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CVR’s C4 Corvette Starter Motor Mega Boosts VIN 8 and VIN J Starting Power

Start Your C4 Corvette Sure and Strong

John Gilbert Nov 6, 2017
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The first thing to let go on my 1990 Corvette Z51 after buying it used with 69,000-plus miles on the clock was the starter, but it didn’t happen all at once. That would have made it too easy to diagnose the fault. It was a sneaky, intermittent problem that at first seemed like ensuring the clutch pedal was fully depressed was all it took to start, but then the problem grew worse.

Having never owned a Corvette newer than a 1959 model I imagined the ’90’s problem was due to some modern-age DOT safety requirement like having a clutch pedal safety switch, so I located it and wired a bypass. This seemed to solve the problem for a few days. Then one early Sunday morning at the Balboa car show it reared its ugly head again. The beauty of a stick shift is they’re easy to start with a bum starter or a dead battery.

A friend and I pushed it to a fast roll then I hopped in and popped the clutch. A few blocks later the ’90 Z51 stalled so I had to crowd source a couple of obliging tourist lads from the crosswalk to help me push-start it away from a green light on Balboa Blvd. From there, I drove straight home and put the ’90 up on jack stands.

The RPO Z51 (VIN code J) with a German-made ZF six-speed manual transmission utilizes a Delco-Remy gear reduction starter (PN 10455702) whereas automatic transmission equipped cars (VIN code 8) use a conventional Delco-Remy starter. The Delco-Remy reduction drive starter is smaller in size, weighs less and offers more cranking power than the conventional Delco-Remy starter.

When my Delco-Remy starter motor worked it cranked briskly, as it should, so the starter solenoid was suspect. Similar to the disc in a conventional starter, the copper plunger contacts in the reduction starter’s solenoid tend to wear out prematurely.

I learned solenoid rebuild kits are not readily available anymore. In the search for Delco-Remy model number 10455702 replacement parts I ran across CVR High-Performance Racing Products (Arnprior, Ontario, Canada) and its Protorque Ultra starter. It was the impressive specifications of the CVR starter (PN 9323) versus sourcing a rebuilt Delco-Remy that inspired the upgrade. Vette

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1. As a matter of safety, the first step was to disconnect the negative terminal (ground) at the battery.

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2. Again it’s about safety. We devised a method on how to raise one side and plant it on jack stands then do the same to the other side, followed by shaking the car to test its stability.

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3. The Delco-Remy starter was disconnected electrically and then unbolted and dropped down.

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4. The Delco-Remy starter (left) puts out 1.4kW of power compared to the CVR Protorque Ultra’s 2.52kW, confirmed with an included test sheet.

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5. The oil filter needs to be removed in order to remove the gravel shield (the flat tin sheet between the bellhousing and the oil pan).

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6. Here’s where the last bolt needed to remove the gravel shield hides. Now is a great opportunity to change the motor oil.

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7. Look for broken or chipped teeth on the flywheel. Next, clearances need to be adjusted.

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8. Important! To adjust the starter-pinion-to-flywheel clearance the pinion was held in an engaged position with a tie-wrap.

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9. Using masking tape helps to hold the bolts in place, freeing the hands to tighten the bolts.

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10. Center a pinion tooth and check the clearance. The clearance should be 0.030-0.060 inch. Check clearances at least three locations 120-degrees apart.

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11. The starter motor rotates (adjusts) on the mounting flange to allow clearance for exhaust and oil pan clearance.

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12. Sans starter motor, bolt the mounting flange on top of (over) the gravel shield and mark where the gravel shield needs to be trimmed.

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13. This photo show the area marked with a Sharpie that needs to be cut out.

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14. Clamping the gravel shield in a vice held it steady while we cut out area using an electric hacksaw.

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15. The final shaping and cleanup work was done with a mill file.

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16. With the CVR starter in the properly aligned position there wasn’t a need to lengthen the factory wiring.

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17. We replaced the wire terminals and repaired (re-covered) worn insulation with Painless Performance Classic Braid.

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18. The CVR Hitachi-type reduction starter (PN 9323) can be used to replace a conventional Delco-Remy starter on a VIN code 8 C4.

Photos by John Gilbert

Sources

Painless Performance Products
Ft. Worth, TX 76105
800-423-9696
www.painlessperformance.com
Harbor Freight Tools
800-423-2567
www.HarborFreight.com
CVR Products
www.cvrproducts.com

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