Rear brake rotors for '67S

[Bram]

Just wanted to to offer a big thanks to everybody who chipped in here -- particularly MT 912RS. I just bolted up a pair of early 944 rear rotors to my '67 S. They worked exactly as he said -- just turned the outside diameter down and on they went. Problem solved perfectly for a fraction of what I thought it'd cost. The traditional payment here in Australia for somebody who helps out like that is a case of beer (usually Victoria Bitter). So MT 912RS, if you're ever down here in Sydney there are 24 cold ones waiting for you. Thanks again.

[MT 912RS]

Hopefully I can take you up on that someday. That little bit of knowledge about the rotors should not be a secret but it seems like it is.

[ttweed]

Originally posted by MT 912RS
That little bit of knowledge about the rotors should not be a secret but it seems like it is.

Ya, I asked my mechanic about it and he had never heard of it, and he's been wrenching on these cars for 18 years now. Thanks very much for the tip, I'll definitely try it when I have to replace the rear rotors on mine. Turning down the edge a little would be simple and cheap for any machine shop to do.

TT

[MT 912RS]

You can actually fit them on without turning them down it's is just very close to rubbing on the caliper. On some cars it may work...

[SprintStar]

Originally posted by Bram
Just wanted to to offer a big thanks to everybody who chipped in here -- particularly MT 912RS. I just bolted up a pair of early 944 rear rotors to my '67 S. They worked exactly as he said -- just turned the outside diameter down and on they went. Problem solved perfectly for a fraction of what I thought it'd cost. The traditional payment here in Australia for somebody who helps out like that is a case of beer (usually Victoria Bitter). So MT 912RS, if you're ever down here in Sydney there are 24 cold ones waiting for you. Thanks again.

Hello,

Can you explain the turning down process in more detail? Thanks!

Sprint.

[Bram]

The outside diameter of the 944 rotor is a shade larger than the original 911S rotor. As has been mentioned earlier you may just get away with it (ie. they're so close they mightn't bind inside the calipers) -- but I took MT 912RS's advice and had the 944 rotors machined to be exactly the same diameter as the 911 rotors. We're not talking much of a difference here -- so any reputable machine shop with a decent sized lathe and the right cutting tool will be able to turn the outside down (and because the cooling vanes of the factory 944 rotors don't make it flush to the edge of the two machine surfaces there's less material to remove). The job cost $40 Australian for the pair (that'd be about $30 US). Altogether too easy.

[SprintStar]

Originally posted by Bram
The outside diameter of the 944 rotor is a shade larger than the original 911S rotor. As has been mentioned earlier you may just get away with it (ie. they're so close they mightn't bind inside the calipers) -- but I took MT 912RS's advice and had the 944 rotors machined to be exactly the same diameter as the 911 rotors. We're not talking much of a difference here -- so any reputable machine shop with a decent sized lathe and the right cutting tool will be able to turn the outside down (and because the cooling vanes of the factory 944 rotors don't make it flush to the edge of the two machine surfaces there's less material to remove). The job cost $40 Australian for the pair (that'd be about $30 US). Altogether too easy.

Ok, by outside diameter, you are referring to the edge, outer rim like the crust of a pizza? That is to say that the 944 rotor has a larger circumference than a '67S rotor? Same thickness?

Then how is the '67S rotor different from the '68-on S?

Thanks!

Sprint.

[Bram]

Yeah, that's right: circumference of 944 rotor is slightly greater than 911S rotor. Otherwise they're the same thickness, offset, handbrake hat diameter etc. (and that's what I believe is the issue with using later 911 rotors -- the handbrake hat diameter changed, so you wind up with no handbrake.) There are only two other slight differences you may observe with the 944 rotor: it has a larger center hole than the 911 rotor -- but this doesn't matter seeing as how the rotors don't centre on a centre hub flange. The original 911S rotors are centred on the studs by way of two countersunk flat-head screws which physically bolt the rotor onto the hub in the right place. The 944 has similar countersunk holes -- but we found that they didn't line up with those on the 911S hub. You've got three choices -- either ignore the issue altogether and don't bother with the screws (though this may produce some shimmy), or drill and tap new holes in your hubs that line up with the 944 rotor holes (a permanent modification to your car) or just drill two new countersunk holes in your 944 rotors. We chose option 3. Make sure when you do this that you line up the handbrake adjusting hole first (and it does line up) -- before determining where to drill your two holes. With a bit of care and a decent drill-press it's a straightforward job. If it helps matters, take a 911S rotor with you when you go to buy the 944 item -- everything should become apparent. We found the whole process relatively simple and inexpensive. Hope this helps, Bram.

[SprintStar]

Thanks for the info! Very detailed. From what it seems, the '67S rotor is a one-year only item?

But is it possible to retrofit the '68-on rotors and handbrake assembly? Won't it be easier? Just a thought...

Sprint.

[Bram]

Hi SprintStar,

First up, I believe the '67 rear rotor was used in '68 as well. The problem is, as has been mentioned in an earlier post, that the aftermarket guys don't do them. I actually thought they were NLA from Porsche (which is not so) -- they just happen to cost $600 Australian dollars each (they're over $300 US each). This is a helluva lot of money for a pretty simple brake rotor. 944 rear rotors cost $165 Australian each (I think Pelican parts does them for something like $84 US each).

As I said earlier, any decent machine shop will turn them down for around $30 US for the pair. You should literally be able to drop the rotors off at your local brake and clutch service place and pick them up a couple of hours later. As for the hole drilling exercise, don't let my lengthy description of the job put you off -- it's quite straightforward. You'll have the new rotors on in half an hour -- for a total cost of around $200 US. This is something like less than a third the cost of original 911S rotors -- and, most importantly, you haven't made more permanent (and expensive modifications) to your car. In my opinion converting the handbrake assembly would inncur greater cost (and effort) and you'd only save 15 bucks per rotor over the 944 option (I think the '69 and later 911 rotors are about $70 US each.) Seems like doing it the hard way to me.

That said, maybe the handbrake conversion is cheaper and easier than I think (but then again, maybe there are other differences in the later 911S rotors that I'm unaware of that may make the job a little more difficult).

Ultimately it's your call -- I just thought the 944 solution was a great one worth sharing in detail.

Best of luck,

Bram.