Suspension Setup - Time Trials/Road Course, Suspension Component Recommendations for V8 Options

[Runner]

Fellow track drivers:
Need some ideas on general suspension components for a V8 track car that you have had good success with. Anyone running a V8 car on road courses that can give me some general set-up ideas would be great.

Thanks,

Mark

[stewteral]

Fellow track drivers:
Need some ideas on general suspension components for a V8 track car that you have had good success with. Anyone running a V8 car on road courses that can give me some general set-up ideas would be great.

Thanks,

Mark

Hey Mark,

Great to hear from you! I've been running and developing my SBC powered 914
at Willow Springs Raceway (SOCAL) for about 5 years....I started out doing ALL wrong, learned a lot and with the help of ACE Engineer AndyS, think I have the car where I want it. I'm still guessing since I was rained out of my December track day and am currently crossing my fingers for a DRY day on 06 February for a track-day with www.speedtrialusa.com guys at Streets of Willow Springs.

If you chase back into previous postings & discussions, I have shared some hard-learned info on making a V8 car work. However, to start our discussion, I'll show you mine if then you will show me yours:
-'73 914 w/complete rollcage that braces all 4 suspension load point.
-383 Chevy SBC with Crane short-track cam, 750 Holley, Schoenfeld 180 degree headers. I've added Rhoades Lifters to make the car tractible on the street.
-930 trans with recently added QUAIF TORSEN Dif.
-Big fender flairs housing: 9.5" x 17" fronts and 11" x 17" rear rims.
-Hoosier DOT slicks 255mm front, 315 mm rear
-I have adapted to 911 front struts with Adapter/spacers for Ford Mustang bolt pattern.
-Rear is Stock, reinforced swing-arms with Mustang pattern spacer/adapters and BRACING at inside and outside mounting points (mandatory with V8).
-Wilwood 4-piston calipers on 12" x 1.25" rotors all-around.

Your turn: Tell me about your setup, where you live and what tracks you are running. I look forward to sharing what I've learned and welcome a discussion.

If you would like to chat directly: stewteral@verizon.net

Best,
Terry

[Runner]

Hey Terry;
Thanks for the reply. In reading your specs your car is obviously more advanced in track refinement than mine. I just finished installing the 327 ci last year and up until then, I was time trialing a 1.7 liter. The car is very basic in comparison to yours:

- 1972 specs set-up for time trials with PCA/POC etc.
- 1968 327 ci
- 901 transaxel
- Rear Suspension: Bilstien sport rear shocks/180 lb springs
- Front Suspension: KYB inserts, 911 15 mm sway bar, stock torsion bar
- 4 point roll bar
- 205/50/15 DOT R tires

I have been running time trials since 2003 at Thunderhill, Laguna Seca, Infineon, Buttonwillow and once at Willow Springs. Problem is that my track times have improved little from when I had the 4 cylinder! The car seems unbalanced and unpredictable with the new power/weight. I am interested in a basic track set up for torsion bar/rear spring rating to get the car to track flat in the corners. Realize my level of track improvements to the car is at it's infancy, but I could use a baseline/basic set-up for the v8 combination. What torsion bar size and rear spring/shock combinations have you had success with? I am thinking of a 21mm Tbar, retain the 180lb springs and add a full cage. Really appreciate any insight you can offer up.

Regards, Mark

[andys]

Mark,

If you have a running car, why don't you bring it to Willow on Feb 6th. You can check out Terry's car and maybe get some ideas; I'll be there as well. How far away is Cottonwood?

Andys

[grantsfo]

Hey Terry;
Thanks for the reply. In reading your specs your car is obviously more advanced in track refinement than mine. I just finished installing the 327 ci last year and up until then, I was time trialing a 1.7 liter. The car is very basic in comparison to yours:

- 1972 specs set-up for time trials with PCA/POC etc.
- 1968 327 ci
- 901 transaxel
- Rear Suspension: Bilstien sport rear shocks/180 lb springs
- Front Suspension: KYB inserts, 911 15 mm sway bar, stock torsion bar
- 4 point roll bar
- 205/50/15 DOT R tires

I have been running time trials since 2003 at Thunderhill, Laguna Seca, Infineon, Buttonwillow and once at Willow Springs. Problem is that my track times have improved little from when I had the 4 cylinder! The car seems unbalanced and unpredictable with the new power/weight. I am interested in a basic track set up for torsion bar/rear spring rating to get the car to track flat in the corners. Realize my level of track improvements to the car is at it's infancy, but I could use a baseline/basic set-up for the v8 combination. What torsion bar size and rear spring/shock combinations have you had success with? I am thinking of a 21mm Tbar, retain the 180lb springs and add a full cage. Really appreciate any insight you can offer up.

Regards, Mark

Thats very soft for a track car with a big V8. I'd reccomend going to minimum of 275 lbs in rear with 21 mm front torsions and at least a 21 mm front bar.

[stewteral]

Mark,

If you have a running car, why don't you bring it to Willow on Feb 6th. You can check out Terry's car and maybe get some ideas; I'll be there as well. How far away is Cottonwood?

Andys

Hey Andy,

I emailed some of my calc stuff to Mark and ALSO invited him to come out for the 06 Feb track day.

Once again, Great minds thinking alike! (IMG:style_emoticons/default/smile.gif)...Oh I wish

Terry

[sean_v8_914]

kyb is an econo shock. koni or Bilstein are required to dampen the stiffer springs you need on a v8. Grant is on teh right track.
I would recommend 22mm front torsion bars, 21mm sway bar
rear should switch to a coil over set up to enable proper corner balance with 250-275# rear springs over bilsteins. 15mm rear bar
I hope you have vented front rotors

[sean_v8_914]

dont forget the suspension bushings. if they werent already dead before teh v8, they will be soon. fat torsion bars with stock old bushings will get a notch rubbed into them

[Runner]

dont forget the suspension bushings. if they werent already dead before teh v8, they will be soon. fat torsion bars with stock old bushings will get a notch rubbed into them

Thanks Sean, I will include new bushings in my upgrade plan.

[stewteral]

kyb is an econo shock. koni or Bilstein are required to dampen the stiffer springs you need on a v8. Grant is on teh right track.
I would recommend 22mm front torsion bars, 21mm sway bar
rear should switch to a coil over set up to enable proper corner balance with 250-275# rear springs over bilsteins. 15mm rear bar
I hope you have vented front rotors

Hey Sean:

I think you are really getting close the the right solution with your recommendations. Of course, only on-track testing will give the final answer.

I Have never seen anything too good to come from KYB and you bring out a VERY GOOD Point that when spring rates get Higher, MORE dampening is required!

I also think your front-end T-bar + swaybar numbers are a good place to start. With my experience of YEARS of understeer with my V8 914, I would tend to go the heavier 275# rear springs to see if the rear will get UNSTUCK!!

I'm running stiffer all around, but in the end, HAD to add a rear swaybar to balance the car......now if it would just STOP RAINING here in SOCAL, I could run the car and KNOW i'm getting the handling to come right. Next week-end at Streets of Willow is another Rain-out!! DANG!

I'm with you on BIGGER VENTED brakes! I have the 12.19" x 1.25" Wilwood rotor and have read front temps of only 450 degrees after a session on the Streets of Willow Springs. With the same in the rear, the temps are still in the 300 degree range. There's nothing like empirical Data: My eBay Tire pyrometer also had a probe for High temps.

Best,
Terry

[stewteral]

dont forget the suspension bushings. if they werent already dead before teh v8, they will be soon. fat torsion bars with stock old bushings will get a notch rubbed into them

Sean:

Ah the BUSHINGS! Great point! I couldn't imagine trying to run a V8 car with rubber bushings! The rear suspension would be dancing all over the place!

After doing the whole nasty Burn-the-rubber-out-of-the-swing-arms thing, I'm installed in poly-graphite all around. They tend to squeak a bit, but squirting lube
via the ZERK fitting I added helps for a while. With the Exhaust open at the track, I NEVER here them! (IMG:style_emoticons/default/smile.gif)

On my home-made tubular front swaybar, I used bronze bushings with seem to work well. In mounting the Rear bar, I used a 1" OD tube and could buy poly-bushed swaybar bracket WITH ZERK fittings from Summit Racing for ONLY $16...what a bargain.

Best,
Terry

[sean_v8_914]

ost a link to the summit parts fro the sway bar. i knwo of others who have adapted NASCAR style sway bars.

those rear rubber bushings account for 25-50 pounds of additional spring rsate. dont forgat to account for that

poly-graphites require alot of labor to fit tham correctly

[sean_v8_914]

the shaft is stationary to the chassis. the arm rotates around it. dont forget to polish your shaft

[yeahmag]

Not to steal the thread, but I find my car is too stiff in front with 21mm torsions. I am still running the rubber front bushings, but it's too the point that I've got the front sway bar off!

Things I've done to try and get bite in front:

* maxed out caster and camber
* full soft on koni yellows
* disconnected 19mm bar completely

Things I may try:

* I've got OLD Falken 215's on there, someday I'll get new tires
* put stock bars back in and hook up the sway bar
* replace stock bushings with something harder

[J P Stein]

A PG rear bushing after about 18 mo. of use.
What you see is plastic deformation. What you can't see is the ID is about .02-.03
out-of-round.......deformed by the weight of the car.

[sean_v8_914]

poly crapite. only cheap alternative. I prefer poly bronze but most owners dont pop for that. Delrin might be better but more exp$
is that bushing out of he shit box? plastic will flow. the shit box has got some serious grip.
...pivot shaft does not bear the weight of the car

[J P Stein]

poly crapite. only cheap alternative. I prefer poly bronze but most owners dont pop for that. Delrin might be better but more exp$
is that bushing out of he shit box? plastic will flow. the shit box has got some serious grip.
...pivot shaft does not bear the weight of the car

OK, Slick, I guess I'll have to be more precise.

Not the full weight of that axle, but a pivot shaft is under constant load when the car is on the ground (less when raised, but still under load). You'll note that the deformation is only to one side of the bushing. The bushings on each side of the car were deformed in the same direction.

[Randal]

poly crapite. only cheap alternative. I prefer poly bronze but most owners dont pop for that. Delrin might be better but more exp$
is that bushing out of he shit box? plastic will flow. the shit box has got some serious grip.
...pivot shaft does not bear the weight of the car

OK, Slick, I guess I'll have to be more precise.

Not the full weight of that axle, but a pivot shaft is under constant load when the car is on the ground (less when raised, but still under load). You'll note that the deformation is only to one side of the bushing. The bushings on each side of the car were deformed in the same direction.

Man, that deformation would seem to relate to camber loss (or gain?). I wonder how much?

[J P Stein]

poly crapite. only cheap alternative. I prefer poly bronze but most owners dont pop for that. Delrin might be better but more exp$
is that bushing out of he shit box? plastic will flow. the shit box has got some serious grip.
...pivot shaft does not bear the weight of the car

OK, Slick, I guess I'll have to be more precise.

Not the full weight of that axle, but a pivot shaft is under constant load when the car is on the ground (less when raised, but still under load). You'll note that the deformation is only to one side of the bushing. The bushings on each side of the car were deformed in the same direction.

Man, that deformation would seem to relate to camber loss (or gain?). I wonder how much?

Not much. .03 is about a half mm so maybe a quarter of a degree.
IIRC, both the inner & outer bushings were deformed but the inner were the worst.....the one in the pic was most obvious for picture purposes so ya got that. The main point is that this was with only 18 months of usage and I would expect it to kept getting worse.....the more OR they got, the more they would bang around & accelerate the deformation. That said, there was probably less movement than with a brand new rubber bushing......but I wanted no movement...or more realistically, as little as possible.

[Randal]

poly crapite. only cheap alternative. I prefer poly bronze but most owners dont pop for that. Delrin might be better but more exp$
is that bushing out of he shit box? plastic will flow. the shit box has got some serious grip.
...pivot shaft does not bear the weight of the car

OK, Slick, I guess I'll have to be more precise.

Not the full weight of that axle, but a pivot shaft is under constant load when the car is on the ground (less when raised, but still under load). You'll note that the deformation is only to one side of the bushing. The bushings on each side of the car were deformed in the same direction.

Man, that deformation would seem to relate to camber loss (or gain?). I wonder how much?

Not much. .03 is about a half mm so maybe a quarter of a degree.
IIRC, both the inner & outer bushings were deformed but the inner were the worst.....the one in the pic was most obvious for picture purposes so ya got that. The main point is that this was with only 18 months of usage and I would expect it to kept getting worse.....the more OR they got, the more they would bang around & accelerate the deformation. That said, there was probably less movement than with a brand new rubber bushing......but I wanted no movement...or more realistically, as little as possible.

We are getting zero movement with the needle bearings installed in my trailing arms; however it was a ton of work to get them installed properly (no slop) and properly sealed. Had to fabricate or re-do just about everything.