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350mm rotor upgrade

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Old 08-31-2021 | 09:49 AM
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Default 350mm rotor upgrade

I wanted to upgrade to slotted 350mm rotors. My stock drilled rotors got pretty ugly after the last track outing at watkins glen. I ordered the bushings and bolts from the guy on ebay a couple weeks ago. I sent a few messages and have not heard back. I have more track days the following weekend so I only have a week and a half to sort it out. Does anyone have info on making your own spacers and what bolts to source. I have a CNC router that I can cut aluminum on. I would like a back up plan in the event I do not get the parts I ordered.
thanks
Todd
Old 08-31-2021 | 10:52 AM
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I am in exactly the same boat - need the new rotors for 9/7 at Lime Rock.
My research has shown that the longer caliper bolts are the same as 997TT caliper bolts: M12x1.5 85mm long.
The caliper spacer, I have found several references to it being 12mm thick.

Now, I do happen to own a machine shop so making the spacers is no biggie. I would love to try the Rennkit finned spacers, they're just not in my budget right now.
For the caliper bolts I am going to use these:
https://www.belmetric.com/12x15-fine...ad-p-3659.html
They're 12.9 M12 socket head cap screws (same as Porsche uses) 5mm shorter. If they look too short I will get 100mm socket head cap screws and cut them down. Bel Metric is 30 minutes away so I can do a will-call and get them same day.
Eventually I plan to change to the caliper bolts.

I should have all these parts on Wednesday and I'll see what happens.
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Old 08-31-2021 | 11:02 AM
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I have made spacers for a couple of cars in the past - on a lathe. It was pretty straight forward - cut the hub to the appropriate size, stencil in the bolt pattern and drill it out. I used 3mm and 6mm stock to start with, and simply lengthened the bolts accordingly.

Doesn't tire rack have this stuff in stock? It'll save you a bunch of time if they do.

Old 08-31-2021 | 11:33 AM
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Not wheel spacers, I would never bother making those when I can buy nice ones. These are spacers that go under the caliper bolts to move the caliper 12mm out from the center of the rotor, allowing a 350mm rotor to fit where a 330mm rotor originally was.

Since you've got PCCB you already have 350mm rotors and six pot front calipers. The rest of us iron rotor guys have been making do with 330mm and four pot fronts. I'd like to get a set of the six pot calipers, perhaps next year.
Old 08-31-2021 | 11:36 AM
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I have 1/2 aluminum flat stock here. Do you thing that would work? And then I can just order 997TT bolts with my calipers.
Old 08-31-2021 | 11:39 AM
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Just order the kit from Freddy Lewis.
Old 08-31-2021 | 11:44 AM
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Who is Freddy Lewis?
Old 08-31-2021 | 11:52 AM
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A member here who sells the caliper spacer/bolt kit to retrofit 350mm rotors. Search for him and send him a message. I'm running his kit and it works great
Old 08-31-2021 | 12:03 PM
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thank you
Old 08-31-2021 | 12:27 PM
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Freddy is busy starting a new company so he may be behind on this. You can connect with him on facebook, he is usually on it.
Old 08-31-2021 | 12:32 PM
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Originally Posted by 02996tt
I have 1/2 aluminum flat stock here. Do you thing that would work?
I think 1/2 inch (12.7mm) might be a tiny bit too big. I can tell you in a day or so.
Old 08-31-2021 | 12:38 PM
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Originally Posted by theprf
I think 1/2 inch (12.7mm) might be a tiny bit too big. I can tell you in a day or so.
You can mill that down - I thought I saw a set of drawings for these adapters somewhere.

There are definitely drawings of the caliper online with dimensions - and if the spacer is 12mm thick, that does seem to coincide with the increase in diameter of the new rotor.
Old 08-31-2021 | 12:42 PM
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Yes, I am going to make the caliper spacers on my lathe so I can make them any thickness. I was thinking more of 02996tt's question about 1/2" flat stock, which may be a bit too thick. Also mill finish 1/2" stock can be anywhere from 0.525" to 0.490" thick.
Old 08-31-2021 | 12:44 PM
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Got it - but he has a little CNC router thing - 1/2 (as long as it is uniform) should be pretty close, no?
Old 08-31-2021 | 12:51 PM
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I have an 8K lb machine that is very stout. I use it for milling wood but with the right cutter I can cut Al. I can surface it to 12mm without an issue. If I am going through the trouble should a make a plate so it acts as a heat sink or are the bushings just fine?


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