Taking Comstars to bits --- Again.

[bluemouse1006]

Hi

Thought i just had to reply to this as you can see from my photos Ive taken the rear hub out of a comstar to convert my rear drum to a disc . I cans see what everyone is on about the bolts that have small dowels onto the threads of the bolts to lock them in place.
when i removed the bolts the threads on the nuts were totally knackered because of the pins in the bolts,ive managed to save 3 of the bolts with pins intact which i will reuse with new nuts (tighten the nuts up then hammer the pins back in the bolts ) I have another wheel with these bolts so should get another 2 out to finish  the rear disc project.
Please give me your view to the use of an other hub in a different wheel and whether you think its safe ? ive moved the wheel spokes a minimal  amount so not to stress the metal,not touched the rivets at all so they should be ok..



Thanks Amos

[hairygit]

I certainly would not attempt to use those spokes again, the angle they have been bent to will almost certainly have caused stress to the metal, that you would not see without specialised X-Ray equipment. The spokes were never designed to be bent like that, the spokes are pressed out at manufacture and bolted and riveted together with extreme care, bending them as you have is a fatigue fracture waiting to happen It would be madness to trust the spokes for integrity now, would it not have been easier (and infinitely safer) to have hunted out a disc braked wheel? (750F2 or even the later DOHC 750?) I'm sure anyone seeing those photos with the slightest knowledge of metal stresses/loadings will tell you the same, it's now just a pile of scrap But ultimately, it's your bike, and your life, if you don't value those things, it's your decision

[Tomb]

What he^ said.

The bolts and nuts are drilled and pinned, "hammer the pins back in" without drilling???!!

If you really want to use the bolts again, angle grind the side of the nut off so the pin can fall out, then wind off whats left of the nut, and use new nuts, and redrill another hole.

I'm sure anyone seeing those photos with the slightest knowledge of metal stresses/loadings will tell you the same, it's now just a pile of scrap

Yup!
Tom (Toolmaker 18 years, Mech Tech 13 years)

[Waggles]

+1 on the 'scrap them'

[bluemouse1006]

Thanks for your input
Luckely the wheel in the photo is a spare one that I had with a rear disc on it I was going to just put the wheel in but the spokes where very rusty and I couldn't polish them up as you can see from one of my photos the bike and wheels are very shiny and I didn't want to spoil it .
I haven't stripped the rear wheel yet off mine or touched the spokes.

I'll be looking out for another rear comstar with rear disc in good condition ( anyone got one for sale ?? ) so I don't have to mess with the spokes.

Thanks for the comments

Amos

[K2-K6]

Just to add a bit to that already posted; The bit where the spokes have been bent is at the point I perceive to be the most stressed, so ANY compromise at this point is likely to raise the risk of failure signficantly.

The materials used including the bolts/nuts/rivets etc will have been specified with the full knowledge of the designing engineer, to substitute off the sheld items without that background information I would place as a high risk choice and one that you may not find out the shortfall of until it stops working.

Believe me, i would certainly re-use anything that I can and not be an advocate of just "new is better" but I consider the risks here just too great to take on without a very good knowledge of what you are doing.

If you get just one joint failure, the design of these wheels to me would seem to have a high chance of the rest following shortly after. They are a very strong reliable design in their original form but rebuilding without an appropriate level of skill is not something I'd like to ride around on.

Just imagine that failure happening while you were on a busy motorway and I think you'd consider it differently, the risk is not worth it.

[UK Pete]

Just think you could do the repair to these wheels, and all goes well,and they seem perfect, you sell the bike at a later date and some poor unsuspecting person could have a nasty accident ,and possibly loose their life
These wheels usually only fetch about £20 second hand, so its well worth replacing with a good second hand one, rather than going to all that effort
Pete

[bluemouse1006]

Point Well made and understood will be looking out for a good secondhand F2 rear wheel comstar,the one i had was very rusty anyway and not usable so stripping it didnt cost me that much.
Would a cb900 early comstar fit does anyone know ?

Thanks again for all your advice im still going to look into a rear disc conversion but without stripping a wheel to do it

Amos 

[mick]

Mickharrow has a set of Comstars for sale in the for sale section give him a shout & see what he has  , cheers Mick.

[steff750]

i got a pair OF F2 wheels front and rear with discs and tyres but im in wales probably to far away for you

[bluemouse1006]

Thanks for the reply
Watching a rear wheel on eBay looks like the  one I stripped ,says its off a CB 900 I presume it will fit ? Anyone have any ideas ?

Amos

[archmill]

Bluemouse1006, I am building a special from a '79 F2 and will not be using the wheels. I will take a couple of photo's for you today and will post tonight. I live in Scotland and have a mate who is a long distance lorry driver so perhaps I could organise a drop off close to you. What else do you need to convert to disc as I have the lot. WHY, am looking for a couple of engine parts.

Archmill

[bluemouse1006]

Thanks

Im bidding on a rear wheel on eBay for 15 quid at the mo but thanks for the offer might take u up on the offer later what engine bits do u need ? I'm selling one on eBay at the moment with 25 watchers !! So should seek finishes on Sunday , I have a casing and some small bits and bobs from another if your desperate ? Let me know

What's the condition of the comstar s ?

Thanks again
Amos

[archmill]

Amos, photo's as promised:- 

I have given you a photo of each side, plus the worst parts of each side.
I am looking for a good alternator caseing ( want to polish it ) and 3 valves.

Let me know mate, the wheel ain't going anywhere soon.

Archmill

[bluemouse1006]

Archmill
Hi recieved the wheel from ebay and its the wrong one !!! its only got 5 studs for the disc and mine has 6 !! Ive decided to paint the spokes now and polish the rims
Ive looked for another but there is a few about but quite rough is yours still about ? how much including postage ? (i was charged £15 for posting the last one from portsmouth to Hull HU129PJ )
I would appreciate it if you could help

cheers

Amos 

PS sorry i dont have any engine parts left