Have You Upgraded Your Brake System?

[Killer Texas GT]

Anyway, I have a question, is that Isuzu 7/8" bore master cylinder quite similar in appearance and mounting to the stock GT master cylinder? I wonder if I could get better stopping using it on my car with otherwise stock brakes but no booster. Would it pass as "stock" to somebody who didn't know anything about Opels?
Any thoughts?
[/QUOTE]

No the Impulse master cylinder will not bolt to the stock Opel Brake Booster, to use it both the Impulse Master cylinder and brake booster are needed, also you have to modify the connection between the brake booster and rod connection of the Opel, the line ports (two only not three as the Opel) are on the opposite side of the cylinder of that of the Opel and so is the vacuum intake for the booster, the bolt patern of the Impulse brake booster is approximately 1/4" wider all the way around than the Opel booster. If you would like pictures I can take some and post.
rk

[jeff denton]

Thanks, Killer, sounds like it will bolt up to my bracket by just moving the holes a bit as I use no booster...
But would I get better braking with it than I do with the stock cylinder?
My instinct tells me that a bigger bore puts out less hydraulic pressure than a smaller one, the opposite of how it works at the receiving end.
Or am I mistaken? Any hydraulic experts out there?

[rangerrick]

On my 3.4 GT, it's all stock, but all new or rebuilt. From the new brake pedal rubber to new shoes in the turned drums, front to back. Now if I can just get to the point where I can put it all in.

Surprised Ron that your'e running stock brakes with that V6, even if they are totally rebuilt. Is this going to be enough? & I take it this means stock 13" wheels as well??? Got a parachute or anchor to deploy just in case? Already got a small fortune and many hours of time in the beast, why skimp on brakes?

Regards'
Rick

[nobody]

Jeff, there is an ATE out there that will mount to stock, again opposite side line location. It will haul a car to a dead stop in very short order. I use it with the Kiwi rear discs and 75 front brake setup. More neutral bias and it is easily adjusted. It's a good way to check your seatbelts, mounts or get whatever you lost under the seat back out. For me it just pulls all the mirrors off location. Use the information at your own discretion.

http://www.opelgt.com/forums/showthr...=brake+upgrade

[namba209 (R.I.P.)]

Well, here's a milestone, kinda, 1500 responses to threads.

Rick, the original intention of this V-6/T-5 swap was to keep everything original, or as close to that as possible, initially. Just to see if it is feasible to change only the engine and tranny and see if everything else holds together. Granted, I've got the ZF posi and new poly bushings front and rear. But, aside from the ZF, it's something anyone with a GT would do anyway, hopefully. My thoughts on the brakes were, if I could lock up all 4 before the swap, why would I put in bigger and better brakes to have the wheels lock up even easier than they do now. Everyone knows, or should know, that there is no control with locked brakes and even less braking power than if the wheels were turning and brakes not quite locked up. Now, if the brakes aren't up to the job, that will be a future mod to the car, and rest assured, I will look hard and fast at the mods that "nobody" has already done to his 2.0 rocket ride. Also how and where you're driving is a prime concern on the brake capabilities. For twisty/turnies, stab and go will work just fine, but for sustained speed on highways/freeways, hard long applications without locking the tires is needed. So we'll see how the brakes perform first, then make mods, if they're needed for my driving conditions.

Jeff, A larger bore MC will put out more fluid in the same stroke as the standard bore MC. Basically it means less pedal movement for the brakes to lock up than before at the same foot pressure on the brake pedal. The reason it works this way, is, it's a closed system. The same amount of fluid will actuate the brake cylinders/calipers as before, you just don't have to push down the brake pedal as far to get that amount of fluid to the cylinders/calipers. HTH.

[jeff denton]

Jeff, there is an ATE out there

Uh, what is an ATE?
Whatever it is it sounds like we need it!
I had thought about mounting up TWO stock master cylinders, one for front brakes and one for rear, like in a real race car. I wonder how bad the tech man would freak? "Hey, they are stock, just doubled!"
Front to rear pressure control would be nice... Rules don't allow any methods of adjusting this though.
It would be nice to be able to get only enough brakes to slow the car but not enough to ever lock up a wheel.
In racetrack test session one I tested the brakes once, they slow the car and didn't lock a wheel but it just felt like there wasn't a lot of brake there, know what I mean? I hate that feeling. I wrecked a big truck once after feeling that, took a Mack mixer head on and lived...
An experienced driver in session two had to use the brakes in the corners and said they were not as responsive as he would like.
Seems like it would be worth a try to install the bigger MC, thanks for all the input. To understand why I'm not concerned with "what bolts up to what" you'd have to look at my Article about my brake pedal relocation. At this point I'm trying to learn brake system theory mostly! Thanks guys.

[nobody]

Almost all GTs came with a ATE brand master cylinder. In the link I posted was a how to use and where to find it.

[rangerrick]

The newer systems have what is called a perportioning valve, that's what my 91 Dodge Dakota has in it's anti lock braking system. It's a known fact your front brakes stop you first as they are closest to the master cylinder, so they would be the ones to grab first.

OGTS states that if you go to the 2.2-2.4 size engine you should think on updating your brakes Of course they are in busines to sell us parts, mine are stock new and seem to work fine; although to me they don't feel like power brakes even with a rebuilt power booster! Had a 1970 Karmin Ghia VW no power brakes, disk in front drums in back. Felt the same as this GT!

Rick

[namba209 (R.I.P.)]

Rick, that's not quite correct, in any hydraulic system, pressure is equal anywhere along that system, which means the fluid/pressure is transferred throughout the system at the same time. The reason the front brakes have more stopping power is because of the weight transfer of the vehicle to the front wheels and less off of the rear wheels, which equates to more traction up front than in the rear. That is also the reason for the proportioning valve, to route a higher flow and pressure to the front wheels and less to the rear wheels. Normally this is done inside the MC and is usually a 60-40 split. For the anti-lock braking system (ABS), there is a magnetic pick-up on each wheel, that sends a signal to the computer or electric solenoid valve of the brake system that a wheel is close to lock-up or doesn't match the wheel speed of the other wheels, and the system bypasses a small protion of the brake pressure from that wheel causing it to free wheel for a milli-second until the speed of that wheel matches the other wheels. When the vehicle speed gets down to about 5 MPH, the ABS system is inoperative, normally. HTH.

[GoinManta]

75' Manta Front brakes, Commodore B 3/4" Rear wheel cylinders.

Havent tested it yet though

Charles

[baz]

Jeff, there is an ATE out there

Uh, what is an ATE?
Whatever it is it sounds like we need it!

your brakes!!!
jeff they are a part of "continental teves"
http://www.conti-online.com/generato...v_1103_en.html
this link gets you to there web
but you are looking at the brakes for opel, ford europe,bmw, mercs audi ,saab (i think ) just a case of hunting in the junk yards for 1 they normaly have "ats" in raised letters on the cap
bmw would be best bet in the states i would guess
and reading your earlyer post the bigger the cylinder the more fluid moves the more the pistons move so more brake powerjust harder to push

[gtzero]

I think I probably have the biggest upgrade on a GT. I will be running 12 1/4" cross drilled and slotted 3/4" thick ventilated rotors with four piston caliber. That is at each corner. Also have 7/8" master cylinder with an oversized perfomace booster. The rear have a e- brake built into the rotor like a mini drum, The drum is almost as big as the original drums that came on the car. I will be running complete stainless braided lines as well.

Hi Bear,

What system are those? Are they StopTech, Brembo, Wilwood, other?

Thanks

[Manta72]

1972 Opel Manta A

Opel Ascona B front rotors and calipers
Opel Ascona B rear wheel cylinders
Opel Acsone B master cylinder and servo unit
EBC front brake pads
Aeroquip stainless steel braided brake hoses
Rear proportioning valve

Works really great. The best part is, the money I spent. Hardly nothing, the most expensive items were the new pads and SS hoses.....

[DennisGardiner]

73 GT
Front: 1975 Big Brake Manta with cross drilled rotors, and kevlar pads, using
stainless lines.
Rear: Straus disk brake with a mini hand brake build inside the rotor hat, similar to older Corvettes & 80's Mercedes.

73 Manta
Front: 1977 BMW vented style caliper with Omega ventilated rotors with
kevlar pads, using stainless lines.
Rear: Heavily modified ventilated Isuzu rear disk to fit stock Manta Axle,
also with the intergal hand brake inside the rotor hat.
Dennis73 GT, 73 Manta

PS. You need serious Wooooooo in CA traffic

[David McCollam]

1975 Calipers with Risse Motorsport expansion kit, Rekord C 2.2i-246mm vented discs, stainless steel braided brake lines with 3/4" rear brake cylinders. All items bolt-on, no significant modifications necessary.

[Mike Preble]

I am running the large 262mm vented rotors and 4 piston calipers from a Volvo on the front of my GT. Also I have a 22mm ATE MC. I don't know what the MC is off of as a guy at a brake place just walked out of the back room and gave it to me. He said it was just laying around in the storage area when he bought the brake shop from some other person. The lines come out of the wrong side but all I did was install longer lines. Also SS lines all around which was interesting as the Volvo calipers take two lines per caliper. You must tee off the main line at the wheel well and use two SS lines per side. Complicated bleeding process as there are three bleeding ports per calipers but was accomplished after consulting with a Volvo mechanic. Could use the 3/4 Manta rear slave cylinders but they are on the Manta already and maybe I will upgrade all the cars to the same systems.

Mike

[nobody]

I've been meaning to write this for a while. use 2 of these.
http://www.partsamerica.com/ProductD...pe=232&ptset=A
and 2 of these'
http://www.partsamerica.com/ProductD...pe=232&ptset=A
and swap the pistons after drilling them out to fit the opel parts then drill out the two mounting holes just a bit and you now have 11/16 bore rear cyliders that cost you 20 bucks a side, and about an hour in labor.

Or you can try to order them for more than double the cost. 45 each or 40 for the pair and now the parts are local and cheap and plentiful. I spent more than a couple minutes on the research and design and they work well so have at it.

[maglinjosvinn]

i'd love to see some pictures of the izuzu impulse switched brakes... if anyone has them?

[GoinManta]

See below..

1985 Isuzu Impulse Turbo Vented Rear Disc Brakes

Took Backing Plates to a Machine shop and had the area for the Opel Bearing Retaining plate routed out and the Isuzu holes filled and Opel pattern redrilled into them.

Parts:
Used Caliper MOunting Bracket (?? The part you dont get of the caliper when you buy remanned)
Used Backing Plate
Used Ebrake Hardware
Used Ebrake Cable
$80 (pick a part)

New Set of Calipers (Remanned off eBay) - $90
New Set of rubber lines - $40
New Pads - $35 (off eBay)

Total cost: $245

Now I spent about another $100 or so on paint, and brake lines, etc.. to prep the "new" 3.67 axle for the Manta too.

I also upgraded the front to 1975 Brakes.

Master is a NOS stock one.. although I have thought of trying to find a replacement for the AC/Delco. So far no luck. but I have connections at NAPA and one day I may go hunting in the warehouse.

Charles

[GoinManta]

PS. You need serious Wooooooo in CA traffic

ESPECIALLY the way he drives

been there done that.. and got the skid marks in my drawers to prove it

Charles