Disc Brake Kits - #3

Disc Brake Kits: First Prototypes

With a 68 VW bug in the shop in desperate need of disc brakes. I decided to make a few quick early prototypes. While the design has not been finalized yet, I feel like I am at a point to make some working prototypes to help finalize the design.

These were made on a 3 axis mill due to the material I had on hand and a machine that was available at the time. So I may run into some run-out issues do to the nature of the setup, but they should be usable.

 

First inner hub, outer hub and studs to hold inner and outer hub together

 

The studs to hold the inner and outer hubs together where designed , at this point, for M12x1.25 conical lug nuts. 

Holes countersunk for 60deg conical lug nuts

 

 Here you can see the earlier mentioned issue with using the Miata rotor with the 4.5" bolt circle and the VW 4 x 130mm bolt pattern. 2 of the studs from the rotor become very close to the 4 bolt outer hub. This will only be a problem with 4 bolt outer hubs, but I was able to minimize all effects by using the same thread pitch on the studs as the stock 4 bolt VW lug (m12x1.5) which allowed me to thread mill both holes at a location where the threads would "intermesh" to allow the maximum amount of material between the 2 interfering holes. In the end it worked great with no interference between the 2 threads.

4.5" rotor pattern on a 4 x 130mm VW outer hub.

 

Final assembly torqued to 90lbs and with bearing races installed next to a stock Ghia/Super Beetle rotor.

 

Test assembly with an import drop spindle and aftermarket ghia caliper

 

Two areas that need adjustments are:

1. When used with caliper brackets on stock spindles the hub and lugs interfere with the brackets.

Caliper bracket interference with the lugs/studs.

 

2. The calipers need to be shimmed to center properly on the rotors. I am searching for some stock Ghia calipers / rotors to further verify the measurements before making a final adjustment of this spec.

Shims needed under caliper.