GenVibe - Community for Pontiac Vibe Enthusiasts

I have a 2004 all wheel drive with abs. The rear brake lines go through this manifold. Just curious what it is and what function it serves?

Thanks!

Looks like a brake proportioning valve, if not the same one, then very similar to the one shown in this ebay listing

https://www.ebay.com/itm/47150-12270-To ... SwkNRd3sIy

not sure why one would be needed with ABS, the internet says those things are used to prevent the rear brakes from locking up in heavy braking. I have no idea how they work. Might be easier/cheaper for the factory to put them on all cars, and not bother going with a different set up on those cars that get ABS

All cars that I know of have a proportioning valve in the brake system if the car has a combination of disc and drum brakes. Others that have disc and disc brakes may still have a proportioning valve too. The valve reduces the pressure to the rear brakes so the rears do not lockup as there is little weight and traction on the rear tires. These have been around since the later sixties when cars came with disc brakes on the front and drums on the rear. Some cars require this valve to be opened (bypassed) before bleeding the brake system; kind of like some ABS systems need to be bypassed before bleeding. Each make and model is different so be sure to check if this is required before you bleed a brake system.

Races cars also use a form of this but is adjustable. It is one of the things the race driver can adjust when driving the race car and does effect the cars handling when braking.

Yeah, it's a brake proportioning valve. I am pretty sure even my non-ABS Vibe has it. Darn near any car these days should have one, regardless of brake set up.