GTD brake upgrade

F

Fred/Belgium

Hi Curt

You have a pm.
What type of carbs would you like to look at ?
Weber preparators are the most difficult to find.
I know someone for Webers but ypou never know when it will be ready (real artist type of mecanic...)
I carbs for Rover engine (SU?), then call Paul Sorret in Hoeilaart with my regards.
I used to have the Rover engine on my first GT40...

Grtz
Fred
 
W

Frank Catt

Curt, as you have found out, there are a lot of individual opinions on this subject, and you will need to consider those that you think are appropriate for your situation. As Fred said, there are some very good engineers in Belgium , again take advice from others who know them. I note your comment on the existing pedals and servos, and again you need to investigate this a bit more. The existing GTD set up with these items is reliant on several things, and not least the amount ( volume and negative pressure you can achieve on the vacuum system if fed from the engine ) , and the better updated solution of using an electric driven vacuum pump rather than rely on the engine intake vacuum. Most drivers using upgraded brakes, particularly for race or track, do not like servo driven brakes, which means you do need better pedal pressures to operate the system. Remember that the original GTDs ran a rather basic ex marine engines, fairly low horsepower relative to todays machines, and later upgraded engines with better camshafts can produce significantly lower vacuum output, which has a significant impact on braking performance if using servos. Couple of pictures of Tilton brake pedal sets, others are available, but in my opinion you might avoid the Willwood option ! Think it through carefully, its your money and your car.
Couple of pictures of Tilton pedals mounted for gtd. Frank
 

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C

Curt

Yes there are a lot of opinions, but certainly out of a lot of experience

@Pierre, I also saw this site, but I also found some bad stories about it?

That saabs had handbrake on front wheels is also new to me..

@Fred, I have Dellortos on 2 of my cars, but basically I need some accelerator pump settings checked, so main point is finding a good rolling road?

But as most of you advised to ditch the servos I think I will go this way. Useless to come to a point that it all does not fit properly together and start again as Frank stated...

And as Malcolm advised I already get in contact with southern GT to see what they offer.

So It will be Wilwood brakes and I'm just design the brackets for it myself.
I will buy them at R&R design. They also going to do a proposal for the cylinder-size needed.
I also wonder if the Excel calculation sheet of "Mike Polan" is good start for cylinder size calculation?

For the brake pads I want to go for the Smart Pads.(road use mainly)
And also what material did you use for the brackets?

Regards, and thank you, Curt
 
C

Curt

Ian, yes I meant Rally design.. In past it was R&M design, my confusion.

I wanted to use the Rally design rear Powerlite callipers with integrated mechanical handbrake.
Professional Motorsport Parts, Spares & Rally Equipment from Rally Design
BUD it seems they only come today with 1" pistons and no 1.38".....

I think that is quite small and certainly not in balance with whatever front brakes up to the job?
With the smaller 6 pot I need 1" front and 0.625" rear master cylinder according calculations.

Any thoughts?
 
IanAnderson

Ian Anderson

Lifetime Supporter
I seem to remember reading that the integrated rear handbrake willwood calipers were very marginal to hold the weight of a GT40, OK on a Westfield or Caterham where the gross weight is a lot lower but not for these cars.

But that was a number of years ago and I could be wrong / faded memory
Ian
 
brettmcc

Brett James-McCall

Moderator
Andy Sheldon said some time back that they had passed on a Tornado, but not sure if they would on a GTD.

I'm getting closer so will find out I guess...
 
C

Cliff Beer

There are other possibilities too - personally, I like four piston brembos. These come on lots of porsches and mercedes and others and are not expensive to purchase used or rebuilt. Most have 3.5 inch ear mount. Some engineering required for the piston sizing, and mount adapter..... If you don't have proportioning valve in the system I would highly recommend using one.
 
brettmcc

Brett James-McCall

Moderator
Malcolm said:
Don't Hi Spec make a hand brake calliper now?
Click to expand...

Yes Malcolm they do. They've modified their design since the initial ones came out.

I bought mine years ago so will see if I can get the Powerlite handbrake caliper to work with mine. Since then, Hi Spec have modified their design.

Though if I was going to do it today, then I would probably go with using Wilwood all round and then their seperate MC4 handbrake caliper (I may still have to do that to be honest)

Brett
 
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Frank Catt

Hi Ryan, its standard what we do! 15 inch Vintage wheels, Aluminium upright as original pattern but with 108mm Dia CVJs AP 4 pot brakes on 305 x 28 discs. Rear upright set at 8 degrees castor angle. ( on Avons CR6ZZ for road use, others for track. ) Frank
 
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Curt

@Clif, yes I also looked into Brembos. But I cold only find the racing line catalogue online. Could there be a catalogue for the other calipers with technical drawings?

@Brett, Yes I think that is also my solution. Using the MC4 handbrake in combination with the (normal) Powerlite caliper on the rear.
 
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Cliff Beer

Curt, yes, I believe that's correct - there is little/no online retail/new sales of the production (non-racing) brembos. You would have to source used or rebuilt brembos, after first identifying the right brembo for your GTD - piston sizing, ear spacing, adapters, etc. Fair bit of work there no doubt.

I have adapted a couple pairs off of porsche (964 and 996) and had good results. Mercedes brembos are good too - just rebuilt the brembos on my S600.
 

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Howard Jones

Howard Jones

Supporter
Here's the specs on my GTD brakes.

17 inch wheels

All 4 corners, 12.18" X 1.25" HD Wilwood rotors, Hats are Wilwoods also but I don't have the off sets in front of me.

Front calipers 1.75 X 4 forged Wilwood superlights ear mount.

Rear calipers 1.38 X 4 superlight ear mount.

Master is the standard GTD Grenada(?) tandem unit. I believe the piston size is 5/8.

Peddle ratio is about 4 to 1, also the standard GTD hanging set.

I am using the standard GTD vacuum assist power brakes units. I am told the resulting combined peddle ratio comes out to about 6 to 1 .

I have plumbed a proportioning valve in to the rear brakes and after a lot of trial and error believe I am reducing rear pressures by about 10%.

PLEASE!!! Those of you who have a known well balanced setup and also know the particulars as above please post them. Two or three more of your setups and we would have a very valuable comparison model.
 
brettmcc

Brett James-McCall

Moderator
Curt said:
@Brett, Yes I think that is also my solution. Using the MC4 handbrake in combination with the (normal) Powerlite caliper on the rear.
Click to expand...

Curt, only thing I would say is that if/when I do another build, I will use the Midlite on the rear, not the Powerlite. Only because the Midlite comes with dust seals.

Brett
 
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