![\"\"](\"https:\/\/datsunworks.com\/Blog\/wp-content\/uploads\/2025\/08\/image.png\")
<\/a><\/figure>\n\n\n\n<\/p>\n\n\n\n
I bought a used TR6 gearbox and gutted it. I then scanned it with my white light scanner.<\/p>\n\n\n\n <\/p>\n\n\n\n I then started the solid modeling process using my existing TL70 parts and using the mesh as a guide to make sure I pickup the necessary features.<\/p>\n\n\n\n <\/p>\n\n\n\n I bought a used TL70 so I could mock up the shifter. In order for this to work the shifter has to be in front of selector rod and that was causing a lot of geometry uncertainty. Generally the way I work is to prototype with plastic and then get as much data as I can and adjust. Rinse and repeat. Since I already had a ton of data from designing the Datsun shifter I was able to get good results on the first try. It shifts and with a better link bar it will be fine. The position of the shifter fore and aft lines up with the existing opening. <\/p>\n\n\n\n <\/p>\n\n\n\n Based on the success of the shifter I decided to go ahead and make the foundry pattern.<\/p>\n\n\n\n <\/p>\n\n\n\n While waiting on bell housing castings I figured I\u2019d work on a new test rig that I\u2019ve been planning on doing. We test each and every bell housing two times for alignment. The test method is we install a master front cover in the bell housing along with an input shaft and bearing.<\/p>\n\n\n\n <\/p>\n\n\n\n We then bolt this up to a test block and crank with the appropriate pilot bushing installed. We spin the input shaft and make sure there is little to no drag. The first test happens during the machining process. The second test is identical except it\u2019s done with it\u2019s forever cover installed and right before it gets boxed up. <\/p>\n\n\n\n The Triumph transmission dropped right on the dowels and after tightening the hold down bolts the input shaft spins freely and the bushing is correctly positioned.<\/p>\n\n\n\n <\/p>\n\n\n\n Now that I have this data I can easily design the pilot bushing adapter based on the known location of the Triumph bushing.<\/p>\n\n\n\n <\/p>\n\n\n\n Picked up the first 2 castings today and they look pretty good.<\/p>\n\n\n\n <\/p>\n\n\n\n I built a mock up rig in order to get the shifter and cross member in the right place.<\/p>\n\n\n\n <\/p>\n\n\n\n Here is The TL70 with the prototype bell housing. <\/p>\n\n\n\n <\/p>\n\n\n\n It looks like the cross member on 73-76 cars may work using the existing bosses on the TL70.<\/p>\n\n\n\n <\/p>\n\n\n\n Finished up the shifter. Works great. <\/p>\n\n\n\n <\/p>\n\n\n\n <\/p>\n\n\n\n Video of running through the gears<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n
\u200b
Since I don\u2019t have a Triumph block and crank I figured this would be a good time to build the rig. As it sits I can test Datsun and Triumph bell housings. Positions 3,4,5, and 7 are for the Datsun and 1,2, and 6 are Triumph. I have .375\u201d dowels in all three blocks since that is what I measured when I reverse engineered it. Based on what I have read the dowels on 6 and 2 are the only ones it uses. The center block holds the pilot bushing. I have it set up with a Triumph bushing in it\u2019s correct position based on the wear pattern I picked up from the old transmission.<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n