Taking Comstars to bits --- Again.

[r1_pete]

I know all the advice is dont, bolts not available, riveted etc........

But,

Has anyone actually done it and had success? I want an 18" front wheel, better tyre choice (OK Cheaper), and I have a really neat mudguard which fits a 100 90 18 perfectly.

I have an 18" front from a CM400, but that only has one disk, I'm thinking of getting a scrap 19" F2 / DOHC comstar and fitting its centre into the 18" wheel, I figure I will only need to remove 2 pairs of spokes, but to balance things I should use the same rim end fittings on all spokes, so would use dome nuts and screws all round, loctited of course.

I can't see a problem bolting it all back together with tight fitting metric fine pitches, optimum torque figures etc.

Has anyone had any success / what are the pitfalls I'm probably missing?

[hairygit]

Please just forget this insane idea Any insurance company would run a mile in the event of a claim, even if you did tell them about it. ) If you could do it successfully (seriously BIG if), you would alter the steering geometry and handling of your bike quite a bit, and the lack of professional wheel builders offering this kind of mod says it all. Honda fitted a 19 inch wheel after incredible amounts of research and development, and this is what they found to be the best size. Also you will reduce your ground clearance as well (I've scraped alternator casings during high speed two up cornering on standard wheels, less ground clearance means even easier grounding, to be avoided at all costs!) I have to ask, WHY?

[UKROBK7]

Hagons used to offer a repair service for comstars, give them a ring and ask their wheel department for advice but I think you will find they only straightened the alloy rims and left the steel parts in place for safety.

Rob

[hairygit]

Another issue is electrolytic corrosion, where dissimilar metals contact each other (thinking steel nuts and bolts) the alloy turns into white powder at a rapid rate, as anyone on here with an old Landrover can testify

[Tomb]

Pete

I removed the spokes and rim from a Comstar hub so I could bolt a Citroen 2CV wheel into my sidecar tug CB550.

Once out I wouldn't have even attempted putting it back together again it was such a mess, and I do this kinda stuff lots (built chops, old Triumphs, trikes, sprinters and other assorted crap )

The route I'd take is trying to fit a second disc to the CM400 wheel, aren't most Honda wheels drilled right through so a disc can be fitted to both sides? even if they ain't I'd do it, the CM400 has a cover over the non-disc side, I wouldn't take that off coz it'd mean removing the pegged nuts but the centre of it could be machined out and the hub drilled and tapped, and the disc spaced out with spacer disc.

As for not fitting a different size wheel? hmm I'd be in trouble if you can't, I do it to get different steering geometry, as well as changing yoke offsets, forks, rake, trail. Using different section tyres can have as much difference. E.g. I have a 16" and 17" rear wheel for one of my bikes, the 16" has a chunkier tyre, I measured the difference in height .....6mm, so a ride height difference of 3mm or put another way  ....tread depth.

If you have some scrap/unwanted comstars have a play, if the end result is crap you've lost nowt but gain knowledge.

[hairygit]

I didn't say you COULDN'T change wheel size, just that it would reduce ground clearance and change the way it steers

[the-chauffeur]

I'm assuming you've seen the Wheel Refurb post by RWG, but in case you haven't, I'll just repeat . . .

 . . . get hold of a copy of issue 14 (Dec 2011) of Practical Sportsbikes.  There's an article in there on a bloke who's worked out a way of taking them apart and rebuilding them on small capacity 125's, but . . .

 . . . like the others have said, this really isn't something you want to try to do it yourself.  It's a seriously specialised job - at the very least you'll probably have to make up some triangular-oval spacers and make rivets out of aluminium rod.  The guy who was interviewed about the job for the article only does them for himself and says he wouldn't want to attempt to rebuild wheels from bikes bigger than 125's because of the risk of something going badly wrong.

[Waggles]

There aren't enough 'spokes' on a comstar for me to even think about this kind of thing, any failure would have to be catastrophic ........

[Bryanj]

Going back a lot of years there was a firm that made disc like rotors that bolted on in place of the comstar spokes with holes for normal spokes so you could lace up a standard type rim, BUT they did not sell well and, from memory, also failed at times so were not really recommended

[r1_pete]

OK Cheers all, that seems pretty conclusive, anyone want to buy a CM400 front wheel....

[Tomb]

The route I'd take is trying to fit a second disc to the CM400 wheel, aren't most Honda wheels drilled right through so a disc can be fitted to both sides? even if they ain't I'd do it, the CM400 has a cover over the non-disc side, I wouldn't take that off coz it'd mean removing the pegged nuts but the centre of it could be machined out and the hub drilled and tapped, and the disc spaced out with spacer disc.

guess not then

[r1_pete]

Hi Tomb, No the cast in lugs for the disc fitting are only half width on the cm400 wheel.
Cheers.
Pete.

[Tomb]

bugger!!

[K2-K6]

As already discussed, it's a noted specialised area as the localised demands are so high that if you do get it wrong it's probably going to be a very quickly occurring failure. I for one wouldn't want to be sitting on it when it did.

On a positive note though the CM400 wheel is from which model? as far as I can remember the bike I know as the "Superdream" had twin discs fitted to the 400 model and not the 250 which could have been 18" rim size, so may be a scource for you.

[matthewmosse]

19 on the superdream front wheel, the cover on the other side to the disk unbolts to allow twin disks on the 250's I've had my grubby mitts on (the wheels are still awaiting being remade into a horse drawn convayance in my garden)