Which brake master cyl? 12mm v. 3/8” switch? - ZR-1 Net Registry Forums

conesare2seconds · 12-17-2017

Hi everyone. Appears I have a leak at the brake master cylinder so I’m preparing to replace it. Rock Auto lists 2 MCs for the 94 ZR-1: one with a 12mm long switch, the other with a 3/8” long switch. Is this referring to the pressure differential switch, and how do I know which one my car has?

WVZR-1 · 12-17-2017

Quote:

Originally Posted by conesare2seconds

Hi everyone. Appears I have a leak at the brake master cylinder so I’m preparing to replace it. Rock Auto lists 2 MCs for the 94 ZR-1: one with a 12mm long switch, the other with a 3/8” long switch. Is this referring to the pressure differential switch, and how do I know which one my car has?

I don't shop RA and I didn't even look but I don't recall hearing that except it being mentioned by someone else who was shopping there. There should be some casting information on your old that could be used as a reference. I'm only aware that it was customary when using the service master assembly from GM the reservoir and level switch needed to be transferred from the old.

What casting information is on your master cylinder? You might need a mirror to read it.

secondchance · 12-18-2017

I replaced my master and the reservoir in October 2016 and did not run into part number/compatibility issue you are having.
Below is the vendor I got my parts from and had no issue. Perhaps part number listed can help you with cross-referencing.

https://corvetteparts.com/catalog?q=...aster+cylinder

Ccmano · 12-18-2017

There are four listed for your car on RA. Only one is noted as 3/8’s. It’s aftermarket. The Ac/Delco unit is 12mm, go with that.
H

conesare2seconds · 12-18-2017

Good advice, so it’s done. I’ll update if any problems but don’t anticipate them. Ty all.

12-17-2017	#1
conesare2seconds Join Date: Jul 2016 Location: Greater St. Louis Posts: 490	Which brake master cyl? 12mm v. 3/8” switch? Hi everyone. Appears I have a leak at the brake master cylinder so I’m preparing to replace it. Rock Auto lists 2 MCs for the 94 ZR-1: one with a 12mm long switch, the other with a 3/8” long switch. Is this referring to the pressure differential switch, and how do I know which one my car has?

12-18-2017	#3
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,723	Re: Which brake master cyl? 12mm v. 3/8” switch? I replaced my master and the reservoir in October 2016 and did not run into part number/compatibility issue you are having. Below is the vendor I got my parts from and had no issue. Perhaps part number listed can help you with cross-referencing. https://corvetteparts.com/catalog?q=...aster+cylinder

12-18-2017	#4
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: Which brake master cyl? 12mm v. 3/8” switch? There are four listed for your car on RA. Only one is noted as 3/8’s. It’s aftermarket. The Ac/Delco unit is 12mm, go with that. H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.

12-18-2017	#5
conesare2seconds Join Date: Jul 2016 Location: Greater St. Louis Posts: 490	Re: Which brake master cyl? 12mm v. 3/8” switch? Good advice, so it’s done. I’ll update if any problems but don’t anticipate them. Ty all.