Road Race car suspension?

[UNGN]

Is that what he's saying? The way he said it, it means something entirely different. And a 7/8 bar mounted to the frame can provide almost any roll resistance, depending on all the other factors involved besides bar diameter. And when you use a statement like: it definitely says that you THINK you know what the factory wanted, better than they do. My guess is that the GM guys got exactly the rate the bar was "supposed" to give. Something about seeing all those race cars with GM design, like the Corvettes at LeMans, that makes me think they do a pretty good job.

He merely is saying if that exact bar was mounted to the frame, it would be the equivalent a 1.3" factory mounted bar.

"supposed to give" isn't saying GM didn't know what they are doing, he is just talking about what a 7/8" sway bar made to the dimensions of the factory sway bar is "supposed to give", when mounted like a sway bar should be mounted.

 

[Marcus]

Hi Ormand. I haven`t posted here for a long time but I thought I should explain my statements.
The rear swaybar on G (and A) body cars must bend in order for the rear axle to articulate. Jack up just one side of your rear axle. Now look closely down at the bushings in the lower arms. You`ll see an angular gap on one sor both sides. That`s because the arms need to move in torsion (twist). Now look how the bar is mounted. In order to twist one side the other end of the bar must change in elevation,but it can`t because it`s bolted to the other arm! As a result the bar is bent slightly in an S shape. Why do you think stock bars sometimes break at the bolts? It takes a fair amount of binding to induce that much stress! Several years ago I built a full sized G body rear suspension test rig (which we still use frequently) that allows us to test different arms,joints,rear bars etc. and actually measure and quantify the results so this isn`t just theory.
We`ve both calculated and measured the rates of the factory rear bar and several aftermarket bars and I stand by those numbers as being more than close enough for the sake of comparison. A force/degree of deflection rating is the proper way to rate a given torsion bar *by itself*. Lbs/in expresses the functional stiffness of a given torsion bar when used with a particular length of arms that allow it to be installed and used in a vehicle,which quite frankly is all we`re concerned about here. That`s why every suspension program I`ve used and every race car chassis builder I know refers to bar rates in lbs/in. One of our test cars (LS1/6 speed/G-5/ 3 link PHB `87 Cutlass) has a road race style adj. rear bar which allows us to swap out torsion bars and change arm lengths to test their effect on the car`s handling characteristics. The reason I said "supposed to be" is that if you run the car with the stock rear bar as designed and then run the same car with a correctly designed rear bar that actually IS 247lbs/in rate the car understeers much less,corners flatter and just plain drives better. I know this because we`ve actually tested them back to back. The rate of the swaybar as a torsion bar is calculated with the effective length of the torsion bar,it`s diameter and the effective length of the arms. Doing so we arrive at #247lbs/in. of deflection (at the end of the arms) with a stock 7/8"OD bar. This is not even close to the stock rear spring rate of a G body which range from 125-147lbs/in (depending on which model and what reference you use). Performance rear springs are generally in the 170-180lb/in range and racing springs 200llb/in+. Anyway,the #247lbs/in is the rate of the bar laying on the bench. Bolt it to the 19.5" long on center lower arms and the rate drops to 49lbs/in. That`s darn near useless. I`m sure it`s exactly what the GM engineers were shooting for but then those same GM engineers designed the horrible understeer,underground roll center and + camber curves into the front end.... Decoupling the rear bar from the lower arms (like GM did on every other car they built except for A bodys and Vega/Monzas) gives you effective bar rates that actually do something. Note 3rd and 4th gen F bodys lower rear arms are interchangable with G body arms but the anti roll bars aren`t mounted to them! That`s because they were designed as performance cars from the get go. If you`ve got any questions about the other "mistakes" on our site please feel free to give me a call at the shop and I`d be happy to explain them to you. I suspect it`s more matter of semantics that anything. Mark SC&C

 

[big reazon]

my monte carlo

I was thinking about a road racing set up and this kept on coming to mind. A lot of chassis bracing. A hotchkis sway bar setup. Home made control arm support mounts. A global west tall spingle converion with rubber bushings. I plan on using the level pro ARC4700L. Plan on also using the cool ride set up. Mini tub. Front wheel wells remade to let me race my car down low. I had my car in those upper speed but it felt lioke it was going to fallapart at stock ride height. All new rubber bushings. and havent chose which sway bar yet. Any suggestion. This is a daily drive so I want to drop it at the races. And ride smooth on the streets. Tell me what you think.

 

[xcessiv6]

suspension

I see all these people who want to road race and drive their Gn every day ther is always a comprise between the two. My car is setup to handle and drive yes it cost money and the tires and shocks have alot to do with it. I use stock spindles up front with BMR upper and lower control arms with QA1 coil over front springs and shocks with front sway bar 1 5/16", rear is cargo springs with air bags and QA1 shocks with ATR rear sway bar.
Wheels are 18x9.5 front and 18x10 rear 245/35/18 Toyo T1R 274/40/18

The car rides good not to ruff, and very little body lean, the first test was for the car was The Tail of the Dragon with some Z06 vettes I kept very well with them and was very surprised it handled as well as it did. It all depends what your goal is and use, pick the parts you want in your budget and go for it these cars handle alot better than most people think with a little work.

 

[TURBOPOWERED68]

I see all these people who want to road race and drive their Gn every day ther is always a comprise between the two. My car is setup to handle and drive yes it cost money and the tires and shocks have alot to do with it. I use stock spindles up front with BMR upper and lower control arms with QA1 coil over front springs and shocks with front sway bar 1 5/16", rear is cargo springs with air bags and QA1 shocks with ATR rear sway bar.
Wheels are 18x9.5 front and 18x10 rear 245/35/18 Toyo T1R 274/40/18

The car rides good not to ruff, and very little body lean, the first test was for the car was The Tail of the Dragon with some Z06 vettes I kept very well with them and was very surprised it handled as well as it did. It all depends what your goal is and use, pick the parts you want in your budget and go for it these cars handle alot better than most people think with a little work.

wow that looks great dude

 

[sailbrd]

Lots of good stuff. I just want to put in a plug for Currie lower rear control arms and Edelbrock uppers. I run the same setup on my GSx and love it. People cannot believe how good this big ol tank can go around corners and still ride great. No bind is the key.

 

[xcessiv6]

I forgot to menton Mteco upper and lower control arms

 

[Gbodyolds]

I see all these people who want to road race and drive their Gn every day ther is always a comprise between the two. My car is setup to handle and drive yes it cost money and the tires and shocks have alot to do with it. I use stock spindles up front with BMR upper and lower control arms with QA1 coil over front springs and shocks with front sway bar 1 5/16", rear is cargo springs with air bags and QA1 shocks with ATR rear sway bar.
Wheels are 18x9.5 front and 18x10 rear 245/35/18 Toyo T1R 274/40/18

The car rides good not to ruff, and very little body lean, the first test was for the car was The Tail of the Dragon with some Z06 vettes I kept very well with them and was very surprised it handled as well as it did. It all depends what your goal is and use, pick the parts you want in your budget and go for it these cars handle alot better than most people think with a little work.

Your car looks sinister, that's gotta be one of the sweetest GN's I have ever seen. where did you get the rocker panel extension / Ground effect and where did you get that exhaust, looks kinda like a nascar style boom tube, I like it.

have you ever seen the FE3X Oldsmobile concept car ? your car can be its long lost cousin
heres a pic from FE3X.com

 

[xcessiv6]

Good eyes it is a boom tube exhaust from Dr Gas the side rockers were made many years ago from GTS I don't know if they still make them
and I have seen that car a guy in dayton is making a reblica of it . I hang at Pro-touring and muscles rides alot because it more of the direction I am going been in drag racing for 20 years tired of fixing all the time and want to drive it more and enjoy it my health hasn't been that good so I been tring to enjoy it.

 

[Gbodyolds]

Good eyes it is a boom tube exhaust from Dr Gas the side rockers were made many years ago from GTS I don't know if they still make them
and I have seen that car a guy in dayton is making a reblica of it . I hang at Pro-touring and muscles rides alot because it more of the direction I am going been in drag racing for 20 years tired of fixing all the time and want to drive it more and enjoy it my health hasn't been that good so I been tring to enjoy it.

Im gonna have to start looking for some of them rockers.
Ill have to check out Muscle rides, Pro-Touring is a good one Lateral-G.net isn't bad (pro touring is better) Corner-Carvers.com is supposed to be ok but it seems weather you have a free or paid for e-mail service its not acceptable for sign up.