Snapped Shock Mount

[Mr.humbucker]

Stipping down a 1982 GS650G in order to have the frame sand blasted and powder coated. The previous owner had extension bolts on the one top shock mounting bolt/thread which snapped off when I was taking it off. There is a wee bit of the thread left, likely enough to get a chrome nut on it. My question is should I remove the snapped bolt and then get a new bolt welded on? If I were to do this where would I get such a replacement bolt as it is quite thick at the part upon which the top shock mount sits and then rapidly tapers to the threads.

Thanks, as always to those who offer their advice and experience.IMG_0681.jpg

[Phred]

For something like that, I would get one machined. In our Vintage club, there are a few members who have mini lathes in their basements and fabricate their own unobtainable parts. Could be easily done from stock material, the thread would not necessarily have to be metric. There must be someone in your area that can do this easily.

[chuck hahn]

Start at post 27 of my Blue 1000C build thread

http://www.thegsresources.com/_forum/showthread.php?248066-Blue-78-1000C-project&highlight=Blue+78+1000+project

[Sam 78 GS750]

I wouldn't trust that stud. There's a couple of threads left, but Chuck's repair looks pretty straightforward...

[Mr.humbucker]

Thanks - I am of the same opinion at the end of the day. I have threaded the nut on and it holds well but there's a reason that there are more than two turns of a thread on a bolt. I am sure there are instances where the pressure on a nut is much greater when riding than sitting in my garage. Chuck's solution of the Kawasaki stud is a good one but yikes that stud is expensive. I may see if a buddy of mine who's a machinist by trade and has a shop will whip one up for me. His first bike was a 78 GS550 so I am thinking he'll do it for sentimental reasons! The other option is for me to buy a small metal lathe and welder. Shouldn't be a problem to make up a stud myself after all I took a half credit course in high school 41 years ago, still fresh in my mind. As for the welder, heck that's what Ewe-Tube is for. I am sure my wife won't mind when the bank account bumps down a few digits after the purchases.

[chuck hahn]

Its a 12MM smooth area. So some 12MM round stock lathed down so you an run a die for the acorn nuts will be ideal.

[Mr.humbucker]

Do you think a 12 mm shoulder bolt work here if the length of the shoulder is correct?

https://www.boltdepot.com/fastener-information/Shoulder-Bolts/Metric-Shoulder-Bolt-Dimensions.aspx

[chuck hahn]

Threads will probably chew up any rubber bushings. Probably why they went with smooth for the shock eye to rest on.

[chuck hahn]

Maybe a 10mm bolt ( at the threads) with a bushing over it would work. Drill and tap the frame and just bolt the shock onto the bike?? Use a few washers like were on the original stud to get the shock trued up and down nicely.

[Mr.humbucker]

From what I see the shoulders bolt do not have threads for a good portion of it length from the head to the threads as per the link chart/illustration below. Seems the "smooth" part or the shoulder is 12 mm and the threads are 10 mm x 1.5 and the threaded portion is 16.4 mm. The length of the shoulder is the key ... it has to go through the frame and then support the eye of the shock.

https://www.boltdepot.com/fastener-information/Shoulder-Bolts/Metric-Shoulder-Bolt-Dimensions.aspx

[chuck hahn]

Yes...i was picturing a fully threaded bolt. Guess that would be a flanged bolt up at the hex head. my bad.

[Mr.humbucker]

Thanks - this is what I really like about this forum - it makes me think and learn. Wish I had more of that attitude when I was in school ...

Seems I can get a shoulder bolt pretty easy that is 80 mm in length, 12 mm diameter at the shoulder and a 10 x 1.5 thread for the remaining 20 mm (where the acorn nut goes).

Minor issue is I "think" the thread for the acorn nut is 10 x 1.25 ??? If there's anyone out there that can decipher the Suzuki stock number and tell me I'd appreciate it.
09145-10001

[Sam 78 GS750]

The acorn nut is 1.25 pitch. I wouldn't worry about that. Just find one that's 10mmx1.5 for that side, and make sure you don't mix up sides during any future shock removal.

[Mr.humbucker]

Good advise - seems the 1.5 is easy to find. Thanks for you suggestion.