Trip Reset Removal

Yes, thank for the suggestion and that's what I tried last night - I used some thick card with a slot to protect the instrument housing with a hairdryer on full heat - tried to loosen the knob after 5 minutes and then 10 minutes of heat without success. Its about 5 or 6 deg C in the UK at present and my garage is not heated so I should have got a pretty good temperature difference despite the plastic knob having poor thermal conductivity...

In this case it does sound like someone "glued" the damned thing! If it were me........I'd keep putting the heat to it. It may turn out that the reset knob will have to be sacrificed so getting it hot enough to be removed albeit it distorted would be better then applying a Dremel or other source of severe vibration.... which could rattle the guts which would be undesirable..

Neville,i just looked again at my knob and the hole you asked about earlier does indeed go all the way through to the end of the threaded shaft.Perhaps some lube sprayed in there might help. Looking at mine, here is what i would do. Keeping in mind that i do tend to get a bit heavy-handed at times. And you're getting a new knob anyway. I would again heat the knob,insert a straight metal pin of some sort into the hole,maybe an allen wrench of the matching size, then using that pin to push against the end of the shaft while pulling forcefully outward on the knob. Sort of like a gear puller would operate. The threads are very fine on that shaft and my knob only turns 2 1/2 turns until it bottoms out against the shaft. I think it would give way and pull off. The framework on the tach drive assembly is pretty robust so i doubt you would be in danger of hurting anything in there by accident. Just another option to think about. Good luck.

Thanks again for all of the suggestions - I tried a hotter hairdryer last night and have also been spraying WD40 into the outer hole in the centre of the knob for the past three days. Again, no joy even though the outside of the knob was too hot to touch - it did get soft and was easy to deform. I am firming up on the theory that a previous owner messed this up...

Interesting suggestion to use an insert of some kind down the hole to the tripmeter thread and use that to push against to pull the knob off with brute force. That sounds like a real "Chernobyl" of all of the Nuclear solutions. I am leaning towards clamping the knob and drilling out the hole as far as I dare with progressively larger drills and then nibbling away from the inside of the hole with my Dremel using my very small (0.8mm) engraving cutters to separate the outer part of the knob - I need to avoid getting any debris inside the meter.

It would also be useful to know if the trip reset seal can be removed from the outside of the housing?

Thanks to all.

Kind of funny where this knob removing solutions thread is going.. LOL Once you decided to sacrifice the knob, why not just to cut off the big wheel part at the base, having any holes tapped off with masking tape and some garbage bag, and remove as much plastic until it hits the metal threaded shaft and disassemble it like if all worked as it should? Once the cover is removed, 5 minutes with a file would cut through the rest of the plastic exposing the metal, clean it up with acetone and voila - ready for a new knob. I wouldn't overthink this issue. The whole thing is subjected to constant vibrations from the engine and road, a high speed Dremel blade or a slow speed hand saw blade will not destroy it, haha

The whole thing is subjected to constant vibrations from the engine and road, a high speed Dremel blade or a slow speed hand saw blade will not destroy it, haha

Think my point got lost - The bike might be subject to engine and road vibrations but absolutely NOT like the high-speed resonation a Dremel will induce ! Look at the label on a Dremel and note the speeds. 10,000 to 20,000 Not just this RPM but also the biting/grabbing/bouncing of a cutting disk.
Is it worth the risk of destroying the needle Hair-Spring, because it will most certainly be "dancing".
The hole in the knob end is blind.
Removing the grommet seal will likely not be of any help - the threaded shaft is well inside the housing.
Still thinking.....................
Use a fine tooth hacksaw blade to cut the knob off. Leave the grommet seal in place as it will act as a guide to keep the blade from marking the housing. The instrument housing can then be disassembled. A pair of needle-nose on the metal shaft should hold it while you turn off the remaining plastic shaft. It may be possible to glue the two pieces back together - depending on how much material is lost due to the cut. On mine, the knob snugs-up to the grommet-seal.