The rear factory calipers on my 914/6 are giving me some annoyance. In this case, the passenger side rear caliper has developed a slight weap. Its been an issue for the past two years. I've addressed the hard line, soft line and had the caliper re-built, but still, there is a slight leak.

Since 914/6 rear calipers are somewhat difficult to find in working order, I am wondering about an alternative use rear caliper while I sort the issue.

Knowing I would forgo the handbrake/e-brake, would then period (early 911 - 69 911T/912) "m" rear calipers work? I imagine the 912 or early 911T had solid rear rotors vs later vented (wider) rotors and calipers?) What are the piston size differences? How different is the mounting? Would I need a portioning valve installed or modified? Do they work with the stock rear rotor?

The car is otherwise very original, so I am not looking to upgrade everything brakes, just the rear calipers

I know the other answer is "reach out to PMB, they can help you"... and I will.. Just thought I'd ask here too.

TIA

Tangerine Racing has the rear brake kit to use 911 rear calipers. The short version for me is just fix the calipers.

The rear 911 M caliper will bolt right on. The 914-6 caliper is basically an M caliper with a handbrake. Same piston, same mounting, same rotor.

And yes, I would send the six calipers to PMB for sorting.

@Racer

Digging around, it would seem the 69 911T and 912's used a solid rear rotor. Starting in 70, they went to a wider (vented) rear rotor. So, the 70+ rear M caliper from a 911 might be too wide. Not sure if they ran spacers to accommodate the wider disc or if the casting was different.

It would seem I would be exchanging one very rare rear caliper for a only slightly less rare rear caliper.

Indeed, I do want to have working 914/6 rear calipers. But given the small production run, if I run into a scenario where the existing rear can't be rebuilt, then I need a back up plan Plus, running an alternate rear caliper would give me time to have the originals rebuilt without losing any driving downtime.

Talking to Eric at PMB about the, at least on paper, insane brake setup my car came with (48mm BMW calipers on the front, 48mm Jag/MG front calipers on the rear), he recommended replacing my rears with 911 M rear calipers and 914/6 rotors since getting 914/6 real calipers would be significantly more money.

My car already doesn't have an emergency brake, so that part isn't getting any worse.

You could always call up PMB and confirm the rotors would fit with the Ms, but seems like best thing would be getting them to fix your current calipers.

Yes. I forgot about the venting. Yes, buy some calipers for solid rotors or remove the spacers and use shorter bolts. Eric might have extra bolts since a lot of guys go the other direction and add spacers. I might have the correct bolts for solid rotors since I had eric build me 914-6 gt calipers with a set of M calipers and stock 914-6 calipers but I would have to search through my stash.

Early solid M calipers are usually ~$100-150 pair.

@Racer
' date='Aug 31 2020, 09:38 AM' post='2847425']
Digging around, it would seem the 69 911T and 912's used a solid rear rotor. Starting in 70, they went to a wider (vented) rear rotor. So, the 70+ rear M caliper from a 911 might be too wide. Not sure if they ran spacers to accommodate the wider disc or if the casting was different.

It would seem I would be exchanging one very rare rear caliper for a only slightly less rare rear caliper.

Indeed, I do want to have working 914/6 rear calipers. But given the small production run, if I run into a scenario where the existing rear can't be rebuilt, then I need a back up plan Plus, running an alternate rear caliper would give me time to have the originals rebuilt without losing any driving downtime.
[/quote]

You can remove the spacers and use the more common 9141 caliper. I would still just fix the original since it is on a six and making changes will only devalue the car.

There are a set of Ferrari - 914/6 GT calipers for sale in the classifieds now. can keep your parking brake setup.

I also had problems with my six calipers. They were rebuilt by Otto’s and within a year the pistons were sticking again. I replaced all my brakes with front and rear Boxster brakes. Couldn’t be happier. I am also running the 911 parking brake.