Air over Hydraulic brakes

[Jasonjones1]

My 98 3500 has air over hydraulic brake system. I need the single brake chamber in the rear. I’ve never seen a setup like this nor my mechanic. Chevrolet can’t help nor Turtle Top who did the body conversion.

 

[GrimsterGMC]

Can you post a picture so we can see what you can?

 

[Jasonjones1]

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[Jasonjones1]

This is mounted underneath near the back axle

 

[GoToGuy]

What conversion do you have? Engine driven air compressor?
I only know of this system as the brake system between normal auto light truck hydraulic, and commercial vehicle full air brake system.
Like a 4500, 5500, 6500 series tucks.

 

[Jasonjones1]

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3500 series with hydraulic bakes… booster, master cylinder etc except this at the rear axle

 

[GoToGuy]

You sure this is not something like Bendix Hydravac, Vacuboost, uses a remote mounted vacuum booster for power brake operation?

 

[GoToGuy]

Who added the third axle? It's a multi passenger vehicle it had to have some kind of certification, manufactur approval.

 

[Jasonjones1]

I wish I knew. Turtle top did the conversion, they said they don’t mess with anything but the body. Chevrolet says they don’t list anything either. No stickers or stamps inside the doors or anywhere I can find.

 

[Jasonjones1]

Inside the canister is a spring and a pancake like a brake chamber.. the spring is broken. The mechanic tells me it’s air over hydraulic… I don’t know… never seen anything like it. The van is in excellent condition everywhere else but sadly I’ve spent $2000 dollars on replacing everything brake wise just to find this afterwards.