Under the driver’s side compartment in the back of my corvette, there is what appears to be a hydraulic unit. When I back out of the driveway, I hear a sound like a scraping noise for just an instant. I’ve checked exhaust for hitting the ground (no marks), checked rear brakes and suspension (found nothing wrong).

Anyone tell me what that unit is? I believe that could be the source of the noise.

Thanks to all replies and Merry Christmas……

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Can you take a picture of what you say is the hydraulic part and post it for clarification?

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I will as soon as the sun comes up.  Okay here's the photo...




|UPDATED|12/24/2014 11:32:08 AM (AZT)|/UPDATED|


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I was looking through an older Haynes manual that I have and I came across something that I want to confirm first. I am going to go out to my 85 and lay on the ground for a minute before I say what the book identifies it as....... give me a minute. I see you are online. 

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I went out to see if the Modulator valve as it is referred to in the manual located behind the driver's seat was there. It is listed in the section about brakes and is supposed to maintain or reduce the brake fluid pressure to the wheel calibers. The book says that if there is a problem that the unit has to be replaced as a unit because it is not serviceable in any way.

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I certainly appreciate your time and effort!! I'll look into a replacement. I stuffed the compartment full of towels and drove it, sound diminished to almost nothing. Leads me to  believe that's the culprit. Again, Thank you! This is what this forum is all about...

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ABS Pump.  It goes through a diagnostic check after start-up and first application of the brakes.  It makes an odd sound when going through the diagnostic check.  It usually only makes that sound once and then it doesn't do it again until the next start-up.  It's normal.  

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1986 "Bright Red" COUPE - Aluminum Heads,
Sport Seats, Bose, Ultra-Flo Exhaust,
Automatic, Bilsteins - "Mostly Original" otherwise.

hi,