Pro-touring suspension vs. 1/4 mile traction

[BigBlockOlds]

Just what others have experienced with their pro-touring type suspension setups and what they've done (if anything) to maximize any drag strip traction?

I have an '87 Olds Cutlass I am currently building and have most of the suspension pieces installed finally. While my 1/4 mile times are secondary to the handling performance of the car, I would still like to try and get some decent times at the drag strip.

This is what is in the car currently:

Front Suspension

-SC&C Pro-lite adjustable upper control arms with racing bushings

-HOWE tall upper and lower ball joints

-Stock lower control arms with Global West Del-a-lum bushings

-Moog 5662 706lb/in springs

-Bilstein S-10 shocks

-17x9.5" TTII Classics w/ 245/45ZR17 tires

Rear Suspension

-Currie-Trac tubular lower control arms with "Johnny Joints" at one end and polyurethane at the other (both greasable)

-Edelbrock double adjustable upper control arms with greaseable spherical bearings on the frame side and polyurethane on the rear end side

-Moog F-body cargo coil springs

-Bilstein shocks

-17x11" TTII Classics w/ 315/35ZR17 tires

Unsure on sway bar sizes at the moment. I have a 36mm hollow F-body bar for the front but think it may be too large to match the rest of the suspension.
Would I benefit from a rear lower control arm relocation kit? Similar to this:

https://static1.pt-content.com/images/noimg.gif

Any other suggestions?

Thanks,

[SN65]

Suspensions built for front line accelleration and those for Autocross or road corse events are often at odds with each other.

For example, For the fastest quarter mile times, you will not run a front sway bar. Also, your rear springs will be as light as possible, your shocks will be valved differently, your rear sway bar will be a stiff as possible, etc...

None of the above will enhance your around town driving experiance.

Drag racing is all about accelerating weight transfer front to rear. Every other form of racing (or driving in general) is about limmiting weight transfer.

If you really want the best 1/4 mile times on a street driven vehicle that you are going to autocross, etc... maybe you should consider two different setups for the street and strip. Yes it is a pain in the butt to change out the springs and sway bars, but the results will be much better than trying to build a single setup that will be a compromise, at best.

Build the car for its #1 purpose and then tune or modify for specific events.

Hope this helps.

[SN65]

SNIP...

Unsure on sway bar sizes at the moment. I have a 36mm hollow F-body bar for the front but think it may be too large to match the rest of the suspension.
Would I benefit from a rear lower control arm relocation kit? Similar to this:

https://static1.pt-content.com/images/noimg.gif


I am not familiar with your particular suspension, but generally speaking, you want your lower control arms to run horizontally to the ground. Being able to fine tune your lower control arm location via an eccentric would be a nice feature.

[ponchopwr70]

I ran 12.64 at 107 with an 1.86 60ft. I ran in street trim with 285/40-17 nittos. My suspension is sc+c stage 2plus, eibach springs, edelbrock shocks, edelbrock arms (boxed lowers and adj. uppers) 1-1/4 front bar and 7/8 rear, also my car is pretty stiff cause I boxed the chassis. All my bushings are poly too (not the best for the rear but they are in there)

[silver69camaro]

Build it for handling, then throw on a set of sticky tires. That's about all you can do.

However, it is possible to devise a three link with adjustable links for varying amounts of anti-squat, or an offset upper link to plant the tires evenly.

[High Plains Mopars]

I'll agree with the previous posts that you can never have the ultimate of both disciplines without swapping out hardware.

One side benefit of a handling suspension at the drag strip is that they are typically very repeatable, regardless of track conditions and weather. If you are bracket racing your ride, this consistency is much more important to winning than simply putting down a quick number. The mph numbers are more a reflection of your engines horsepower and will not vary much anyway, regardless of suspension, and the only thing you are giving up with your handling set up is the quickness of your e.t.

[parsonsj]

Build it for handling, then throw on a set of sticky tires. That's about all you can do.

However, it is possible to devise a three link with adjustable links for varying amounts of anti-squat, or an offset upper link to plant the tires evenly.What Matt said. Doing it the other way around is not ever going to work.

jp

[Norm Peterson]

The rear LCAs in these cars converge in plan view, so you can get away with running them slightly "uphill" from axle to chassis without driving the axle steer into vehicle oversteer. Actually, a little uphill will take out some of what's too much axle steer (in the vehicle understeer direction) to begin with.

Relo brackets could be particularly worthwhile in this case, as it isn't all that difficult or time consuming to swap the LCAs to a lower set of holes for more anti-squat at the strip and back to the PT setting before you leave. It's only two bolts.

Up front, you can always disconnect one endlink (I think the driver side may be the better choice) and you might even loosen the chassis bracket bolts a turn or so to cut friction there as the bar rotates in the bushings. There isn't much that you can do about the front roll stiffness of those 700 lb/in springs, but if the straight line activity was to become more frequent, a rear sta-bar that you could adjust to MUCH stiffer than PT-friendly specs could be used to put relatively more of the roll resistance out back. Only two more bolts to mess with if you use the type of sta-bar that has endlinks like the front bar instead of like the OE A/G body bars that bolt up to the LCAs. Essentially, that's what those huge rear sta-bars that you may have seen on similarly suspended cars do - they use the engine torque reaction (and the roll that it develops) carried back through the chassis to re-plant that RR tire and equalize traction. Less front roll stiffness and more rear roll stiffness are the tuning directions for greater RR tire loading.


Norm

[speED]

I agree, that you can quickly disconnect the front endllink as well as invest in some adjustable shocks. Again it will always be a compromise.

[nitrorocket]

Serious powerplant, you can overcome the traction issues during the last 1/8th.

That is really the only way without swapping parts.

[BigBlockOlds]

Thanks for the replies everyone. Really I'm not wanting to disconnect anything or switch parts out. Just looking for the possible little things that would help with 1/4 mile traction without hurting the handling characteristics.

I'm hoping for something in the low 12's on a bad day, high 11's on a good day. Engine is a fuel injected 455 Olds, aluminum heads, aluminum rods, 11:1 compression, etc. Should be around 530HP-550HP I hope. This will all be going through a T-56 (stock for now, I'll see how long it lasts) and an 8.5" rear with 4.10 or possibly 4.56 gears depending on cam size.

[Slow Ride]

Use really big tires with lots of sidewall, and dump the clutch. You should be able to shock the tires into hooking. Adjustable shocks up front would help alot too. Setting them on full soft would let what energy is stored in your stiff springs to be released on launch. The rears should be set rather stiff for a stick shift car so your body lifts and separates to plant the tires hard.

I don't have much into the suspension for my street/strip car. Single adjustable QA1 shocks up front and cheap $10 shocks in the rear. Lakewood slappers on the leaf springs. but I do run lots of tire for the size/weight of my vehicle. I run a 315/60R15 BFG drag radial on a '90 S-10 Blazer. I don't have much HP/$ so my MPH is low, but I 60' well for my ET.

1.52 - 60'
7.193 @ 93.320
11.430 @ 114.286