I want to run an OEM steering wheel with a quick release. That combination isn’t common because the quick release takes up space, modern OEM steering wheels are deep to accommodate an air bag and stacking the two moves the steering wheel too close to the driver.
The adjustable electric power assist (EPAS) column from DC Electronics (DCE) doesn’t contain any stalks and I was planning on welding an adapter to keep everything as compact as possible. However, the column contains a pressure sensor which would be damaged by the heat. According to DCE I would essentially need to destroy the column to remove the sensor. There goes plan A.
Plan B was to adapt a steering boss to fit the spline. This was when I learned that the column is sourced from a Renault. Unfortunately the spline is some proprietary French invention (D’oh!) and DCE indicated that the only aftermarket steering boss was available from MOMO. So I was in a bit of steering wheel boss hell…
In heaven the French are the cooks, the Germans are the engineers and the English are the police. In hell the French are the engineers, the Germans are the police and the English are the cooks.
The MOMO steering boss has a steel spline and a steel collapsible section cast into an aluminum hub. The collapsible section takes up a lot of space and isn’t required because I have a custom lower shaft that provides over four inches of zero-resistance collapsibility BEFORE the steering wheel hits me. So I cut the steel section off with a bandsaw and faced the surface on a lathe. I was concerned about machining the steel embedded in the cast aluminum, but that went better than I expected. It was at this point that I realized that I’d need to remove the outer aluminum shell to accommodate the six mounting screws for the adapter. Once that was done I realized that I’d also need to machine the inner hub as well. All in all a lot of time on the lathe. As can be seen in the picture below there were some air pockets which don’t provide a warm-fuzzy feeling.
To accommodate the 70 mm hole pattern for the quick release the outer shell had to be completely removed and the OD of the inner hub needed to be reduced
Air pockets in the MOMO cast aluminum
MOMO unit with collapsible section cut off, outer shell removed, inner hub reduced and six mounting holes drilled. Note the steel pieces that remain in the hub.
Joel, who also has a DCE EPAS, mentioned that OMP makes a compatible steering boss so I ordered one from eBay in the UK. Unlike the MOMO unit, the steel collapsible unit is attached with four screws. I was then able to quickly machine the front and rear faces. I didn’t like the lip on OD, so I cut it off in a lathe. Once machined, the OMP is about 0.8” shorter than the MOMO.
Front side of OMP being machined
Backside of OMP. I probably didn’t need to machine this side, but I wasn’t sure how I was going to mount the quick release and it was easy to do. The lip which I also machined off is the outer ring sitting on the wood table.
MOMO on left and OMP on the right. Removing the outer shell on the MOMO reduced its OD. The MOMO has been drilled with the six holes to mount the quick disconnect whereas the OMP hasn’t been drilled yet (the four holes were used to mount the collapsible section).
MOMO on left and OMP on the right
For my purposes, the OMP unit is a much better starting point. Less machining, no air pockets or steel remnants in the casting and a reassuringly robust piece.