dzltek

Looking at some suspension pieces, and noticed that some of the adj panhard bars have rod ends, and some are poly bushings. My question is what are advantages and disadvantage, if any between the two. Are the rod ends race only, if so why couldn't they be street/strip? I'm wanting to work on my suspension before making more power. I'm also trying to get the car in the 8.80 range with tires, suspension and gear. The car is a 1995 m6, and completly stock as far as I know. Any and all info is appreciated. Should also know I've made a little over 40 passes, and my personal best is 9.26 with a 2.15 60 ft.

Injuneer

In certain applications - notably the rear lower control arms - the stiff poly bushings can cause suspension bind when the chassis starts to roll. The rod ends provide an additional degree of freedom, which eliminates the bind. I don't see where this is particularly applicable to the panhard rod, which has a very limited range of motion, almost exclusively in one plane.

The suspension bind is more of a concern for the street car designed for good cornering, than it is for a 1/4-mile car.

The rods ends are also very noisy. One solution is to use the spherical rod end on the axle end of the panhard rod or LCA, and poly on the chassis end. That limits transmission of the rod end noise to the chassis. Rod ends also can wear out, from the dust that gets in them in normal driving. There are boots available, and premium ends with better seals though.

I have rod ends on everything in the rear, including the sway bar end links, and don't mind the noise. But it's basically a track car.

dzltek

For now, I'm wanting a street/strip car. Drive it to the track, and Drive it home, occasionally drive it to work and home and around town. So if I understand right, theyre a little more flexible than poly and just make a little noise. Sounds like unless I'm pulling the front wheels, the extra money would be better spent on something else. This is what im thinking for the suspension, BMR track pak, tubular panhard and lca's. If i'm not lowering the car, do I need an adjustable panhard bar and adjustable lca's? I'm guessing that if i use anadjustable torque arm bar, that I do need the other stuff adjustable as well. Also, what about a good set of adjustable coil overs? Any suggestions an drawbacks over a stock setup? I had posted before about suspension on a budget, but i've come to the realization that its not as simple as I had planned. lol Also, Injuneer, do you think my goal is obtainable as far as my 1/8 mile time of 8.80's without touching the engine?

Injuneer

I ran poly LCA bushings for years, and never found any problems with the street handling. And I pushed the car hard. I think the suspension bind issue is primarilly for people who auto-x or road race, or just insist on the ultimate cornering capability.

Steve Spohn was doing some work on my car one day, doing a prototype install for one of his parts, and basically gave me a set of rod end LCA's, so that was the main reason I have them.

You might need an adjustable panhard rod even if the car is stock ride height. It moves the chassis side-to-side over the rear axle. Measure the existing centering of the chassis, by picking a point on the subframe on each side, and measuring to the edge of the wheel. The dimension should be the same on both sides. If it's not, you need an adjustable.

If you lower the car, the chassis will shift slightly to the passenger side, relative to the rear axle. With a 1" drop I think it works out to about 1/10th inch. Whether you need to adjust the panhard rod will depend on where your car sits now.

The LCA "adjustment" has nothing to do with lowering the car. What you want if you lower the car (or even if you don't, in my opinion) are LCA relocation brackets. They help keep the LCA's pointing "up" toward the chassis. You don't want the front (chassis) pivot point to drop below the rear (axle) pivot point, or you'll experience serious wheel hop. The LCA relo brackets allow you to drop the axle end of the LCA to keep it below the lowered chassis end. The holes in the bracket are arranged in an arc to compensate for the change in horizontal position that occurs as the end of the bar drops.

The LCA adjustment allows you to move the rear axle forward or backward to center the tires in the wheel well. I had to use the adjustment to move the rear axle backward about 1/4", when the slick started to grow enough at 125MPH trap speeds to contact the metal quarter panel at the front of the wheel opening.

The adjustable torque arm works indpendantly of the other components. It's just rotating the pinion shaft upward or downward to achieve the correct pinion angle, relative to the driveshaft.

The main advantage of a coil over suspension is the ability to adjust the ride height of the car. You already have coil over front springs/shocks, so you would use a shock with an adjustable lower spring seat height. I have the QA1's in the front with that feature. Since the rear is not a coil over, you would need a conversion kit. I like the Spohn kit, with the weld-in reinforcement for the chassis at the upper shock mounting points.

dzltek

Thanks Injuneer, I really appreciate the info.