240Z Suspension

OK, so I'm not actually building an IT car, but I figure this is the best place to get advice for setting up a 240Z. My brother in law is building an LS1 powered 240. The good news is that this combo only adds 30 pounds to the total weight of the car so the suspension stuff should be similar. We're building the car for One Lap of America so on- track handling is the priority. I currently daily drive a Civic with 400#/450# f/r springs, so obviously street comfort is not an issue. So what kind of spring rates do ITS Datsuns run? Can the Tokicos handle those rates, or will we need to go with Koni? Sway bars? Poly bushings? Camber plates? Strut tower braces? What kind of alignment settings? Thanks in advance, I can't wait to get going on this project!

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Scott Sawyer
1991 Honda Civic Si,STS 22
http://www.teamunderdog.com

[This message has been edited by reddog_es22 (edited May 11, 2004).]

Although it doesn't exactly pertain to what you are trying to do, found this June 2003 post from our good friend and 240Z guru "katman" who developed a couple of ITS 240Zs. Hope it is of some help. Katman himself may show up and provide more info that is specific to what you are trying to do.


"The basic difference between my novice (less than 2 full seasons) setup and what happens later is spring rate (and whatever corresponding shock changes need to happen, obviously). I like to start them out softer rather than stiffer because I believe it helps them reacclimate to the car quicker during the course of a weekend (remember, we're only driving these things once a month or so) so they're up to their potential sooner. Softer is generally less twitchy (which 240Z's have an abundance of to start with) and easier to stay on top of until such time that the gluteus maximus becomes a finely honed and worthy sensing instrument. Plus, off roading is easier on the unibody with soft springs.

My progression on springs goes something like (front/rear) 285/240, 325/275, 350/285, and finally 400/350. The 350/285 and the 400/350 each won an ARRC. For whatever reason the west coast seems to run in the 250/275 neighborhood as I recall. I don't know if that's because the tracks are bumpier or what. Me thinks those running bigger spring in the back than the front are either in the 6 inch ride height neighborhood or aren't really driving that hard. Also, lots of folks run ungodly big sway bars, like 1+ inch front and 3/4-7/8 rear, which really distorts what the springs should really be (personally I don't like how bars wanker the chassis so I prefer to balance with springs and trim with small bars). I've also come to the conclusion, correct or not, that the spring rates you need to achieve comfortable front/rear balance are very sensitive to roll center. The lower the car gets the more the front roll center heads toward China and the more spring we need to overcome the roll leverage that results. Anyway, be prepared to own a good collection of springs. Ride heights at the rocker around 5-1/8 to 5-1/4, cold with driver.

Here's my preference for things not so varied. Rear toe: I believe in the low drag setup, zero or at most 1/32 total toe in. I refuse to correct bad handling at the back by dragging the tires around. At the front I used to like 1/32 to 1/16 in, but to overcome persistent low speed corner entry problems we eventually settled on 1/8 total toe out. If I can get away with less for some tracks I do (again, low drag), and I begin to squeal when I start needing over 3/32 total out to get it to turn in.

Camber for the Hoosiers is in the 2.5-3.5 front and 1.5-2.5 rear neighborhood. I quit being anal about measuring camber because I tune with the pyrometer, for better or worse, and near the end we weren't visiting many different tracks. When properly measured and repeatable (i.e. I never change the camber unless for two sessions in a row I get the same answer), I like about 20 degrees hotter on the inside than the outside (and I won't be too bothered by 25). With the old bias ply's I shot for almost no bias but that's another kettle o' fish.

Sway bars: Like I said, in the SE the tracks are pretty smooth so I can get my balance with spring. If you have lumpy tracks and need more roll control than you can get with the springs because you got potholes to contend with then you're out of my realm of expertise. We ran a front bar equivalent to a 15/16 solid with one end of the end links mounted in poly so it was somewhat adjustable by preloading the poly- so its torsion rate was probably closer to a 3/4 solid. Our bar was something I made along the factory shape but in a 4130 tube (heat treated to a Rc=63), which only wighed a few pounds. Nicest part I ever made. I miss that bar.....

Shocks will eventually be very important. When the overall understeer/oversteer balance is achieved with the springs and bars for sweeping smooth turns, everything else is tuned with shocks (tire longevity, transitional handling differences between high speed and low speed turns, daily changes to the track affecting one end of the car or another, transitional differences between entry and exit, blah blah). I doubt the Illumina's will be enough shock (I'd revalve a Bilstein since the rule change outlawed my real shocks if it was still my problem)if you get over the 250lb/in spring zone. If the average tire temps from each corner vary more than about 20 degrees you may not have enough shock. That's a provocative statement (i.e. most people would blame the difference on the fact that there's more right turns than left, of the spring balance is off, etc.) I'll address later.

Corner weights- put everything on the right side of the car you're allowed to move, including the driver (our seat was offset 1.5 inches to the center from stock). A very good "with driver" distribution with a mid race fuel load would be 648LF, 625RF, 598LR, 580RR. Heck, that's EXTREMELY good for with driver.

A 240Z can be a handful for a novice. The back end loves to dance around under braking, and most of the time stomping on the gas when you don't want to will save you. Rotsa Ruck."

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Bob Pinkowski
Atlanta Region SCCA
OPM Autosports
ITS Honda Prelude (for sale)

[This message has been edited by bobpink (edited May 11, 2004).]

Scott:
It's been a while since I built a race 240 but I suggest you make contact with Dave Turner of Dave turner Motorsports in California.
He used to supply Z-car suspension upgrades and is very smart about what works well.
Another good source is Kim Blough at Idaho Z-car. Get him at '[email protected]'
And don't overdo it on stiff spring rates - the 240 is a light car and rates above 375 may just get you a latterday buckboard that tramps in rough turns.
Best Regards - Bill Miskoe

Quote:

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Originally posted by bobpink:
A 240Z can be a handful for a novice. The back end loves to dance around under braking, and most of the time stomping on the gas when you don't want to will save you. Rotsa Ruck."

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Bob-
Thanks, that's exactly the kind of info I was looking for. The good news is that a car that is a handful is nothing new, right now I'm playing with a Legends car. Taln about TWITCHY! Now another question, any idea where to
a)get Bilsteins
b)where to get them revalved?
Koni and Tokico I know, but I don't have any experience with Bilstein. Thanks again!

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Scott Sawyer
1991 Honda Civic Si,STS 22
http://www.teamunderdog.com

Quote:

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Originally posted by irondragon:
Scott:
I suggest you make contact with Dave Turner of Dave turner Motorsports in California.
He used to supply Z-car suspension upgrades and is very smart about what works well.
Best Regards - Bill Miskoe

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Bill-
Thanks, I knew Turner did BMW's in a big way, I didn't know about the Z-car heritage. I'll definitely get in touch with him!



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Scott Sawyer
1991 Honda Civic Si,STS 22
http://www.teamunderdog.com

For Bilstein's in the ITS spring rates we're talking about and shortened (2") 240Z struts you want part number P30-0032 revalved to 300/100. By them from any old distributor (like shox.com) and have them sent to Bilstein for revalving (at $65 per). Since the P30-0032 is a VW part you'll need the gland nut for a 240Z strut which is part number 450424 ($20 each). For 240Z struts shortened 2" you end up needing about 1/2 inch worth of spacer under the front shocks and 2 inches worth under the rear. Then of course you'll have to fab some stuff to adapt them to whatever camber plates and upper spring perches you're using.

Or, you could buy my no-longer-ITS-legal Bilstein and Penske based custom designed ShockTek remote reservior adjustables for a song and have the cat's meow for 240Z shocks.

In the end make sure you have at least 2.5 inches of bump travel and 2.25 of rebound from static ride height in the shock.

I still agree with what Pinky quoted me on (thanks dude) with the caveat that that's a good high speed track setup. We think the "west coast" spring setups that are softer and rear biased might be what is required for lower speed tight turn tracks and autox. Jury still out on that.

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katman

Quote:

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Originally posted by kthomas:
For Bilstein's in the ITS spring rates we're talking about and shortened (2") 240Z struts you want part number P30-0032 revalved to 300/100. By them from any old distributor (like shox.com) and have them sent to Bilstein for revalving (at $65 per).

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So the Bilsteins need to be revalved and the Tokicos are borderline for IT spring rates. Does anyone have any experience with Koni shocks? I'm just trying to figure out what all the options are. Katman how much do you want for the illegal shocks? Are you selling just shocks or is it the whole coilover package? Thanks again for all the help!

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Scott Sawyer
1991 Honda Civic Si,STS 22
http://www.teamunderdog.com

Keith,

How much do you want for the shocktek setup?
I thought that stuff was on Grayson's car.

If you still have it, I'm interested.

Tom
email me at [email protected]

The tokico's aren't close. Benefit of the Bilsteins is they are serviceable and revalveable. I also like the inverted design so they cool better. Koni's can be had adjustable, and they can be rebuilt. The downsides are they are more expensive both for initial cost and servicing/revalving. I've been told by a trustworthy ITS 240Z owner and others in years past that the Koni's upper bushing wears out quickly. The Bilstein setup I mention is the same thing we ran on the ERadatz/Grayson Upchurch/Kemp Huemann EP 240Z that finishes second at the RunOff's all the time, before we put a set of ShockTeks on it (and still finished second).

The ShockTek setup includes the shortened Z struts, and coilovers less springs. I'd sell them for 1/2 what they originally cost, or about $1700 plus shipping. Otherwise, they're going on my street car where there's no stinkin' rules!

BTW, another option is Ground COntrol's AD adjustables at about $399 per, but they really don't have enough rebound control for 300+ lb/in spring rates. One of my competitors that did the ShockTek to GC AD swap hated them.

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katman

[This message has been edited by kthomas (edited May 12, 2004).]

Paging Mr. Bill Miskoe......
Hi Bill -I may have lost your email address and was looking to coordinate the upcoming event.
Please contact me when you get a chance
Hows the pending grand child?
Thank You, Drew