s197 weight distribution

[crownaviation]

I have a vert to begin with but trying to guess on my weight distrubution and cg in stock form. I am attempting to do some suspension work and tuning but here are thoughts..

the vert is more likely heavier in the rear than the coupe. They have extra structure back there along with the motor for the top etc..

So, the cg is likely shifted aft from the coupe to begin with?

Now, to top it all off I have a 6 point bar which would further shift cg aft (toward rear). That and I have the battery in the trunk, a huge 7 gallon intercooler tank in the spare tire cavity and add a little weight when we upgraded the rear. I also run the shaker 1000 subs on the street.

I estimate all the weight I have removed from the front basically is a wash for the increase in weight from the blower and dob manifold

I still need to weigh the car each corner but just as a guess that puts the cg much further aft which will raise my percentage ratio quite a bit.

Thoughts..

This is contrubuting to a anti-squat well below 100% (without changing the instant center). Now, to correct the instant center I will use adjustable lca mounts and keep the upper as long as possible (lower hole) while keeping the pinion angle around -2*. Problem is since the cg is likely way aft, I will need to bring the instant center way back to keep above the normal (or neutral) line. This may bring my IC behind the cg (going off rough numbers and theory). Problem is this will contribute to raising the rear of the car on launch... How can I avoid this or minimize the IC going too far aft chasing the AS ratio?

Going to try to start with about 80/10 in front and keep the rear stiff to see what happens with the tires and go from there

Car is getting a big whipple and will make around 1000 or less on motor alone, getting rid of the nitrous. Also using a auto with tb (converter flashes around 3400 but will likely change with the different blower and no nitrous). Using steeda ultralite lowering springs atm and off the top of my head I do not know what the spring rates are but they seem "soft" and tend to bind with my 27" hoosier qtp

Want this to be a street car primarily but considering a 4 link and coilover

 

[Whiskey11]

Want this to be a street car primarily but considering a 4 link and coilover

I'm not entirely sure why you'd want to go to all the work for a 4 link for a street car. I'm not sure why you'd want a 4 link AT ALL from a geometry stand point. Both a 3 link and 4 link behave exactly the same for IC location. You can notch the frame for a longer 3rd link a lot easier than swapping in a complete 4 link.

You are definitely right about the Vert having a more rearward CG than the coupe but I'm not sure that you can say for sure you are going to run into %AS problems without knowing exactly what/where it is.

Finally, if you are looking for some geometry changes for improved launching, have you looked into a torque arm setup? With a torque arm your IC location is significantly more stable than a 3 link will ever be. At stock ride height a torque arm setup that is approximately 47" long returns about 80% AS with no other changes to the geometry of the car. Considering that the IC location is confined to a line that is perpendicular to the Torque Arm's angle at the torque arm mounting point, the only reason the %AS is going to change is with body squat causing the LCA angle to change. At near 100% AS this will be drastically reduced so you'll stay at consistently higher %AS through launch.

Finally, a TA setup wont require extensive and permanent modification to the car. Cortex Racing makes a unit that BOLTS into the stock S197 floor pan at the center driveshaft bearing mounting point and works with stock exhaust routing and most aftermarket mid pipe setups. It also works with 1 pc. driveshafts.

 

[crownaviation]

Sweet.. sounds exactly like what I am looking for. Thanks!

I had considered the 4 link as I had also considered doing a mini tub. That is only going to happen it I can't resolve since of my launch issues.

With my smaller blower (ported m122) I was getting way better 60' times. I am just overpowering my poorly setup suspension now in a big way

 

[crownaviation]

Jim the next time I see you and my car is running I'll let you drive it. I have a Griggs TA and watts link, and it's AMAZING how well the rear end plants.

Get that thing or her quick! need to make up my mind soon. Does your griggs torque arm allow you to adjust the pinion angle?

I spoke to a rep at cortex today and their torque arm does not allow much. They say it should be in tolerance for a car lowered like mine (1.5" in back.

I suppose I could shim the tranny mount if I really had to but it is a shame that it is not really adjustable. He said I could use a small shim in their torque arm but I really did not follow and does not sound like it would adjust much even then

But..it is full bolt on including the watts link. I like their lca's also. Around $2500+ shipping and tax for the complete system


http://www.cortexracing.com/shop/torque-arm-s197/

 

[05stroker]

You lost me at $2500 plus shipping...

 

[lindertw]

have you thought of having your car scaled and/or plotting the suspension measurements so you'll know exactly where your CG is?

seems like you might be chasing your tail trying to make suspension changes when you only have a hunch where the CG currently is...

 

[crownaviation]

have you thought of having your car scaled and/or plotting the suspension measurements so you'll know exactly where your CG is?

seems like you might be chasing your tail trying to make suspension changes when you only have a hunch where the CG currently is...

Having the local shop that built my roll bar do that as soon as the tranny is back in. Their cobrajet still holds a couple nhra records and they did some of the stuff Ford racing now uses.

 

[Dubstep Shep]

You don't have to adjust pinion angle with the stock two piece driveshaft. If you use a one piece, you just shim the mounts at the front of the axle housing.

 

[Department Of Boost]

Just set your car up like 05stroker's and call it good.

 

[05stroker]

Just set your car up like 05stroker's and call it good.

Haha, my car is by far the perfect settings. I just got lucky that my setup worked. I mean, hell, I set the rear shock full stiff and the fronts 2 out from full soft! Just the opposite of what you are "supposed" to do. LOL

 

[crownaviation]

For a couple hundred bucks I am going to get the adjustable lca brackets and cortex lca's for now.

When I get done with the new blower setup I may push for the rest of the cortex stuff.

What all are you using Billy?

 

[05stroker]

For a couple hundred bucks I am going to get the adjustable lca brackets and cortex lca's for now.

When I get done with the new blower setup I may push for the rest of the cortex stuff.

What all are you using Billy?

If Kelly would like to send me some BMR springs and shocks to test, I wouldn't mind! LOL



: Suspension
· Totico D-Spec adj. shocks
·Eibach Sportline springs
· BMR adj. UCA
· BMR LCA
· BMR LCA relocation brackets
· BMR adj. panard bar
· BMR panard relocation bracket
· BMR panard brace
· BMR k-member
· BMR tubular a-arms with updated bushings
· BMR rear extreme anti squat
· BMR boxed sub-frame connectors
· BMR upper poly bushing

 

[Whiskey11]

Get that thing or her quick! need to make up my mind soon. Does your griggs torque arm allow you to adjust the pinion angle?

I spoke to a rep at cortex today and their torque arm does not allow much. They say it should be in tolerance for a car lowered like mine (1.5" in back.

I suppose I could shim the tranny mount if I really had to but it is a shame that it is not really adjustable. He said I could use a small shim in their torque arm but I really did not follow and does not sound like it would adjust much even then

But..it is full bolt on including the watts link. I like their lca's also. Around $2500+ shipping and tax for the complete system


http://www.cortexracing.com/shop/torque-arm-s197/

You don't really need to adjust pinion angle with a torque arm unless you are using a 1 piece driveshaft and there are a number of ways to adjust it should it be necessary to do so.

The guy you spoke with at Cortex was probably Filip, the owner. He's a solid guy and wont bull shit you.

I don't think Grigg's unit is adjustable for pinion angle either.

 

[crownaviation]

You don't really need to adjust pinion angle with a torque arm unless you are using a 1 piece driveshaft and there are a number of ways to adjust it should it be necessary to do so.

The guy you spoke with at Cortex was probably Filip, the owner. He's a solid guy and wont bull shit you.

I don't think Grigg's unit is adjustable for pinion angle either.

Spoke to Filip and yes he was pretty helpful. I am using a 4r70w tranny with custom 1 piece ds. I have a Freddy Brown mount that I can adjust along with a little shim that can also be used in the cortex ta mount.

Should not be an issue but would be a $2500 chance there could be... and griggs is the same.

I think I would prefer the cortex and really like the idea of the ta

 

[Whiskey11]

Spoke to Filip and yes he was pretty helpful. I am using a 4r70w tranny with custom 1 piece ds. I have a Freddy Brown mount that I can adjust along with a little shim that can also be used in the cortex ta mount.

Should not be an issue but would be a $2500 chance there could be... and griggs is the same.

I think I would prefer the cortex and really like the idea of the ta

Definitely have options. I have enjoyed my Torque Arm but my uses and needs are slightly different than yours are and it filled a roll that could only be accomplished by a TA.

 

[Dubstep Shep]

Griggs TA is adjustable.

 

[crownaviation]

Griggs TA is adjustable.

as in ability to adjust pinion angle to correct ds angle on lowered car?

 

[Dubstep Shep]

as in ability to adjust pinion angle to correct ds angle on lowered car?

More or less.

With the Griggs setup, the TA is at a fixed angle to the axle. You can change that angle by either shimming the rear mounts on the TA and Pinion Housing or the front mounts on the TA.

 

[crownaviation]

More or less.

With the Griggs setup, the TA is at a fixed angle to the axle. You can change that angle by either shimming the rear mounts on the TA and Pinion Housing or the front mounts on the TA.

Ahh, yeah same for the cortex