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I'm about to install a new Big Brake Booster/MC on my 73 GT, is there a step by step install sheet anywhere? I have the Green/Yellow Workshop Manual but it really isn't helpful for the booster.
- Jay
 

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I'm about to install a new Big Brake Booster/MC on my 73 GT, is there a step by step install sheet anywhere? I have the Green/Yellow Workshop Manual but it really isn't helpful for the booster.
- Jay
Am in the middle of this Job on a 72 GT
Step by step Ok I'll try.. maybe baby steps lol
Make sure you can raise the Hood fully for clearance of new Booster unit

1. drain old MC ( you choose best way)
2. Protect Belly pan from dripping Brake fluid ( stuff with towels,etc)
3. disconnect hard brake pipes from Banjo fittings 3 lines
4. remove plastic reservoir
5. Remove the two bolts holding MC and remove MC
6. loosen Brake Rod Nut 19 mm and disconnect
7. remove the four nuts holding booster and remove old ""Power Booster Unit""
8. Reverse Install LARGE Booster unit w/ four nut lock washers
9. install brake rod and jam nut ( adjustment later)
10. Install new MC two nuts/washer / Install Hard Pipe brake line with banjo fittings
Then all you'll need to do is find which way your going to bench bleed the MC..
Before you install it... is best... or after ( Dry) Bench bleed installed on car. ( Is much Harder way) Then a complete bleeding of the System necessary ..hope you have good bleeder screws lol
Hope that helps.. Good Luck I have a Thread posting on another community site FWIW
 

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Am in the middle of this Job on a 72 GT
Step by step Ok I'll try.. maybe baby steps lol
Make sure you can raise the Hood fully for clearance of new Booster unit

1. drain old MC ( you choose best way)
2. Protect Belly pan from dripping Brake fluid ( stuff with towels,etc)
3. disconnect hard brake pipes from Banjo fittings 3 lines
4. remove plastic reservoir
5. Remove the two bolts holding MC and remove MC
6. loosen Brake Rod Nut 19 mm and disconnect
7. remove the four nuts holding booster and remove old ""Power Booster Unit""
8. Reverse Install LARGE Booster unit w/ four nut lock washers
9. install brake rod and jam nut ( adjustment later)
10. Install new MC two nuts/washer / Install Hard Pipe brake line with banjo fittings
Then all you'll need to do is find which way your going to bench bleed the MC..
Before you install it... is best... or after ( Dry) Bench bleed installed on car. ( Is much Harder way) Then a complete bleeding of the System necessary ..hope you have good bleeder screws lol
Hope that helps.. Good Luck I have a Thread posting on another community site FWIW
Has anyone tried installing the MC onto the booster and installing as a unit? At first I thought, "No way", because the unit would need to go forward for the booster's studs to go into the radiator support holes and it is tight for space there. After thinking about it, if the booster is in, the MC needs to go forward to go over the 2 studs coming out of the front of the booster, so it kind of equals things out. Thoughts?
 

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Yes, The Booster and MC cylinder can be Installed together,,, Yea,,, trick,, Have someone hold the hood as fully open as you can,,, Clear the Hood hinges that are blocking when hood under the prop...so you can fig naggle the unit into place for mounting.. It worked in my situation ... give it a try..

Good luck bleeding that sucker too :ugh:
 

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Just Some Dude in Jersey
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Basically you jiggle it all on like an accordion with the booster and mc just fitted together loose over the bolts. Yeah, it's a chore and it would be advantageous to remove the hood. Yes, that sucks, too. You would be wise to drill one 1/8" hole in each hood hinge bracket and into the hood to mark their positions to each other. After you conquer the booster, get some assistance and fit the hood to the hinges with the bolts loose, then run screws or slip an 1/8" drill bit into each hole and tighten the hinge bolts. Readjust as necessary. I installed the big booster/mc combo and they're bigger, but I managed to do it in a half hour or so by laying on the car from the passenger side.
 

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Just Some Dude in Jersey
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I found the bleeding to be really easy. I took a tall plastic cup from the cupboard that was taller than the mc, put the mc in it, filled the cup almost to the top with fluid totally immersing the mc, and then pumped the plunger until no more bubbles came out. I then used a Power Bleeder when everything was all hooked up.
 

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I found the bleeding to be really easy. I took a tall plastic cup from the cupboard that was taller than the mc, put the mc in it, filled the cup almost to the top with fluid totally immersing the mc, and then pumped the plunger until no more bubbles came out. I then used a Power Bleeder when everything was all hooked up.
That's a Good Idea... never thought of that ..Then you clean the outside of the master cylinder,, before all that extra brake fluid eats the paint up too. Kinda do the same

I bench bleed in vise ,, and then plug the ports a install ... I have bench bleed while on the GT with short plastic hoses

See this link... Good Photo's of my project https://classicopels.com/index.php?thread/7121-overhauling-a-opel-gt-rear-diff-unit/&pageNo=3
 

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Good luck bleeding that sucker too :ugh:
I found the bleeding to be really easy. I took a tall plastic cup from the cupboard that was taller than the mc, put the mc in it, filled the cup almost to the top with fluid totally immersing the mc, and then pumped the plunger until no more bubbles came out. I then used a Power Bleeder when everything was all hooked up.
That's a Good Idea... never thought of that ..Then you clean the outside of the master cylinder,, before all that extra brake fluid eats the paint up too. Kinda do the same

I bench bleed in vise ,, and then plug the ports a install ... I have bench bleed while on the GT with short plastic hoses [/url]
I contemplated bench-bleeding my new OGTS 22 mm master cylinder (and matched 9" booster, which I was able to install in one piece), but dreaded the resulting mess of brake fluid on all my fancy new paint. No matter HOW careful one is, that damn brake fluid gets everywhere.

So I read up about pressure bleeding, found some info on DIY pressure bleeders, and this is what I built. It is a stock MC cap, drilled out with a nipple that is sealed in place with rubber gaskets and the cavity filled with Goop (a very effective urethane). The "pressure" and brake fluid supply comes from a common garden sprayer, connected with hose. I looked at larger garden sprayers, but the small one I had was 1 1/2 litres (same as a US quart) and even half full, it very effectively filled and flushed the brake system.

I filled the reservoir to the top with fluid, connected the pressure bleeder, and pumped it up to about 10 psi. I opened up the furthest bleeder (PS rear), got fluid in a dozen seconds. Repeated for the other bleeders. The best part is that the pressure reservoir continually fills the master cylinder reservoir as it is bled; so as long as the bleeder has fluid, so does the master cylinder reservoir.

I then conventionally bled the brakes with my check valve bleeder hose, starting at the nearest bleeder (DS front, as per the FSM) and worked my way out. Pedal is nice and hard. I'll probably do one last flush and bleed when I put the car on the road in the spring.

I haven't yet installed a gauge on the sprayer body, but I tested the output with a gauge and 30 pumps, half full, gave a bit over 10 psi. The recommended procedure is to use between 10 and 15 psi.

HTH
 

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I contemplated bench-bleeding my new OGTS 22 mm master cylinder (and matched 9" booster, which I was able to install in one piece), but dreaded the resulting mess of brake fluid on all my fancy new paint. No matter HOW careful one is, that damn brake fluid gets everywhere.

So I read up about pressure bleeding, found some info on DIY pressure bleeders, and this is what I built. It is a stock MC cap, drilled out with a nipple that is sealed in place with rubber gaskets and the cavity filled with Goop (a very effective urethane). The "pressure" comes from a common garden sprayer, connected with hose. I looked at larger garden sprayers, but the small one I had was 1 1/2 litres (same as a US quart) and even half full, it very effectively filled and flushed the brake system.

I filled the reservoir to the top with fluid, connected the pressure bleeder, and pumped it up to about 10 psi. I opened up the furthest bleeder (PS rear), got fluid in a dozen seconds. Repeated for the other bleeders. The best part is that the pressure reservoir continually fills the master cylinder reservoir as it is bled, so as long as the bleeder has fluid, so does the master cylinder reservoir.

I then conventionally bled the brakes with my check valve bleeder hose, starting at the nearest bleeder (DS front, as per the FSM) and worked my way out. Pedal is nice and hard. I'll probably do one last flush and bleed when I put the car on the road in the spring.

I haven't yet installed a gauge on the sprayer body, but I tested the output with a gauge and 30 pumps, half full, gave a bit over 10 psi. The recommended procedure is to use between 10 and 15 psi.

HTH
Good Idea Keith,, I like that Garden Sprayer idea,, What did you do to make the nozzle adapter.. that the thing ..How you do that?..... and I see a funky new black MC Cap with two wires hooked up ( what's up with that??))
 

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Good Idea Keith,, I like that Garden Sprayer idea,, What did you do to make the nozzle adapter.. that the thing ..How you do that?..... and I see a funky new black MC Cap with two wires hooked up ( what's up with that??))
Yeah Keith, that is pretty slick. A great idea with the Sprayer. The one cap was just drilled out to accommodate the brass nozzle? Question. What type of brake fluid are you using? When I rebuilt my Gt I used some high boiling point Brake Fluid. (I'd have to get my notes to see what it was).Thanks, Jarrell
 

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What did you do to make the nozzle adapter.. that the thing. How you do that?..... and I see a funky new black MC Cap with two wires hooked up ( what's up with that??))
I didn't modify the sprayer at all, at least initially. Initially, as in earlier today, when I built the pressure bleeder and bled the brakes. I simply pressed the tubing over the nozzle tip and clamped it with a hose clamp. The photo shows one change I made (earlier tonight) which was to drill and tap the handle so that the thumb screw shown can lock the lever down. Much easier to use as a one-person procedure then.

As for the MC cap, I found that cap a few years ago at the local PicknPull from a late '80's BMW (a 5 series IIRC). It is an ATE cap, but with a float that closes a set of contacts when the fluid level drops. I wired it in to the brake circuit warning lamp, so the red light will come on if the brake fluid gets low. Since the new OGTS "Big" master cylinder doesn't have the stock Opel MC malfunction switch, I am glad to have something to let me know that something is amiss with the brakes before I find out the hard way.

I was down at PicknPull a couple of days ago to pick up a new space-saver spare ('92 VW Passat was the ticket; 4x100 PCD, ET40, 57 mm hub hole, and a 15" wheel to clear my Big Brakes) and found that early '90's Golf's have a similar but fancier cap with a better wiring harness connection. It fit the Manta/Ascona reservoir I brought for testing perfectly, but the float tube is a bit too deep for the GT reservoir. I think the bottom of the float tube could be ground down to fit a GT reservoir, but I don't need it at present.

The one cap was just drilled out to accommodate the brass nozzle? Question. What type of brake fluid are you using? When I rebuilt my Gt I used some high boiling point Brake Fluid. (I'd have to get my notes to see what it was).Thanks, Jarrell
Yep, I simply drilled and reamed the metal cap and inner plastic part to allow a 1/4" male NPT barbed nipple to poke through, with another 1/4" female nipple screwed on from underneath to hold the top nipple in place, and to ensure the supplied brake fluid goes down into the MC reservoir. That is optional. The OEM cap has a rubber "hat" inside it, which I left intact, and the small hole in the top of the "hat" is stretched over the barbed nipple threads. I added the Goop between the inner plastic and the rubber "hat" just to ensure that it sealed fully, as it has to withstand 15 psi, and I fabricated a rubber sealing ring as the cap I had was missing it.

I am using DOT 3 fluid, but higher temp stuff. DOT 4 is pretty similar, and both are glycol-ether based. After reading about the advantages and disadvantages of DOT 5 (silicon-based) fluid, I decided to stick with DOT3/4 glycol-ether and just flush it every few years. While DOT 5 has less inclination to absorb water, it is more inclined to allow what water might enter the system to gather and corrode on the low points.

HTH
 

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I didn't modify the sprayer at all, at least initially. Initially, as in earlier today, when I built the pressure bleeder and bled the brakes. I simply pressed the tubing over the nozzle tip and clamped it with a hose clamp. The photo shows one change I made (earlier tonight) which was to drill and tap the handle so that the thumb screw shown can lock the lever down. Much easier to use as a one-person procedure then.

As for the MC cap, I found that cap a few years ago at the local PicknPull from a late '80's BMW (a 5 series IIRC). It is an ATE cap, but with a float that closes a set of contacts when the fluid level drops. I wired it in to the brake circuit warning lamp, so the red light will come on if the brake fluid gets low. Since the new OGTS "Big" master cylinder doesn't have the stock Opel MC malfunction switch, I am glad to have something to let me know that something is amiss with the brakes before I find out the hard way.

I was down at PicknPull a couple of days ago to pick up a new space-saver spare ('92 VW Passat was the ticket; 4x100 PCD, ET40, 57 mm hub hole, and a 15" wheel to clear my Big Brakes) and found that early '90's Golf's have a similar but fancier cap with a better wiring harness connection. It fit the Manta/Ascona reservoir I brought for testing perfectly, but the float tube is a bit too deep for the GT reservoir. I think the bottom of the float tube could be ground down to fit a GT reservoir, but I don't need it at present.



Yep, I simply drilled and reamed the metal cap and inner plastic part to allow a 1/4" male NPT barbed nipple to poke through, with another 1/4" female nipple screwed on from underneath to hold the top nipple in place, and to ensure the supplied brake fluid goes down into the MC reservoir. That is optional. The OEM cap has a rubber "hat" inside it, which I left intact, and the small hole in the top of the "hat" is stretched over the barbed nipple threads. I added the Goop between the inner plastic and the rubber "hat" just to ensure that it sealed fully, as it has to withstand 15 psi, and I fabricated a rubber sealing ring as the cap I had was missing it.

I am using DOT 3 fluid, but higher temp stuff. DOT 4 is pretty similar, and both are glycol-ether based. After reading about the advantages and disadvantages of DOT 5 (silicon-based) fluid, I decided to stick with DOT3/4 glycol-ether and just flush it every few years. While DOT 5 has less inclination to absorb water, it is more inclined to allow what water might enter the system to gather and corrode on the low points.

HTH
PURE GENIUS,
you sir rock :shocked::You_Rock_
 

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Yes, The Booster and MC cylinder can be Installed together,,, Yea,,, trick,, Have someone hold the hood as fully open as you can,,, Clear the Hood hinges that are blocking when hood under the prop...so you can fig naggle the unit into place for mounting.. It worked in my situation ... give it a try..

Good luck bleeding that sucker too :ugh:

I used the lower washer hose hole in the hood to hold it up

Bleed mc downward into a Tupperware large enough to hold it after, I felt good about the bleed I left it downward in Tupperware to allow any air that might have still been trapped to rise out while we were prepping for everything else.

yea a little grueling for sure I was fortunate to have my youngest son help me smaller hands and arms stretch a long way :yup:

We finished the brake system I think around 1:30 A.M
 

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I'm about to install a new Big Brake Booster/MC on my 73 GT, is there a step by step install sheet anywhere? I have the Green/Yellow Workshop Manual but it really isn't helpful for the booster.
- Jay
Don't know if this helps I got my upgrade from OGTS and it came with tech sheets can post them if needed.:yup:
 
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