I know little about cars in general and even less about suspensions. I'm hoping some of you can give me some ideas. I've spent the last week searching in this forum and in the suspension forum but I think I've become more confused rather than less.

I've got a 2006 Grant Touring Coupe. I've only autocrossed for a little over 2 seasons with this last year in the Z. I've been running street tire BS but because I added the 5/16th spacer, I'm bumped up to BSP. I still want to run street tire. BSP gives me lots of options for suspension and it is the number of options that is confusing me. Also, I'm not a very good driver. My car as it is setup now (all stock suspension) is a lot faster than I am.

Here are my priorities:
Streetable:Affordable:Auto-X performance:Minimal Drop:Simple:On my RX7, I went with springs and adjustable shocks. It was clean and simple and it did what I wanted. The advantage to the 3rd RX7 is that it had been raced for 15 years and there was a lot of consensus as to what setups worked the best. Not so for the Z.

Sways: Hotchkis adjustables look good to me.
Springs:
RSR Ti 2000 have a minimal drop, but it appears as if the spring rates are about the same as my stock springs.
Hotchkis springs seem quite a bit softer in the rear than my stock and lot stiffer in the front.
Tein S-Tech: Minimal drop. Rear a bit softer and front quite a bit stiffer.

Shocks: I have no idea. Considered staying with stock until they blow.

Coilovers: I have no idea. Most of what I've been able to read about coilovers has been either geared to track use or those who want a very large drop.

Thanks for any ideas or suggestions.

 

Man, I'd save my money for driving schools and traveling to more events if I were you.

If you already acknowledge that the car is faster than you and that you could use some improvement (kudos to you, btw!! the only way you can learn is if you realize you don't already know everything ) then you'll get a lot more out of improving yourself as a driver than you will making your car more complicated and possibly even harder to drive well.

Also, if you want to run on street tires with BSP-like mods, check out STR. It's a new supplemental class for 2010, and there are several threads on here about what you can do, and what some of us that are building our cars for the class are planning to do or have already done.

 

Good advice guitarist.

I'd enjoy a school. If I can get the time.... I'm fortunate in that there are more events local to me than I could ever hope to make it too. Too many work and family commitments.

I'll check out the thread. I'll admit to being generally confused as to classing.
Even so, if you have any insights as to what suspension setups may work for my situation, I'd love to hear them.

 

I have been autocrossing for over 4 years and bumped myself into BSP with my frst mod. (Quaife LSD)

My Z is a base model and, after my first autocross, I knew the open diff had to go. I did many events on the open diff and even developed a "soft touch" with the throttle, but differential moved to the top of my mod list quickly.

The Quaife is better than the stock VLSD, but I wouldn't spend the money to upgrade if I had the stock unit, unless I had done a lot of other things first. (It would be toward the bottom of my mod list if I had the stock LSD.)

Tires will make the biggest difference. I "run what I brung" so I don't use race tires. Kumho XS (not ASX) is what I use, but there are some other good choices too.

Wheels; A good set of lighter and wider wheels will allow you to run wider rubber. I went with 16lb SSR's, and run 275/40-17 F and 285/40-17 R.

(Some venues offer an STU-2 class that has a 275 tread-width limit. I run 275 all around for those events)

Springs; The tire sizes I was running before (255/40-17 F and 275/40-17 R) created a lot of fender gap, so I chose the RS*R Ti2000 springs to stay close to stock spring rates and end the "pickup truck" look I was sporting.

The RS*R's are close to stock but slightly stiffer up front. I had a little underster after installing them. Not much, but enough to enter a drawing at ZdayZ for a Hotchkis TVS kit. And won!

Sway bars; The Hotchkis stuff worked well for getting my car into balance. I highly recommend the Hotchkis sways.

Shocks; My stock springs didn't last a year before it was time for new shocks. I asked around at the track and Koni "Yellows" were very poplular. I bought a set and Jason (TractionCircle) helped me install them.

The Koni's are great, and allow me to fine-tune my suspension without having to mess with the sways.

I recently allowed a 370Z owner to drive my car to film some stuff I was doing on an oval track (in another car). He said my Z felt more "responsive" than his 370Z.

There is still a lot I could do to make the car faster in BSP, (alignment parts, power, etc.) but the Z is "dialed-in" pretty well for the few mods I have.

Seat time trumps all of the above, however. This can't be stressed enough.

 

Thanks for the information.

The 5/16th spacer did it for me. That is another question, does the new STR allow a plenum spacer?

I ran street tire this year and will again next (they use PAX indexing) but the new STR sounds interesting.

I just picked up a set of Track v.1 wheels. They are much lighter weight than my Track v.2 wheels. I just have to figure out what rubber to put on them. The STR may dictate that for me. I was going to go with 245/40, 265/40 but now may look at 245/40, 255/40. I know that tires make a huge difference, but that is also where there are huge differences in cost as well.

Springs and shocks are the real question for me.

This looks like the way I'll go.

I've heard good things about the Koni Yellows, but I may do springs and then look at doing shock when my stock ones need to be replaced.

I recently allowed a 370Z owner to drive my car to film some stuff I was doing on an oval track (in another car). He said my Z felt more "responsive" than his 370Z.

I agree. As I said, my car is MUCH faster than I am. All season I was being beaten by 2-3 seconds by another driver in a stock Z and 2+ seconds by a driver in a BSP G35. Both of them simply drive much better than I do.

 

You cannot use a plenum spacer in STR. The air box and the tube is all you can touch. Refer to the STR thread in this section.

 

Shocks first then springs, especially for an autocross car.

 

Major +1 here.

I had good luck with just shocks in BS (Yellows). You can crank rebound to add a little "fake" spring, whereas the springs won't help you much at all in the transitions.

That's especially true if they're under-damped, which by definition they would be if you go to an aggressive spring that's going to produce real handling benefits while staying with the stock shocks.

Sport-style springs for the street are mostly only good at lowering the car, which is fine if that's what you're after. But I wouldn't expect any performance increase out of them, especially if they are progressive-rate springs.

 

Thanks. I read through that thread but must have missed it. I also read the rules, but I'm afraid that the SCCA classing rules tend to confuse me. (What can I say? I'm old.)

So, I'll be in BSP then for sure. Our local (non-SCCA) club has a street tire class that uses the PAX indexes. So I'll be indexed as BSP. For the SCCA regional events, I'll probably run in BSP and just do it with street tires. I'm not a competitive driver so the couple of seconds that I lose by not being on R compounds won't really matter anyway.

 

If front camber arms are allowed , get them and bump the camber to -1.5 to -1.8 that will help with front end traction and help your tires last a hell of a lot longer.

 

Upper OR lower (not both) arms are allowed in either STR or BSP.

I'd go with a lot more than -1.5-1.8 personally.

I'd call -2.0-2.5 a compromise setup for daily driving, and -3 degrees (what I run) a pretty solid full-autocross setup. I drive the car to and from events like this no problem, btw.

I also run -2.5 degrees rear, which I can get on the stock adjustment, though not all cars can go that far. My car will actually get close to -4 in the rear stock. Kind of weird, I guess.

Since we're talking alignment anyway, I'd also recommend a little toe-in at the rear if you're gonna stay on street tires. Tames the twitchiness. Also a tiny bit of toe-in or neutral up front, for the same reason.

 

I sure appreciate all the information and suggestions.

Currently, my front camber is -1.2 left and -1.5 right, rear camber is -1.7 left, -1.5 right
Front and Rear toe are +1/16" left and +1/32" right

So, it looks like I could do with a touch more camber but I'm not too far off.

 

David, I would take the plenum spacer out and go back to stock. You stated that you what to keep it a DD and don't want to spend a lot on the suspension. If you move to BSP and want to be competitive you will need to do alot of things that will make the car not to DD friendly. With the index the way it is you still beat me at the last event even though I had a lower time and Chip beat both of us and he is stock. PM PDX Racer on the forum for advice on setting up the car in the stock class, I believe he does very well. I don't think he comes out for the BSCC events but he is local and attends the SCCA events. I think a good set of shocks and good tires like Star Spec, AD08 or RE11 and a class from Evalution and you will be much more competitive than spending money on you car. You can always make the car faster but you need to be able to make the driver faster.

Greg

 

Looks like if you stay stock you will now be CS. They just changed everybody in BS to CS and moved AS to BS and created a new AS

 

I've been considering just that the last few days. If I remove the plenum spacer then I'm back to stock. If I understand it correctly, I could change the front sway bar, shocks, and the exhaust. I'd probably leave the shocks as is and change the front sway and do the exhaust. I know that spending money on the car won't make me competitive, but it sure is fun. ;-)

Street tire is a fun class at BSCC. So does that make us CSP then?

 

Carter Thompson, who placed 6ths at nationals in 2003 and 2nd in 2005 has been very public about his setup receipe, he even posted his custom shock specs for his Koni DA's


Same thread

Cut and paste with the shock specs

I have the dyno charts but the units are metric.

Velocity(meters/sec)........0.033.....0.066.....0.099.....0.132
Force(newtons)
Frt.Rebound......................900........1600.....1800... ..2200
Frt. Bump..........................600........1200......1300....1 400
Rear Rebound...................400.........700.......1000....1250
Rear bump........................200........400.........750.....1 000


Here's a link to his username you you can look at his past posts if you'd like.
https://my350z.com/forum/members/7892-tomsn16.html

 

Carter is a good guy, have talked to him several times. He likes to talk about his setup and has many suggestions. Bottom line, this guy knows his stuff

 

No, still BSP. Only stock classes are what changed.

 

Thanks the links and the information. That is helpful.