Front Brake upgrade

Tru-Craft · 11-30-2005

OK, I have read lots of posts and looked at different sites!
Lots of members have upgraded there front brakes, so you guys know what works! What is the simplest bolt on and go method? and the cheapest way to improve the front brakes on a street GT?

I want to keep the stock master cylinder!
I have 14 x 6 BMW wheels.
Are the 75 Manta disks vented?
Should I just cross drill stock GT disks?
Use 74-75 Manta calipers?
Places to find the parts?
Your input would be appreciated!
Thanks Lyle

markandson · 11-30-2005

No, the 75 big brakes are not vented or cross drilled, but I would say they are the easiest and least expensive upgrade. Take a look a what FrankDaTank did which are available from precisionbrakes.com for about $1200, which is a 4 piston bolt on set.

Tru-Craft · 11-30-2005

Jeff, The Tire-rack sells Brembo disks for a GT for $25/pc. I was going to slot & cross drill them on the CNC.
Will the larger Manta calipers work with this disk?
or should I use the Wilwood calipers?
Lyle

hrcollinsjr · 11-30-2005

If you use the earlier discs with the '75 calipers then a small portion of the pad won't be on the disc negating any advantage the larger pads of the late model calipers might have had.

Harold

Tru-Craft · 12-01-2005

Harold, thanks for the info. So the disks are larger in diameter, how about width?
I cant find Manta Brembo disks! If I do will they fit on my GT?
Any suppliers you know of ?

Has anyone just slotted & cross drilled the stock GT disk? And used ceramic pads? Simple and cheap!
Lyle

GT Tim · 12-01-2005

I have the Brembo's with BMW calipers.I don't need bigger M/C.Fit fine with 14.I got the last set of Brembo's in the states they should have more soon.They fit just fine you use the gt hubs.

Tru-Craft · 12-01-2005

Originally Posted by GT Tim

I have the Brembo's with BMW calipers.I don't need bigger M/C.Fit fine with 14.I got the last set of Brembo's in the states they should have more soon.They fit just fine you use the gt hubs.

Tim, who used to have the Brembo's?
What year BMW calipers did you use?
Lyle

nobody · 12-01-2005

Lyle the mid 80s BMW 318I calipers fit just fine. You can get them for around 50 a pair used. I got the direct # for Brembo through autobarn and they hooked up a Texas distributor that had 2. part # is 25052 and they sell for about 32 each including shipping. Tim's set had a built in switch for pad wear that I thought was cool. Ya I did the parts setup for Tim.

kwilford · 12-01-2005

Lots of good info on this Forum, but have a read at

http://www.opelgt.com/forums/performance-suspension-braking-upgrades/1094-bmw-77-320i-front-disk-brakes.html
especially post #7

and

http://www.opelgt.com/forums/performance-suspension-braking-upgrades/6623-increasing-brake-size.html
in post #4

HTH

nobody · 12-01-2005

I'm still waiting to hear about the rear ones from that set, Now that was a major design.

hrcollinsjr · 12-01-2005

If anyone is planning on using the '75 calipers on the GT the bleeder screws wind up on the bottom and a different fitting is required for those calipers. I believe it is called a ISO bubble type fitting.

I put my calipers on so that the bleeder screws were on the top like they are supposed to be but had to make a really short metal brake line.

HTH,
Harold

bq97 · 12-01-2005

Harold,

I think your thinking of the BMW brake calibers; they have the bleed screw on the bottom if put on the correct side but there is no problem if you switch them left for right. I have the '75 Manta lager brakes on my GT and the calibers are on the correct sides, per the markings on the caliber, and the bleed screw is on the top. Both the 75 Manta calibers and the BMW calibers need an inlet adapter or a specially made flexible brake hose. The adapters are available from OGTS and from Earls Fittings.

hth
Brian

Tru-Craft · 12-01-2005

Thanks for the help, this site as usual has so much info! Sometimes, its confusing to put all of it together!
Since Im not racing, and live in flat country, brake fade will not be an issue.
Here is the plan:
*Brembo 75 Manta solid disks, if I can find them! I will cross drill them myself.
*BMW 318I calipers (1985)
*Stainless brake lines
Any part #s for the calipers? Napa?Auto zone?
Are the bleeders on the top?
Lyle

Tru-Craft · 12-01-2005

Originally Posted by bq97

Harold,

I think your thinking of the BMW brake calibers; they have the bleed screw on the bottom if put on the correct side but there is no problem if you switch them left for right. I have the '75 Manta lager brakes on my GT and the calibers are on the correct sides, per the markings on the caliber, and the bleed screw is on the top. Both the 75 Manta calibers and the BMW calibers need an inlet adapter or a specially made flexible brake hose. The adapters are available from OGTS and from Earls Fittings.

hth
Brian

So the (75 Opel) or (BMW) one's will work! Great!
Will start to look for parts!
Lyle

RallyBob · 12-01-2005

Originally Posted by Tru-Craft

Since Im not racing, and live in flat country, brake fade will not be an issue.
Here is the plan:
*Brembo 75 Manta solid disks, if I can find them! I will cross drill them myself.

Brake fade may be an issue after cross-drilling. Removing material (mass) from an iron rotor will make them more prone to fading. It will improve initial pad response (bite), but will ultimately overheat far quicker. Just an FYI.

Bob

David McCollam · 12-01-2005

Why not use the vented BMW 320i rotor with the 320i caliper, or the Risse Motorsport caliper expansion kit and the stock '75 calipers that bolt right on?

That's what I have on the front of a Manta.

Tru-Craft · 12-01-2005

Originally Posted by David McCollam

Why not use the vented BMW 320i rotor with the 320i caliper, or the Risse Motorsport caliper expansion kit and the stock '75 calipers that bolt right on?
That's what I have on the front of a Manta.

Read that on the GT you need spacers, longer studs, increases track width, wheel clearance problems..........
I just want a simple/cheap bolt on improvement.

Bob, I will take your advice and keep the disks un-drilled. Less work is good!
Lyle

markandson · 12-01-2005

Lyle,
I don't know how much $ you want to spend but it sounded to me like the precision brakes thing I mentioned at the top of this thread was specifically designed for the GT and bolts up the way you want it to.

petrieopel · 12-01-2005

The Precision Brakes upgrade kit is very nice but needs 15 inch wheels or larger and also has a different wheel offset.
Trent

hrcollinsjr · 12-01-2005

I have or had two sets of calipers off of '75 Manta's. IIRC the GT calipers had the inlet hose at the bottom of the caliper and the Manta's bleeder screws and inlet were at the top. I'll have to go check now.

Harold

GTJIM · 12-02-2005

Originally Posted by Tru-Craft

I will cross drill them myself.
*Lyle

Cross drilling and grooving are FADS! RiceBoy Fads to make the stuff they buy more expensive....
There may be some slight use for drilling holes in brake discs on heavy, short term use on race tracks but on the street drilled discs crack between the holes; the holes fill with mud and rust which just means that the softer street pads get ground away faster.
Drilling the discs yourself is not quite as simple as it seems at first glance. What hole size? How are they to be spaced? How are they to be champhered to reduce stress raisers and the impact of the hole edge on the pad? etc. etc.
Even professionally drilled rotors can fall apart under heavy use with a stuck caliper puck which puts huge side thrusts on the disc. This is all more likely to "go sour" on the street under extended usage. Good Luck!

GT Tim · 12-02-2005

The set up I got from Dave is almost a plug and play.At least as far as everything else I have heard of doing.This setup is pretty easy install besides I was replacing all my susp any how.Hope this helps you Lyle.

Tru-Craft · 12-02-2005

OK, no drilling or slotting! Too much work anyway!
What about the ceramic pads? Another racing product, not needed on the street?
Do I really need to upgrade my street GT's brakes at all?????
Lyle

yellaopelgt · 12-02-2005

my brakes on the gt just plain out SUCK!!!!! I hear alot of good things about the green stuff pads and I will be giving them a fair chance this coming spring....
Joe

nobody · 12-02-2005

Opel in thier infinate wisdom did a brake bias of 65/35 on the GT. This means the fronts do almost all the actual braking. With a very lite car and tendency for the rear not to hook up all that well just spells disaster. Granted my brakes are nowhere near stock now but at least it stops flat. Better pads are a good idea but more braking force all the way around sure makes a difference. I run a 50/50 bias and the change is night and day compared to stock. You have to look at the whole picture when you start modifying the stock brakes.

11-30-2005	#1 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	Unanswered: Front Brake upgrade OK, I have read lots of posts and looked at different sites! Lots of members have upgraded there front brakes, so you guys know what works! What is the simplest bolt on and go method? and the cheapest way to improve the front brakes on a street GT? I want to keep the stock master cylinder! I have 14 x 6 BMW wheels. Are the 75 Manta disks vented? Should I just cross drill stock GT disks? Use 74-75 Manta calipers? Places to find the parts? Your input would be appreciated! Thanks Lyle

12-01-2005	#9 (permalink)
kwilford Über OpelGT.com Moderator Join Date: Mar 2002 Location: Calgary, Alberta, Canada Posts: 4,087 Real Name: Keith Wilford Provided Answers: 4	Lots of good info on this Forum, but have a read at http://www.opelgt.com/forums/performance-suspension-braking-upgrades/1094-bmw-77-320i-front-disk-brakes.html especially post #7 and http://www.opelgt.com/forums/performance-suspension-braking-upgrades/6623-increasing-brake-size.html in post #4 HTH __________________ Keith Wilford working on my '71 GT and '75 SportWagon

12-01-2005	#16 (permalink)
David McCollam Member Join Date: Jan 2004 Location: Texas Posts: 589	Vented rotors Why not use the vented BMW 320i rotor with the 320i caliper, or the Risse Motorsport caliper expansion kit and the stock '75 calipers that bolt right on? That's what I have on the front of a Manta.

12-01-2005	#19 (permalink)
petrieopel Member Join Date: Aug 2003 Location: Bonney Lake, WA Posts: 255	The Precision Brakes upgrade kit is very nice but needs 15 inch wheels or larger and also has a different wheel offset. Trent __________________ Trent www.OpelGTMotorsport.net

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11-30-2005	#3 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	Jeff, The Tire-rack sells Brembo disks for a GT for $25/pc. I was going to slot & cross drill them on the CNC. Will the larger Manta calipers work with this disk? or should I use the Wilwood calipers? Lyle

11-30-2005	#4 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,269 Real Name: Harold Collins Provided Answers: 14	If you use the earlier discs with the '75 calipers then a small portion of the pad won't be on the disc negating any advantage the larger pads of the late model calipers might have had. Harold

12-01-2005	#5 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	Harold, thanks for the info. So the disks are larger in diameter, how about width? I cant find Manta Brembo disks! If I do will they fit on my GT? Any suppliers you know of ? Has anyone just slotted & cross drilled the stock GT disk? And used ceramic pads? Simple and cheap! Lyle

12-01-2005	#6 (permalink)
GT Tim Member Join Date: May 2005 Location: Utah Posts: 479	I have the Brembo's with BMW calipers.I don't need bigger M/C.Fit fine with 14.I got the last set of Brembo's in the states they should have more soon.They fit just fine you use the gt hubs.

12-01-2005	#8 (permalink)
nobody No Access Join Date: Nov 2003 Location: in transit Posts: 3,873 Provided Answers: 1	Lyle the mid 80s BMW 318I calipers fit just fine. You can get them for around 50 a pair used. I got the direct # for Brembo through autobarn and they hooked up a Texas distributor that had 2. part # is 25052 and they sell for about 32 each including shipping. Tim's set had a built in switch for pad wear that I thought was cool. Ya I did the parts setup for Tim.

12-01-2005	#10 (permalink)
nobody No Access Join Date: Nov 2003 Location: in transit Posts: 3,873 Provided Answers: 1	I'm still waiting to hear about the rear ones from that set, Now that was a major design.

12-01-2005	#11 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,269 Real Name: Harold Collins Provided Answers: 14	If anyone is planning on using the '75 calipers on the GT the bleeder screws wind up on the bottom and a different fitting is required for those calipers. I believe it is called a ISO bubble type fitting. I put my calipers on so that the bleeder screws were on the top like they are supposed to be but had to make a really short metal brake line. HTH, Harold

12-01-2005	#12 (permalink)
bq97 Member Join Date: Sep 2003 Posts: 217	Harold, I think your thinking of the BMW brake calibers; they have the bleed screw on the bottom if put on the correct side but there is no problem if you switch them left for right. I have the '75 Manta lager brakes on my GT and the calibers are on the correct sides, per the markings on the caliber, and the bleed screw is on the top. Both the 75 Manta calibers and the BMW calibers need an inlet adapter or a specially made flexible brake hose. The adapters are available from OGTS and from Earls Fittings. hth Brian

12-01-2005	#13 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	Thanks for the help, this site as usual has so much info! Sometimes, its confusing to put all of it together! Since Im not racing, and live in flat country, brake fade will not be an issue. Here is the plan: Brembo 75 Manta solid disks, if I can find them! I will cross drill them myself. BMW 318I calipers (1985) *Stainless brake lines Any part #s for the calipers? Napa?Auto zone? Are the bleeders on the top? Lyle

12-01-2005	#20 (permalink)
hrcollinsjr 2200 Post Club Join Date: Jan 2003 Location: Chapel Hill, TN Posts: 2,269 Real Name: Harold Collins Provided Answers: 14	I have or had two sets of calipers off of '75 Manta's. IIRC the GT calipers had the inlet hose at the bottom of the caliper and the Manta's bleeder screws and inlet were at the top. I'll have to go check now. Harold

12-02-2005	#22 (permalink)
GT Tim Member Join Date: May 2005 Location: Utah Posts: 479	The set up I got from Dave is almost a plug and play.At least as far as everything else I have heard of doing.This setup is pretty easy install besides I was replacing all my susp any how.Hope this helps you Lyle.

12-02-2005	#23 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	OK, no drilling or slotting! Too much work anyway! What about the ceramic pads? Another racing product, not needed on the street? Do I really need to upgrade my street GT's brakes at all????? Lyle

12-02-2005	#24 (permalink)
yellaopelgt No....its not a Buick.... Join Date: Feb 2005 Location: IL. Posts: 1,042 Provided Answers: 1	my brakes on the gt just plain out SUCK!!!!! I hear alot of good things about the green stuff pads and I will be giving them a fair chance this coming spring.... Joe

12-02-2005	#25 (permalink)
nobody No Access Join Date: Nov 2003 Location: in transit Posts: 3,873 Provided Answers: 1	Opel in thier infinate wisdom did a brake bias of 65/35 on the GT. This means the fronts do almost all the actual braking. With a very lite car and tendency for the rear not to hook up all that well just spells disaster. Granted my brakes are nowhere near stock now but at least it stops flat. Better pads are a good idea but more braking force all the way around sure makes a difference. I run a 50/50 bias and the change is night and day compared to stock. You have to look at the whole picture when you start modifying the stock brakes.

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