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 inflatable Sport seat bladder for lumbar and side bolsters stops working. The pump runs audibly; but the actuated bellows housing membrane, or diaphragm, has ruptured.
Instead of replacing the whole pump from GM you may be able to order just the membrane from the manufacturer, Jasco Products, in Sun Valley, CA. Phone number is 818-504-2516.
Another fix from member Mike Zeeff:
I know you can order the diaphragms from Jasco, but here is a better fix for 99 cents. Some of the info came from the vette net by Jim Mason, but I found an easier way to make the fix. Both of my diaphragms were blown out on my 90 ZR-1. Total time to fix both sides was 45 minutes.
  1. Purchase a pair of latex rubber dishwashing gloves from your local 5&10. Make sure they are the heavy duty kind, and not the ones the thickness of a condom. Also make sure they have a good portion of flat texture on the cuff. You'll need enough to cut out two 1" round diaphragms.
  2. Remove the lower seat cushion. There is a wire retainer at the front bottom of the seat. Carefully flip the seat bottom up and out of the way to expose the bladder pump. It is the one with the tubing's attached to it.
  3. On one one end of the pump you will notice two small phillips head screws, holding on a retaining plate. Remove both screws and the retaining plate. The bottom one is a little hard, but it can be done with a small jewelers screwdriver. You do not have to remove the pump itself.
  4. Once you remove the retainer, you can wiggle out the diaphragm assembly. It has three tubes attached to it on one end, and the plunger assembly on the other. If your diaphragm is busted, then the plunger will be separated.
  5. The diaphragm assembly, is held together by four small bolts and nuts. Remove all four, and break apart the diagram assembly. You can now take it to your workbench.
  6. By this time you will clearly see how the diaphragm works. Pull the old diaphragm out, and use it as a template for your new one. Once you cut out a new one, you can mount it on the plunger. Since there is a screw that retains the diagram to the plunger, it is a good idea to use a small dab of silicon sealer to the screw hole.
  7. Re-assemble the entire diaphragm assembly and pump. Be careful to get the plunger back on the motor rod.
  8. Test the unit before you put on the retaining plate. You will see the pump motor spinning the plunger. Make sure it is inflating the bladders.

Author: Various ZR-1 Net Registry members
Posted in: Body, Seats
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