F: Frame Comet Frame Tie

davidd

Well Known and Active Forum User
VOC Member
I have always made the F106's for the BAR gearbox. As a result, I used an American bolt and had to make the splined nut. I turned it up on the lathe and put a 1/2" x 13 tpi thread inside for my bolt. I made it to the dimension with no attention to interference, but I used a chisel to stamp a few splines in place. Pushed it in with some Loctite and none have ever failed. I did not line bore, but on the F106's I cast up I worked hard to get everything lined up.

I am not suggesting that this is the best way. It worked for me with good alignment, etc.,

David
 

Black Flash

Well Known and Active Forum User
VOC Member
Maybe you can remake this lipped nut with a course o. d. thread instead of the splines and tap a thread into f106.
then screw in the nut with 638 or 648 loctite. I would believe this will do the trick permanently.

Cheers Bernd
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
These are not splines, as Frank Griffin calls them serations, I make them with a knurling tool with straight teeth, same hole and sleeve/nut knerl it then fit with assistance of a strong vice.
The damaged one you are talking about, how much is the hole out of round? If not too bad make slightly larger O/D knurl it and force it in, I removed this one and fitted a S/S one because Eddy s/s Stevens did it too !.
bananaman.

IMG_1379.jpg
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Certainly Bill,

Straight knurler. use it to make battery clamp knobs and rear wheel adjusters and some where I also have a straight knurling wheel mounted the other way to use as a boring when I do bearing housings to make a bearing fit more tightly
Diamond knurler uses two oposite handed helical wheels but is a little chunkier as it has 6 wheels in pairs and it all revolves round on a central axel but that is down on the big lathe down the road in Harvey's big workshop.
Not that he uses it much but handy for me.
IMG_1387.jpg
 

oexing

Well Known and Active Forum User
VOC Member
I cannot see any benefit of the splines, they do not hold any pull from the bolt, just prevent a threaded insert from turning in its bore while doing up the bolt. You´d typically go for a helicoil but I guess the mangled bore is too large for that. So instead I´d fabricate a bush with threads inside and out after finding a tap for the oversize F106 bore. With that lipped nut all the force from bolt load goes into the small cross section at the lip/head. So no wonder you can snap it and pull the knurled part into the frame tie - not great.
An even easier way is to line ream the frame tie to get a nice parallel bore out of the mangled hole. Then you can do a decent measure of the bore and fabricate a nice threaded and lipped ss bush with the 1/2 " thread and loctite it into the frame tie with type 638 or 648. Still all load will go into the lip cross section but there will be a bit more material after reaming to oversize first. No need for knurling,the Loctite cares for locking the bush safely while tightening the bolt.

Vic
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
Thanks for all your input. The bike in question is not mine, its not a matching numbers and it has been somewhat 'enhanced' 600cc kit,electric start and lots more so no need to fuss about keeping it original.

Based on comments received I propose to recommend to the owner that the elongated hole in the F106 be enlarged to a 'standard' size that is in alignment with the hole on the other side then make up a bush from aluminium or brass that is a light press fit (helped out with loctite) into F106 and has a bore that will accept a new shaft that will replace the gearbox upper bolt - this new shaft will be approx 3/4" longer than the original so when fitted it protrudes a sufficient distance out from the F106 to fit a washer and nut.

Other than purist cosmetics - are there any problems with this?
 

Bill Thomas

Well Known and Active Forum User
VOC Member
I cannot see any benefit of the splines, they do not hold any pull from the bolt, just prevent a threaded insert from turning in its bore while doing up the bolt. You´d typically go for a helicoil but I guess the mangled bore is too large for that. So instead I´d fabricate a bush with threads inside and out after finding a tap for the oversize F106 bore. With that lipped nut all the force from bolt load goes into the small cross section at the lip/head. So no wonder you can snap it and pull the knurled part into the frame tie - not great.
An even easier way is to line ream the frame tie to get a nice parallel bore out of the mangled hole. Then you can do a decent measure of the bore and fabricate a nice threaded and lipped ss bush with the 1/2 " thread and loctite it into the frame tie with type 638 or 648. Still all load will go into the lip cross section but there will be a bit more material after reaming to oversize first. No need for knurling,the Loctite cares for locking the bush safely while tightening the bolt.

Vic
Vic , The bit that snapped on mine was the other end, Standard it is 1/2" stud with a nut brazed on the end, But the new one I bought was Stainless !, The stud was one type of stainless and the nut was another,
It had been on there for a long time and some sort of reaction had happened, I put photos of it on the Forum,
I was a mechanic all my working life, Not known for over tightening things, But I had put a spring washer under the head, And one day as I was about to go for a ride, I looked down and saw the nut part was on the piss,
Soon as I touched it, Off it came. Cheers Bill.
 
Top