to lower the car, sure. But I don't want to be stuck between "really low" and "way too low". I would like to be able to get within 1/2" of stock ride height as a starting point and go down from there.

2) The helper spring seems to be fully compressed at "full droop". If that's the case, a spring/collar combo seems overly complicated for what amounts to a shim.

3) If the helper spring decompresses at some point and actually "helps", wouldn't that necessarily lift the aluminum collar off the perch and make some sort of metal-on-metal "clank" when it compresses again?

 

i am sitting in between 26-27in to the top of the fenders which is about an inch drop. obviously the car is corner balanced. i dont have any issues with ground clearance or scrapping any more so than i worried about with stock ride height. Duplicate my setup and you will be fine.

on another note I did my first autox saturday. settings that day were as follows

2.38deg front 10min toe in 1000lb spring front bar on full soft and shock full stiff
2.0 deg rear 30min toe in 800lb spring rear stock bar connected shock mid stiff
played around with tire pressures. not enough camber (heating up the outside)

pushy as hell but really fun to drive (i also need a diff bad)

doing the autocross in NJ this saturday with some updates
1200lb rear springs
getting the car realigned with as much camber i can get in the front (3deg i think im at now after shaving down the kinetix arm some)
zeroing out the toe front and rear
disconnecting rear bar

 

I will say, I'm impressed by these Megan front arms.. i got -5 deg camber with zero modification.

 

?!?!??!?!?!

That's a heck of a jump. I'm curious to see how that works out. Bold move man.

So far we've got great tire temps and balance running lighter springs (800/680), but the only real action we've seen is on asphalt. I've got some concrete time coming up at the end of the month, so that may change things.

The ISC shocks work surprisingly well, but I'd love to have some compression adjust to play with. Those have probably been the most pleasant surprise so far.

Alignment wise, we're at 2.9 negative camber in the front, 2.0 negative in the rear. Fronts are toed out about 1/16" and rears are straight ahead. 9.something degrees of caster in the front.

J.G. Pasterjak
Production Manager/Art Director
Grassroots Motorsport magazine
Classic Motorsports magazine

 

This is what I was expecting when I looked at the spring rates on paper. -Particularly when considering that the rear sway bar will hopefully get disconnected.

That being said, I would expect full-stiff on the front shocks and toe-in up front to be significant contributors to understeer as well.

I don't know that I would work shocks valved for 800lbs with 1200lb springs though.

Was your camber up front maxed-negative with stock Kinetix A arms and a 1" drop?

 

800f 680r?


Have you disabled your rear bar?

 

im using the stock spring bucket. are you guys running a true coilover in the rear? the spring bucket has a crazy motion ratio. with an 800lb spring you have a wheel rate of 250lbs~ the front 1000lb spring yields a 550lb wheel rate. the math doesnt work when you look at the corner weights.

 

ya this was with an unmodified arm and about a 1in drop. i shaved down the threaded ball joint adjustment and was able to get a bit more camber added in. every 1/16 is about .2 deg so i should now be at about 3deg camber.

Regarding the shocks ehhhhh itll be fine worst case scenario i revalve them


PS - the helper spring never decompresses its 6in free length + 6in from the main spring. I actually needed a second hand to help bolt the bucket back into the car. Trust me you will need it. I already did the trial and error on this.

 

Actually they're 14kg/mm fronts, which is like 783lb/in. Rears are 12kg, which works out to 671lbs.

Bars are still stock, but there's a set of Whiteline bars that just arrived today sitting next to me in my office. Their installation and ultimate setting depends largely on what I can put together for testing, though. Personally I've always preferred as light a spring rate as I could get away with, and to do most of my tuning with bars. But at some point I think it comes down as much to driving style as anything.

I gather conventional wisdom is medium stiff on the front bar and no rear bar. What sort of characteristics are you looking for with the rear disconnected that it's not doing with the rear hooked up? Right now our car seems to tend more to understeer on corner exit which would tend to make me want to increase rear roll stiffness. But every car reacts differently, and I'm still definitely learning the nuances of the Z.

J.G. Pasterjak
Production Manager/Art Director
Grassroots Motorsport magazine
Classic Motorsports magazine

 

Yeah. Stock buckets with adjustable height perches. Ride height sounded like it is right about where yours is. Main thing I was looking for was decent corner weights and lower arms parallel to the ground at rest (or close, anyway).

I heard a few scrapes at Turner Field last weekend, but I haven't got the car in the air yet to see exactly what was rubbing. It didn't look like it was fender lips, so I'm assuming it has to be on the liner somewhere. Nothing major, though. On a smoother lot it probably wouldn't have rubbed unless I did something stupid.

J.G. Pasterjak
Production Manager/Art Director
Grassroots Motorsport magazine
Classic Motorsports magazine

 

The Quaife diff needs resistance on both tires to work properly. I have not noticed any issues on flat pavement, but I unload the inside tire on some of the turns at the Tail of the Dragon (and/or other well-banked turns), and my diff goes open when I do. The rear sway bar increases roll stiffness by effectively trying to lift the inside tire in a turn. I would rather get my roll stiffness from the outside spring/shock combo and have the inside spring continue to apply pressure to the inside tire/pavement. (Rather than having the rear sway try to compress the inside wheel's spring)

My Z is currently running stiffer springs in the rear than the front. (410R / 345F) My Hotchkis sways are set to medium rear and medium stiff front. My rear OTS Koni "Yellows" are set about dead center and the fronts generally stay within a half-turn of dead center. (which way depends on tires and courses)

I absolutely LOVE the balance it exhibits now. The car turns right now and rotates predictably, when asked to do so, with either trail braking or throttle in steady state sweepers.

Since I hope to have more grip with wider tires and wheels, I expect to need some more roll stiffness. I also expect F/R matching offsets and tread-widths to make the car move toward the "loose" end of the spectrum. Disabling the rear bar will probably over-compensate for this though, so I actually expect to need a wider spread in spring rates than I have now.

I honestly don't know how much though.

I'm starting to think I would be better off getting the wheel/tire combo next and then experimenting with disabling the rear sway and softening the front bar. The car will no doubt become "floppy" when I increase traction and decrease roll resistance, but I should be able to experiment and get an approximation of the car's behavior with the current F/R spring rate spread minus a rear sway bar.

I hope I can then make a somewhat-educated guess at where to go with spring rates from there.

That is, unless someone has a high-spring-rate Z they are willing to let me warm the tires on as a point of reference.

 

Glenn, what are you using for the rear motion ratio? I think you are wayyyyyy off based on your stated wheel rates. FWIW, that is way more rear spring than I use even on the BSP car (without a bar).

 

Glenn, do you have any pics of how the fronts sat with 2.4 camber? Also, you mentioned that the 7" springs were too long on the front. Where was the car sitting up front at the lowest setting on the 7" springs?