There is no doubt there are better rear suspension systems than were put in the 82-92 fbodys. However, when GM was designing these cars they were keeping cost in mind, along with intended use.
During the 80 and early 90’s many people were still used to driving RWD solid axle vehicles, and given that it was cheaper to install the famous 10 bolt than do an entire IRS, that’s what was destined for what some would call the economical version of the corvette.
There has been alot of talk lately about what is the best PHB (panhard bar) setup, and want to make a few points in this article to clear up some confusion and misconceptions.
Starting off, you need to learn the proper terminology before we go any further. There are 2 parts of this system:
- The Upper Panhard Bar (UPHB) – Shown in RED – This bar connects to the body on the driver side, and connects to the passenger side frame bracket. The purpose of this bar is to provide lateral support to that bracket. This bar does NOT move.
- The Lower Panhard Bar (LPHB) – Shown in YELLOW – This bar connects to the passenger side frame bracket to the drive side rear end bracket. The purpose of this bar is to center, and keep center the rear end with the body. Notice how I said keep it centered. Most of the aftermarket bars are adjustable to move the rear end left to right on demand. This bar moves when the suspension is compressed or rebound.
Above you will notice it only focuses on the LPHB’s movement. Since the UPHB is fixed and doesn’t move, it isn’t shown.
Now whether it be due to age or simply wanting the best parts for your car, you may be thinking of replacing either one of these two bars. Great! But there are some things to take into consideration first before making a decision.
Lower Panhard Selection
- Honestly the only thing to take into consideration with a LPHB is whether or not it’s adjustable, or fixed, and if you want rod ends or poly ends.
I personally have tried both styles and prefer the poly ends. Why? The rod ends allow for too much articulation in the joints, making the rear end feel more unpredictable and detached from the vehicle. That’s the best way I can describe it. Some may disagree, but that is my experience.
As far as buying fixed vs adjustable? That should be a no brainer, always buy adjustable. Reason?
If you remember earlier, the purpose of the LPHB is to center the rear end, and keep it centered. If you lower your vehicle with different springs, or if your body isn’t perfectly straight, or if the manufacturing process didn’t make 2 bars exactly the same length, you’re going to want to correct it with an adjustment. It’s important to note that there are tolerances built into everything that’s manufactured. Meaning no 2 cars are exactly the same. Buy adjustable. Companies to choose from that make a quality adjustable LPHB are:
Upper Panhard Selection
Upper panhard bars are fixed and don’t move with the rear end, so you would think this would be the simplest bar to buy and install. Nope! The problem is, no one that I’m aware of makes a factory replacement upper panhard bar to stock dimensions.
Most are bent in such a way that they create more clearance for an exhaust. Great right? No.Here’s the problem:If you take a look at a factory setup you can see the UPHB is mostly straight, and the LPHB is mostly level.
If you take a look at a modified setup with an aftermarket founders “panhard bar relocation kit” which is a fancy term for a modified upper phb replacement, it looks like this:
Since they create more room for the exhaust, they must bring the mounting location on the passenger side down further, which also requires the LPHB mount to be moved down even further, that’s the problem.This was on my car using the same kit, not lowered
Why is this a problem?
There are a couple of issues one you may have noticed already.
The bars are going to hit each other on lowered vehicles.
Look at the 2nd photo of the new parts installed.
This car has been lowered, bringing the LPHB very close to the UPHB. When the suspension compresses they will hit each other. They are closer because the “relocation kit” brings the mounting point for the pass side down, while the driver side remains fixed on the rear end. When the owner lowered the vehicle, this brought the driver side mount up even closer to the frame. That extreme angle of the UPHB creates that corner where the two with eventually hit each other in this scenario.
The LPHB is not level.
Looking at both the 2nd and 3rd photo of the new parts, you can see neither LPHB is level. This is a problem because the rear end, as it compresses the suspension, will shift towards the passenger side. Remember, the whole point of the LPHB is to keep the rear end centered with the body.
When the LPHB is not level, it increases the rate at which the rear end will shift under load.
By far the best selection for correcting these issues is the
1982-2002 GM F-Body Competition Panhard Bar Lowering/Leveling Kit
After installing this kit, you will have adjustability via 5 notches on each side of the LPHB, allowing you to even out the geometry of the suspension. The picture below shows the suspension loaded, with the kit installed. Notice how the bar is now level