oldguy wrote:

What if instead of using irelands 320i spacers for the diffs if you could mount rotors there and have inboard disc brakes? Anyone done this before or have pics of inboard disc brake setups? shave a ton of unsprung weight off the rear...

Couple of thoughts. Look at early Audi 100LS (had inboard disks in front). Then you have the XKE with rear inboard disks. The Audi's use of CV Joints would lend itself to your idea, but a lot of machining would be involved. I considered this until I thought of another couple of stranger ideas.

SOT to the inboard brake idea but any progress on the 2.3 head?
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We have planned it for our racecars and my friend was close to try it. I was quite worried about half shafts and joints durability. Especially because of frequent change of loading from pulling to braking. The slack (theres always some) in joints is making a the force quite brutal.

The plan was to machine mounts for calipers that would bolt under diff back plate bolts. Or maybe whole back plate with the mounts. Disks would go between half shaft joint, maybe with some locking tabs so something.

But we never did it - so go for it - I think you would be first.

Tommy

PS. I'm also interested about the 16V engine project.
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Racing is Life - everything before and after is just waiting!

soon as I'm done with my nissan I can pick back up on the 16v head project. It's much easier now that I've got my CNC worked out.

I like the audi idea. The joints themselves take a beating regardless of where the disk is placed and, if a bunch of re-engineering is required, why not start with the the bigger half shafts and joints from the 6cyl models? Even if the stock joints wear out prematurely, what does that really mean? 100k instead of 150k? Of course there is still the issue of a parking/emergency brake, but Jaguar solved that.

You could talk to lee about getting a hat machined to the bolt pattern of the CV/Diff flange - you could also probably build a caliper bracket and integrate it into the rear diff hangar off the chasis, but you'd need solid or at least hard urethane diff mounts.

I'd notch the CV, hat and diff flange with a sortof woodruff key style notch & groove so that the loads do not shear against the diff bolts.

There are stories of guys shearing half-shafts in moderatley powered cars. You need to be sure that the caliper stays connected to the wheel or it could be a major problem.

Once you have a hat machined the rotors & calipers are easy. Go for it & post pictures!
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I was not worried about wearing but breaking the joints. E-brake was not our concern because we have already left it out from our racers.
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Racing is Life - everything before and after is just waiting!

Frankly, I would think it'd be a problem of supporting the
stub shaft coming out of the diff well enough.

It's not designed for forces acting in that fashion, and when the car's under
power, the splines on the inside are loaded, tightening up the shaft.
When it's unloaded, the shaft can float a bit in the single ball bearing.

At the very least, it might be a pad knock- back problem.
As the rear brakes usually only see 30% or so of the brake force,
the shafts and such should be OK- I weld my diffs, and that puts a lot
more torque reversal on the shafts than the rear brakes do.

Also, cooling an inboard brake is really problemmatic on a sedan.
As calipers, rotors and hardware have gotten lighter, hardly anyone's
doing that anymore. You get a lot more air out in the wheel well...

But it would sure look cool as hell- do it!

t
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I have a car disease. There is no cure.
I'm not even managing the symptoms very well...