c15 left hand footrest stud, what thread

[shoal48]

Mornin'all
Does anyone know what thread the stud is which secures the left hand front footrest on an early (60/61) c15. The stud is part 40-4807.

I got a frame a little while ago to rebuild the box of bits that was once a bike and realised yesterday that the stud had been snapped off in the frame and powder coated over. I know its left hand thread and taper easy-out wont shift it so will need to drill out and re-tap.

I have ordered a new stud/nut but does anyone know of a supplier who might be able to supply the correct left hand thread tap?

[DAVE BRADY]

Hi,

Try Tracy Tools.

Dave.

[shoal48]

They look promising Dave, now just need to know the thread and size

[Roy]

Both of mine have 1/4 x26tpi bolts (cie) ,

[Rupert]

7/16" 20 tpi lefthand

[Stubaker58]

Rather than drill it out completely as it's left hand thread would it be possible to drill a pilot hole and screw in a self tapper and keep tightening until the left hand thread undoes?
Just thinking out loud!
Regards

[Roy]

Woops my post of saying 1/4 x 26 should have gone into the rear brake pedel post ,sorry

[shoal48]

Rather than drill it out completely as it's left hand thread would it be possible to drill a pilot hole and screw in a self tapper and keep tightening until the left hand thread undoes?
Just thinking out loud!
Regards
Good plan and I tried it, including freezer spray down the pilot hole and warming the lug with hot air gun but it didnt budge at all

[shoal48]

7/16" 20 tpi lefthand

so i definitely need a 7/16" 20tpi left hand thread tap, is that a CEI thread?

[Rupert]

Yep, CEI

[V500]

My old B40 from years ago had a snapped-off stud too, and I got the stud out by tapping it round with a centre pop.
Funny thing was I never did use the replacement stud even though it was so hard to source.

[shoal48]

My old B40 from years ago had a snapped-off stud too, and I got the stud out by tapping it round with a centre pop.
Funny thing was I never did use the replacement stud even though it was so hard to source.

I hadnt thought of trying that but I did try drilling out centre of stud to slightly smaller size then tapping a few turns of rh thread into hole and screwing in bolt with a bit of heat and impact wrench....the bolt just kept on cutting its own thread but didnt shift stud. There isnt really enough thickness in the remaining stud to to try & use a centre punch to move it

[shoal48]

so, I have been searching for a supplier for a 7/16" CEI20 left hand tap to retap my frame for the left footrest stud and have drawn a blank so far. I know there are other 7/16" 20tpi threads but they all have either different thread angle or crest/root shape so may not give a secure fitting if i try and bodge it.

does anyone know where I might be able to obtain a 7/16" CEI/BSC 20TPI left hand  tap? if not then I guess plan B is to use maybe a UNF tap into the frame lug and make a stud to suit.

[shoal48]

an update,
I emailed Tracy Tools to see if they could supply a 7/16" cei20 left hand tap even though they don't list this size.
Extremely quick reply and advised that this size was not generally available & would be expensive to get made but UNF tap would work ok as they are both 20tpi with a 60 degree thread angle and they had supplied a number of these for CEI20 studs. The CEI thread has a rounded root and crest & UNF is flat but hopefully it will be good enough & will probably loctite it in