Need some coilover over advice

[Marty Rogan]

I am considering switching over to some Ground Control coilovers.

First, here is some information on my car:

Early '71 240Z

currently has stock struts, 5-way Illuminas, MSA lowering springs, short steering knuckles, PU bushings. 15x7 Konig Rewinds mounted with 225/50/15 RA 1's.

'83 280ZX engine, bored 40 over, with '83 5 spd and 4.11 open diff.

I mainly use the car at track day events like NASA HPDE and similar events.

So far I have only done bolt on mods to the car, since it was a fairly low mile, early car. I pulled the original engine and set it aside for safe keeping. I figured once I retire it from track duty, I would restore it to stock condition.

Is it worth going with coilovers without also doing the camber plates? I did not like the idea of cutting into the strut towers.

Does anyone know which Illuminas fit into the sectioned struts? Or would you advise going to a different shock?

What would you recommend as far as spring rates go?

Thanks,

Marty

[rxsleeper]

Time for JohnC to weigh in but here are my thoughts if you do not want to install camber plates.

Go with JohnC's coilover setup using EMI camber plates at the top and eccentrics on the control arms. Use eccentrics on the rear control arms. As for shocks, I will defer to others more knowledgeble as I only have experience with Bilsteins but I am currently running #325 Front and #275 rear spring rates with custom valved Bilsteins. I have been told that #400f/#325R is the max I should try with my current shocks. I also am not using any rear sway bar and a locked diff.

I guess the best question to ask you is what tire are you going to be using and do you have a pyrometer available to help set up your suspension? and What do you want to achieve by going to coilovers?

It may be that just by changing shock valving and adding camber adjustments front and rear you may be happy with what you have and not beating your teeth out if you choose to drive it on the street.

Just some thoughts to start the discussion........

Paul

[jmortensen]

BZ3099 is the front strut to use if you're sectioning, use it with the stock 240 front strut in the rear. Personally I don't like the Illuminas for track work and was happy to get rid of them and switch out for something else. I would suggest Koni Sport or Bilsteins. Bilsteins are cheaper and with the stock valving I would think they'd be good for spring rates into the mid 300s. The revalve that everyone is doing is not very extreme. The Illuminas are good to mid 200's spring rates.

I would go with camber plates, because that's what it takes to remove the deflection in the rubber isolator and also it lowers the car another inch or inch and a half without sacrificing bump travel. I also wouldn't bother with returning it to stock afterwards though, so it is one of those different strokes for different folks deals. The EMI camber plates would work in front and wouldn't require cutting, but I wouldn't put them in the back. I'd run the stock isolators and camber bushings. If you did that you might even consider sectioning the back shorter than normal and running the BZ3099's all the way around, since the isolator will add that inch or inch and a half of height in comparison to the front.

[Marty Rogan]

Time for JohnC to weigh in but here are my thoughts if you do not want to install camber plates.

Go with JohnC's coilover setup using EMI camber plates at the top and eccentrics on the control arms. Use eccentrics on the rear control arms. As for shocks, I will defer to others more knowledgeble as I only have experience with Bilsteins but I am currently running #325 Front and #275 rear spring rates with custom valved Bilsteins. I have been told that #400f/#325R is the max I should try with my current shocks. I also am not using any rear sway bar and a locked diff.

I guess the best question to ask you is what tire are you going to be using and do you have a pyrometer available to help set up your suspension? and What do you want to achieve by going to coilovers?

It may be that just by changing shock valving and adding camber adjustments front and rear you may be happy with what you have and not beating your teeth out if you choose to drive it on the street.

Just some thoughts to start the discussion........

Paul

The tires I have are Toyo RA 1's size 225/50/15. I wanted to lower the car more to improve handling. Friends of mine have said that they have knocked off several seconds in their lap times by going with coilovers.

I have a cheap pyrometer that I got from Harbor Freight. Not sure how accurate it is, but I figured it would give me SOME idea what tire temps were.

I have not had much experience with suspension tuning, so I am trying to learn and see what I can do to improve the car at a reasonable cost.

Thanks,

Marty

[rxsleeper]

Well, I guess it is time for you to hit the purple crack. Get some Hoosier R-6's in an appropriate size for your currrent set up. If your spring rates and shocks are working properly with your current set up, add what you need to to be able to get -3 or so camber in front and -2 in the rear, add Hoosiers and watch your times fall.

FWIW, I have seen lap times drop by 2+ seconds with no changes in the car except for tire compound.

IR pyrometers might give you a trend but tires often cool too quickly to use an IR type. You really need to see core temps with a 25-30 degree variance from outside to inside of the tire.

YMMV and good luck. I would think someone at your track days would have a good pyrometer that you could borrow.

Just some thoughts but I think you would see the largest benefit with camber/toe adjustments and better compound tires. We really need some of the oother guys to check in as well.

Paul

Edit: And you really need to consider an LSD or locked rear. I would go with LSD if the $$$ are right. That alone could be worth another second or two.

One other thing Go Illini! I was born in Urbana!

Edited December 31, 2009 by rxsleeper

[Marty Rogan]

Well, I guess it is time for you to hit the purple crack. Get some Hoosier R-6's in an appropriate size for your currrent set up. If your spring rates and shocks are working properly with your current set up, add what you need to to be able to get -3 or so camber in front and -2 in the rear, add Hoosiers and watch your times fall.

FWIW, I have seen lap times drop by 2+ seconds with no changes in the car except for tire compound.

IR pyrometers might give you a trend but tires often cool too quickly to use an IR type. You really need to see core temps with a 25-30 degree variance from outside to inside of the tire.

YMMV and good luck. I would think someone at your track days would have a good pyrometer that you could borrow.

One other thing Go Illini! I was born in Urbana!

Just some thoughts but I think you would see the largest benefit with camber/toe adjustments and better compound tires. We really need some of the oother guys to check in as well.

Paul

Edit: And you really need to consider an LSD or locked rear. I would go with LSD if the $$$ are right. That alone could be worth another second or two.

All good suggestions.

Thanks Paul.

I am anxious to hear what other have to say too.

[John Coffey]

The single biggest improvement in lap times comes from a LSD. If you don't already have that, spend the money there instead of coil overs.

Some would say I'm shooting myself in the foot because I won't be selling Marty coil overs and camber plates, but I do sell the OS Giken Super Lock clutch pack LSD so I can still maybe get his money that way.... :-)

Seriously, buy a LSD before spending another dime on your suspension.

[Marty Rogan]

The single biggest improvement in lap times comes from a LSD. If you don't already have that, spend the money there instead of coil overs.

Some would say I'm shooting myself in the foot because I won't be selling Marty coil overs and camber plates, but I do sell the OS Giken Super Lock clutch pack LSD so I can still maybe get his money that way.... :-)

Seriously, buy a LSD before spending another dime on your suspension.

Ok, so you have my interest. Do you have an LSD that would bolt into my 4.11 R180 diff and how much do those run?

Thanks,

Marty

[jmortensen]

I'd be more interested in the stub axles John is selling which would allow you to run the WRX STi R180 LSD.

[John Coffey]

Marty,

Send me an e-mail.

[Marty Rogan]

One other thing Go Illini! I was born in Urbana!

Cool!! Do you ever get back there? My 2 oldest sones go to U of I. I go down there 2 -3 times a year.

Marty

[Marty Rogan]

Marty,

Send me an e-mail.

John,

Email sent.