Front Brake Upgrade

[Motor Mouth]

Well now that the GT is putting out a few more BHP I think it's time to consider upgrading the front brake set up. I currently have the GM big brake set up, vented discs, but don't find these too confidence inspiring.

Having spoken to a racing friend of mine, 450bhp E30 BMW, he's suggesting BMW E34 (5 series 89-95) with VW Corrado Vented discs.....just wondering what thoughts / suggestions you guys might have?

[nobody]

Every increase in bore size decreases the effeciency of the master cylinder to get the most out of them. If you go even larger then it will only make it worse. I'm no fan of the stock 60/40 bias in a stock GT either, I prefer to continue looking out the windshield after hard braking on less than ideal surfaces.

Personally, I'd be out shopping for a BMW 5 series master cylinder that bolts right up and checking the seatbelts. HTH

[markandson]

Went looking for precision brakes, which is an upgrade that I had looked into a while back. Member here "FrankDaTank" has it installed in his car. I remember it costing about 1200 but now it is quite a bit more, if the company I found is the same one. When you go to precisionbrakes.com it no longer takes you to the site I remember. I kept on searching and found this one http://www.revolutionbrake.com/files...its-03-072.pdf
They do have a front kit for the Opel GT, so I have a feeling it is the same place. If I find my old printed material I can confirm it.
Update...just found my printed stuff..The company was/is called Precision Brakes Company, 1010 Benson Way, Ashland, OR 97520
Phone is 541-488-2604. According to the info I have on file they have both front and rear kits available for the GT.

[rstrel]

Nobody,
What year BMW 5 series mc bolts right up?

[StefanLee]

Hi guys.

I contacted Precision Brakes about their kits in february (wilwood dynalite kits, the ones frankdatank is using)

The prices are much higher now (under new ownership), a front kit is 1859 and a rear kit is 2548 = 4407 dollars and that is without new master brake cylinder etc. Pricey!

But that includes a completely new parking brake assebly in the rear and the kits are bolt on.

I´m going for a home-cooked setup myself...

Stefan

[Lindsay]

Hi guys.

I contacted Precision Brakes about their kits in February (wilwood dynalite kits, the ones frankdatank is using)

The prices are much higher now (under new ownership), a front kit is 1859 and a rear kit is 2548 = 4407 dollars and that is without new master brake cylinder etc. Pricey!

But that includes a completely new parking brake assebly in the rear and the kits are bolt on.

I´m going for a home-cooked setup myself...

Stefan

It would be interesting to know what the WILWOOD P/N is for the $1859 front brake kit. Forged, DYNALITE calipers list for $140 each + pads ($42) from Summit or Jegs. Two front, brakes hoses are $60. Etc. Appears to be big $$$ for brackets and kitting.

[Motor Mouth]

Sounds like my original idea is a good idea......now way I'm forking out thousands of $$$$ or ££££ for a brake set up. Someone out there must have done an upragde, beyond the Opel 'Big Brakes', for a couple of hundred $$$ or £££, I reckon I can get the basic parts for $200 with some fabrication.

I'll keep you posted later in the year.

[nobody]

Being on that side of the pond a few of the pieces would be easier to get. Try expanding your search for a write up on "brake upgrades" that went far beyond the big brake setup. 4 wheel discs that would about pull you out of the seat. A full part by part and how to. HTH

[dallasmanta]

Mark,

you need to talk to Rodney the President of the Texas opel group. He has effectively replaced the brakes on his Killer GT with those from an Isuzu impulse including the master cylinder and it is disks all the way around. I have driven his car and the brakes are to die for. They will stop on a dime/ or pence in you case. Ron

[GTJIM]

The GT already has a pretty good set-up for a disc/drum system of the 1970's - it is all to easy to "over-brake" a car and have brakes that lock up too soon and cannot be aggressively used. Balance is the key.

The Impulse disc/disc set-up is just about perfect for the GT as they come off a slightly heavier car and are just that wee bit bigger, plus the front discs are ventilated and so have greater braking capacity. Another great plus is that the Impulse discs are considerably lighter than the older GT set.

A set of Impulse 10" (246mm) ventilated front discs and 9 1/4" (236mm) solid rear discs are an ideal GT replacement. Unfortunately, most of the US Spec Impulses have the larger 10 1/2" (266mm) ventilated rear discs which are way heavier and give too much rear brake 'bite' without a proportioning valve.

[baz]

whats wrong with using opel ?

get the vented ones from a 2.2 calton bolt right on and just need the calipers sorting (with the bmw ones dave mentioned i think )

[RallyBob]

Mark, check with these blokes here.

Although their on-line catalog doesn't show anything, as I recall from a few years back when I received a paper copy of their catalog they have numerous kits in varying stages (from small to utterly large) to fit the Manta A/B, Kadett B/C, ETC. Therefore they should fit your GT. They were fairly reasonably priced as I recall, and of course shipping would be far cheaper since they are in the UK.

HTH,
Bob

[blancojp]

GM brakes with vented disks are pretty good, I would not change that setup.
There are multiple upgrades you can do however I would concentrate first on the rear wheel cylinders and the brake booster since the 7" unit is not the best. I have a few more horses under my hood than normal and my '72 has Honda vented rotors on all four corners, Chevy truck aluminum front calipers, Eldorado rear calipers with em-brake, Honda master cylinder and a Girling 9" booster.

Towards your side of the pond, there are many 4-pot calipers and vented rotors you can use if you in fact want to upgrade.

[bello]

Hello folks- Try this- VW Scirocco 16V, 86-87 Front calipers and rotors. The calipers bolt right on after you drill the caliper bracket out to 12mm- the are 10mm. You have to fabricate the brake hoses (local hydraulic supply house) or discover which hose just happens to fit.The rotor is the sticky part: The center hole has to be bored bigger (2-3mm) to clear the Opel hub. Then the rotor has to be drilled for the 4 hold-down bolts. Now have a machine shop make you an aluminum spacer ot the corect thickness to center the rotor in the bracket: measure carefully!! to sandwich the whole thing together. Here are the specs: OE Opel to 74 was 239 mm diameter, 11mm? thick rotor, 48 mm caliper piston; 75 Opel was 246mm, 13mm? thick, still a 48mm piston. The 16V Scirocco is 250mm, 20mm, 54mm piston! You will need nothing bigger than this unless you road race the car and are very fast! The brake pedal will require a bit more stroke, (that 54mm bore) but you will soon get used to it. Careful selection of brake pads material will yield amazing results! This statement assumes the rear brakes are working/adjusted/bled etc. I used this setup on my Kadett racecar for years with the stock 20mm Delco France master cylinder. For the racers out there, i can tell you what I am using now which is even more trick! Ernie bello

[gearheadeh]

Okay ernie bello! What is even more trick? My opel is and will always be a gutted out rollbar equiped ROADRACE car.! Please sir can I have more..... said oliver twist.

[bello]

Hey there- The "trick" front brakes are fairly simple- but you must upgrade the rear brakes to discs or you will be braking mainly with the front brakes! Get a set of calipers with brackets and the rotors off a Saab 9 3. Mine came off a 1996 V6 Wagon. The caliper bolt spacing is the same, the offset you have to adjust with a spacer between the front face of the rotor and the back face of the opel hub. Yes, You need to re-drill the rotor to the Opel 4-bolt flange, then bolt the rotor, the spacer, and the hub together from behind. The bolts will need to be longer due to the thickness of the spacer. Write back & I'll tell you the spacer thickness- can't remember right now. These rotors are 288mm diameter, 24 mm thick, the caliper pistons are 54mm, and you can use BMW e36 M3 brake pads- easily available. Yes, it will stop fiercely, lap after lap, you will never warp rotors or boil brake fluid again! The rotors are huge, calipers are single piston: no more problems. In the rear you need calipers with a 36-38mm piston and about a 9.5 or 10-inch rotor. Mine are off a '90 5-series BMW- 38mm pistons, solid rotors. The Germans state that you need 4-wheel discs when you exceed 150HP- The more HP, the more brake you need to handle the commotion! Hope this helps! Ernie

[opelwasp]

Don't most cars brake "mostly with the front brakes"? Isn't that why I replace my front pads 2 to 3 times more often than my rears?

[Paul]

On most cars the front to rear bias is roughly 80/20

[nobody]

I was thinking about cutting mazda (piaza) adapter plates. Then using RX7 rear calipers with BMW front calipers and bigger rotors and a 5 series MC on the wagon. The new adapters will be ali tho. If I only had a CNC plasma cutter and a vertical mill it would be easy. I'd still need a print of the adapters tho. A new set of rear bearings would be nice for this little project too..Ok I have the print and the plasma cutter and the vertical mill. The bearings and seals are already here. The axle keepers can be purchased but the rest of the parts are already here. It was the adapter print that was lacking. Thanks Gene

[BQS4]

I was thinking about cutting mazda (piaza) adapter plates. Then using RX7 rear calipers with BMW front calipers and bigger rotors and a 5 series MC on the wagon. The new adapters will be ali tho. If I only had a CNC plasma cutter and a vertical mill it would be easy. I'd still need a print of the adapters tho. A new set of rear bearings would be nice for this little project too..Ok I have the print and the plasma cutter and the vertical mill. The bearings and seals are already here. The axle keepers can be purchased but the rest of the parts are already here. It was the adapter print that was lacking. Thanks Gene

The one dimension that's missing is the thickness of the plate, which is about 6mm