rx7mark
Guru
This weekend I finished my Emeljay mod for my T50 commuter. I did this mod not for aero performance, but I wanted a more adjustable seat to handle bar relationship, the way it was I had to buy new stems every time I wanted to try a new seat angle or handle bar position.
The over all impression is great, the steering is a little different but is more precise than the old version. Better for me is that I could lean the Thor back a little more, now at about 34 degrees, though sort of hard to measure precisely on the Thor. I used a board on the back of the center part of the Thor.
Now some details. I noticed that a 31.8mm seat post with a rack attachment was exactly the same width as the existing steering mount on the fork. They come with a little lip to keep it located at the top of the seat post that has to be filed down. This pic shows one finished and one left to file.
The next step was to fabricate to flat plates to connect the stock steering bracket to the two seat posts. The first picture shows the plates mounted. They needed two washers on each side to match the original thickness. I made the plates from 6061-T6 .125 thick, using a hack saw and files to finish and debur the edges. I did bolt them together during filing and drilling to make sure they are identical. In the second picture you might be able to see the chrome spacer I cut from the taller steering extender that was included with my T50 but wasn't used in the original build. I cut it down to length and then split it longitudinally with the hacksaw to make sure I could get it off in the future, if required. You might just be able to see the vertical saw cut.
Now here it is assembled. Notice the oval hole, that is to get access to the allen head bolt that tightens the upper seat post clamp to allow for adjustment. I used the same 2 foot long 1.25 inch OD tubing that Emeljay used. Lucky for us T50 owners no sanding is required. The mounting hardware is all stainless allen head screws, 5mm for the rack mount holes on the pair of seat post clamps.
The trickiest thing was the bar stem mount to the tube. I wanted to reuse my Soma Gator bars which are already 31.8mm. So I really needed a 31.8 x 31.8 stem, which do not exist. But I had a really nice machined aluminum short stem from a previous bar location trial, that was 31.8mm on the bar side. I just needed to have the stem side machined out to 1.25 to match the slider tube OD. A buddy of mine traded some golf club building and did the deed on his post mill. Here you can see the stem in its new home. Note the Wahoo is now mounted right on the stem, I just had to get longer zip ties.
Sharp eyes might note in the main picture that the seat struts have been replaced with new parts also, I will post pics next of those parts.
Let me know if you have any questions.
Mark
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