P-000011 Porsche 944 Kokeln Dual Master Kit
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While working on our 944 Rally project, we decided a 35-year-old brake booster and master cylinder were too dangerous to run down gravel roads at breakneck speeds. So, we attempted to find a “kit” that could be purchased and used to run dual master cylinders. Sadly, there was nothing available. After searching around a bit more, we found that their used to be a company called “Kokeln Racing Products” that sold a Porsche 944 Dual Master Kit. Unfortunately, Kokeln has long been out of business, taking the dual master kit with them into obscurity. We purchased a used kit from a fellow 944 racer, and decided to reverse-engineer the kit and share it with the community. Under normal circumstances, reverse-engineering an identical copy of another company’s product would be highly unethical. However, because Kokeln no longer exists, we believe that as long as the CAD files are used in a non-commercial manner, we are well within our rights to reverse-engineer this design.
Before taking measurements and drawing a sketch of the Kokeln dual master design, we need to make sure it is compatible with the latest universal master cylinder technology. In this case, we chose Tilton master cylinders and bias bars, because they offer free CAD models of those products. We downloaded the CAD models and imported them into our software. After taking a few quick measurements and comparing them to the Kokeln bracket on our desk, unfortunately, neither the master cylinder or bias bar is directly compatible. This means we will have to design our own bias bar, and then modify the master cylinder to fit.
Using digital calipers, the original design was sketched-out and then modeled in CAD.
- Thread Sizes
- M10 x 1.5
- M8 x 1.25
- M4 x 0.7 (91290A139)
You are welcome to download the high-resolution CAD files HERE.
Please be sure to respect my CC-BY-NC-SA license. Thank you for your understanding.
Unfortunately, since the Kokeln bias bar is missing from this kit, we need to modify the Tilton bias bar to fit, using universal components that can be sourced from places like McMaster-Carr.
- Parts Used
You are welcome to download the high-resolution CAD files HERE.
Please be sure to respect my CC-BY-NC-SA license. Thank you for your understanding.
In order to make the dual master bracket natively compatible with the Tilton 75-series master cylinders, and the Tilton 600-series bias bar, we had to increase the hole size for the master cylinder body, increase the overall length of the bracket, widen the interior channel, and completely change the design of the push bar. Aside from having to machine the bracket, and weld the new push bar design to the Tilton bias bar tube, everything has been created with basic universal components and tools. If you have a machine shop and some experience, I would recommend creating a more robust push bar design, as the fully-threaded rod can only handle so much abuse. As for the Tilton master cylinders, they have a very long push rod, which will need to be cut down to fit.
You are welcome to download the high-resolution CAD files HERE.
Please be sure to respect my CC-BY-NC-SA license. Thank you for your understanding.
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This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License