manual master cylinder

[blancojp]

Howdy All!
I got a few Pm's and emails on installing a manual master cylinder on the Opel and here are a few pics that show how. The full price on this complete install was $30 and the gains are substantial since you can purchase a replacement master cylinder on every corner. Pedal effort is slightly more than the original however you can install any caliper/drum combination without any increase in pedal travel. On the average installation with a Volvo front setup, pedal moves freely 1/2" and the rest is braking force.

I started by doing a little research and a few trips to the junk yard for design data. After a few days of internet research with the previous data, I found that most older Ford cars and trucks had manual units with the ports on the right side, just like the Opel unit. The Ford manual units had two outlets instead of three and most of them were tied to a distribution valve or proportional block. I chose to not use the Ford proportional block and used a brakequip BQ91 "tee" ($5.00) for the front brakes. The Ford 1" master cylinder cost $11.65 with a whopping $1.00 core charge. The other adapters needed can be derived from an old front brake hose and brazed onto the master cylinder supplied port connectors.

You can derive the rest from the pictures however if there is additional info required, just let me know.

[73Manta72gt]

what year/model Ford was the cylinder you used from?

[blancojp]

you can use any 1981 to 1986 master cylinder from any Ford products that have the ports on the right side. Mine is from a 1983 Ford F-150 truck which is 1 1/8" piston size but any 7/8" or 1" will work extremly well.

[baz]

it looks like the one i had on my 73 mustang

1 question though if you go to the trouble to reinforce the fire wall why not route the pipes to there and mount the M/C there ? it would take the long bar and cage out of the system and reduce the flex they can cause when you have no servo to reduce the pressure you have to put on them , its how i always did it and it sure makes for easy fitting ,the pipes are where you can get at them and adding fluid is much easyer

[blancojp]

been there and done that however, it is not a simple replacement to go that route specially if you have a manual transmision.

I don't understand the part about flexing, with the tower connecting both walls together no flex should be experienced. And in the six years I have been driving the car, this is the best master cylinder I ever had.

[blancojp]

OK, after a few PM's lets clear a few things:
1) The plate in the pictures is an interface plate so I can bolt the new master in the booster location without drilling any holes.
2) The rod is 7" in length total including the screw in portion. The end of the rod was made by inserting the Opel lock nut into a 3" emt 3/4" tube. I welded two nuts, one at each end, and the rod was welded to one of the nuts.
3) The "tee" is a 10x1.0mm unit made by brakequip. I reused the connector and the banjo from the old master cylinder for the front brake circuit. The rear circuit I made from the supplied m/c connector and an old brake hose by cutting and brazing them together.

I hope this clears up a few questions.

[deaner]

Howdy All!
I got a few Pm's and emails on installing a manual master cylinder on the Opel and here are a few pics that show how. The full price on this complete install was $30 and the gains are substantial since you can purchase a replacement master cylinder on every corner. Pedal effort is slightly more than the original however you can install any caliper/drum combination without any increase in pedal travel. On the average installation with a Volvo front setup, pedal moves freely 1/2" and the rest is braking force.

I started by doing a little research and a few trips to the junk yard for design data. After a few days of internet research with the previous data, I found that most older Ford cars and trucks had manual units with the ports on the right side, just like the Opel unit. The Ford manual units had two outlets instead of three and most of them were tied to a distribution valve or proportional block. I chose to not use the Ford proportional block and used a brakequip BQ91 "tee" ($5.00) for the front brakes. The Ford 1" master cylinder cost $11.65 with a whopping $1.00 core charge. The other adapters needed can be derived from an old front brake hose and brazed onto the master cylinder supplied port connectors.

You can derive the rest from the pictures however if there is additional info required, just let me know.

I have to say. I really like your work. And can see you put a lot of effort into what you did. But, I can't see were anything that is less Braking, can be considered a " substantial gain. Less Braking is never good. I've always wanted more Braking.
However, it is a substantial savings on the pocket book. Just my 2 cents.

[baz]

been there and done that however, it is not a simple replacement to go that route specially if you have a manual transmision.

I don't understand the part about flexing, with the tower connecting both walls together no flex should be experienced. And in the six years I have been driving the car, this is the best master cylinder I ever had.

the flexing can be seen on the rad cross member when you have a nonservo system and get some one to give it a simulated emergancy stop , you get fluid lock once the brakes have all locked up solid and the wall of the cross member is the next flexable thing
i have always built up the firewall as you have with the plate (but welded in) and bolted to there as it less to flex so a better pedal when in heavy use (tarmac rally stages with slicks [dont know how you would call it in the states as we rally on the pavment and on gravel roads])

I have to say. I really like your work. And can see you put a lot of effort into what you did. But, I can't see were anything that is less Braking, can be considered a " substantial gain. Less Braking is never good. I've always wanted more Braking.
However, it is a substantial savings on the pocket book. Just my 2 cents.

dean you have the same brakes if you have the servo conected or not , its just the effort to work them changes [much more effort without a servo] , so to reduce the effort you use a bigget bore M/C this moves more fluid for a given push on the pedal
it is used in race and rally cars like this so you get much better feel of what the brakes are doing and means you can run 2 M/C's to make adjustable brake balance
i think bob said a while ago that he runs his cars without a servo as it feels better and he can stand the upped pushing he has to do to have the better feel

[blancojp]

Baz remember that my car has a V-6, not a 4 cyl and all that section has been reinforced. But I have come to like my manual brakes alot since I use close to the same setup on our '23T chassis. Now if people like to have the brake booster in place, that is no problem either. I had installed in this vehicle 9 different bolt on type master cylinder/booster combinations and still like the manual units better.

But just because you eliminated a component does not mean you are getting less. Just get a racing engine at WOT and see how much vacuum you have for your booster.

[namba209 (R.I.P.)]

Just get a racing engine at WOT and see how much vacuum you have for your booster.

That's the reason there is a one-way check valve in the booster hose. With the engine not running there should be about 3 full vacuum boosted applications before the brake booster quits working from loss of vacuum. Of course it is presumed that when you need brakes, you're off the throttle and the vacuum will be applied to the booster to replenish it.

[RallyBob]

dean you have the same brakes if you have the servo conected or not , its just the effort to work them changes [much more effort without a servo] , so to reduce the effort you use a bigget bore M/C this moves more fluid for a given push on the pedal
it is used in race and rally cars like this so you get much better feel of what the brakes are doing and means you can run 2 M/C's to make adjustable brake balance
i think bob said a while ago that he runs his cars without a servo as it feels better and he can stand the upped pushing he has to do to have the better feel

Other way around Baz! With a larger bore M/C, the effort goes up appreciably, since you are moving more fluid with a given pedal travel. Remove the booster and it goes up exponentially!

For race/rally use with twin non-assisted master cylinders, I use 3/4" bore M/C's (smaller than the standard 22mm/.866" bore). Effort is still higher than standard, though it's liveable. If you increase the bore at the calipers and/or wheel cylinders, then the effort becomes easier, and the travel of the pedal is greater. It's a juggling act, you need to make sure you don't have so much pedal travel as to 'bottom' the M/C's out. So for the 'Turd' rallycar, I increased the front M/C to 7/8" to deal with the larger 1.75" 4-pot Wilwood calipers I'm using. They have a whopping 70% more caliper piston area than the 1975 Opel 2-pot calipers I was using!

I've used a 1.0625" bore master cylinder (unassisted) in an Ascona racecar before, and with standard Opel ATE front calipers and 19 mm rear wheel cylinders, the pedal effort was extremely high, especially when cold (racing brake pads). I ended up relocating the brake pedal pivot point 3/4", and that reduced the effort appreciably but increased the pedal travel. But it was easier to modulate, and the leg muscles sure appreciated it. Before the pedal ratio change, the total pedal travel was about 5/8" before the tires locked up.

Bob

[RallyBob]

That's the reason there is a one-way check valve in the booster hose. With the engine not running there should be about 3 full vacuum boosted applications before the brake booster quits working from loss of vacuum. Of course it is presumed that when you need brakes, you're off the throttle and the vacuum will be applied to the booster to replenish it.

Assuming you have vacuum to begin with! I've had engines with racing cams only pull 7-8 inches of vacuum at idle, compared to a stock engine making 21-23 inches. Good for maybe 1/2 pedal travel before you deplete the booster, and nearly stall the engine. When run at WOT, there's NO vacuum at all, so the booster becomes a paperweight very quickly! At that point it's just extra weight under the hood, so it needs to be removed.

[namba209 (R.I.P.)]

Good point Bob. I was looking at going from WOT to off the throttle completly, then with the throttle plates closed there is an instant increase in vacuum that "should" replenish the booster before the valve overlap comes into effect. But without a gage to check it out, IDK. Way back when, I've seen vacuum gages peg out when coming completly off the throttle, then stabilize at a lower setting. I was going on that presumption. Could be I'm wrong in my thinking on a flat out racing engine.

[N61WP]

A few of you know what I've been through in the last year with this. I have installed a 1" Wilwood aluminum M/C with an aftermarket booster in the stock location. I couldn't see putting a 12lb lump of cast iron in front of the front axle line. The Wilwood cost me $100, but weights about 2lbs. The 1" bore is a little too large for decent pedal feel, but that's the only size this dual circuit M/C comes in. I only have about 6psi of vacuum at idle....they claim you need 18psi (at idle) to operate a booster correctly. I added a vacuum canaster and a electric vacuum pump from a Volvo cruise control. The pedal effort is still higher then I like with the Porterfield pads, so I have since moved the brake rod pivot point up by 1/2" and lenghtened the brake pedal by 1". The stock pedal ratio is 5:1, I now have almost 6:1.
I have a track day next month, I'll let everyone know how it works then.
Jc

[RallyBob]

I have installed a 1" Wilwood aluminum M/C with an aftermarket booster in the stock location.

Just an FYI, if you end up still having too high a pedal pressure, there are alternatives. The Wilwood dual circuit M/C is basically a Kelsey-Hayes unit. I did some research some years ago and purchased a mid-'80's Chrysler (I think it was Omni?) master cylinder, since it is a Kelsey-Hayes unit (identical bolt pattern to the Wilwood, and also made of lightweight aluminum), but it's only 7/8" bore. Doesn't sound like much, but going from 1.062" down to .875" was about a 33% reduction in piston area!

Bob

[N61WP]

Thanks Bob, I'll look into that. I would really like to leave the M/C in the front, but remove the booster all together. That difference in diameter might be all I need.

Jc

[baz]

oops my bad bob but theres been more tins of beer caught than fish this last week and a bit and im still a bit fuzzy

[RallyBob]

and im still a bit fuzzy

I hear ya mate...I'm a bit fuzzy too, unfortunately every year it's less and less on the top of my head and more on my back

[oldopelguy]

5,6,and 7 series BMW's almost all use hydro-boost master cylinders. No vacuum needed, just a power steering pump. Toyota MR2's, Opel Vectra's, and some Saabs use electric power steering pumps. Food for thought?

[GTJIM]

Some Diesels use a vacuum pump on the back of the alternator and early British cars had a piggy-back vacuum pump under the mechanical fuel pump .... to operate the vacuum windshield wipers!