Pud, its not a simple case of buying some GTA calipers and fitting them:
This is my own opinion, I’m sure other people here will have differing views.
There are several options, the first and most obvious choice would be to fit GTA 4 pot calipers. This is not as simple as it sounds.
Your standard barking set up on a 156 has a single piston, sliding caliper and a 284mm ventilated disc. The caliper is bolted to a hanger which is then bolted to the hub carrier. The mounting holes in the hub carrier are spaced differently to the GTA calipers and are incompatible as a result. I.E. you cannot fit GTA calipers to a standard 156 upright. Dimension comparison below:
Horizontal dimentions - i.e. not slope dims.
Viewed from the top
Dims measured from wheel mounting face.
Viewed from the bottom (lower arm...)
There is a thread here about the specific differences between a 156 upright and a GTA upright:
http://forum.alfa156.net/forum/forum_posts.asp?TID=31195&KW= comparison
I am not saying its impossible to fit GTA calipers to a standard upright, people have done it, most notably PJD30, all I am saying is its not easy and requires fabrication of a mounting bracket which is not ideal on a track car IMHO as its unproven in terms of strength and thermal affects.
Soooo as far as I’m concerned if you want to fit GTA brakes to a V6 you will need the GTA uprights. When costing these up I would advise you to consider the additional costs involved. You will need to remove the hubs from the uprights as they’re different and fit the V6 hubs into the GTA uprights, requiring new wheel bearings. Additionally the ABS sensor wiring on a GTA will be different to your cars wiring loom and you will need to either replace the sensor or bodge the connector like I have.
Once you have fitted the GTA uprights to your car you have a choice of 2 set ups; 305mm discs or 330mm discs. Alfa upgraded the brakes on GTA’s after production halted Nov 2003 and restarted 2004. The reason being was the 305mm brakes were warping under heavy use. Alfa raided the parts bin and started fitting larger 330mm discs with bigger calipers, allegedly off the rear of a F360. The 305mm calipers are lug mounted and the 330’s are radially mounted.
If I was going down the route of fabricating a bracket to mount the GTA brakes to a standard upright I would start with a radially mounted 330mm caliper complete with bracket and work from there. The problem is 99.9% of the GTA brakes that you see for sale on E-bay are the 305mm brakes. 330’s are a bit like chicken lips to find 2nd hand.
305’s and 330’s side by side:
Fitment isn’t easy for any 4 pot caliper in terms wheels. 17’s are essential for the 330s and even then there are clearance issues with both wheel diameter and wheel spokes. 305’s are better but spacers may still be required to avoid the wheel spokes fouling the brake caliper.
Another option and possibly cheaper is the Brembo granturismo kit. This is an aftermarket kit developed by brembo specifically for 156’s (not GTA’s). they use the 305mm disc but they bolt onto a standard 156 upright. This is the plug and play option. Tim has this setup on his 156. Beyond this I can’t tell you a great deal.
As does a forum member here called Prizam. I know he is looking to get rid of 156 so it may be worth your while contacting him and seeing if he would consider selling them to you.
Beyond this you’re looking at kits from autodelta etc. HamishMoo had a custom set up on his monster, it might be worth your while chatting to him too.
In terms of cost, 305 calipers go for 150 – 200, complete 330mm setups are worth around 450 – 500 (They’re 600ish new from Alfa) GTA uprights are worth around 150 a pair. I don’t know what Brembo kits are worth, I would be inclined to say around the 600 mark.
