GTD brakes?

linder · 10-24-04, 02:16 AM

Can I use the gtd standard brakesystem without using the servos? Can anyone please inform me which donor car/cars whas used to the gtd brakesystem disc/calibres and mastercylinder.I have read that it use granada/scorpio disc/calibers but I dont know which mastercylinder to use.I dont want to use servos on my car...so if anyone could help me out I would be pleased.

best regards

Michael [img]/ubbthreads/images/graemlins/confused.gif[/img]

gt40rick · 10-24-04, 04:05 AM

I chose not to use the servos when I built my GTD, only difference is that more pedal effort will be required. Going to a smaller bore master cylinder will correct pedal effort. I am not sure if your laws require the use of servos.

Tony Jasper · 10-24-04, 11:34 AM

Hello Michael,
Yes, The GTD40 used Granada/Scorpio brakes as you say. Like many others though, I threw mine away and fitted much bigger brakes. Why not miss a stage and not fit the GTD brakes ? My car now has 320mm vented disks back and front, with 4-pot calipers, all made by Willwood. I have a pedalbox with a 6:1 ratio and no servos. Both front and back master cylinders are 0.75 inch bore. The caliper bores on the back are smaller than the front as a crude brake proportioner, and I have an adjustable bias on the pedalbox, which may not be legal in your country.The '40 now stops, every time ! My worthless advice is to go straight to big brakes. Another potential pitfall is the handbrake. You will either have to fit an additional spot caliper, or fit an hydraulic handbrake (quite simple) or use the Granada setup on the back.
Tony.

Phil · 10-24-04, 09:28 PM

Michael
Going for the bigger brakes (IE Wilwood or comparable) and it is always easier to remove braking power than add it, also I seem to remember that Wilwood or some other aftermarket caliper manufacturer offers a "spot" caliper with a lever for attaching a cable, that would solve the emer brake problem
Good Luck
Phil

Fred/Belgium · 10-25-04, 03:48 AM

Michael,

PLs look at Part for sale section
Item: Suspsension for sale from Julian West.

I am interested in the whole set except the brakes wich are upgraded ones for GTD standard (I already have them).

If you are interested pls ctc Julian as he knows I am only interested in the other pieces.We could make all a best deal.
Let me know.
Fred

linder · 10-25-04, 02:19 PM

Thanks for all the replies. First I would really like to buy willwood brakes and a tilton box but my economy dont allow it for the moment.I really want to get my car on the street for then later upgrade my brakes/engine/suspension aso.I know that it is not the most money sawing process in the long line but for the moment it is the only solution to get the car on the street.
best regards

Michael Linder [img]/ubbthreads/images/graemlins/cool.gif[/img]

Julian West · 10-26-04, 05:45 AM

I've had several people email re the suspension/brakes for sale & whilst I don't claim to be an expert on braking systems here's my 2c worth.

The original GTD brakes are ford granada items mounted on GTD fabricated rear uprights/granada front. AFAIK a granada is way heavier than a GTD & has to be able to stop safely with four people on board, luggage, caravans etc etc... therefore (IMO) Granada brakes are plenty good enough for granadas!

Lots of people complain the standard GTD brakes are weak. When looking to improve the brakes, maybe it would be worth looking at the brake system as a whole, rather than focusing on the calipers/discs.

I beleive there is plenty of room for improvment in the GTD pedal box, M/C & servo setup. If you are at an early stage in your build it would be well worth looking closely at the pedal ratio & MC size. The GTD pedals are very short & a longer pedal could give a much better ratio. If you are using servos, make sure they are correctly plumbed, with the right type of vacuum hose.

Bear in mind that on a completed car, calpiers & discs are easy to change, they just bolt on! However, changing the pedal box may not be so simple.

Another key factor is cost. If you want good quality 'race' spec discs & calipers then consider a budget of around 2000 ukp. Consider doubling that figure (& then some) if you want ally uprights, rose jointed etc.

At the end of the day you pays your money & takes your choice, if you buy granada brakes for a few hundred pounds they'll be 'ok', but if you want a top spec race car/track day setup then you'll have to dig alot deeper! [img]/ubbthreads/images/graemlins/grin.gif[/img]

Fred/Belgium · 10-26-04, 06:48 AM

Julian,

Any news futher to my mail?
Tx
fred

Julian West · 10-26-04, 07:25 AM

Fred,

Will email you off list.

best regds,

Fred/Belgium · 10-26-04, 08:32 AM

Julia,

I cannot reach you by mail.Could you ctc Michael as I would preffer do it via him.

Tx
Fred

Malcolm · 10-26-04, 01:35 PM

The solid disc rear granada brake set up on a GTD is one to change quickly. It really lets the side down. That is why the factory switched to vented rears and moved the caliper position.

Howard Jones · 10-26-04, 03:53 PM

The granada parts will work at road legal speeds and for road legal type brake stoping rates and distances. Also they will stop you ONCE from high speed. The rears are the problem. They will heat up the pads very fast and then with the fronts left to do all the work they go away quickly. Two stops from about 130MPH and the brakes on my car were DONE! It's not the weight ITS THE SPEED!!!!!!

So if you are in the lets get the car done mode, I was, then you will be fine until you can do a proper brake upgrade later. Just remember to take it easy on the shakedown drive!!! You don't want to scare youself right out of the box!!!!!

The peddle box would be my first upgrade during the build with the wheel assemblies, rotors and calipers, next and hubs last if ever.

Dave Bilyk · 11-17-04, 08:53 AM

I spent an afternoon on the track last saturday.
After all the trouble I have had with the servos (brakes not releasing), I had lost faith in them, so decided to remove them as a test.
A quick shakedown test showed that I could still lock the wheels, but naturally had to press mightily hard to do it.
On the track I had sufficient braking, but was not prepared to break my leg with the effort, so I braked reasonably early.
The brakes are the standard GTD setup (on a DAX) so I wasnt expecting miracles anyway.
Back in the garage, I noted that the rear pads were down to 1mm, while the fronts were still 10mm+.
I have 5/8" Tilton master cylinders with brake balance bar.
Now thinking what I need to do to improve on this setup, but I want to keep within the 15" wheel size.

Howard Jones · 11-18-04, 01:20 PM

The best I could do for my GTD with the same parts as you was to reduce front brake effort by 10-15% with a wilwood type adjustable valve in the front brake line.

This will give you ballanced EFFORT at both ends of the car but will not give you ballanced capability for very long.

You brake pad wear is telling you what is going on. The rear disk/pad combo will not stand up to the amount of heat you are giving them. You might be able to help youself with better pads, higher friction type, but one way or another the rear disks will overheat.

This car, or any other for that matter, needs to be able to reject the heat being pumped into them at a rate that will not overheat the pads.

So you can try whatever pads you might find that can help you a little, slow down, resulting in longer lap times, or upgrade the brakes on the rear at least.

I am not sure how the car would do with better rears, say disks and calipers that were more or less equal to the fronts, but on a limmited buget I would do this first as far as the disk and calipers are concerned.

I would also hook up the boosters again and lengthen the brake peddle as much as room and your foot posistion will allow.

As you can see the cars has really two problems. First the pad/disk systems are marginal at front and nearly unuseable at the rear and second the peddle ratio is about half of what it should be.

Since you have the car apart I would do the peddle box first as suggested above. If you can install a dual master type with a ballance bar that would be my advice. You would then not need to keep the boosters. If you make your own you need a peddle ratio of at least 5 to 1 and really should be 6-7 to 1.

If the car had correct peddle effort going in you might be able to get by with better pads, replacing them offen, and taking it easy at the track. But in the end the entire system is not worth keeping on a track car.

Dave Bilyk · 11-18-04, 03:20 PM

Howard,
thanks for such a clear and concise diagnosis. Looking at the rear pads, they do look as though they got quite hot.
The pedal box is already a Tilton top mounted dual cylinder with balance bar, the pedal ratio is 6 or 6.2 to 1, so I dont plan to change that for now. I dont want to replace the servos, and I guess you already said I dont need to with this pedal box type. So I think I will start with a revised rear disc arrangement.
In agreement with your words, I already have the balance bar full to the rear and yet actual braking is still biased to the front.

Howard Jones · 11-19-04, 02:50 PM

The peddel box you have is PERFECT!!!.Could you post some pictures of it installed.

Simon · 11-19-04, 03:36 PM

Dave, if you want to upgrade your rear brakes, hispec to a big disc conversion which enables you to use granada scorpio cosworth rear calipers with big discs that fit inside 15inch wheels, a worthwhile upgrade

Simon

Dave Bilyk · 11-19-04, 05:01 PM

Howard, this is the only pic I have so far.
Simon, thanks for that, I'll look into that. You back on the road now?

Simon · 11-19-04, 06:12 PM

No, be a while yet.
If you'd like a pic of the rear conversion bits (not fitted yet) let me know and I'll post a pic and dig out the invoice.
Simon

Howard Jones · 11-19-04, 07:17 PM

Thanks for the picture. It looks like the brake fluid tanks are in the drivers compartment up under the dash. Am I correct on that? I wonder if I would have room to do it that way. I'll have to check when I get my car back from the shop.