I'm currently in the middle of a refresh on my 24 Roadster. As I wait for milder and drier weather to paint, I decided to start on the top bows. I found a couple earlier posts that showed the overall lengths and exposed lengths between the irons. When I went to test fit the front bow before riveting, I've got about 3"extra and the clamps don't even come close to lining up with the windshield stanchions. The lengths I found also get progressively longer from front to back. Shouldn't the middle bow be shorter so that they nest when folded down? I've learned the hard way to not take for granted that anything the previous owner fabricated is correct, so I'm afraid to use the old bows as patterns, especially since I've got so much invested in a replacement top kit. Does anyone have the proper lengths for these pieces?
If I recall (it has been nearly 5 years ago) I had to trim the length of my Lang's reproduction bows to fit, but I was installing roadster bows and irons onto a 1924 cut-off touring car (see my profile picture).
I trimmed the width of the front bow as required so that the windshield clamps fit onto the windshield posts properly.
I trimmed the width of the rear bow as required so that the ends of the sockets fit naturally onto the body irons without strain.
Once the width of the rear bow was set, that set the distance between the sockets of the middle bow, and I was able to trim the middle bow as required so that if fit into its sockets without strain.
For stuff like this, I use the "trim only half" method. I measure to determine the amount that needs to be trimmed, then only trim half that amount before checking the fit again. That way, I sneak up on the correct length without trimming too much.
At some point I plan on doing the roadster top on my 25 cut off too.
They do not nest, when folded they are stacked.
These are wood bow dimensions that work for factory style top irons.
’23- ’24 Roadster
Front 33” Middle 32 ¼” Rear 32 ¼” Top of seat to top of rear bow 22”
Those measures are the exposed spans from end to each end of the metal iron sockets. The actual wood bows are longer, as each have 2 1/2" long undercut ends that inserts into each iron socket, and held with rivets.
Shown are '26-'27 runabout wood bows, they are longer, as the front bow is 36" span between top iron sockets metal to metal ends. The undercut is for insertion to the iron.
The top assembly when folded will stack, without nesting the bows. The front irons lock with pins to the rear iron, and sandwich on the center iron.
Thanks for the quick responses everyone. This project is starting to pick up steam toward the finish line. The expertise and experience on this forum has been a huge contributing factor to fill in all the blanks not covered in the manuals.
Be sure to use semi tubular rivets. Some vendors are selling solid rivets which are not correct.