6G Celicas Forums

I know the brake booster works off of vacuum, and my engine is now turbo'd, so now their is boost when it is under load. I put a check valve between the engine and the booster. The car has been sitting for 5 years (and yes I still have full brake fluid), so I'm hoping it's just calipers sticking. Now I'm thinking about running the brake booster pre-turbo since it's not working that well. I've been wanting to do a 7th gen rotor/caliper swap. What have you guys experienced with the brakes when the st204 is turbo'd? It should work with the check valve.

the brake booster has a built in check valve. i had no brake issues when i turboed my GT. if you are having brake issues, while anything is possible and it could be the booster, i would look elsewhere.

how do you plan on running the booster pre turbo? where are you going to get your vacuum source?

Um, you just hook it up to the factory location on the side of the intake manifold. Don't install any check valves or anything like that!
My car has been swapped for about 8+ years now. Trust me, there are no brake booster issues to figure out or rig up.

I didn't know it had a built in check-valve. I know some brake boosters have single diaphragm, and others have dual diaphragm, so they work on turbo'd cars. And I've heard of the diaphragm in the brake boosters blowing when a non-turbo car is turbo'd.

For the pre-turbo setup I was going to run it to in front of the turbo, that way it wouldn't have vacuum at low boost (car isn't moving), but it would have vacuum under higher boost (when driving)



Cool, I'll switch it then. This is good to know.

I took out the check valve a few days ago and that didn't change a thing. I don't have a vacuum tester, so I bought 6ft of vacuum line and connected my car's brake booster to the vac port on my truck and drove my car forward and backward for 3 - 4 feet. The entire braking system works perfectly. The car stops very easily running off of the truck's vacuum. VERY easily, perfectly in fact. So it has absolutely nothing to do with my braking system. I don't think the engine is providing enough vacuum to operate the brake booster.

I ran the data logging software that came with the Autronic ECU and logged the idle and a quick run around the block to look at before I had to leave the house, but my laptop keeps getting the blue screen of death when I disconnect the usb cable while the software is running (example: turn key off, logging software recognizes the connection drop, I unplug the USB, and blue-screen-of-death). It gets me every time and I know I have to shut down the software first before I unplug the usb, but I keep doing it the other way . Anyway, I was going to check over everything after driving around the block but lost the data log, so I'll have to run it again to get the idle vac/boost pressure.

if you dont have enough vac to get good brakes, then you still have very serious air leak issues, or some other issue.
even guys running massive cams, dont report issues with braking like your having.
do you have it connect like it is in stock form with the hardline along the firewall?

Thanks, I found the problem already. I T'd off the vac line to the brake booster and connected a check valve for the other connection. I haven't gone to the trouble of switching the brake booster to a dedicated line yet, but I will be shortly.