Thread identification

Hi I have been asked by a friend to identify a thread on his motorbike. I don't know the first thing about bikes but I said to him I know somewhere were people will know the answer!

The bike is a Honda CX500

It is probably a half nut that screws onto the end of the swing arm pivot bolt.

The thread outside diameter is 22.5mm and the pitch looks to be 1.0mm

All I need to know is what thread this could be.

Thanks for your help

Well its probably a m22.5 x1.0

big threads like that are made to suit the purpose so no standard form was used

Your measurement may be correct, the thread is probably a special which could be unique to that particular Honda.

Thanks guys for your quick response!

I had no idea that it could be a custom made thread.

I will see if i can get one made at work, might be able to get it thread milled.

My machining skills are not that good.

Do you mean it might be a thin nut rather than a half nut (in the sense of a lathe half nut)? seen plenty of CX 500 swingarm pivots with thin nuts but never a half nut. Ready to be educated.

Anyway rather than spend a lot of time making a special nut to retain the swingarm pivot, a critical component, I would suggest calling a Honda dealer, Honda bike breaker, or David Silver Spares to see if there is one available off the shelf (which will have exactly the right thread, width, metallurgy, finish, etc) and usually nuts of this type are not a lot of money from Honda or a breaker. You will need model and serial number off the plate on the frame, usually near or on head bearing tube of the frame, for the firms to look up the part number.

Hi Jeff, thanks for your help.

I had just finished ordered a nut from David Silver Spares, hopefully the correct one, when I read your posting!
It looks like a castellated nut.

Glad to hear you could get one Andy. Good luck with getting the CX500 back on the road. Great bikes.

A long time ago one of the many students in company where I worked was advised to come and see me as he had a problem identifying a thread on a Honda motor cycle and I was into bikes. the thread was around 12 mm and the pitch was really odd ,not in any engineering thread tables,so I contacted a tap and die supplier, to be informed that it was quite common to find odd threads on Hondas and other far eastern products.Around the same time a friend had a gearbox bearing fail in a Dihatsu 4 wd ,similar reply from local bearing supplier ,thats off a Dihatsu only available from a dealer and will cost an arm and a leg. I wonder are the manufacturers being devious,and they can supply spares at high prices, or has a designer come up with the correct specification for the part in hand and the parts are made in such high volume that variation from standard does not increase manufacturing cost.

In the 1980's I was reading for a postgraduate course in technology and one of the things we worked on was just in time manufacturing in the far east. As far as I can remember, one difference between manufacturers like Honda and the then UK practice was that in the UK it would be normal to buy such items from independent manufacturers who kept stock ranges whilst in Japan items were ordered from many small manufacturers who made the items to a drawing from the purchaser as required and delivered in small batches 'just in time'

So it would not matter that the item was not a stock size, as the bearing (or whatever) maker didn't keep stocks.

Forty years is a long time, so I cannot quote or swear to the exact details, but that was the gist of it.

On topic, I hope.

I have recently unearthed a 'Rotozip' drill/sander/polisher W.H.Y. kit and the collet closing 'nut' is missing. Difficult to measure, but the thread appears to be 28 tpi and diameter 1/2". Zeus doesn't list anything matching. Does anybody know what it would be ?

rgds

Bill

Probably 1/2-28 UNEF see table

When Mitsubishi took over the Chrysler factory in Australia and set about instituting Just In Time JIT supply lines it became known as NQIT -- Not Quite. In Time.

My experience of Hondas around the seventies was that all the general fasteners were ISO metric standard, That would not of course necessarily apply to special ones like the swingarm above, but nuts and screws were readily available. I changed all those cross point ones to allan screws..

One handy feature, on all the ones I ever had occasion to play with, is that the back axle could be used as an extractor to take the permanent magnet alternator rotor off the crankshaft. You took the screw out of the crankshaft, then screwed the axle into the female thread on the alternator, tap the end a bit and wiggle it, and the taper would let go and the rotor would come off. One less special tool needed!

John

Hi all, when I was a young apprentice I campaigned a150cc BSA Bantam & when it became time to dismantle the engine I was struggling to remove the flywheel of the Wipac flywheel magneto having a boss with a large fine thread on the outboard end to accomodate an extractor, I consulted with the foreman of the toolroom where I was working as he used a 175 Bantam as a ride to work bike, he took me to the place where they made large steel hydraulic pipework & picked up a couple of large conical nuts, one then placed a 5/16 plain washer on the last diameter of the crankshaft screw the nut onto the large thread snugged up to the washer then 1 clout with a brass hammer & the flywheel was off! , so if a thread exists you can usually find something ready made for a one off job like the one described above. PS later I learned that you could make all sorts of interesting things for yourself in a large machine shop with an attached toolroom, who knew?

BobH

manufacturers make odd sizes / pitches as a means of holding onto the spares aftermarket.

Fords need a 7 mm Allen key for the brake callipers at one time.

European vehicle manufacturers seemed to like the "odd" A/F sizes for nuts, where Far Eastern seemed to prefer the "even" sizes.

A friend had the bearings fail on the roller of his lawnmower. Guess what, they were a special for that machine, and no longer available!

Four standard 12 x 28 x 8 2RS bearings, a length of silver steel, and opening up the 27 mm bore in the rollers, and bit of drilling and tapping, solved his problem at fairly minimal cost, preventing an otherwise useable machine from being scrapped.

Model engineers, the scourge of the unique aftermarket vendors!

Howard

Edited By Howard Lewis on 30/06/2020 19:04:45

The use of 'specials' is not uncommon on machine tools either. For example the thrust bearing on the rear of the spindle on a South Bend 4 1/2" is of 'odd size' but by grinding out a standard ball thrust race by (IIRC) 0.010" it will fit the spindle. Came across the same in an Atlas pillar drill. The Atlas bearing was a really odd size but I found a Peugeot wheel bearing that would fit with an inner bush to accommodate the inside diameter.

The SB was my first lathe! A 14th birthday present to me from my father. It was from a Tank Regiment LDU mobile workshop - he found it in a scrap yard and paid 25/- for it including the motor. I've still got it along with a couple of other lathes as I'm really attached to it. It is currently under refurbishment - having just had the bedways reground - next job is to mill the saddle ways and tailstock to correct the wear on them.

A word of caution - early Japanese metric screw threads may be of a Japanese 'fine' form which is not compatible with ISO or SI metric form. I believe the use of this Japan standard was in use up until the 1980's on very limited areas in the motorcycle and automotive trade.

editted for spelling mishtaks

Edited By Oily Rag on 30/06/2020 20:32:34

It's amazing the threads that come up.

I have a couple of 1/4" BSP injectors on large scale model locos. That is, the union tails are threaded 1/4" BSP, the union nuts that hold the tails onto the injector body are larger. One was lost (reprehensible, I know) during a protracted overhaul. No matter - just make a new one. Close measurement with micrometer and thread gauges revealed that the nut thread was 22mm x 18tpi ! And that was measuring all three threads on both the injector that was missing a nut and the spare one in the drawer.

In truth, it was no harder to cut than any other thread, beyond having to fit off the tool. No die to finish it with.

Mike

Thank you, Jason - looks to be what's needed. Don't understand why I didn't pick that up in the Zeus.

rgds

Bill

Another pitfall for the unaware was the ''Phillips '' screw heads on Japanese bikes. They weren't Phillips they were JIS, Japanese Industry Standard form. They were usually torqued up to the max from the factory and a Phillips would just mangle them even with an impact driver. Hence the aftermarket allen screw kits that were so popular at the time.

Edited By JasonB on 01/07/2020 06:57:11

I was never bothered by those screws. The local Honda emporium used an impact screwdriver but I found (for most screws) a tap, with a flat punch, on the side of the screw head allowed easy removal. Some countersunk screws (on the contact points and oil ‘filter’ covers?) remained a problem, for first removal, as I recall, but not when once removed.

Some of my screws did show that treatment after several removals but the surface treatment was good and the only evidence of removal was a small flat on the side of the screw head at most.

Likely a proper tool - a shaped brass drift - would have been better and would likely not have left any marks at all, but my solution was improvised by a teenaged non-engineer back in the 1960s. Steel hammer and punch were the tools available.

Edited By JasonB on 01/07/2020 06:57:48