Has anyone ever replaced the threaded part on the frame where the swingarm bolt screws into? I have a frame that the threads are worn to the point that they do not hold the bolt anymore. As a short term fix, I welded a 8mm nut to the end of the swingarm bolt, and then put an 8mm bolt through the frame screwed into the nut. It works, but for how long???? Any thoughts, options, ideas? Any frames out there for sale?
There is a 76 MC5 frame on eBay for $125 or best offer. Check out item number 204167571218.
Dave McC
Yeah I saw that listing Dave. Looks pretty rusty. Thanks for pointing it out!
Can you post a photo of the offending part? It's been a while since I have a frame down that far, but if it's like I think it is, is there enough meat around the original threaded hole to drill it out and tap it for a Keen-Sert threaded insert? These inserts require more meat around the hole for the threads, but I like them much better that a Heli-Coil. What size is the thread on the swing arm bolt? If it is like 10mm, and there is room around it for a 12 or 14mm threaded hole, I would go this route. Once you get the hole drilled and tapped for the external threads on the Keen-Sert, you thread that in until you get to the proper depth. The outer part of the insert is threaded and also has 4 slots for 4 pins that get driven in place to lock the insert. Anything that is excess and sticking out either side can be ground off smooth. In certain cases on the job, I have made custom threaded inserts out of bolts. If yo need to replace a 10mm thread, just use a bolt that is large enough to be drilled and tapped with an internal thread that is needed. Sometimes you can cut it pretty close if you have access to a lathe. Drill the hole through the center of the bolt, run the required tap into it it, then cut off as much as you need. Tape a Dremel cut off tool and cut a screw driver slot across one end so you can turn it into the threaded hole in the frame. You can lock it in place with red lock tight, and then stake around it with a sharp center punch to help out. I have put steel inserts into aluminum castings this way. I've done it as small as putting 4-40 threads into the middle of a 6-32 bolt with good success, and then put that insert into an aluminum casting for a muffler for a model airplane engine. It holds just fine. Applying JB-Weld to the threads as you insert it will lock it in place also. If I have explained it clear enough, I think you shouldn't have any problems. When the swing arm bolt seats, it tightens the head against the other side, so there is really not that much stress on the threads that you repair. Let me know what you think.
Type at you later,
Dan McEntee
Hey Dan, wow lots of options there! Not sure if I can do most of them but surely some great ideas to think about thanks! Here is a photo of where the swing arm bolt screws into. 51FB89D6-DCF1-4B6A-9DE6-1792ED6BD4CA.jpg
I would weld it mostly shut then drill and re tap.
Quote from: Mike Lenz on March 28, 2023, 10:13:18 AMI would weld it mostly shut then drill and re tap.
That's a thought.... I like what Dan is saying, but I don't think there is enough material for the oversize drill. I have thought about slicing accross the existing hub, and welding a nut onto that. I don't want to remove the entire hub due to creating issues with not getting the new nut exactly in the correct allignment with the axle.