Inboard Rear Disc Brakes - Plausibility

[dd-ardvark]

First off guys, not that your insight isn't any good on this forum, and I do want you to prove me wrong on that statement. It's just the question that I'm posing is generally not in the street scene of things. "Inboard Rear Brakes", If their so good, why don't you see them more. I know this question may not be for this site, but I'd like to run them on my Speedster Kit car. If you have insight into these..., Please enlighten me. I know their a high dollar item, so besides cost, what's the down side, you know..., the bad things to using them.

Is their a problem with transmission output stub axle flex and breakage?

With respects to hanging the caliper and disc in close proximity to the transaxle..., does it cause excessive overheating of the trans?

Is cooling a problem for the rotor / caliper itself?


I can see the plus side, that mounting the assembly inboard -vs- at the wheel would allow a very light unsprung wheel, although rotational mass would remain close if not the same.

I remember seeing these a lot in the early to mid eighty's on off road racers and a lot of European road race cars. Again please enlighten me with comments and criticisms.

Thanks, dd-ardvark

[Panelfantastic]

I don't know the tech reasons why OEM wouldn't do it but I'm willing to throw out some ideas about retro fitting a set.
I bet racers don't do it to keep the heat out in the airflow and to keep the clamping force close to the largest area of rotatating mass and for design/packaging reasons (they usually run big rotors and calipers).
The only place you see it in the aftermarket are street rods where cost is usually not a concern, you would have to have some pricey billet pieces made and you would have to design everything yourself.

[DORIGTT]

I've always considered doing a conversion like that for the 'coolness factor' but for practicality, my lowly Ghia doesn't have the performance specs or room to effectively do it while being cost effective. But here are some pages to check out on it.

http://www.jag-lovers.org/xj-s/book/...keUpgrade.html

Various cars with inboards standard to check out their system.
http://www.answers.com/topic/inboard-brake

A company that has kits for sprint cars. http://www.sanderengineering.com/cat26.htm

Scroll down to the lower items for Wilwood inboard kits.
http://azracemart.com/store/brakes.html

[Tedzbug]

it's a stretch, but the military HUMVEE has inboard brakes also.......... not that it helps you much..... just FYI

[R2.0]

Inboard Brakes Advantages:
- Reduces sprung weight/helps handling
- protects brakes from damage (fewer lines ansd flex lines)

Disadvantages:
- Takes brakes out of airflow/cooling problems
- Makes the rear assembly more complex (Only works with IRS, needs extended stubs with more support, etc.)

[yetibone]

The only production based cars I know of that use inboard brakes were Jaguar XKE, XJ6, and XJS. Mabye others within that marque as well.

Replacing the rear rotors on those is no fun at all. Most labor guides say it's a 10 to 12 hour job.

I believe the benefit of lower unsprung weight is outweighed by the complexity, inability to shed heat, and difficulty to service.

Also, in a VW, you may also have to use shorter axles.