ZR-1 Maintenance Tips

General Maintenance

by Jim VanDorn


The most common call we receive by far is from a confused ZR1 owner. After years of reading everything from which thermostat to use, to what type of spark plug is best, the average owner is totally and completely confused...and for good reason. There are many varied opinions of what is best for our cars but that may depend greatly on how you use your ZR1.


After seven years plus, many ZR1's are finally accruing some mileage. We have had the opportunity to closely inspect many engines with a variety of types of use from normal street driving to severe "weekend" use (track time). Compiling this information we can now offer the ZR1 owner some observations. One rule we've adopted after hearing so many owners say the same thing is the "DIMWIT" or "Darn, if I didn't Mess With IT" rule. In other words, if you didn't have a problem, then what are your intentions in the first place? To date, the only company known to have a fleet of engineering ZR1's to test with was GM and it's affiliates.


Therefore, we must ask ourselves if their suggested procedures and parts recommendations should have a considerable amount of merit. Obviously they do, but on the other hand, there are no doubt areas for improvement. Although we will begin our segment discussing the routine and normal maintenance of the ZR1, there are many areas where an upgrade will be suggested.


Please understand that these are personal opinions and experiences and are not intended to conflict with service procedures outlined in the appropriate service manual.

The clamshell hood, a dramatic styling element, is responsible for much of the C4's perceived looseness and interior noise, including rattles, squeaks, and groans. These are noises you would not think were related to the dash area.
My car, once I got used to it, had several sharp-sounding rattles, especially in the right dash area. Also squeaks and other rubbing noises.
I noticed that if I lubricated the hood hold-down pins and their sockets, a lot of the rubbing and squeaking noises went away.
For a while at least; they would come back, sometimes in one day.

But the real point was I would have sworn that those noises were in the dash structure. They were actually being transmitted through the firewall. And that was the discovery.

I had three objectives:

  1. Eliminate the rubbing squeaks and groans permanently.
  2. Eliminate, if possible, the "jiggling" of the hood as the car goes down the road.
  3. Last, but not least, look for any other noises that were related to the hood.

Lock-Down Pin modifications.

First I got some 3/16 inch thick neoprene rubber (already had it from a boat project). I fashioned a "donut" like piece to go over the pin. It's job is to:
  1. Hold lubricant for an extended time,
  2. Regardless of lubricant, act as an isolator between the pin pad, and the lock down pad, and
  3. Because it is compressible (different from the spring), it allows me to really snub down the lock pin.

Once the piece is lubricated with grease, fit it onto the pin. Then loosen the locking nut at the base of the pin, and adjust the pin to be as tight as possible, and still be able to close the hood without having to slam it so hard it is damaged.
Don't worry. This adjustment is only about how tight the pin holds the hood.
The alignment of the hood to the panel is done with the separate adjustment pads. You may check this first.
NOTE: Be sure to close the doors before doing any of this. The hood has been known to hit the door if the door is open. Doesn't happen usually, but only once can ruin your day!
Once you are sure about the positioning, go over the pin again, and make sure it is a tight as you can stand it. It is important for the hood to be held very tightly by the pin, as that is what stops it from jiggling when it is driven.
You may have to experiment with how tight is tight, as no two cars are alike, but you will immediately notice how much tighter the hood looks when you drive, and how much quieter it is.
It is incredible how much generic "noise" comes from the pin socket, and the moving hood.
This takes care of objectives 1 and 2. 


Alignment Pin Modifications

Once you are comfortable with the hood adjustments, here is another problem that creates an incredible amount of noise... in this case, a rattling type of noise, out by the ends of the dash, near the doors.
Look back at the hood, near the lock pin. You will see, lower down, a sharp pin about the size of a pencil.
Follow it down, and you will see that when the hood closes, it fits into a square, plastic lined, hole in a bracket located near the door hinge area.
If the plastic liner is still there, it is probably loose. More than likely, it is gone. One of mine was gone. When the pin is in the hole, plastic or not, it rattles sharply when the hood moves as the car is driven.
Even with the improvements we just made on the lock down pin, the rattle will come back.
So I made a piece of rubber and fit it into the square hole in such a way that the pin slides into it, and it is prevented from rattling.
It is held tightly, but more important, it cannot touch the bracket.
This rubber piece has to be positioned carefully, and lubricated with grease, so the pin will go in. I cut the rubber piece like the drawing, and as you can see in the photo, the notches hold the front up, which holds the piece in the right position.
A quick mod, and an essentially free mod, and as big an improvement as you can imagine.
This fulfills objectives 1, 2, and 3.
 Author: Art Colley
Posted in: Body
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