Brake rotor general "catalog"?

[69427]

Just curious if anyone knows of a site or source for brake rotors that could be ordered by size (and offset), not by make or model of car. Working on a project, and I can save some time and labor by finding a specific rotor for the application, instead of modifying the caliper mounts and rewelding stuff.

Thanks for any information.

 

[BBShark]

I used to have a Brembo catalog that had rotors by dimension. I cant find it now but Brembo does have a search by dimension at:

https://www.bremboparts.com/america/en

I do have some catalogs (EBC and Australian) that have rotor dimensions:

 

[69427]

I used to have a Brembo catalog that had rotors by dimension. I cant find it now but Brembo does have a search by dimension at:

https://www.bremboparts.com/america/en

I do have some catalogs (EBC and Australian) that have rotor dimensions:

Those are the general type of lists I'm interested in, but I'm looking for an odd size so I need to find a (long) list of just the dimensions themselves. Basically I'm trying to replace a 12" rear rotor off a late C4 suspension with an 11.75" part on my street rod truck. I'm mixing and matching early and late rear suspension and brake pieces, and I'm stuck either doing some welding/drilling/reshaping of the caliper mount, or putting a smaller diameter rotor on it for a near bolt-on fit.

I've been told "elsewhere" that I can't do this, and I don't see any technical reason why I can't.

 

[BBShark]

You should be able to search 11 3/4 inch rotors on the Brembo site. I found Mercedes rotors for mine. I had to re-drill for GM pattern but found exactly what I needed.

Or, could you turn the rotors down from 12' to 11 3/4"?

 

[69427]

You should be able to search 11 3/4 inch rotors on the Brembo site. I found Mercedes rotors for mine. I had to re-drill for GM pattern but found exactly what I needed.

Or, could you turn the rotors down from 12' to 11 3/4"?

I kicked around doing that, but I don't have a lathe, so I would have to contract that out. For the same cost I hopefully could just buy some garden variety rotors (as these parts would have a pretty easy life on the back of a street rod pickup).

Just engineering curiosity: What kind of fixture did you build to be able to accurately drill the new bolt pattern in those rotors?

 

[BBShark]

You should be able to search 11 3/4 inch rotors on the Brembo site. I found Mercedes rotors for mine. I had to re-drill for GM pattern but found exactly what I needed.

Or, could you turn the rotors down from 12' to 11 3/4"?

I kicked around doing that, but I don't have a lathe, so I would have to contract that out. For the same cost I hopefully could just buy some garden variety rotors (as these parts would have a pretty easy life on the back of a street rod pickup).

Just engineering curiosity: What kind of fixture did you build to be able to accurately drill the new bolt pattern in those rotors?

First I opened up the center bore on a lathe to match the Corvette hubs. Then I made a plug that I could clamp to the mill table that would allow me to center (on the hub bore) for all 4 rotors.

So I had XY co-ordinates for the 5 x 4.75 pattern. The fronts I was able to drill for the studs and the screws (to replace the rivets). The rears had large holes for the Mercedes lug bolts. I milled a hole for the studs that was large enough to encompass the Mercedes and threaded aluminum pieces onto the studs to center the wheels.

I think your challenge is finding 11 3/4 rotors with the correct GM lug pattern, offset, thickness and hub bore.

 

[69427]

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I think your challenge is finding 11 3/4 rotors with the correct GM lug pattern, offset, thickness and hub bore.
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You are correct!

 

[BBShark]

What about 2-piece rotors where the rotor is bolted to the hat?

 

[phantomjock]

That is a good approach - but finding a combination of hat, with correct wheel pattern, depth and matching mount hole, well, equally frustrating! Wilwood has some help, but not a full catalog last I checked.

Cheers - Jim

 

[69427]

What about 2-piece rotors where the rotor is bolted to the hat?

Well, at the risk of sounding silly or hypocritical, I've spent the money to do that on the Corvette, but I'm having difficulty justifying the money for two piece rotors on a modest performance usage street rod pickup.

I suspect down the road I may just have to accept reality, and pay to have the current 12" rear rotors on the '94 C4 suspension cut down to 11.75".

 

[69427]

What about 2-piece rotors where the rotor is bolted to the hat?

As I mentiomed above, I've got two piece rotors on the '69, but currently only on the front (the rear has stock C4 rotors). Looking at some old paperwork I see that the one piece rear rotors are about 3# heavier than the two piece fronts. Given that I've run into a wall trying to pull more weight off the car, maybe I'll do some searching over the winter for the correct depth hat to put two piece rotors on the rear. I've been running pretty abrasive brake pads the past few years, and the current rotors are showing some wear.

Meanwhile, I did some rough power sanding on the OD of the 12" rotor and took about a sixteenth of an inch off a length of the circumference. The caliper now bolts on, but there's minimal/no clearance between the rotor OD and the caliper steel slide bracket. Looks like milling a full eighth inch off the radius will get me the clearance I need.

 

[BBShark]

Mike,
I could turn the OD down. It would be easy. Shipping might be the hardest part.

 

[69427]

Mike,
I could turn the OD down. It would be easy. Shipping might be the hardest part.

I greatly appreciate the offer. Thank you. I'm currently in the middle of trying to figure out which option/direction I'm eventually going to go on this. The possibilities I'm kicking around are:

1) Have .125" cut off the rotor radius, make two 9/16" spacers to center the caliper and then everything just bolts together.

2) Keep looking over the winter for an 11.75" OD, .81" thick one piece rotor, make the appropriate thickness caliper spacer, and everything just bolts together.

3) Pull the 11.5" rear early C4 rotors off the '69, and mock up the setup to see if the reduced OD is still acceptable. In the event that the pads aren't sticking up higher than the OD of the rotor, then use these rotors, and use this as an excuse ro buy lighter weight two piece rotors for the '69.

Right now the '69 has the higher priority for my time, as I've got to pull the engine to replace the cam (a small chunk broke off of one of the lobes for #7 cylinder), so I've got all winter to finally make a decision on the truck brakes.

 

[BBShark]

Yeah, I can see where the 69 goes to the front of the line. Sounds like that will keep you busy for a while. And, I'm sure you will do some more tweaks "while your in there".

 

[69427]

Yeah, I can see where the 69 goes to the front of the line. Sounds like that will keep you busy for a while. And, I'm sure you will do some more tweaks "while your in there".

Well, in addition to working on the engine interior, one other tweak I've thought about for a long time was to move the engine to the right another inch to reduce the heaviness of the driver's side of the car. On some truck scales the left side is 40# heavier than the right (and obviously substantially more once I'm seated in the car). I've already moved the alternator and battery to the right side, and significantly lightened several parts that are "stuck" on the left side (steering column support bracket, brake booster and master cylinder, and the p/s pump). So, I thought about the engine, but when I took a serious look at it the other night I see that I have only a finger's thickness of space between the right side UCA and the block. So, that idea is shot to hell.