Lowdown on suspension, wheels and tires

[khronus79]

Well guys, I've decided to buy a new project car and chose the 1st gen as my starting point. I have read countless of threads on the SA/FB but none of the touch on the subject that I'm looking for.
First of let me say that I have yet to buy the car, but that is only a phone call away. I'm a member of various rotary clubs and attend MANY rotary specific events, I live in FL and 1st gens are plentiful so finding a car would be quite easy.
I would like this car mostly for show duty but also for some occasional road race/auto x fun, the look I'm going for is the flush/stance look, it looks amazing on other old school rides but I have yet to see a Rx7 pull off this look, so I thought I'd give it a try.
Here's what I'm looking for:










So here are the questions:

1. Suspension.
-What suspension options are out there to lower a 1st gen???
-Are there any coilovers made for this chassis??? and if so, how low do they go???
-What other modifications can I do to "slam" the car???

2. Wheels.
-What is the widest wheel you can put under the stock fender???
-What is the maximum backspace possible before making any contact with any suspension part???

3. Tires.
-What is the the widest tire one can put on a 1st gen, front and back???

[IH8DSM]

ok first one is easy billy at re-speed, everything suspension wise youll want from him.

As far as width thats up to you anything past 7 wide youll have to run flares. id say 15 x8s and 15x9 with a proper offset should work for what you want. Probably have to be like a 15 or so offset

[Kentetsu]

Definitely talk to Billy about this. You can find him at his forum at www.re-speed.com, or over at http://www.iwankel.com/ where he seems to spend more time.

I'm running their front coilovers, and the rear adjustable perches. Awesome!

As for wheels, I'm running 13x8 Revolutions. They fit great with the coilovers, but I might have had issues with the stock springs. Backspacing is 4 inches.

The tires I use are dirt cheap, but perform great. I consistently beat Miatas on race rubber with these babies. They're Sumitomo HTR 200s, and they're going for under $50.00 each if you shop around. The size I run is 215/50/13.

Great shots of those Z cars man! I used to be a Datsun guy before I caught the rotary bug.

You may have seen my car at DGRRX (I think you were there, IIRC). I haven't seen any FBs running a lower ride height than mine, but I could go a lot lower if I wanted to (but it is also a daily driver).

[ducktape]

Lowering a first gen dramatically in the back is typically going to cause bump-oversteer issues. Such is life with a watts link.

/I've got a cheapskate coilover recipe using aftermarket Miata parts that will give you that stance in the front tho. Total cost ~$199.

[khronus79]

Originally Posted by IH8DSM

ok first one is easy billy at re-speed, everything suspension wise youll want from him.

As far as width thats up to you anything past 7 wide youll have to run flares. id say 15 x8s and 15x9 with a proper offset should work for what you want. Probably have to be like a 15 or so offset

So with proper backspace and offset, 7" is the most you can get under the fenders?????, that's quite small.

Originally Posted by Kentetsu

Definitely talk to Billy about this. You can find him at his forum at www.re-speed.com, or over at http://www.iwankel.com/ where he seems to spend more time.

I'm running their front coilovers, and the rear adjustable perches. Awesome!

As for wheels, I'm running 13x8 Revolutions. They fit great with the coilovers, but I might have had issues with the stock springs. Backspacing is 4 inches.

The tires I use are dirt cheap, but perform great. I consistently beat Miatas on race rubber with these babies. They're Sumitomo HTR 200s, and they're going for under $50.00 each if you shop around. The size I run is 215/50/13.

Great shots of those Z cars man! I used to be a Datsun guy before I caught the rotary bug.

You may have seen my car at DGRRX (I think you were there, IIRC). I haven't seen any FBs running a lower ride height than mine, but I could go a lot lower if I wanted to (but it is also a daily driver).

I remember you and your car, in fact I asked you about your wheels right before I took this pic:


So maximum backspace with coilovers is 4" and you barely clear those??? how much lower can you go with your current setup???
I also have never seen a FB lower than yours, in fact yours is the lowest FB I've ever seen, and trust me I've seen countless amounts of 1st gens.

Originally Posted by ducktape

Lowering a first gen dramatically in the back is typically going to cause bump-oversteer issues. Such is life with a watts link.

/I've got a cheapskate coilover recipe using aftermarket Miata parts that will give you that stance in the front tho. Total cost ~$199.

Care to elaborate on said recipe???

[ducktape]

Originally Posted by khronus79

Care to elaborate on said recipe???

Gladly.

Six years ago I was picking through a friend's part collection when I ran across a set of these:

Arospeed coilovers for 89-97 MX5 Miata

The kit comes with 4 identical coilover bodies, 4 springs all the same length (2x 350lb, and 2x 450lb), and 4 urethane isolators.

You remove the strut assembly from the car, compress the spring and remove the strut nut to release the strut top/bearing, upper spring-seat, and stock spring.

Here's a pic of the assembly removed as a unit:


Slide the coilover body onto the shock body til it seats against the lower spring perch, and spin the adjuster all the way down to the bottom. Choose which spring rate you want, and place the spring onto the coilover body (I used the 450lb springs).

Now the tricky part. If you try to put the upper spring-seat back on you'll notice it simply won't work... The problem being that the stock spring diameter is way bigger than the Miata springs, which means the spring just flops around on the upper spring-seat. The solution is simple; flip the upper spring-seat and install it upside down. Through some freak accident of engineering, this seats the Miata spring perfectly. You'll need to put 2 or 3 1/8" thickness washers in between the upper spring-seat and strut-top bearing. You'll know you've done this right when you can spin the strut-top freely without any part of it contacting the upper spring-seat. Replace and tighten the strut nut, and reinstall.

That's all there is to it. With the coilover sleeve adjusted near the top of the range, you'll be close to stock ride height... Meaning with this kit you can drop the front of the car damned-near on the ground (-4"!!!).

How's the ride? Stiff, what do you expect?

Here's what they looked like on my car:





I've taken a lot of flak over the years whenever I post this mod. People think anything without a brand-name is junk, but I look at it differently. As far as I'm concerned, a linear-rate spring is a linear-rate spring... I ran this setup on my 436whp GSL-SE for 3 autocross seasons and 2 years drag racing and it performed like a champ. With the right set of shocks I cut 1.4s 60ft times at the strip and took home more than a few trophies in Emod.

[JShiz]

Originally Posted by ducktape

Gladly.

Six years ago I was picking through a friend's part collection when I ran across a set of these:

Arospeed coilovers for 89-97 MX5 Miata

The kit comes with 4 identical coilover bodies, 4 springs all the same length (2x 350lb, and 2x 450lb), and 4 urethane isolators.

Hmmm... Thanks for the heads up. I may get this and pair it with the re-speed rear inserts. I wish i seen this before buying my rb springs.

[IH8DSM]

Originally Posted by khronus79

So with proper backspace and offset, 7" is the most you can get under the fenders?????, that's quite small.

well the problem is the play between the fender and the front spring if you run to low a offest to fit a wider wheel you can hit the fender, not run a low enough you will rub the spring perch. Then theres the whole thing of if you wanna run a stretched tire, which is what the z's are doing. If thats the case you can run a wider rim and just stretch the tire. Just all depends on what your wanting out of the car.

[Kentetsu]

I seem to have avoided the typical lowering issues through ride height and heavy swaybars. The car has no lean, therefore the Watts has no work to do and cannot bind.

[khronus79]

^^^, this looks like a great solution, what setup did you run on the rear????
So based on this, do you think other miata front coilovers would work for the front????
I might be able to get a decent used set for cheap.

1 more question, are there any major differences in terms of suspension, between S1, S2 and S3 SA/FBs?????

[ducktape]

Originally Posted by khronus79

what setup did you run on the rear????

The rear was not as cheap, and never quite that low. Ended up with a Ford rear-end and custom watts link. You'll have to find someone on here's who has slammed a stock rear to answer that question

Originally Posted by khronus79

So based on this, do you think other miata front coilovers would work for the front????

Probably. The diameter of the RX7 strut assembly is the same as the strut on an MX5, so I would imagine any coilover body meant for an NA Miata would work.

Originally Posted by khronus79

1 more question, are there any major differences in terms of suspension, between S1, S2 and S3 SA/FBs?????

I can't speak for all revisions, but I've had this work on an 85 GSL-SE and an 83 GSL.

[Kentetsu]

On the wheel back spacing, I don't believe 4" is the max I could run with coilovers. I haven't measured, but I believe 4.5 would fit easily. There's a bit of room between the 215s and the spring.

My car can go way lower than it currently is. In fact, I believe I could rest the frame rails right on the ground. Still plenty of adjustment left, even as low as I'm running. I use the race version of the coilovers, which mounts lower than the stock spring seat, with a longer spring to maintain range of motion. That's the one thing that I'm not sure of with the Miata solution, since it uses the stock spring seat, it must be using a very short spring if you can drop it that low (can't view the pics from this computer).

Spring rates: I just have to say this. Don't over spring it!!! So many people go for high spring rates like 400+, which is fine for a track car but not exactly daily driver material. I run 275F/150R, and coupled with heavy swaybars the car handles like it's on rails, but it was still comfortable enough to drive it from Michigan to DGRRX. I know I'll get some argument on the spring rates, and I don't want to offend anyone, but I had to state my own conclusions here.

If you haven't seen any of my race videos, check the link in my sig. There are some external videos that show how the car handles the curves. Some of the very old stuff is on RB suspension, which I "upgraded" to first. After about a month I outgrew it and knew that I had wasted my money because I wanted much more than that.

I also wanted to mention, if you go with new struts, I've been very happy with the Illuminas. If you're going to run camber plates from Respeed (I don't know about others), then get the "race" version of the Illumina, which is actually intended for rear of an MR2. This is slightly stiffer at the high setting, and the diameter of the shaft is what is needed to fit the camber plate. If you get the standard version, then you have to have the shaft turned down to a smaller diameter.

[ducktape]

This pic was I think -1.5", which is where the car was most of the time:



Sorry for the crappy pic. I can't for the life of me find a decent one showing the stance.

[IH8DSM]

Originally Posted by ducktape

This pic was I think -1.5", which is where the car was most of the time:



Sorry for the crappy pic. I can't for the life of me find a decent one showing the stance.

im jealous of your front bumper

[khronus79]

Originally Posted by IH8DSM

well the problem is the play between the fender and the front spring if you run to low a offest to fit a wider wheel you can hit the fender, not run a low enough you will rub the spring perch. Then theres the whole thing of if you wanna run a stretched tire, which is what the z's are doing. If thats the case you can run a wider rim and just stretch the tire. Just all depends on what your wanting out of the car.

I know exactly what you mean, which is why I'm more interested in backspace than offset at this time, I want to stay clear of the springs/coilovers without the use of spacers, the fender doesn't worry me much because that can always be modified.
My Rx8 comes with 8" wide wheels and with proper backspace and offset I've come to find out you can stuff 11s all around by just rolling the lip of the fenders.

Originally Posted by IH8DSM

im jealous of your front bumper

x2 What bumper/lip is that????