Alfa 75 front discs

[AlfettaResto]

Hi, i want to run the Alfa75 front vented discs in my Alfetta and keep the Alfetta PCD of 4x98.  I was going to just have the Alfa 75 discs redrilled for the Alfetta pcd but was concerned that a couple of the bolt holes overlap a bit and that it may cause a problem getting the car re registered.  Has anyone had experience with this.  I've tried to find blank discs with no luck and custom 2 piece discs are pretty expensive. Is there another option?  Is there any appetite for a special run of undrilled blanks?
Regards
Mark

[GTVeloce]

When I bought my GTV it had 75 ventilated discs that had been drilled to suit 4x98. The PO had achieved a RWC with this mod albeit in Shepparton...

I was never a huge fan and have changed hubs to 5x98. With 4x98 the screws holding disc to hub don't line up so the only thing holding the disc on is the wheel and therefore the wheel nuts. That said, I drove it for a couple of years with no issues in that guise.

[AlfettaResto]

Thanks for the feedback GTVeloce.  I've  now be considering using FIAT 500 front discs.  The outer diameter will need to be machined down by 7mm and a 8mm spacer between the disc and the hub will give me the right height.  Still have to measure the internal diameter to see if that will fit or not but may also need a slight adjustment as will the wheel studs.  Anyway this option will look more professional and won't have me worrying that the disc will fall off.

[NSharpley]

Hi Mark,

Its a very common practice, particularly as a first step brake upgrade for race cars.

Ive done it a few times with no issues.

Once the discs and hubs are assembled and on the car its not obvious to the eye that the discs have been drilled.

So unless your RWC guys are VERY thorough Id be surprised if they'd see it.

Saying that, Ive never had to register / RWC a car with this mod.

Why not register the car with the standard brakes then do the disc upgrade?

The GTV6 / 75 calipers bolt straight on too ...

[MD]

Why not do the job properly and do a front and rear hub conversion for a 5x98 PCD and have no legal or safety compromises?

Otherwise file through the DBA catalogue for a rotor that has a close offset and smaller hub bore with a 4 bolt mount. Machine out the bore for a good hub location and redrill to 4x98 PCD.

Option 1 is the preferred choice.

[NSharpley]

Why not do the job properly and do a front and rear hub conversion for a 5x98 PCD and have no legal or safety compromises?

Otherwise file through the DBA catalogue for a rotor that has a close offset and smaller hub bore with a 4 bolt mount. Machine out the bore for a good hub location and redrill to 4x98 PCD.

Option 1 is the preferred choice.

Option 1 means new wheels.   Not the simplest option for most people.   Option 1 would also be far more expensive and option 1 involves more work.

[AlfettaResto]

Thanks for the fed back.  Wanted to keep the original look of the car hence staying with the 4x98 pcb.  Also as mentioned the wheels.  I have a real nice set of 15" bwa sportsline.  While there not original they are period correct.  The fiat 500 discs are the way I'll go. I'll get engineer sign off and be up front about it.  I don't want any issues if i have an accident and the insurer avoiding the claim because of it.  Better safe the sorry.

[17fitty]

Yep a mate did the fiat 500 conversion on his race car and was very cost effective and stopping effective-look for brook308 posts i think he may of put up some info etc-it would be 4-5 years ago now.

[GTVeloce]

I would also be interested in this because Fiat also uses a 5x98 brake disc (500L) and I have been thinking it could be a nice and cost effective upgrade to the standard Brembo brakes however I would like a better understanding what is required before I try it.

[AlfettaResto]

The FIAT 500L PCD is compatable being 5x98 but you would need a spacer to centre it to the caliper.  As the disc diameter is taller you would need an adaptor of sorts to raise the existing caliper but i question how much better braking you would get.  If you were changing the calipers to something that provides greater brake pad surface area then you may have a difference in performance.  I'm no expert so I'll leave it to others to argue what's better.

[Darryl]

It works fine (redrilled). Another alternative is separate disc rotors and hats. If you can find a set of hats (eg from a turbodelta) or you can get them made. The rotors are (or were) a common size for some race car class or another... Been a while...