8 PISTON Brake upgrade for Alfa GTA !

all they do at work is make windscreen wipers, so can't really help i think... but I'll try to get hold of an advandced code reader, and see if anything can be changed in the GTA abs ecu. maybe i can get hold of a Texra unit...

Originally Posted by GTAFAN

I said Maranelo calipers but no disks . 300mm rotors with ALU hats made special for 5/98. That is 5,5 kilos .

Something doesn't make sense to me.. Why would you mount the Ferrari 575 caliper? Apart from the lug mounts, is it not the exact same caliper as fitted to GTA's, or GTA's with the 330mm upgrade.. If you fitted the Maranello calipers with 330mm discs i could see a point.. but in combination with 300mm disc, which is even smaller then the smallest GTA disc of 305mm... why?

Below is a photo of your Maranello set up which you posted on a diffrent site.. I am having a very hard time spotting the disc as a two piece lightweight type with Alu "hat" as you call it.. Where is the seam where they bolt together?

Originally Posted by Cuore_Sportivo_155

all they do at work is make windscreen wipers, so can't really help i think... but I'll try to get hold of an advandced code reader, and see if anything can be changed in the GTA abs ecu. maybe i can get hold of a Texra unit...

Cheers CS, i'd be very gratefull for some help on that subject.. i tried contacing a Bosch centre, but they knew virtually nothing..

Bosch stores are not able to do anything to our units.

For my Maranelo setup the disks was 330mm with alu hats. ( 300 was wrong typing).

Maranelo calipers are from the strongest 4 piston on the market.
Are not the same as Alfa 330. They have Bigger pistons 38mm* 46mm and ceramic hats for thermal insulation. Also different pads and not the same brackets. New brackets need to make for fitting.
All that make sense. Maranelo is V12 and much heavier than GTA.

Ferrari have biggest budget to spent on Brembo for calipers than Alfa.
You get what you pay for.

http://img228.imageshack.us/img228/1...rari22swj0.jpg

Peterk: his diagnostic equipment isn't working currently, seems to be software related. I think it'll get fixed next week, the dealer is coming by... I'll be there too

Hi,...

pistons on the 330mm calipers are also 38mm diam. for the GTAs original ones

@GTAFAN

I looked the Ferrari 575 calipers up. Price per caliper is €463,00 remarkably thats less then the GTA 330 calipers at €543,00

Secondly I do not understand your last post and photo. You are saying that the 575 caliper has bigger pistons compared to the GTA.. you quote the 305 and 330mm GTA calipers as having 38-42 (post #12 of this thread)

You then quote the 575 Maranello calipers as having 38-46 pistons.

As i understand it and from looking at the photo of your ferrari calipers you linked to in the post above (see photo enlarged below) the 38-46 relates to the inner outer diameter of the piston. as you can see on the photo the Bore Gauge is positioned at the bigger of the two pistons and set at 40mm which clearly is between the inner and outer diameter of the Ferrari caliper Piston.

I always like to fact check so i found a 305 GTA caliper (the smaller one of the two GTA calipers) and measured the pistons. As you can clearly see it appears the pistons of the GTA calipers are bigger then the pistons of your Ferrari caliper. how do you explain this?

You measured the pistons of GTA? Ok write to me what you have found? How we measure the pistons from a caliper? Lets clear this out. Since you know how to measure the pistons.

Then find a Maranelo caliper and measure the pistons. Then write to us what you found.

That's accurate information. and not speculation from photos that others posted here.

So???

Now I am really confused.. you post a photo of your Ferrari caliper with a Gauge placed over a piston. The gauge reads 40mm and covers a slightly smaller diamteer then the visible area of the piston. You claim the pistons are 38-46 mm which to me in your photo looks like the piston head is 38mm and the dust boot is 46mm?? (your dust boot is cracked BTW) When i look at the photo of the Ferrari caliper and compare it to the GTA caliper it looks to me like the GTA pistons are larger.. If they are not perhaps you can explain how we deterime it.. and what was then the purpose of your photo with the Gauge over the Ferrari caliper piston?

I have a pair of 305mm gta calipers here on my lap, I measure 34.5mm and 38.5mm with my digital gauge, not including the rubber sleeve...

why the difference in piston width? My guess it's for use with a I+H configuration of the brakes?

The bore difference could be because of the way pressure is distributed to the pistons..?

Anyway, not having my Gauge here i concur with CS measurements. the GTA pistons being 38.5 and 34.5mm.

Now looking at the photo GTAFAN posted of his Ferrari caliper, would you not agree that the pistons in it looks smaller, or at least that the smalles of the two ferrari pistons looks smaller then the smallest (34.5mm) GTA piston?

It looks the like the large of the two Ferrari pistons cold be 38mm as well (gauge is at 40mm)

OK. I see that you don't know how to measure caliper pistons.

THE DIAMETER OF A PISTON IS THE REAR SIDE INSIDE THE BODY OF THE CALIPER.
Is the area that brake fluid push to come out. And not the area that comes in contact with the pads.

THE PROPER WAY TO MEASURE IS TO TAKE OUT THE PISTONS AND MEASURE THIS REAR SIDE.

The photo with the gauge(caliper) I posted doesn't show anything.
I just posted this to see if anyone new how to measure brake pistons.

So Peter you did the same mistake. Please for the sake of everyone here don't write something that you don't know.
Never judge by the appearance !!!

So if you take out the pistons from GTA caliper and measure the rear side of the calipers you will find 38mm , 42mm.

And IF you find a Ferrari Maranelo caliper and take out the pistons and measure you will find 38mm , 46mm.
And between 42mm and 46mm is a difference of 4mm for every side of the caliper. That makes 8mm for both sides. And 16mm for both calipers.
THATS A BIG DIFFERENCE !!!

I cannot see the lettering well enough to be sure, but best guess the piston looks like 40mm tops... so about the same... but until we get a better look it's just guess work

so you're saying the piston cannot come out the front, because the rear is wider... I'd have a look, butr it would get messy here... it's unusual though, at least for single pot calipers, who will pop the piston if the brake is applied without pads or discs mounted...

Originally Posted by GTAFAN

And IF you find a Ferrari Maranelo caliper and take out the pistons and measure you will find 38mm , 46mm.

That can't be right... From what i can see on that photo the bore of the biggest hole (the one where the gauge is) is not even 46mm..the gauge is at exactly at 38mm..so thats another 8mm needed. plus a little extra or the piston body will rub against the cylinder wall, causing the piston to stick..Looking at the other photos of the calipers when mounted, it is clear that the pistons can only come out from the inside, so it is not possible for the piston be larger then the bore in the photo.

OK. I see that you don't know how to measure caliper pistons.

THE DIAMETER OF A PISTON IS THE REAR SIDE INSIDE THE BODY OF THE CALIPER.
Is the area that brake fluid push to come out. And not the area that comes in contact with the pads.

THE PROPER WAY TO MEASURE IS TO TAKE OUT THE PISTONS AND MEASURE THIS REAR SIDE.

The photo with the gauge(caliper) I posted doesn't show anything.
I just posted this to see if anyone new how to measure brake pistons.

So Peter you did the same mistake. Please for the sake of everyone here don't write something that you don't know.
Never judge by the appearance !!!
So if you take out the pistons from GTA caliper and measure the rear side of the calipers you will find 38mm , 42mm.

And IF you find a Ferrari Maranelo caliper and take out the pistons and measure you will find 38mm , 46mm.
And between 42mm and 46mm is a difference of 4mm for every side of the caliper. That makes 8mm for both sides. And 16mm for both calipers.
THATS A BIG DIFFERENCE !!!

THE PROPER WAY TO MEASURE IS TO TAKE OUT THE PISTONS AND MEASURE THIS REAR SIDE.

If you don't know how to take out a piston you can not speak about
the diameter of a piston. Go to a brake specialist and remove the pistons. Then measure.
Then take a Maranelo caliper. Go to a break specialist remove the calipers. Measure and say the difference.

You can't measure with a gauge with out to remove pistons. Forget what you see on the photo. The gauge on the photo is just a shining object. Doesn't measure anything. I just placed it like that to see if anyone knows. Never judge by the appearance !

Originally Posted by GTAFAN

I just placed it like that to see if anyone knows. Never judge by the appearance !

Is that the whole idea to post your car with non-GTA interior to see if anyone knows it is not a real GTA. and never judge by the appearance??