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Cruse control vacuum servo.
Thread Starter
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
Cruse control vacuum servo.
I've been looking for a replacement unit for my 78. I'm not finding this item anywhere... so I'm thinking that this part got 'lawyered' off the market.
I can find plenty of cables, switches and encoders but no servo motors.
Does anyone have a source?
I can find plenty of cables, switches and encoders but no servo motors.
Does anyone have a source?
Le Mans Master
Joined: Jan 2001
Posts: 9,247
Likes: 221
From: Dryden MI
Try calling Tracey's Performance in Roseville, MI. He has a lot of Corvette parts, used and NOS.
https://tracyvette.com/apps/site/page/home/
https://tracyvette.com/apps/site/page/home/
Thread Starter
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
Try calling Tracey's Performance in Roseville, MI. He has a lot of Corvette parts, used and NOS.
https://tracyvette.com/apps/site/page/home/
https://tracyvette.com/apps/site/page/home/
Thread Starter
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
I'll keep looking.
Thanks!!
Last edited by ThePabst; May 9, 2017 at 01:52 PM.
Race Director
Joined: Oct 2000
Posts: 12,682
Likes: 3,135
From: Shamong, NJ
The 78 Corvette used a metal back servo, part number 6466530. It was used on 78 Corvettes and Camaros, and some 79's. The servo was changed to a plastic back version, at some point during 79. The plastic back version was used through 81 on Corvettes and some other GM vehicles. Neither of them have ever been reproduced, and both are near impossible to find in usable condition.
I have one good used 79-81 plastic back one, I've been saving as a spare for my 81. I have it stored in my basement, in hopes that the cooler air down there, will help preserve the rubber plenum of the servo.
I don't think the part was "lawyered" off the market. Being that it was only used in 78-79, I'm guessing that it was discontinued for lack of demand, and hasn't been reproduced for the same reason. Even if it has applications beyond the Corvette, how many other 78-79 cars are still on the road, and of them, how many owners are worrying about having an operating cruise control system?
I have one good used 79-81 plastic back one, I've been saving as a spare for my 81. I have it stored in my basement, in hopes that the cooler air down there, will help preserve the rubber plenum of the servo.
I don't think the part was "lawyered" off the market. Being that it was only used in 78-79, I'm guessing that it was discontinued for lack of demand, and hasn't been reproduced for the same reason. Even if it has applications beyond the Corvette, how many other 78-79 cars are still on the road, and of them, how many owners are worrying about having an operating cruise control system?
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
Watch ebay. While you may not find the exact part, millions of GMs used these servos. The mountings (rear for the part itself and front for the throttle linkage) are the only differences in many. A great many GMs with V8 engine and Quadrajet carburetor used the identical or nearly identical part. Mine is a new old stock part intended for a Chevy Nova. I just had to shorten the linkage rod a bit to use in my '79.
Search for "cruise servo" or similar and be patient. Photos are generally good enough to let you know if the rear mounting will work with your bracket. New old stock servos for Corvettes seem to be of the "unobtanium" variety with used ones surprisingly expensive. Unless utter originality is important to you keep your eyes out and you may find a new old stock servo that will work with a little adaptation and cost less than a very used servo from a Corvette.
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
One only needs to apply vacuum to the can to determine if it is functional. That could be via a hand operated vacuum pump...or you could just 'suck'. 
If you apply some vacuum to get the can arm to move....and it doesn't lose vacuum, it's good.
If you apply some vacuum to get the can arm to move....and it doesn't lose vacuum, it's good.