Lower fork leg stripped thread.

[Worty]

Hiya guys.  Went for a 160m run yesterday.  When I got back, there was a small pool of oil under L/H fork leg.  Stripped it all down today and rebuilt the fork with a new seal and a replacement lower fork leg (broken mudguard stud on the other).  Got it all back together and was putting the last spindle clamp bolt in and, low and behold, discovered the f&^%(*g thread was stripped. 

So, question is, how can I fix fairly quickly.  I could tap it out to 10mm and find a bolt??  I know the purists will want imperial, but I need to get back on the road asap.  Not done much of this, but would I need to drill the hole out a bit before attempting a 10mm tap?  Don't want to strip the whole thing down again, so an in-situ fix would be great.  Helicoil may be another fix, but I'd need help with locating suitable item.

Cheers guys

[RDfella]

Helicoil is your best bet by far. Ebay, Tracy tools - loads of people supply.

[muskrat]

G'day Worty.
I agree with RD.
But in a pinch I would try an 8 x 1.25 metric first. 8mm is just slightly bigger than the 5/16 x 26. That way a future 5/16 cei helicoil could still be used.
Cheers

[Rex]

So why not use the 5/16 BSCy helicoil now?
Actually this size helicoil kit isn't too common, so there's always 5/16 BSF. Anything but sh*tty metric.

[Swarfcut]

 You could try a brand new CEI  Bolt or threaded stud. All depends whether the slider thread is worn or deffo damaged, Clean out the hole and use a stud  to the  bottom to take advantage of any remaining thread.  Safety critical so no half measures for a permanent fix.

 Tracy Tools in Devon are worth a try for Helicoil kits.

 Swarfy.

[JulianS]

That bolt is 3/8 x 26tpi cycle.

For a quick fix, if thread is stripped out try a longer bolt with a nut to lock it?

[muskrat]

G'day Julian.
My book and web searches shows 42-5084 being 5/16", 26 tpi, 1-7/16" long.
Did they grow in 62 for the A50/65?
Cheers

[JulianS]

I assumed the screw in spindle type but on rereading I see it is the clamp up spindle type which certainly is 5/16.

Sorry for confusing.

[Worty]

Thanks for all the replies folks.

I'll keep this thread in favourites for future reference.

Ok, now I'm going to annoy you all.  The hole was a mess, no threads until the last few.  Tightening the bolt just ended up with it coming loose again.  I only have a metric tap and die set so drilled the hole out to 9.5mm and tapped it to accept a piece of 10mm threaded bar to form a stud.  Stud was secured by screwing it in using the two nut method and copious amounts of thread lock.  Once assembled, an angle grinder took care of excess stud.  Nut bolts up nice and tight.  I had to drill out the clamp a little for it to accept the stud - didn't want to do that but it was that or the summer off the road.  This was a temp replacement whilst I fix the original anyway, which leads me to my next question.

The mudguard studs are goosed.  They appear to be welded to the lower fork leg.  Obviously, I want to take care with any drilling, as I don't want to go into the tube!!!  Thoughts are taking it to an engineer's workshop to get the studs removed and new studs welded in (don't have a lot of equipment, expertise, or welding stuff).

Thoughts always welcome!

By the way, when I have time, are there any helicoils that are metric on the outside and imperial on the inside to change the metric fix.  To be honest, BSA seemed to use all sorts of nut and bolt sizes at different times, so I don't really know the actual size of any given fastener.

[jhg1958]

I am really unhappy with the bolts on the bottom of my forks.  Could these be replaced with studs and a nut?  You could get the stud to the full depth of the thread in the fork and if you do bugger up the stud or nut thread at least you could change the stud.

John

[RDfella]

Worthluck - no such thing as a helicoil with different internal/external threads. They are basically a piece of wire, so inside and outside are same pitch. If you want differing threads, a custom insert will need to be turned up.

[Worty]

I am really unhappy with the bolts on the bottom of my forks.  Could these be replaced with studs and a nut?  You could get the stud to the full depth of the thread in the fork and if you do bugger up the stud or nut thread at least you could change the stud.

John

I had exactly the same thoughts John, and I'm going to pursue that idea with my spare set of sliders.  Given the number of times the front wheel has to come off sometimes, it'd be far easier with a stud and nut arrangement.  I'm not going to change the original thread at present, but I will secure the stud with threadlock.  Always wondered why BSA went for the clamp as other models simply have a pinch bolt setup.  If you really want to upset the purists, you could always finish it off with a nice set of dome nuts????

[Worty]

Worthluck - no such thing as a helicoil with different internal/external threads. They are basically a piece of wire, so inside and outside are same pitch. If you want differing threads, a custom insert will need to be turned up.

No probs mate, I'll return the sliders to the original spec when I've got the time.  Just have to work with what I've got at the moment.  Would rather spend time on the road than in the garage!

[chaterlea25]

Hi All,
Wortluck,
The tapping size for 10mm x 1,5mm is 8.5mm not 9.5 that would only have a half mm of grip 

I have to say that I am not a fan of the clamp on wheel spindle setup, Happy to say my BSA's have the screw in spindles
It should be straightforward to fit studs instead of the bolts, If the threads are buggered the fork leg can be tapped out, If you want it more "original" a stepped stud could have cycle threads at the lower end

I have rescued a couple of fork leg studs for the mudguard stay where the threads were stripped by re threading to 7mm, even going to the trouble of making the nuts from 1/4W hexagon LOL

Welding on new studs can lead to distorting the fork leg which leads to more issues 

John

[Worty]

Sorry John, it wasn't 9.5, it was probably 9.  The stud tightened really nicely and the nut belted up really tight.  I've done around 200 miles along some rough roads and it hasn't fallen out yet!  I could have done with a 'bottoming' tap to thread it all the way, but my tool range doesn't extend that far.  The plan is to sort it properly (with studs) when the other slider is fixed.

Don't really know what to say about the welding of new studs onto the tube.  Either I do that, find another way of fixing the mudguard on, or scrap the whole thing and think about how to fabricate a new one (beyond me, I'm afraid).  Not sure how you rethreaded the studs, surely there's not enough depth for it to be secure?