Fixing a stripped thread

[grhm]

Right, I'm a muppet. Thought I'd get that out the way.

My wife has an old Pashley Picador trike. I was trying to get one of the wheels off the rear axle and though the injudicious use of a hammer have damaged the thread on one end. To compound matters I then attempted to screw on the nut on the end and in so doing stripped part of the thread on both axle and nut. See muppet confession above.

I've spoken to my local Pashley dealer, they contacted Pashley and a said a replacment axle could be ~£130 but depends on the age of the trike if its compatible. Quoting the frame number, apparently the trike is too old and Pashley cannot help.

I'm now stuck with an axle that has some thread missing and a bulge where it deformed under the hammer and a nut that has the first half of its thread missing.

What do I do to fix it?

Wife is not likely to want to use the bike for months, so it's not urgent. But it's really pee'd me off, especially as I was only trying the remove the back wheels to fix punctures and take it for a spin. I'd like it sorted but have no idea - and suspect this is going to be a vary expensive puncture repair.

 

[Proto]

If it's any consolation, I never managed to get the wheels off our Pashley Picador trike either. Removed the nut, pushed, pulled, hit it, swore at it, but never got it budge, even a millimetre.

 

[gbb]

Right, I'm a muppet. Thought I'd get that out the way.

My wife has an old Pashley Picador trike. I was trying to get one of the wheels off the rear axle and though the injudicious use of a hammer have damaged the thread on one end. To compound matters I then attempted to screw on the nut on the end and in so doing stripped part of the thread on both axle and nut. See muppet confession above.

I've spoken to my local Pashley dealer, they contacted Pashley and a said a replacment axle could be ~£130 but depends on the age of the trike if its compatible. Quoting the frame number, apparently the trike is too old and Pashley cannot help.

I'm now stuck with an axle that has some thread missing and a bulge where it deformed under the hammer and a nut that has the first half of its thread missing.

What do I do to fix it?

Wife is not likely to want to use the bike for months, so it's not urgent. But it's really pee'd me off, especially as I was only trying the remove the back wheels to fix punctures and take it for a spin. I'd like it sorted but have no idea - and suspect this is going to be a vary expensive puncture repair.

Probably not a lot grhm

Is the axle out now, and can you take a picture.
If the axle protrudes out of the nut when its tightened, its just possible you could cut off the excess (and hopefully damaged bit of the axle) Ive done it with normal bolts etc...but not an axle before, although the principles the same. If you get a clean cut and dont damage the thread as you cut it, you might get a new nut on without too much aggro.
Can you use the cone locknut to reform the thread as you wind it off ? I woudnt try reforming the old damaged thread with the locknut. It'll just damage the locknut as well. But you can clean up a freshly cut thread with one.

If the axles out, is it threaded all the way along it (not very likely, but you never know). Is it possibe LBS's have a thread die and recut the thread from the other end.


There could be options, but its difficut to say without seeing it.

 

[grhm]

If it's any consolation, I never managed to get the wheels off our Pashley Picador trike either. Removed the nut, pushed, pulled, hit it, swore at it, but never got it budge, even a millimetre.

I got one wheel off, just not the other. And to add insult to injury, I've since found that if I undid the bolts holding on the mudguards, it gave sufficient clearance to get the tyres off and fix the punctures

 

[grhm]

Probably not a lot grhm
Is the axle out now, and can you take a picture.
There could be options, but its difficult to say without seeing it.

I'm not sure how best to describe it, but I can remove the axle from the frame. There are two bits that bolt to the frame that the axle revolves in (bearings?) that I cannot see how to remove (if they are indeed removable). I'd assume if I ever wanted to replace the single cog that's between the two, I'd need to remove one...

Having removed this axle/axle assembly, I end have a wheel at each end, both have two washers and a nut outboard of them. The nut does not have a hole the whole way through, so no cutting of the end of a protruding axle.

From memory, so don't trust these measurements, the axle sticks out about 1cm beyond the edge of the wheel and washers. I've stripped/deformed half of the thread on the axle and a similar amount inside the nut.

I'll try and get some pictures tomorrow in daylight.

My current thoughts are:

1. Re cut a smaller thread and try that.
2. Drill a hole through the axle and use a split pin to hold the wheel on.
3. Throw it away
4. Buy another trike on ebay (or part of, or a fixer-upper and get one working trike)
5. Hire someone to nick it and claim of the insurance. (Except now I've said that if someone does go and pinch it, and the insurance see this I'm stuffed (which would be just my luck)).

This was supposed to be a cheap way to get the missus and toddler out cycling - we were even talking of going on a cycling/camping holiday this summer - although she's now pregnant so that's wasn't going to happen this year anyway.

 

[Dave5N]

Or get a local engineering co to make up a new one. That sort of work can be surprisingly inexpensive, if they fancy doing the job.

 

[gbb]

Or get a local engineering co to make up a new one. That sort of work can be surprisingly inexpensive, if they fancy doing the job.

I was thinking of that...they'd usually charge an hours labour to set up the machine, but the cost of the materials is relatively insignificant. The thread pitch may or may not be an issue for them.
Also, i'm not sure if an axle HAS to be case hardened or any other treatment. If they're a friendly bunch, they could stick it in with some other work.
Worth a try if you've one locally.

 

[grhm]

There is a local engineering firm that I could try - I suspect I'm have to take some time off work (or have one hell of a lunch break) to take the axle down there and see what they can do.

 

[tyred]

If you could indentify the thread type, it's probably something fairly standard (UNF, BSF?) so you may be able to find a die nut in the right size. A decent engineering shop should have a device for measuring the TPI, pitch etc.

If you happen to know someone with lathe, get them to tun it down to the next size and re-thread.

 

[grhm]

Right, got some photos up on flickr
Doesn't look too bad in these photos, here's the best shot.

 

[grhm]

Also spoken to a local engineering firm and they said they could do me a new axle, no probs, but not for a couple of weeks. Didn't mention price.

And a couple of other people have been mentioned as possibly being able to help - so am chasing those down too. I'll let you know how I get on.

 

[very-near]

The problem with using a die to recut the thread is ensuring that it goes on square. You would struggle to achieve this without a lathe to hold the spindle in place.

The ideal solution would be to use a thread rolling die as this just pushed the metal around and doesn't actually cut the metal, but this would depend on whether the spindle has been heat treated - it would need annealing if this is the case and heat treating once more when the repair has been effected.

The lesson to be learned is if you do need to clout the threaded end of a spindle or shaft, leave the nut on there to take the impact to avoid thread damage.

Throw the existing nut away if it is chewed.

 

[tyred]

Right, got some photos up on flickr
Doesn't look too bad in these photos, here's the best shot.

I've seen much worse. You may be able to touch it up enough to get the nut started with a hacksaw blade and small half-round file. Starting on the inside at the last undamaged thread, cut into it with the hacksaw blade, picking out the groves of the thread. Work carefully, and you should be able to get the nut to start. Ideally, if you could find another "plain" nut of the right thread size, cut across it to form a type of die nut and screw it on first, reversing it a 1/4 turn every 1/2 turn. This should be good enough to be able to screw on the nut then.

 

[mickle]

I used to have a file for cleaning threads, about 8 inches long and 15mm square, there were eight different thread pitches on it. Brilliant thing if a little tricky to use as it had to be perfectly aligned with the thread and each pass had to follow thee thread around the bolt. Some bugger must have nicked it.

You can acheive the same thing with a good sharp file in a matter of minutes. Forget about using an engineering company. Honestly, buy a good quality set of teeny files and have at it yourself. Just follow the last good thread off the axle.

 

[02GF74]

what is so special about this axle?

every bike that has wheels will have an axle so will not another one fit?

the important thing is the cones and bearings - the diameter of these should match the cone in the hub but I reckon you could get something pretty close that would work.

as they say ^^^ cutting the thread to be square requires it to be done on a lathe. If the replacement costs £ 120 !!!! , then maybe you should get the shop to make a few, set up would be the main cost and then punt them off on ebay to recover your costs.