Got Power, Got Brakes, Need to turn

[Guest speedmon]

OK ..... I'm the new guy. I just started work on a '72 240 about a month ago....and had it out to the track last week and it was pushing so bad I couldn't keep up and had to let many slower cars by because they were kicking my ars in the corners. The car has a 2.9 liter with 3 mikunis and Wilwood brakes from Arizona Z so it accelerates and decelerates very, very well.....it just doesn't want to turn.

 

The car has the Eibach springs, KYB shocks and bars (1" & 7/8") from Z Motorsports. I will go coil-overs as soon as I find someone who knows what they are doing around Orange CA, but would like to align and neutralize the car as much as possible until then.

 

I read this post on here that spoke about adjusting the front sway bar....so I will try that. Otherwise, member input would be appreciated.

 

Thanks

[Thumper]

One of the easier things to change would be tire pressure. In solo II tire pressure can make a big difference. In my z I would run my front tires at 38psi and my rear at 37psi. Upto roughly 40psi the higher you go the better grip you have. So if your car likes to push then higher pressure in front and lower pressure in rear. Also you can tighten or loosen your sway bar endlinks. To get rid of push loosen the front or tighten the rear. Also you might want to look into getting a strut bar. A good tri-angular bar will help wonders. Good luck.

[fastzcars]

welcome. Try these. design products racing . They are in O.C. They can even cut and weld your struts for you.

[260DET]

What are your wheel alignment settings and what tyres do you use?

 

Anyway, for radial R tyres, on the front try ~3.5 neg camber, 2-3mm toe out.

[evildky]

TIRES! (this side fo the drink it's spelled with an "I") yes R compound or a good STS tire will take more off your times than any other mod, seat time might have it beat but not by much

[Pop N Wood]

TIRES! (this side fo the drink it's spelled with an "I") yes R compound or a good STS tire will take more off your times than any other mod, seat time might have it beat but not by much

 

 

Well I don't have a dog to run away, but in Australian English it is tyres. They talk funny down there.

 

If you are in Orange County, then get ahold of JohnC. He most definately "knows what he is doing" and can make your Z handle like no other.

[Guest grimlynsan]

It's not funny English. It's correct English. This way we can differentiate between the uses in the sentence: "shopping for tyres tires me out"what say you?

[johnc]

As asked above:

 

1. What size and type of tires?

2. What size wheels?

3. What are your alignment settings?

4. How much driving experience do you have?

[Guest speedmon]

Thanks for all the input...I appreciate it.

 

To address the questions:

1. What size and type of tires?

Answer: 245/50s on 15x8 and 15x10, street tires or tyres...BFGs

2. What size wheels?

Answer: 245/50s on 15x8 and 15x10

3. What are your alignment settings?

Answer: Don't know....just got the car, put some brakes on it cause the stock ones looked scary. I scheduled an appt with my alignment guy, but he was not too optimistic as he said in stock form there are very few adjustments that can be made......

4. How much driving experience do you have?

Answer: about 10 years...Porsches, Corvettes (Z06s), instructor with POC and several other clubs.

 

P.S. I am looking for some "sticky" tires but wheel size/tyre combos are not common for this car's 4 lug set up. I run Kumhos and Michelins with CCWs on my vette so that is where I'm leaning. Aside from sticky tires though, I should be able to neutralize the push.

 

Thanks

[JMortensen]

What is the suspension like? Stock? Stock suspension allows for one adjustment. Front toe. That's it. Stock caster is ~2.5 or 3 degrees. Stock camber is 1 degree positive. Not very racey. With the car lowered you get more negative camber, but you still have no method of adjusting it side to side, and generally you'll end up with a lot more neg camber in back than in front which is not going to help your understeer situation.

 

If you want to make a track day car out of this Z then I'd suggest you start looking at adjustable suspension. Camber plates, adjustable control arms, adjustable TC rods, this sort of thing. Then you can really get into making the suspension work.

 

Caster is a biggee. Some guys are running 8 degrees here. Makes a big difference over stock. Since you're talking radial DOT tires you'll probably want to follow 260DET's advice and shoot for -3.5º camber in the front, maybe something like -2.5 or -3 in the rear. Front toe out from 1/8" to 1/4", I prefer rear toe in of about 3/16" in. Check your rear sway bar for bind. My 7/8" Motorsports rear bar was binding big time. I switched to the Suspension Techniques rear bar to fix that issue.

 

The most popular vendors for adjustable suspension would include:

Arizona Z Car http://www.arizonazcar.com

Ground Control http://www.ground-control.com

Modern Motorsportshttp://www.modern-motorsports.com

 

You can get different pieces from these guys, and then there are lots of threads about making your own control arms, rear toe adjusters, etc. When you think you want to adjust something search for it here first, and when you think you want to buy something search for it here and you'll undoubtedly find opinions on it. That's what I do. The search function will save you $1000's of dollars if you let it.

[johnc]

Here is a good general purpose track alignment setting for a 240Z with tires in the 225 to 245 range:

 

Front

 

Camber: 3.2 negative.

Caster: 6 to 7 positive.

Ride height (measured at the front/horizontal part of the rocker panel): 5"

Toe: 1/8" out.

Increase track as much as possible using wheel spacers.

 

Rear

 

Camber 2.5 negative.

Ride height (measured at the rear/horizontal part of the rocker panel): 5.5"

Toe 1/16 in.

Adjust track with wheel spacers so the rear is about 1" narrower then the front.

 

Unitl you can get to those number understeer will be a problem.

[Pop N Wood]

It's not funny English. It's correct English. This way we can differentiate between the uses in the sentence: "shopping for tyres tires me out"what say you?

 

 

What's the saying? Two great people separated by a common language...

[260DET]

In my limited experience the Z does tend to understeer but if it turns in push may not be such a problem. One of the good things about a Z is you can get great drive out of corners, that may be associated with understeer in some situations.

 

I was out at the track today trying a 24mm front sway bar, up from 23mm. The car did tend to understeer, particularly in slower corners, but it was bloody quick out and down the straights

[260DET]

C'mon John C, tell us what setup characteristics you found fastest with the ROD. Not the nuts and bolts, the handling characteristics you found fastest.

 

That info is surely declassified by now

[Guest speedmon]

Thanks for your input.......

My experience was that the understeer was more severe in the slower corners, sometimes correctable with throttle. But on uphill corners throttle made it worse and I just had to slow down.

 

It's looking like I need camber plates and coilovers and then a "track" alignment. Hopefully then I'll be able to put more power down in turns.

 

Any thoughts on what spring rating to use in the front and back? The car WILL BE primarily a track car with the only street usage being when its driven to or fromo the track.....I hate trailering.

 

 

Thanks again.

[johnc]

C'mon John C, tell us what setup characteristics you found fastest with the ROD. Not the nuts and bolts, the handling characteristics you found fastest.

 

That info is surely declassified by now

 

Nothing about the ROD was classified. Myself, Erik Messley, Bryan Lampe (and I'm willing to bet Keith Thomas too) don't have any handling "secrets." Its all about attention to detail and taking the time to get things right.

 

For example: Properly aligning a 240Z for the first time takes about 8 hours and often takes longer because, when you can't get the numbers you want, things have to be fixed. Just making sure the rear track matches the front can take days.

 

I guess the only "secret" on the ROD was the shocks, which was a very well known secret. Multi-adjustable shocks, properly valved and frequently adjusted by a knowledgeable person, can make any driver into Speed Racer - if the car was prepared with a lot of attention to detail.

 

If they car is setup correctly, you should be foot to the floor (or very close to it) at the apex of the corner. That's the most fun part of handling because that's when you start driving by cars that have a lot more horsepower then you - and a 20mph head start on the straight generally means you'll beat the big horsepower guy to the next corner.

 

EDIT: I guess there's one "secret", but it shouldn't be if people pay attention: rear alignment and compliance.

 

Making sure the rear is properly aligned and the friction in the rear suspension is reduced as much as possible does a lot to increase power down. A Quaife diff is wonderful IF the suspension is designed to work with it. Also, moving weight back in the chassis helps.

[260DET]

...........................................

 

If they car is setup correctly' date=' you should be foot to the floor (or very close to it) at the apex of the corner. That's the most fun part of handling because that's when you start driving by cars that have a lot more horsepower then you - and a 20mph head start on the straight generally means you'll beat the big horsepower guy to the next corner.

 

.............................[/quote']

 

You had ~300whp from memory. So that indicates the ROD was set up with some understeer, at least at lesser speeds, which you drove over by doing an 'old time' drift out of the corner. Get some turn in, car then starts to push, nail it and hang on!!! Yes/no?

 

Because its funny you mentioned that, my Z is now setup a bit pushy, love the helical diff, traction unlimited, almost.

[johnc]

No.

 

It really didn't drift that much, about the same as a normally setup 240Z. Clean and tidy lines were the fastest way around. If you started drifting it too much the rear tires would go away.

 

With a Quaife the rear needs to be pretty soft in roll to keep from lifting an inside wheel. I ran 300 rear springs and a 18mm rear anti-roll bar. 275 rear tires also helped.

[Guest speedmon]

Yeah.....the fastest line is always without sliding, but sometimes you have to compensate if car is uncooperative.....like mine in its current state.

 

So if I run 300 springs in the back, what should I run in the front? I don't have much reference as my Porsche runs 600s in the rear and the vette runs a 950 monoleaf in the front. I know there are other variables involved, but lets say running on a track like Buttonwillow with Victoracer 255/40s and 275/40s on 17" wheels.

 

Thanks

[johnc]

Regarding spring rates on a track 240Z, there are basically two schools of thought: West Coast and East Coast (doing a search on this site will bring up a bunch of threads that discuss this at length). Both seem to work and which setup is better depends a lot on the track and the driver.

 

West Coast (generally for tighter, bumpier tracks)

 

225 to 275 lb. in. front springs.

250 to 300 lb. in. rear springs.

 

25 lb. in. difference between front and rear springs with the fronts being softer.

 

25 to 23mm front anti-roll bar.

19 to 17mm rear anti-roll bar.

 

East Coast (generally for faster, smoother tracks)

 

250 to 350 lb. in. front springs.

200 to 300 lb. in. rear springs.

 

50 lb. in. difference in front and rear springs with the rears being softer.

 

25 to 27mm front anti-roll bar.

17mm rear anti-roll bar optional.

 

A very, very general observation:

 

The West Coast setup allows faster corner entry and mid-corner speed but exits can be tricky. Its pretty easy to get the back out and end up in the dirt. Lifting is almost a guarantee of an off track excursion. This setup is more of a momentum setup and rewards precise driving.

 

The East Coast setup gives better power down and the car is easier to control under power. Corner entry is slower but line adjustment in the corner is easier because lift throttle is more controllable. This setup seems to work better as the Z gets more powerful.

 

Comments from others regarding this observation is encouraged.

 

EDIT: Another way to look at is: The West Coast setup is more of a qualifying setting and the East Coast setup is more of a race setting.