Minimize Lean for AutoX

[Bartman]

So I did my first Autocross a couple of weeks ago, and it was a blast. I still have a lot of room for improvement on my diriving skills, but I'd like to start improvements on my car as well.

 

Here's a pic from my first event taken by HybridZ member David K:

 

I'm looking at getting some more rubber on the ground already, and I'd like to minimize the amount of lean as well. With budget being a major factor, what step(s) can I take now to help? I'm thinking installing a rear sway bar and maybe a larger front sway bar may be a good investment at this point.

[JMortensen]

Lower the car, stiffer springs, bigger sway bars.

 

If you're going to limit the roll with huge sway bars you had better beef up the mounting points. I think larger bars might help with the current setup, but you'd need some really big bars if you're planning on going to stickier tires as well.

 

I would guess that the cheapest thing you can do is replace the springs.

 

What's in there currently?

[Bartman]

Lower the car, stiffer springs, bigger sway bars.

 

If you're going to limit the roll with huge sway bars you had better beef up the mounting points. I think larger bars might help with the current setup, but you'd need some really big bars if you're planning on going to stickier tires as well.

 

I would guess that the cheapest thing you can do is replace the springs.

 

What's in there currently?

The rear's are 225 and I think the front's are 200. JohnC posted a while back that the Tokico's made for our Z's are only good to 250, so there's not too much room for improvement without the extra cost of changing shocks as well.

[evildky]

sway bars! thats kinda what they are designed for, I'm running the MSA set, cheap and efficient, I recently sectioned my struts and added camber plates, I've settled on 440lb front springs and 350's out back, it sucks on the street but turn in is amazing and the car rotates so much better now, I also went crazy and put 315's out back and 295's up front, honestly more tire tant power than the weight of the car will allow for me to use, if you plan to shell out the cash for r compounds you might want to save till you can afford coil overs as well, I think a 16x10 would be a great set up and could still be covered with zg flares

[JMortensen]

I've never really put too much thought into spring rates vs vehicle weights before, but now I'm thinking since the car and the suspension is heavier, why wouldn't you be able to run a heavier spring than in a 2000 lb Z. To state in another way, if the car is 30% heavier shouldn't a 30% heavier spring act the same as the lighter spring in the lighter car???

[tube80z]

I've never really put too much thought into spring rates vs vehicle weights before, but now I'm thinking since the car and the suspension is heavier, why wouldn't you be able to run a heavier spring than in a 2000 lb Z. To state in another way, if the car is 30% heavier shouldn't a 30% heavier spring act the same as the lighter spring in the lighter car???

 

If you tune to a specific suspension frequency it takes this into account.

 

C

[tube80z]

Here's a pic from my first event taken by HybridZ member David K:

 

I'm looking at getting some more rubber on the ground already, and I'd like to minimize the amount of lean as well. With budget being a major factor, what step(s) can I take now to help? I'm thinking installing a rear sway bar and maybe a larger front sway bar may be a good investment at this point.

 

Do you have a real pic in a corner? This looks like you're about to lose it and have lifted off the gas. Often when the suspension is compressed and you do this it makes the roll look worse because the suspension has overshot on rebound.

 

When you start looking at putting on sticker tires, etc. you will need to increase spring rate. They should be used to support the chassis. So if you increase the amount of traction the they will need to increase. I guess the trick is figuring out how to do this in the best way. Probably swaybars first. You can also try to raise the RC and that will help cut down the roll angle. The problem will be the lowering the car causes this to go down too. So on one hand lowering both helps and hurts you.

 

If part of your roll is caused by the suspension jacking up you can try and use the droop limiting crutch. It's worked for me and is cheap to implement. Many people don't understand how it works very well and like to claim it's BS. It can really help with turn-in.

 

Cary

[JMortensen]

The problem will be the lowering the car causes this to go down too. So on one hand lowering both helps and hurts you.

Maybe not if he traded those 17's for some 15's...

[johnc]

Bart,

 

Fix your brakes before starting on the suspension. A stock 240Z will easily out brake your car in the condition I drove it at the autocross school.

[tube80z]

Maybe not if he traded those 17's for some 15's...

 

Good point Jon!

[Bartman]

Do you have a real pic in a corner? This looks like you're about to lose it and have lifted off the gas. Often when the suspension is compressed and you do this it makes the roll look worse because the suspension has overshot on rebound.

 

When you start looking at putting on sticker tires, etc. you will need to increase spring rate. They should be used to support the chassis. So if you increase the amount of traction the they will need to increase. I guess the trick is figuring out how to do this in the best way. Probably swaybars first. You can also try to raise the RC and that will help cut down the roll angle. The problem will be the lowering the car causes this to go down too. So on one hand lowering both helps and hurts you.

 

If part of your roll is caused by the suspension jacking up you can try and use the droop limiting crutch. It's worked for me and is cheap to implement. Many people don't understand how it works very well and like to claim it's BS. It can really help with turn-in.

 

Cary

Yes, the pic I posted earlier was prior to a spin. You can see a pic during a slalom section by clicking on the hyperlink in my signature.

 

Bart,

 

Fix your brakes before starting on the suspension. A stock 240Z will easily out brake your car in the condition I drove it at the autocross school.

The brakes were a bit soft, but I think they just need to be bled. I'm running Toyota vented 4x4 front and ZX in the back with a larger master cylinder.

 

I thought I could upgrade my wheels fairly easily, but just that is winding up being much more expensive than I figured. Even going with inexpensive rims I'm looking at around $600 for a set and then around $800 for tires not counting adapters/spacers.

 

So I can definitely afford to bleed the brakes, and maybe the next thing would be some sway bars from MSA...after that I'm not so sure.

[260DET]

Yeh that looks like a throttle off oversteer situation, not representative, nice action pic though

[cygnusx1]

That's pretty much what the skunk saw when I tried to avoid hitting him the other night! I was pretty much in the same attitude but at the last second I got off the brakes and straightened it back out before a spin into the woods. Really nice photo DavidK!

 

If you are going to bleed the brakes, put in some fresh racing fluid like ATE Super Blue. You can get JC-Whitney swaybar urethane bushings, and see a big improvement over stock for not a ton of money. Also make sure you set the proper toe angle, that's free too. You can also tweak your caster a bit with washers, also pretty much free. Springs are pretty cheap but they lead to shocks which gets more expensive. However, it would be the best way to steady the car.

[wheelman]

Bart,

You saw how flat my car corners in the short video on youtube right?

I'm running the MSA sway bar set, GC coilover set with 250 rear/225 front, Tokico HP blue strut inserts and have the car set where the front crossmember is about 4" off the ground with no rake front to rear. I've added camber/caster plates as well.

 

Here is another link to the video.

http://www.youtube.com/watch?v=Azjf_6PF2uo

 

I'm running 225/50-16 Falken RT-615 Azenis on ROHS rims with 1.5" thick spacer/adapters.

 

I agree with Jon, the first thing is lower the car and if you go with large sway bars make sure the mounts are solid.

 

One thing I've found is I gained some negative camber in the rear when I lowered my car. When I added the camber plates I was going to try to add some more but my 300ZX rear axles are compressed as much as they can be. I retained all the camber I gained by lowering, but can't move the plates any further to gain more.

[Bartman]

Bart,

You saw how flat my car corners in the short video on youtube right?

I'm running the MSA sway bar set, GC coilover set with 250 rear/225 front, Tokico HP blue strut inserts and have the car set where the front crossmember is about 4" off the ground with no rake front to rear. I've added camber/caster plates as well.

 

Here is another link to the video.

http://www.youtube.com/watch?v=Azjf_6PF2uo

 

I'm running 225/50-16 Falken RT-615 Azenis on ROHS rims with 1.5" thick spacer/adapters.

 

I agree with Jon, the first thing is lower the car and if you go with large sway bars make sure the mounts are solid.

 

One thing I've found is I gained some negative camber in the rear when I lowered my car. When I added the camber plates I was going to try to add some more but my 300ZX rear axles are compressed as much as they can be. I retained all the camber I gained by lowering, but can't move the plates any further to gain more.

I'll have to measure my car, but I don't think mine is too much higher than 4". I've heard those Azenis may be a good compromise for street and AutoX, Ill have to look into that more. How wide are your rims, mine are 7"? Maybe I could keep my current rims and just get stickier tires.

 

It still sounds like the MSA sway bar set would be a good upgrade for me. At $229.95 it doesn't sound to expensive either.

 

BTW - I have Bad Dog framerails sitting at my house waiting to be installed as well.

[JMortensen]

I'd be careful with the MSA rear bar on a 240. I don't think the 280 is a problem because the mounts are further away from the frame rails, but the 240 is not right in my experience. Mine bound on the frame like crazy and I would pick up inside rear tires when slaloming. Of course at the time I was too lazy to take the time and figure it out, so I only really realized the true extent of how bad it was when I went to make the bars adjustable last year. Get the ST rear bar and then space it back off of the uprights about 1/2" would be my suggestion, parroted from John Coffey. Whatever you decide to put on there, you should take the time to push the suspension all the way through its travel and make sure the sway bar and the end links are not binding. You can also shim under the bushing straps to minimize the squeeze of the swaybar bushings and free it up a bit, and it's really really simple to add zerks to the straps and drill a hole in the bushings so that you can grease them up. Teflon tape as suggested will go away in short order, and grease dries up fairly quickly too. Adding the zerks means you can maintain the sway bar bushings instead of just waiting for them to get worn out and replacing them.

 

EDIT--Actually now that I think about it didn't the 73 come with the later style mounts? If so maybe you can use the 280 bar... then your only disadvantage is that it weighs about 3x as much as the ST bar.

[COmputoman]

Bartman,

Your Z is absoultly sick! I agree with everyone else, with some sways, springs and shocks your suspension should be a lot more responsive, and keep your contact patches stuck to the floor. Otherwise your Z is fantasic. Keep up the good work

 

Ben

[Bartman]

I'd be careful with the MSA rear bar on a 240. I don't think the 280 is a problem because the mounts are further away from the frame rails, but the 240 is not right in my experience. Mine bound on the frame like crazy and I would pick up inside rear tires when slaloming. Of course at the time I was too lazy to take the time and figure it out, so I only really realized the true extent of how bad it was when I went to make the bars adjustable last year. Get the ST rear bar and then space it back off of the uprights about 1/2" would be my suggestion, parroted from John Coffey. Whatever you decide to put on there, you should take the time to push the suspension all the way through its travel and make sure the sway bar and the end links are not binding. You can also shim under the bushing straps to minimize the squeeze of the swaybar bushings and free it up a bit, and it's really really simple to add zerks to the straps and drill a hole in the bushings so that you can grease them up. Teflon tape as suggested will go away in short order, and grease dries up fairly quickly too. Adding the zerks means you can maintain the sway bar bushings instead of just waiting for them to get worn out and replacing them.

 

EDIT--Actually now that I think about it didn't the 73 come with the later style mounts? If so maybe you can use the 280 bar... then your only disadvantage is that it weighs about 3x as much as the ST bar.

Thanks for the sway bar info. I have the Q45 LSD, Adjustable LCA's made by Tim240z, and rear suspension from a 75 280Z; so maybe I do need the 280 bar anyway.

[ARZ_]

I agree about the photo, this isn't the best shot but I am fully loaded in this corner and hard on the gas, this is the time (or maybe just before) that you want to snap the shot. Also it would be nice if the camera man was directly in front of or behind the vehicle for the proper photo to witness the maximum "body roll" (not lean).

 

Also I too should entertain smaller wheels but I love how the car goes down the road and my selection for tires is much greater. In this photo I do not have the strut spacers and my sway bar was also binding on the frame. I welded a (needed because my frame was cracking out around the swaybar mounts) spacer/doubler on the frame and installed my swanky CNC swaybar mount along with the rest of my new suspension.

 

[wheelman]

Bart,

My rims are 7" wide, the 225s were a tight fit. I also had to roll the fender lips in the rear. I wanted to get 40 or 45 profile tires but they don't come in that size for 16" rims.

 

The Falkens are very good tires if you don't get them to hot, when hot they get a bit greasy. Most of us use water sprayers to cool them between runs. If you can find a set of Falken RT-215s get them. Falken doesn't make them anymore but they handle hot temps better. The hard part will be finding a new set that has been stored correctly.

 

The 73 240 does have the later sway bar mounts in the rear but you have to check that the bar will not bind on the frame rails at full compression. I shortened my end links by 1/2" to prevent it. The other thing you'll want to check is clearance between the CV joints and the end of the bar. I assume you're running Q45 axles which have CV jouints instead of U-Joints. If you have the CV joint axles you can't use the rear mount ST bar Jon reccommended, it won't clear the axles. One 240 that showed up at a local event placed the rear bar beneath the control arms. It looked a little goofy but didn't bind or drag the ground.

 

My car may actually be lower than 4" at the crossmember but it's close to that. I have a cheap 2 ton floor jack that just fits under it if the rear is not jacked up.

 

Edit: I forgot to mention I've replaced all the bushings with urethane. Have you replaced any of yours?

You don't need to spend $800.00 for tires. I got my Falkens from Edge Racing for ~$500.00 shipped to my door.

Right now the RT-615s are listed on their site in 225/45-17 for $110.00 each, same price I paid for mine. The site says their sold out but you could call and ask.

 

Wheelman