Ditching the GT Master cylinder....

[G-Spec]

has anyone completely ditched the existing master cylinder brake servo?

Im thinking of doing this modification in favour of direct braking so i can relocate the master cylinder and installing a balance bar inside the cockpit, that way it clears up some space in the engine bay and i can get rid of the linkage which gets in the way.......

anyone done this? what was the outcome?

[benncojr]

G-Spec,
Take a look at this tread. It is the way to most of the folks upgrade their brakes.

http://www.opelgt.com/forums/showthr...inder+relocate

It may have some ideas that could help you.

[gtjames]

One of my GT's had a brake master cylinder and Vacuum booster off of a Manta. Thanks to Gil's expertise at OGTS we figured that one out. It bolted right in. Now, Im not sure if thats much better, but its food for thought.:27:

[jtb]

Originally Posted by G-Spec has anyone completely ditched the existing master cylinder brake servo?

By the brake servo, do you mean the booster (vacuum unit?) or the master cylinder?
I looked into changing the booster (briefly). Tough to fit anything on the firewall. There is such a thing as a remote booster (check some hot rod sites), but they were beyond my budget!

I use the stock opel booster in its original location with a dodge talon m/c and a proportioning valve for rear disks.

jtb

[jtb]

Wait a minute.... Must learn to read more carefully.
are you talking about losing the booster altogether and running two master cylinders on the firewall like a race car? With the balance bar proportioning between front and rear circuits, right? Hope you have strong legs...

anybody done this on an Opel?

[G-Spec]

Originally Posted by jtb Wait a minute.... Must learn to read more carefully. are you talking about losing the booster altogether and running two master cylinders on the firewall like a race car? With the balance bar proportioning between front and rear circuits, right? Hope you have strong legs... anybody done this on an Opel?

Yes, thats exactly what i mean.....i drove a track car a while back which had this setup and the braking was phenominal. You could feel everything, it makes for better control, no fade at all and of course its fully adjustable for different driving styles (including the drift technique)

[GoinManta]

Originally Posted by jtb By the brake servo, do you mean the booster (vacuum unit?) or the master cylinder? I looked into changing the booster (briefly). Tough to fit anything on the firewall. There is such a thing as a remote booster (check some hot rod sites), but they were beyond my budget! I use the stock opel booster in its original location with a dodge talon m/c and a proportioning valve for rear disks. jtb

The Talon M/C fit? What year?

Charles

[oldopelguy]

Originally Posted by jtb Wait a minute.... Must learn to read more carefully. are you talking about losing the booster altogether and running two master cylinders on the firewall like a race car? With the balance bar proportioning between front and rear circuits, right? Hope you have strong legs... anybody done this on an Opel?

Not on a GT, but I did get that much done to my Kadett wagon this past summer. Choose a smaller MC diameter if you need more pedal, I've got 5/8 for the rear and 3/4 for the front in there now and it seems to be pretty decent. Since the car still has drum brakes in the rear I added a 10lb residual pressure valve to the back, but I didn't add the 2lb-er for the front because I just didn't feel like it. Seems to be fine, though the adjustment is rather to the back to get an even lock-up on my gravel road.

I liked it so much I'm in the process of doing the same thing to my Jag right now. I'm using the pedals from Stock Car Products, as opposed to the Wilwood or Afco ones, because they are a bit longer and have a bit more leverage. That, and they're cheaper and I "get" to do all the welding myself.

[jeff denton]

Yes. I ditched the power booster on Speedway GT. The stock master cylinder was relocated to the inside of the cab, mounted to one of the rollcage legs. The stock pedal , clutch workings, everything was all incorporated into the mounting bracket. The rules said it all had to be stock but didn't say we couldn't relocate it...
And the brakes work fine.

[asdasc]

I would love to hear your opinions on this, but are the stock brakes that bad on a GT? I have driven pretty hard, but never really needed more brake than what it came with. Maybe the difference is in the tires? I run stock rim with P185, so maybe it isn't a big deal for me. With better tires and wheels you might see more of a difference? Curious, that is all.
Thanks,

[jtb]

Originally Posted by GoinManta The Talon M/C fit? What year? Charles

1995 Talon fits if you redrill the mounting holes on the m/c to fit the Opel booster. Uses metric fittings, too.

jtb

[rstrel]

Has anyone tried to swap the brake servo (booster) from other late model Opels into a GT? Looks like it would fit from an Opel Corsa, maybe even late model kadett (Pontiac LeMans)? Maybe even the master cylinder would fit with minimal adaptation?

[FrankDaTank]

Originally Posted by G-Spec has anyone completely ditched the existing master cylinder brake servo?... anyone done this? what was the outcome?

...just a tought
Could you Disconnect the Vacum Lines in the break Booster to get an Idea of how it would feel?
...Not sure if it would be the same as not having the booster vs. not working properly.

[rstrel]

Frank, I did that out of necessity. My booster is leaking...which means when I applied pressure on the brakes...the revs went down so much, sometimes the engine stalled. I plugged the vacuum intake by the manifold and car doesn't stall anymore. You do have to apply much more pressure when you brake though.

[jeff denton]

One time last summer there was a terrific Maalox moment during my race, I just knew I was gonna be in the carnage unfolding before my eyes. My first reaction was to hit the brakes, witnesses in the grandstands say my tires were smoking. This story ends very well, a hole opened up and I hit the gas and shot through without a scratch. But my leg hurt. I had stood so hard on the pedal that I strained a muscle in my calf. But like I said before, the brakes work fine. They locked up, right?
To test this without messing with the brakes, drive the car at sixty MPH (in zero traffic, please) and then shift the trans to Mexican Overdrive (put it in neutral) and shut off the engine. Hit the brakes and bring the car to a stop as soon as possible. Now you know what your brakes feel like without the booster.