Inboard Disk Brakes

[nimblemotorsports]

Seems to me a lot of significant advantages move the brakes inboard. No longer unsprung weight, weight moves to the center,
divorces wheel size to brakes. I'm thinking this might make sense with the 944 rear setup in the pinto, as the 944 disk are big and heavy,
and i need to change bolt pattern. Could do it on the Corvair project too.

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[dontlifttoshift]

The only upside is the loss of the unsprung weight......everything else is compromise.

Inboard rotors run hot as there is no air flow, they are typically undersized due to packaging and that exacerbates the problem. Maintenance is harder as the parts you need to change are under the car instead of on the side of it......on that note, I consider rotors to be a consumable. A whole bunch of disassembly to change a rotor sounds like no fun.

[JustJohn]

Second the above.

I've rebuilt 2 Jaguar IRS rears and removed the entire assembly on a few of these cars entirely because it is easier to service the brakes that way. Pad changes are hard, caliper changes are a swearing match, and seals do break down faster due to exhaust heat.

[cornfedbill]

All facts aside, inboard brakes are cool.

One issue is that you need to rely on the axle shafts and joints for braking. If you have a failure, you risk losing your brakes.

But I still like them, especially if you don't want to run large diameter wheels.

[BonzoHansen]

Second the above.

I've rebuilt 2 Jaguar IRS rears and removed the entire assembly on a few of these cars entirely because it is easier to service the brakes that way. Pad changes are hard, caliper changes are a swearing match, and seals do break down faster due to exhaust heat.

IIRC the r&r book time on rotors on the old jags with inboard brakes was like 11 hours.

[nimblemotorsports]

Just because Jag had a poor setup doesn't mean much of anything, everything on a jag took hours to fix!
In fact, it took me 5 days to remove the engine from a 944, hand wrenches needed everywhere, forget air ratchet,
so I guess a front-mounted engine is a bad idea? lol There are difficult to change outboard rotors in many cars too.

The advantages are not just unsprung weight, which itself is a big deal for some cars, maybe not so much for smooth tracks, but city street racing or offroad. It is funny, but reading through some forums, some guys say 'what is your problem, why aren't you using inboard brakes like everyone else?" lol.

It moves the weight to the center of the car, this makes more difference the lighter the car gets, like midget racers which use them, or sand rails, my 914 project is going to be rather light, so it would make more sense there. Putting the hot disks inside a wheel seems rather stupid, it is much easier to cool them inboard, if you duct air there.
Then the wheels can be solid covered which had better aerodynamics with fender skirts.

There is obvious fabrication to do, and if it requires having to fab a custom disk this is a big downside since one can't just buy a new one off-the-shelf.
I enjoy fabricate stuff, but if it breaks, there is no joy having to do it all again, usually in a rush!

So btw, here is the single center diff brake I put in my ultralight MG. Apparantly Forumula SAE cars do the same thing, 1/3 braking in the back, only needs one disk!

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[rickpaw]

I guess it's all depends on what you want to do to the car. Daily driver, then I wouldn't go thru the expense/trouble of doing inboard brakes, for reasons stated above. Race cars/trailer queen - why not.

[Skip Fix]

"There are difficult to change outboard rotors in many cars too."

My old full sized Bronco front rotor service required the entire front locking hub to be dissembled.