When converting from HydroBoost to Vacuum Brakes ...

[Rob_85Ttype]

I have found that the brake lines going from the hydroboost master cylinder to the proportioning valve are the reverse of what I have seen on every vacuum system. The big line is to the rear of the master cylinder (rear brakes), and the small line is up front (front brakes). I know this is not correct for the vacuum setup. Was my car put together wrong at the factory, or are other hydroboost systems like that as well.

When converting, what needs to be done? Reverse the brake lines? Is the proportioning valve going to work with the lines reversed for the vacuum system?

 

[REDS HOT AIR]

dont know if its right but i switched em on mine and it stops..

 

[TurboBuickSix]

Originally posted by Rob_85Ttype
I have found that the brake lines going from the hydroboost master cylinder to the proportioning valve are the reverse of what I have seen on every vacuum system. The big line is to the rear of the master cylinder (rear brakes), and the small line is up front (front brakes). I know this is not correct for the vacuum setup. Was my car put together wrong at the factory, or are other hydroboost systems like that as well.

When converting, what needs to be done? Reverse the brake lines? Is the proportioning valve going to work with the lines reversed for the vacuum system?

Yes,simply reverse the brake lines to fit.The proportioning valve is the same.The line from the power steering pump goes into the box now.The extra line off of the back of the pump can be plugged with a piece of hose and small bolt or a vac plug.there is no pressure on this one.I was able to put a little bend on my ps line and get it to go into the box.You will need the brake pedal from the donor car as well.Any more probs just ask.

 

[FJM568]

Not a flame, but personally, I don't understand the need to swap to vacuum brakes from hydroboost...Switching from Powermaster, I could understand, but the hydroboost setup is virtually bullet-proof...Rock-solid stopping power...Were you having problems with yours???

 

[Rob_85Ttype]

FJM568,

No, I wasn't having any stopping problems. I'm in the process of converting the car to 86/87 induction, and I made the decision early on when collecting parts. At the time, I didn't know what would be involved with running the hydroboost coupled to the 86/87 pump. It may have been as easy as cutting and splicing the hydraulic lines together with some heavy duty clamps, but now that I have the parts, I'm going vacuum.

How's your car running with your sorta hybrid setup these days?

 

[FJM568]

Ahhh, I understand your situation now!!!!

My hybrid setup has been down for a while Just need to get up off my lazy butt and sweat in the 100* heat and finish the doggone thing...Put a new cam in and re-made my custom upper plenum(all aluminum now)...it used to have a steel tube mounted on an aluminum plate and I couldn't get it to seal and hold boost for anything...

In the middle of deciding on whether to relocate the alternator to driver's side where the coil pack is located and relocating the coil pack(somewhere???), to clear up some room on the driver's(edit, supposed to say passenger) side for at least room for radiator hose off of the 87 intake to clear the support for the alt., which would get replaced with a NA alum a/c bracket with the alt support cut off...hehehe, confusing as hell, huh??? hmmm, may just go one step further and yank all the a/c stuff off and put an 86/7 pass side header and relocate the turbo up front, while I'm at it!!! nahhh, then I'd have to get another DP...

In replacing the cam, I pulled the CC981 valve spring on the #3 exh lobe and replaced that spring with an old worn out stocker for breaking in the new cam with...I will run that for a while and then either switch it to a 979 or 980 on the position or take the bigger chance and put the 981 back on...don't know for sure yet there...

I still have to modify my up-pipe from the pass side header to the turbo so it fits better...Always had a slight leak there...

Just a bunch of nagging little things with it to get it going...Finished getting a braided line for the turbo oil feed and tee-ing off of it for the mechanical oil pressure gauge...If just wanting to replace the solid oil feed line with braided, I've figured a fairly easy and relatively easy way to do it...About $30-$35 in parts locally...

Oh well, it's always something with these cars!!!

 

[Rob_85Ttype]

Wow, does sound interesting. Remember that I mentioned a while back that a later model FWD intake (don't know which-may have been a 3800) had the same style radiator hose connector for the intake (oring style), but was a 90 or so degree fit instead of straight. You might check to see if that would accommodate you hose fitment woes somehow. Good luck. I hope to be through with this endless project soon.

 

[cool 84]

Originally posted by Rob_85Ttype
FJM568,

No, I wasn't having any stopping problems. I'm in the process of converting the car to 86/87 induction, and I made the decision early on when collecting parts. At the time, I didn't know what would be involved with running the hydroboost coupled to the 86/87 pump. It may have been as easy as cutting and splicing the hydraulic lines together with some heavy duty clamps, but now that I have the parts, I'm going vacuum.

How's your car running with your sorta hybrid setup these days?

My dad retained the hydroboost with his conversion to the stage II/IC setup and it was as easy as adding a hydraulic hose, MUCH easier and cheaper than installing vacuum brakes. Plus I like the feel of the hydroboost much better.

 

[Rob_85Ttype]

Thanks for the tip Cool!

 

[FJM568]

My radiator hose thing really isn't that big of a deal...It still fits, but there is a lot of wiring harness crap right there, along with the alternator support bar to the intake, etc...Just a little crowded there...Most likely, I'll just put it back together like it was...Just doing some thinking...I did have 13000 miles on that setup and other than the boost leakage on my custom upper plenum(now fixed) and wiping the cam lobe, I didn't have any problems with the setup...