Need advice!

[vinnysnova]

First post here, was looking for some advice on suspension. I am building a 62 chevy II with mustang II front, truck-arm rear, coilovers, c5 brakes, twin-turbo 5.3 set back about 5", 4l80 w/2000 stall. I need some advice on sway bars and front end setup. Would the nascar takeoff sway bars work and if so what sizes should I start with? On the mustang II front suspension is there any general caster/camber settings to start with? I know that front end is not the best handling but it is what I had back in 1992 when I started this project. I have a build thread on ls1tech here http://ls1tech.com/forums/forced-ind...gasquirt3.html

Thanks for any help or criticism

[Ben@SpeedTech]

Man, that looks like a bad ride! I seriously considered a long arm suspension for my wagon when I was in the planning stages. Trouble is I couldn't find much info on the web about them and making them work. Hot Rods to Hell sells kits but I'm not sure how loose they are at giving out info. I found only two different companies that sold the parts individually for circle track car builders, but after considering how "mysterious" they are to most folks I decided to stick with what is more mainstream where I knew I could get a lot of support. Sounds like your car is already done, so maybe you could get on some circle track forums to find out more there.

I'd suggest first off getting in touch with Ron Sutton, either here or on Lateral-g, he comes from a long background of building circle track cars and has a lot of insight into suspension systems, and is always happy to help where he can.

[vinnysnova]

Thanks for the reply. I built all the rear components from scratch so it all fit with the car, it seems to go straight and rides great. I really want to go to ls fest this year and have some fun.

[vinnysnova]

nobody even wants to tell me i'm waisting my time?????

[LUV2XLR8]

I would ask ron sutton, a member here on the site. I'm sure he can point you in the right direction.

[RobNoLimit]

Looks really cool. Don't listen to the nay-sayers. The MII suspension can be made to work very well. The SAI of the OE spindle is appx 8 degrees. So, I would suggest trying to get to that in Caster angle as well. You probably can't do that with the current upper arm. Check out the adjustable SPC upper arm. Splined sway bars are a great way to tune without a big $$change each time. But, the first time can be a few extra bucks. Speedway Engineering is a good source. I have a similar IFS on my 46 ford (Hey, it's won the GoodGuys auto-x a few times) I use a 1 1/4" x .188" wall front bar, and a 1" solid rear bar. You may have a higher ft. weight percentage than me, so a 1" x .120" rear bar may be a better starting point. The Wilwood Pro MII spindle is a nice piece, and will cut some unsprung weight and if your going with a bigger brake it makes it an easier swap. Use urathane - or aluminum, rack mounts. The rubber mounts move way to much. Go ahead and get a Baer "bump-steer" kit now. Once you get enough caster, the steering arm will be higher than it should be, causing toe IN under compression, no good. If anything, you may want a little toe OUT under compression. Next, if the front bushing of your trailing arm is a normal bushing and sleave, you may want to change it. Using a piviting bushing, or a spherical bearing (check out Speedway Motors leaf spring bearing kits for Hobby Stock cars) This will allow the rear axle to articulate without 'adding spring rate' to the rear suspension. Hope that helps.

[vinnysnova]

thank you, i will look into the a-arms. I found a front bar that looks like it will be a good starting point

[Ron Sutton]

Looks really cool. Don't listen to the nay-sayers. The MII suspension can be made to work very well. The SAI of the OE spindle is appx 8 degrees. So, I would suggest trying to get to that in Caster angle as well. You probably can't do that with the current upper arm. Check out the adjustable SPC upper arm. Splined sway bars are a great way to tune without a big $$change each time. But, the first time can be a few extra bucks. Speedway Engineering is a good source. I have a similar IFS on my 46 ford (Hey, it's won the GoodGuys auto-x a few times) I use a 1 1/4" x .188" wall front bar, and a 1" solid rear bar. You may have a higher ft. weight percentage than me, so a 1" x .120" rear bar may be a better starting point. The Wilwood Pro MII spindle is a nice piece, and will cut some unsprung weight and if your going with a bigger brake it makes it an easier swap. Use urathane - or aluminum, rack mounts. The rubber mounts move way to much. Go ahead and get a Baer "bump-steer" kit now. Once you get enough caster, the steering arm will be higher than it should be, causing toe IN under compression, no good. If anything, you may want a little toe OUT under compression. Next, if the front bushing of your trailing arm is a normal bushing and sleave, you may want to change it. Using a piviting bushing, or a spherical bearing (check out Speedway Motors leaf spring bearing kits for Hobby Stock cars) This will allow the rear axle to articulate without 'adding spring rate' to the rear suspension. Hope that helps.

Hi Vinny,
I got your PM requesting input. Sorry for the delay in responding. Paying projects take priority.

I agree with Rob's suggestions. He & I have both raced with the Pinto/Mustang II spindle & know how to make it work. Rob's suggestion of 8° caster is a great place to start. I think if you AutoX it, you may find closer to 8.75-9.0° is optimum, but that's just my opinion. I suggest you make your UCAs adjustable so you can tune it, just as Rob suggested too.

I do not know what springs & sway bars to recommend without knowing your suspension geometry measurements, suspension strategy & the type of events you'll compete in. I know one of those ... AutoX.

For my personal, in-house & client projects, I decide the suspension strategy, calculate the roll angle from the projected G's & end up with a target "Total Roll Stiffness" (TRS) number for the car. This number guides me on how much total spring & sway bar rate to put in the car.

I put 5% more roll stiffness in front than the front weight bias. Don't confuse this with roll couple. I'm referring to what are referred to as FLLD & RLLD ... Front & Rear Lateral Load Distribution.

For example ONLY: If a car weighs 3000# ... and we choose a "Moderate Travel & Roll Angle" strategy ... targeting an average roll angle of 2.0° for the car at max g-force (say 1.1) ... that calculates out to needing 1650# of "Total Roll Stiffness" (TRS) in the car. If the car's weight bias is 53%/47% F/R ... then I want to put 58% of that 1650# roll stiffness in the front (aka 58% FLLD) & 42% in the rear (aka 42% RLLD).

I don't just guess at these numbers, because roll centers & motion ratios all play a big role in the calculations. If you're hardcore & looking to do the work to measure & learn this stuff about your car, I'll guide you. But if not, Rob knows the rates of sway bars to suggest from experience, as he did above.

Frankly, I believe you will be damn close with Rob's recommendations, and I would suggest you start there. If after running the car awhile, you want to tweak on it & find a little more, then doing all the suspension geometry measuring would be worthwhile. I urge you not to "pick & choose" between Rob's suggestions, but instead commit to doing them all and your car will be on the right track.

Best wishes.

[vinnysnova]

Been driving the car all summer and it is a blast!
It made good power (not enough, building new 370 now), and ran ok at the drags. Need a higher stall to get into boost at the line. No sway bars yet, doing them with the cage this winter.

[Crestronwizard]

Looks great. Some tuning and hookup and I bet you'll be in the 6's 1/8th mile