S197 SLA Suspension System from Cortex

[BlueGTGS]

For whatever its worth, if you can get your front brakes (during an SLA conversion) to fit under 16 inch wheels, the GT Hoosier slicks are considerably faster than A7's on an autocross course and would probably be a worthwhile investment long term. Unlike the Track Attack tire, the GT slick development included a lot of input and testing by the autocross dealers (me and Ron) and testing by fast autocross guys and it really is very good. And pricey by even A7 standards.

DaveW

Wilwood has a brake kit that bolts in to support 16 in wheels. That's part of the plan also. As far as cutting fenders. I'm all for it, just as long as I'm compliant with the CP Rule set.

 

[DaveW]

@ArizonaBOSS @Fabman

Do you happen to know what length and stroke your shocks are? And what ballpark spring rate you are in relative to the rear or what you ran with struts? Looks like 2.25" x 7? springs? The mentioned a extended length of 18.5" to make a setup rod to get my car mobile, but I am at 18" give or take for a very rough ride height. I assume at that short of a shock, it's a 5inch stroke.

I hope it doesn't come to this, but we are going into 45 days with suspension but no shocks, and 5 months from order and payment to Cortex and I am losing confidence that they are ever going to send them to me so I need to plan on sourcing my own and I guess writing off the $3750 I sent them for the shocks....I really, really, really hope the original stuff shows up to me this week and i don't have to deal with this....

Also, where did you guys set the lower control arm inner mount height and what spacers on the rear legs of that arm? It looks like bottom and of course it would be ride height dependent, but looking for starting points here.

Thanks,

DaveW

 

[Fabman]

@ArizonaBOSS @Fabman

Do you happen to know what length and stroke your shocks are? And what ballpark spring rate you are in relative to the rear or what you ran with struts? Looks like 2.25" x 7? springs? The mentioned a extended length of 18.5" to make a setup rod to get my car mobile, but I am at 18" give or take for a very rough ride height. I assume at that short of a shock, it's a 5inch stroke.

I hope it doesn't come to this, but we are going into 45 days with suspension but no shocks, and 5 months from order and payment to Cortex and I am losing confidence that they are ever going to send them to me so I need to plan on sourcing my own and I guess writing off the $3750 I sent them for the shocks....I really, really, really hope the original stuff shows up to me this week and i don't have to deal with this....

Also, where did you guys set the lower control arm inner mount height and what spacers on the rear legs of that arm? It looks like bottom and of course it would be ride height dependent, but looking for starting points here.

Thanks,

DaveW

Drew’s setup and mine differ so the answers may also differ. He is running a modified stock k member (for rules) and the cortex aluminum spindles. I am running the cortex tubular k member but modified stock spindles. The geometry is likely to be somewhat different. What setup did you purchase?

 

[DaveW]

I have the radialx spindles and cortex k member (no rules for me!!!!)

 

[Fabman]

I have the radialx spindles and cortex k member (no rules for me!!!!)

Yes after a reread of the thread I see what you have. My setup is different so the holes/spacers etc will likely be different, but I can give you my strategy on why Ive done what I have and share my setup. Cortex gives you a lot of flexibility in setup options so season to taste I suppose. I’m hammering this out on my iPad so gimme some time to reply….my thumbs are not that fast.

 

[Fabman]

First off, this is my experience, not sanctioned or recommended by by cortex or anyone else so take it with a grain of salt.

The front springs take 2.225 x 8” while the rear use the more common 2.5” x 8” variety. I do not use the spring tenders most use so your length may vary. I also have my car slammed, so again, your use may vary. I have experimented a lot and found this setup to be fastest for me and my car. I set the ride height where I wanted it and chose the hole that got my control arms parallel with the ground. (I run them 1* up towards the ball joint). I set the spacers in the rear so that when the control arms go through travel they go perfectly straight up and down and zero amount front and back. I set a carpenters square against the arm and jacked it through travel and watched the arm move forward and back until I got the combination that kept them running true to vertical. Part 1

 

[Fabman]

Part 2
This gave me 1* of camber gain/inch so I run a pretty low static camber. Again, this is me with my spindles etc. and I may be all screwed up but it’s been pretty reliably fast for me and tire temps validate the setup. I have had springs from 250 to 450 in the rear and 850 to 1200 up front. I have typically run 1000/300 with no rear sway bar. I recently installed the cortex competition rear sway bar and have experimented with that by zip tying one link up so the bar is defeated and then having a crew member cut the ziptie in the hot pit and run some laps with it connected. Takes like 10 seconds to do this.
At the last event I ran the rear sway bar, an 850/350 spring package and a vastly improved rear brake package (still no ABS) and the car was a rocket. I had tried running the car a little higher but the car slowed down considerably. Again, this is me with my setup and I’m probably an idiot so take it with a grain of salt.

 

[DaveW]

@Fabman thanks so much for the info...beyond the not getting my shocks issue, this overall was exactly what I was looking for and also the direction I was thinking about the slots and spacers on the fronts.

Off topic - is your frame notched in the back in order to get the car so low?

 

[Fabman]

@Fabman thanks so much for the info...beyond the not getting my shocks issue, this overall was exactly what I was looking for and also the direction I was thinking about the slots and spacers on the fronts.

Off topic - is your frame notched in the back in order to get the car so low?

No, the shocks bottom before the axel would hit. I do not run the stock bumpers. Just the bump stops on the shock shaft. The shocks are JRI singles in back and doubles up front.

 

[Fabman]

I run a fair amount of rake. I don’t have the numbers on hand but can update when I return to the shop on Monday.

 

[DaveW]

No, the shocks bottom before the axel would hit. I do not run the stock bumpers. Just the bump stops on the shock shaft. The shocks are JRI singles in back and doubles up front.

Looking at your photos I think we are close on rear ride height, but you have the front lower and more rake. I also ditched the stock bumpers long ago (and the brackets) but it would hit the frame before the shock bottoms with the current bump stop.

I will have to play with all this stuff some more. I can add more bump stop to the shock shaft and tweak the rear ride height.

I haven't done a ton with the rear since I did the cambered axle/TA/Watts since the car lacks front grip not rear. Hopefully the SLA shifts that paradigm.

Thanks again!!!!!!

 

[Don Lariviere]

Mustangs really like rake since they inherently push. I would say 1/2 degree minimum, 1 degree is more common and what I run. Easiest way to measure is to put two marks on the pinch seam 57.3 inches apart, then the difference in ride height at those 2 points (in inches) equals the rake in degrees (1inch/sin(1°)= 57.298".) I have that marked on all my cars frame rails for easy setup.

One degree is almost 2 inches over the wheelbase of the S197, so it's substantial.

Don

 

[Fabman]

I made these ride height checkers.
I have 1" jacking rails so I put these under the rail right where the stock jack would go by the notches in the pinch weld (approximately the same height as the pinch weld)
I use one front and one rear and lock them down then measure where I am with a combination square and mark it with a sharpie.
Then I set them where I want the car to be and mark with a different color sharpie and set the car at that height with drivers weight in the car and a half fuel load and sway bars disconnected.
For reference, this is with 25.5" tall tires 335/30/18
Below is right off my setup sheet from last time out. Hope this helps.








Rear trailing arms up 3*

Track: Front 77.75 / Rear 78.75

Camber LF 2.1 RF 2.0

Ride Height F: 3.312 R: 3.875

RAKE .625

Splitter Height: 2.75”

 

[dragoon]

Not to derail the thread but how come most of my square heads are missing the level vial too


Fabman’s photo ^^^^^^^^

 

[Mad Hatter]

I made these ride height checkers.
I have 1" jacking rails so I put these under the rail right where the stock jack would go by the notches in the pinch weld (approximately the same height as the pinch weld)
I use one front and one rear and lock them down then measure where I am with a combination square and mark it with a sharpie.
Then I set them where I want the car to be and mark with a different color sharpie and set the car at that height with drivers weight in the car and a half fuel load and sway bars disconnected.
For reference, this is with 25.5" tall tires 335/30/18
Below is right off my setup sheet from last time out. Hope this helps.


View attachment 100936

View attachment 100935

View attachment 100938

Rear trailing arms up 3*

Track: Front 77.75 / Rear 78.75

Camber LF 2.1 RF 2.0

Ride Height F: 3.312 R: 3.875

RAKE .625

Splitter Height: 2.75”

Must be a hard lift loading your tool box!!!

 

[Fabman]

Not to derail the thread but how come most of my square heads are missing the level vial too

View attachment 100943

They fall out father quickly along with the scratch all . This is a Starrett so top quality stuff and still....

 

[Fabman]

Must be a hard lift loading your tool box!!!

My tool box?

 

[dragoon]

Not to derail the thread but how come most of my square heads are missing the level vial too

View attachment 100943
Fabman’s photo ^^^^^^^^

My 70 year old craftsman plus, like @Fabman , the mini scribe went missing too ??

 

[Fabman]

My 70 year old craftsman plus, like @Fabman , the mini scribe went missing too ??

View attachment 100945

yup...immediately. I have 4 of these....all missing the same parts.

 

[Fabman]

Must be a hard lift loading your tool box!!!

We only bring the small one. It has all the race car specific tools and supplies in it.