Ok, little design challenge for you all.
Thinking about brake caliper on the rear of my challenge car, fdat (under 1k lbs with driver, basically a formula car frame with a Datsun body, 100hp 600cc Honda power).
For the rear brakes, I'm planning a single brake on the diff rather than wheel brakes. Here's my caliper (no slides, it has a piston on both sides):
One thought was to apply this caliper directly to the sprocket for a "sprotor". I'm convinced this would be "ok" but only "ok". Thinking of attempting to improve that.
I may also be able to add a real rotor, but it will be physically close to the sprocket. That means I'd love to put the hydraulic line "away" from the sprocket. To make it worse, my easiest and best close structure to bolt the caliper to is outside the diameter of the sprocket. So building to the existing caliper mounts would mean going out around the caliper (and rotor).
Soooooo, can I attach to this instead? These threads are currently used from the other side for the bolts that hold the caliper halves together. I'm thinking I would get caliper bolts that are much longer and therefore threads stick out the back here. I would bolt a bracket to those threads and then mount the caliper with that.
kb58
UltraDork
3/26/23 4:22 p.m.
It's not a black-and-white answer... it'll "probably" be fine due to the low vehicle weight, but with the mount so far off the disc axis, there'll be more torque on the connection. So where's the second attachment point?
Also, try to end up with the bleeder at the top, else it'll have to be removed to get all the air out.
I have never seen a caliper mounted using the outside bolts, always the inside. For that reason alone I wouldn't do it.
Noddaz
PowerDork
3/26/23 6:08 p.m.
And just where is the chain going to go? It sounds great to use a chain sprocket as a rotor. I guess it is hard enough. But after you clearance the caliper for the chain there isn't going to be much caliper housing left.
If that is what you were going to do.
One usually mounts the caliper on the "inside" of the chain, between the two sprockets where the chain doesn't run.
As long as the mounting is fairly stiff, I don't see it as being a problem. It only has to be as strong as the sprocket attachment...
OK....
First things first....You need to treat the Brake rotor and caliper as a system.
Figure out where the obvious position is for the rotor. Are you running a locked diff, or a spool?
If yes, it doesn't matter which side of the diff the rotor goes. If you are running an open diff, U have just made your life more difficult.
When you have sorted all of that out, then you can figure out how to mount the caliper. Caliper mounting is probably straight forward. But you gotta sort out the rotor mounting first.
Sound llke a fun project!
Keep us informed.
Rog
No really good reason why you can't mount your caliper using the clamping bolts but there is potentially one minor drawback to doing so depending how you actually do the mounting. Most trial bikes from this century use at least one of the clamping bolts to mount the caliper to the fork leg - see picture below of the 4 pot used on the front of current Beta's.
The drawback, of course, is that using both makes removal messy in a spilled fluid sense. As per an earlier reply it is well worth getting the bleed nipple at the highest point - don't be afraid to drill and tap if you need to. If you can't manage that you can always bleed off car with dummy rotor / pads in place.
R
Sorry all I was presenting two options. If I go with the sprotor, then yes the caliper has to fit inside the chain rather than clearancing the caliper so it fits around the chain. My main worry with sprotor is heating up the sprocket and ruining the teeth quickly.
But if I go with a separate rotor, then I might be mounting via the clamping hardware holes. Which is why I asked this question.
