WhiteKnight2001

So I got a brand new set of tires on my '01 Z28. Firestone Firehawk Wide-Oval Indy 500 tires, they seem to be a good tire with good traction, and handling is decent, but it seems like at speeds over 70MPH if I wiggle the steering wheel a little bit the back end sways and wobbles a bit. This was greatly increased by checking the tire pressure and setting it to 36PSI, rather than 46 which came in the tires when I bought it. They are 245/50-16, original equipment tire size. However I was wondering about some other things to increase my handling. Here are some things I have thought about.

1. Tower strut brace bar - I believe this goes in the engine bay, anyone know exactly what this does and how much it helps? Is it worth it?

2. Panhard bar - I heard this goes in the back, near the axle I believe, and it keeps the rear end of the car aligned with the front end of the car, so the rear end becomes better balances and predictable, I think. Is this true? Is it worth it?

3. Sway bars - Front and rear sway bars, I think thicker is better, but is there a a preferred brand or certain size I should aim for? Should I keep the stock bushings or go for polyurtherane ones? And how does this help the car's handling?

4. Tie rods - I've heard the inner tie rods affect steering tightness, do they really? And do they do anything else in the handling department?

5. Shocks - I have brand new bilstein shocks on all 4 wheels, they barely have 10,000 miles on them.

Is there anything else I can add or change to increase my handling? All ideas and advice is appreciated, thank you.

Injuneer

Let's move this from "Wheels and Tire" to "Suspension....."

WhiteKnight2001

Sorry, I didn't see a suspension section? This place is not set up like LS1tech. Can I get an answer though?

jloshotz

While no single upgrade you have mentioned will do much by itself, all of the above combined will make a great difference. Start with what you can afford one at a time and just keep adding. That is what I did. I'm running 275 40 R17's & have the shock tower brace (engine bay across the two towers; yes) sub frame connectors, aftermarket panhard rod, rear lower control arms, aftermarket torque arm relocated to an aftermarket Trans x-member. My car stays very flat around turns at higher speeds. The quality stuff is expensive, but makes a nice difference. Koni makes an excellent high end shock, AGX makes decent adjustable or non adjustable that are priced a bit less. The sky is the limit.

Injuneer

I'll get you started:

1. You are asking about a "shock" tower brace. No "struts" on a 4th Gen F-Body. The brace connects the towers that the upper srping/shock/a-arm mount connects to. The value of the brace is highly debated. I feel that mine helped stabilize the front end and tighten it up. Others claim it's pure window dressing, and does nothing.

See the black bar in this photo:



A more noticable improvement would come from sub-frame connectors. These are tubular or reectangular bars that connect the front subframe box sections to the rear subframe box sections, and stiffen the chassis, reducing twist and bending. Add SFC's and when you jack one wheel, both wheels on that side come off the ground - amazing difference. I have custom SFC's, integrated with a 6-point roll bar, and the chassis is extremely tight.

2. The panhard bar (or rod) centers the body side-to-side over the rear axle assembly. Since the bar is connected to the left side of the axle assembly, and an arm on the right side of the chassis, it prescribes an arc as the body moves up and down. So there's always a bit of side-to-side movement of the chassis as the chassis rises and lowers in response to bumps and cornering. An adjustable panhard bar allows you to center the chassis, and is almost a certainly a necessity when lowering the car, to recenter. The stock bar is a stamped steel channel, with rubber bushings. Aftermarket bars are tubular (= lighter and stiffer), and can use polyurethane bushings, or spherical rod ends to reduce the looseness of the stock rubber bushings.

See the black bar just in front of the rear axle in the photo below:



3. The sway bars resist body roll when cornering. Stiffer bars reduce roll. Hollow bars weigh less. While making the bars larger will reduce body roll, you have to be careful to keep a balance between the larger front diameter and the smaller rear diameter, to avoid changes to the oversteer or understeer characteristics. The rear sway bar in the photo above is only for "drag" applications, and would not be useful for improved handling.

4. I'll pass on this one.

5. Bilsteins are good if they are valved specifically for the car and the springs you are using.

I'm no expert in street handling, auto-x, road racing, etc. My setup is strictly for driving straight ahead 1/4-mile at a time. There are others who can give you better information. I like the Spohn Performance aftermarket parts, but that is strictly a personal preference. We have Supporting Vendors that sell suspension components.

A site that I have found interesting for ultimate handling is:

Strano Performance Parts - Parts Catalog

WhiteKnight2001

Thank you for the very detailed reply, this helps immensely.

JETMAN95Z28

I added 275/40 ZR17's on all 4 corners, plus a full set of Koni adjustables too. I also had a set of UMI subframe connectors welded in to my car. My car is a stock height t-top car and these 3 changes alone made a HUGE difference in my cars overall cornering and handling. I may at some time in the future go to a panhard bar and lower control arms with urethane bushings, but for now I'm very happy with the way it handles as it is.

Bud M

I'd do things in this order:

1. Check for worn out suspension bushings, lower front A arms in particular.

2. Strano swaybars. Front especially. Strano's 35 hollow front bar is the best. A 21/22 solid on the rear is ok too.

3. panhard & rear lcas. Will really tighten up the rear end. Yes, it's worth it. Don't go poly/poly on the lcas. Get a set that has at least one end that allows the rear axle to twist. Steel rod ends will be noisy on bumps. I haven't tried the UMI roto joints but I'd look at these: 1982-2002 F-Body Lower Control Arms & Panhard Bar Kit- w/ Roto-Joints [203336] - $324.99 : UMI Performance, Inc.

I found the shock tower brace to make a subtle difference, not a mod I'd do before just about everything else suspension related.

WhiteKnight2001

Thank you for the advice on parts to get. Sorry for the noob question, but what do the lower control arms do in terms of handling for the car?

Bud M

You know how the car goes side to side when you spin the tires? Especially when you're hot ******* it out of a corner? That totally went away when I changed lcas and phb. Now it's totally stable and controllable.

WhiteKnight2001

What is the Icas? PHB is pan-hard bar. How much did yours cost? Recommend getting the adjustable one?

Bud M

LCAs=rear lower control arms

I don't recall what mine cost, it's been several years since I bought them.

Adjustability isn't needed on the LCAs but is a good idea on the phb. It allows you to center the rear axle between the fenders, and allows for adjustability should you decide to lower the car.

If you get adjustable, I recommend one that has threaded ends like this one:



not one that has a threaded adjuster in the middle like this one:

zmike

Bud M, I have been debating between the two styles of panhards that you mentioned. Can I ask why you recommended one over the other? I am about to buy an on-car adjustable.

Bud M

I'm not an engineer but it seems to me that the pushing/pulling forces on the bar as you turn left and right would make the bar want to flex toward the center of the bar, so I'd want my joints to be as close as possible to the ends.

I don't see the need for on-car adjustable. When you pull the stock bar, just set it to the same length. If you should eventually change the springs, changing the phb length isn't a big deal. Drop one end, adjust, put it back together. Takes only minutes. Technically I have an on-car adjustable bar (rod ends), and I've never readjusted since I set it up originally.

BTW this is the bar I have

My rear suspension:

mzgp5x

I have done just about everything to a 1997 SS with an MM6 transmision. I noticed a big increase in road performance with an Energy Suspension bushing upgrade over the stock bushings. I have after market bushings everywhere. I also upgraded the engine and trans mounts. B.