Beware Shiney Comets

Bill Thomas

Well Known and Active Forum User
VOC Member
Just been trying to make my Comet Faster,I blame that Greg!! Looking down I saw the top gearbox fixing bolt, The big one that goes at the bottom of F106, The head looked , Not flat ! I bought it some years ago, I think as stainless, As you know the standard one is a Stud with a nut brazed on, I changed a few bits to make it more Shiney, Can't remember where I got it from, The nut is not Magnetic, Stainless ? But the stud is, But it has that stainless look about it ! Something Funny is afoot !! Cheers Bill.
001.JPG
 

davidd

Well Known and Active Forum User
VOC Member
Bill,

The warranty is probably expired by now. It is a nice clean fracture!

When I was installing the BAR in the racer I thought I would save the original bolt for a stock machine. I pushed out the insert in the other end that the bolt threads into and made a new insert with an easily available thread. This way I could shorten an "of the shelf" 1/2" bolt to do the job.
100_1526.jpg


David
 

Bill Thomas

Well Known and Active Forum User
VOC Member
The funny thing is I went straight to my tool box and picked up the old one !! Now I have to paint it Silver again !! Looking Rubbish !. I wonder if it was chromed to make the end of the stud shiny, Can you chrome stainless ? You can see signs of Rust inside the nut, Strange, Cheers Bill.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Hello Trev, Looks like the nut is just screwed on, The old one was screwed and brazed, If the stud was not cromed it would go rusty, You can lift it with a magnit, But the nut you can't, ie Stainless. I know I did it up tight some years ago, Never had anything like this befor. I have seen befor that chroming can make things brittle ? Cheers Bill.
 

clevtrev

Well Known and Active Forum User
VOC Member
Could still be stainless, even if you can lift it with a magnet, it`s called Martensitic, as opposed to the Austenitic that you know as stainless. The crack I see here is similar to a martensitic stainless break, but that usually occurs after the material has had some heat applied, i.e. welding, but that does not appear to be the case here, maybe someone tried to braze it at some time. Martensitic can go rusty, when in contact with another electrolytic material.
Any electro plating can potentially be subject to hydrogen embrittlement, if not given the right heat treatment immediately after plating, but you will have to specify that to the plater, because they don`t normally bother.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Cheers Trev, So I think we are back to two types of stainless, I said I thought the stud looked stainless, So it must have been put together with Loctite So you can unwind it . Wish I could remember where I bought it , They should be told, I don't keep the bills in case the Wife sees them !! Cheers Bill.
 

john998

Well Known and Active Forum User
VOC Member
Hello, both the silencers on my bikes are chromed stainless. That way they dont yellow with heat.
You have to be careful with stainless in any stressed application especially if you dont know the grade.

John.
 
Top