BSP 240Z Solo2 - Set up help request

[CTR98]

Looking for help in old posts I found this from John C. (2002) and am hoping John, Tom, or one of you other knowlegeable people will help me.

If a person gets serious about building a dedicated BSP car, then there are a number of things that have to be done to get a Z to turn in well and stay planted.

And, no, I'm not going to list those things until I think someone is serious... ;-)

Here is what I have: '71 240Z series 1, built to the rules '76 2.8l currently with '70 SUs, light flywheel, '73 4-speed trans, 3.54 r200 gleason LSD, GC coil overs and camber plates at all four corners, Tokico Illuminas in shortened struts (Illuminas will be replaced later this month if I figure out spring rates), poly bushings throughout including steering rack and coupler, aluminum upper strut bars f/r, MSA street flares, 16"x10" Real Racing Wheels (14.8lbs), 265/45 Kumhos. Plan to add full fuel management with fuel injection within the next two months.

I spent all last season playing around with different spring rates, ride heights, alignments, etc. I have not found anything that seems to work together and would rather not spend another season making major changes. This is a 34 year old car, I can't help but think there is someone who knows what works best and is willing to share the information. :classic:

[240ZX]

CTR98, while I'm certainly no expert on the subject, I do have a couple of suggestions. Alot of people go about changing this and changing that in search of a better setup, which is a normal process. However, making changes without knowing the specific reasons for doing so is similar to shooting in the dark without night vision....you might get luck or you may never find a combination that works. So, educating ones self about modern suspensions is essential to knowing why and which direction one needs to venture for a good setup. There are a number of great books out, by reputable people in the racing industry, that go into get detail on the subject.

Secondly, as you likely know, starting out with a stiff chassis is essential to a good handling car.

Lastly, and like must of the books will tell you, once you get a grasp on the theory and reasoning behind suspensions, it will by no means give you any specific answers for setting up your car, but only a good set of mental tools to work with. Experience with your car, under certain conditions, is the key to a successful setup. Sorry my crystal ball is out of service or I would provide you with the secret setups.

[gnosez]

I have a copy of John C's AX set-up somewhere in my files. There's several suspension suggestions (camber, caster, toe-in, etc.) and the like. It's a full page and I don't have a scanner here. If you PM me I will fax the info to you. Perhaps you can scan and post it later.

[zguitar71]

http://forums.hybridz.org/showthread.php?t=98315&highlight=bump+steer

There are some good ligment tips here.

Go with the set up that worked best for you in the past and stay with it for a season. Work on yourself not the car it already has all you need for BSP. If your mental state before a race is about your car being set up wrong you will drive it wrong. I do not mean to sound pompus but the right frame of mind will get you farther than the set up. You migh do these thing already, but here it goes. Walk the course 2 times by your self looking back a lot, then discuss it with the people that always do well. Mentally picture yourself in the car on the course. Picture your car on the course from the outside too. When you are in line to race clear your mind and clam yourself through breathing (like meditation, in through the nose and out through the mouth), picture the race in your mind and nothing else. Do not try to win just try and have your times improve on every run. If you have a bad run don't get pissed just know you are going to do better in the future and you will. Do not think about the cars set up and do not compare your car to other peoples. Cars go fast around the course because of the driver more than the car. Some of the best racers in the world started with underdog cars but still won race after race because they are gifted racers. When your mind is in tune you will start winning races. Then tweak your car. This all sounds pompus but it is avice that was given to me and it works great for me so I am passing it to you.

[gnosez]

With no disrespect intented, I disagree with 2 out of the 3 suggestions re: car set-up for BSP recently posted. The one I totally agree with is the course walking and attitude. Nothing beats seat time unless you're doing it wrong. As to the link over to Hybridz, it's like walking into a conversation with a few PhDs if you aren't up to speed yet. The question was car set-ups not theory.

For let's start from the beginning:

1) www.autocross.com (advise, clubs, rules, car set-ups, links, etc.)

2) Secrets of Solo Racing by Henry Watts - very good book on the topic

3) Evolution driving school - from basic to nationals prep

4) car set-up as per John Coffey:

Camber - 3 degrees neg front and 2.5 neg rear

Caster - 6-8 in front (you can decrease camber if you have more caster)

Toe - 1/4 to 3/8 out in front and 1/16 to 1/8 in in the rear

Ride Height - 4.5 to 5 inches at the rocker

Springs - 225 to 250 front and 275 to 200 rear

Sway bars - 1-ich front and 5/8 rear

Offset bushing - yes

Poly - yes

Roll bar/cage - yes

Tranny - "b" 4-speed

Diff - 3:54 w/Quaiffe LSD

Belts - 5-point

Seat- the best you can afford

So get your car sorted out, then get it aligned, then corner balanced and then re-aligned. Now try not to make more than one change until you figure out what that did. Buy a tire pyrometer, pressure guage and a log book. Take a lot of notes and keep track of what you do and how the car handled.

Good Luck and remember seat time, seat time, seat time........I go AXing in rental cars when I'm away on a business trip. It's a hoot.

[CTR98]

Thanks for the advice and none of you, "sound pompus", in fact you gave me the same responses I would have given if asked.

What caught my interest was John saying, "there are a number of things that have to be done to get a Z to turn in well and stay planted" and he was, "not going to list those things until...someone is serious." Well I'm serious and that is why I listed what I have on my Z. I would simply like to know the things John was talking about now instead of spending years trying to find them out on my own. :classic:

Thanks gnosez, I'm pretty close to those now.

[gnosez]

My street car is set-up close to these specs so I know exactly how it handles as opposed to other 240s (and it handles very well, thank-you Mr. Coffey). Since we now have a "club" race car I use that for most of my autocross and time trial runs instead. We don't have enough information on either of these cars to make the next steps to improve the handling since we don't really know what to change. Our plan is to start from scratch and go back through the set-up steps and verify we have everything were we want it and then it's time to put our butts in the seat.

Get the car finished and then run it and record the data. The data will tell you what to do next. I'm looking forward for the season to begin but the forecast is for a mini-blizzard on Thursday ......

[tholt29]

If this is not your daily driver, those spring rates sound kindof soft. I know Vic Sias was running 400 lb springs on each corner with the Advance Design shocks, when he last won BSP at Nationals. That's what I run on my FP car and they definitely work. That being said, for autocross, I am still of the opinion that spring rates are not nearly as important good tires, correct alignment and good damping. Autocrossing gives you so many opportunities to make mistakes that it dilutes the importance of spring rates. (that's not true in road racing) The shocks definitely need to be matched to the springs, so pick something and stick with it. I have run spring rates from 150 lbs to 400 lbs and won National trohpies with both setups. I've used the same sway bars so long I can't remember what they are (24 or 25 F/19 R, I think). Just make sure you are not bottoming the suspension (like I was with the 150/200 lb springs).

You never mentioned what your car was doing to make you say it's not working. Tell us what's wrong and we can probably help you correct the problem. Chances are your hardware is fine, you just need to get it tuned correctly and then, as others have said... drive it!

Tom

[CTR98]

It pushes like crazy in slow tight corners, not bad in slaloms as long as I'm smooth, and loses the rear on big fast sweepers. Occassionally it will still push on corner entry but I would think that is me not the car. I can pull decent times but it isn't easy.

I'm pretty sure one of the main problems is ride height. I started last year by simply setting it up to where the front and rear control arms were parallel with the ground. That left the car with an "up hill" rake. I then lowered the front to level the car and then left it alone to get used to the car. The Beast seemed to do whatever it wanted, sometimes pushing, sometimes oversteering. With two events left last year I determined I was bottoming out the front struts and raised the whole car. It improved.

My current set up (used my last two events of 2004):

Camber: Front 2.75 negative, rear 2.0 negative

Toe: Front 1/8 out, rear very slightly in from 0 (0 was my target)

Springs: Front 225#, rear 250#

SB: Front 1", rear 7/8"

Air Pressure (start): Front 29, rear 27 (Victoracers 265/45/16)

Ride height: now at 4.5

I noticed over on Hybridz JohnC said he was running his car with a ride height of 6.5" at the front rocker and 6.75" at the rear with 265/45/16 tires. That seems high to me but his explanation seems to make sense. The #29 doesn't look like it is that high and I'm interested in knowing where it is set.

From what I have found Vic would sometimes run springs between 400 and 450#. I tried 400# all the way around but did not feel that the Illuminas could handle those rates. What is the advantage of 400# vs. 250#?

Thanks

[jmortensen]

I'm pretty sure one of the main problems is ride height. I started last year by simply setting it up to where the front and rear control arms were parallel with the ground. That left the car with an "up hill" rake. I then lowered the front to level the car and then left it alone to get used to the car. The Beast seemed to do whatever it wanted, sometimes pushing, sometimes oversteering. With two events left last year I determined I was bottoming out the front struts and raised the whole car. It improved.

My current set up (used my last two events of 2004):

Camber: Front 2.75 negative, rear 2.0 negative

Toe: Front 1/8 out, rear very slightly in from 0 (0 was my target)

Springs: Front 225#, rear 250#

SB: Front 1", rear 7/8"

Air Pressure (start): Front 29, rear 27 (Victoracers 265/45/16)

Ride height: now at 4.5

Sounds to me like your car is too low. Look into roll centers and you'll find out what negative effects they can have when low lower strut type suspension too much. The big one is that lateral force compresses the suspension, and your camber curve isn't good either. Bumpsteer spacers will help correct the roll center, but to really correct bumpsteer you need to measure it and adjust it out. It's worth doing both.

My friends running Kuhmos are running slightly lower pressures than you, like 26/24, but you'll have to do that by feel or better yet by tire temps.

The HUGE thing that you didn't mention is caster. Caster makes a major difference in turn in. I've had good luck with a pretty similar setup with 5.5º of caster and more toe in on the back end. You might try a little more toe out in front too. Some others are running more caster than I am. I think John Coffey was running 7º if memory serves.

Stiffer spring rates are going to reduce body roll and squat and dive and keep the suspension in the "sweet spot" with regards to camber curve, but are definitely going to require different struts. You're at the limit of what the Illuminas can handle as far as spring rates according to Ground Control so you'll need Konis or the GC Advance Design like Tom has.

[gnosez]

I looked over your set-up specs and agree that caster could be a factor in the way it handles now. I'm unsure for AX events what 400 lb spring rates will do on a 2100 lb vehicle. On the track, yes. To me it seems that the right tire pressure, properly adjusted sway bars, and corner balancing would come into play more than spring rates. And I agree that you need to check the bumpsteer issue out for a car that is this low.

[Steve Parmley]

You could try contacting Vic Sias himself. His business is at http://www.siastuning.com/ Maybe if you bought something from him the secrets might flow.

I rode with him in his car before he sold it and was amazed at how much quicker his car turned in compared to my FP car. He was making great power from a near stock 280 by just using his customized fuel injection setup. I guess that is why his business is doing so well.