Topic: Drilling and tapoping a bolt - For those who know their metal

[KB02]

As I postulate possibilities for mounting Rearsets on my 750 F1, I had a question:

If you had read this thread: http://www.sohc4.us/forums/index.php?topic=25671.0 You will have seen that I bought a set of rearsets off of Ebay with mounting points that are 110mm apart. I thought that these would be able to mount right on the engine mount bolts. As it turns out, I am an idiot and on the bolts I was planning on using is the rear swing arm bolt.

Anyway, this brings up two questions for me to ask:
#1.) Would it be possible to use the bolt as a mounting point for rearsets, or would it not be advisable to mess with the swing arm bolt?
#2.) Is it possible to drill and tap a hole in the ends of this bolt, and then bolt the rearsets into these hole? Would this weaken the bolt too much for safe operation?

[rhinoracer]

I think the swingarm bolt on my 71 750K is already drilled for a zerk fitting, although it's a very small hole compared to what you would need.

Yes, opening up the center of that bolt will surely weaken it.

No, I wouldn't advice on trying to mount a stressed component on a bolt set to allow movement of another component.

That's just my 2 cents, let's hear from other members.

[Soos]

On using the swingarm mount bolt as the rearset mount point(or one of them) I would strongly advise against...
and as to drilling and tapping (i'm assuming you mean the swingarm bolt)....
again I would say no.

If you used the motor mount bolts, I would say the first option sure, but the second, no.


l8r

[jevfro]

I would also look for other alternatives.  I also jusbought a pair of those rearsets, http://www.sohc4.us/forums/index.php?topic=25671.0 and mine are spaced @ 78mm center to center.  I am contemplating just using clamping brackets to attach the rearsets like ohiocaferacer shows in this link http://www.sohc4.us/forums/index.php?topic=5724.0.  It is tempting to drill into the part of the frame there where it is boxed in and just use grade 8 bolts and nuts (if I ccould get them to line up in a comfortable position).  I'm concerned that this might also be a bad idea and weaken the frame.  I know alot of ppl just weld a piece of bar stock to the frame and drill that and bolt their rearsets on there.  I might just go this route but I'm a little hesitant to weld on my frame after hearing, if not done correctly (and what is correct?), that can also weaken things.  I know I'm paranoid, sorry...  :PThe strongest way would probably be like the dunstall's mounted. you could make a mounting plate and attach it to the frame via, some sort of mounting clamp, or a u-bolt, and a maybe a motor mount bolt or two.  I know it's most likely overkill but I'd rather be on the safe side as it could really suck to lose a rearset at the wrong time.

[KB02]

yeah, I pretty much felt like a complete A$$ after I had ordered the rearsets and then realized that I was thinking of the swing arm bolt as a Motor mount bolt.

That's okay. I'm not out of ideas... yet. And my dad is a machinist, so like I said, I'm not sunk... yet...   

Yeah, the reasons I would like to avoid welding anything to this frame are 1.) The obvious issue of doing it "Wrong" and screwing something up, and 2.) Everything that I have done to this bike has been bolt on: I want to leave the bike in such a manner that if a subsequent owner decided they want to make everything original again, there are no mods to the frame that they would have to "fix"

Like i said, I still have some ideas.

[old750]

If you drill the swingarm bolt you can't grease it anymore. I found post a while back that had these clamps that can go on the frame. They are like 10$. Usually parts shops sell them.

http://www.jpcycles.com/groups.aspx?LID=818d032e-7a88-48ae-b68a-7d6e09b825b4&DID=d7a33dbb-d2d0-4105-a63f-c662532d5201

[rhinoracer]

I want to leave the bike in such a manner that if a subsequent owner decided they want to make everything original again, there are no mods to the frame that they would have to "fix"

Like i said, I still have some ideas.

Unless you cut a piece off the frame, welded brackets are pretty easy to remove and return the frame to stock. If I'm modifying a bike I like it to look like it's built-in not bolted-on, there's only so much you can bolt-on to a bike before it starts to look funky. But that's just me. Post some pics when you're done, those rearsets look trick.