GS850 brake disc doesn't fit hub?

[GS850bobber]

Hi all, it's been six months since I bought a half-finished project GS850 bobber and now some nice weather is finally here it's time to finish it off and get it on the road!

The guy I bought it from has stripped many parts that I am replacing, indicators, rev counter, switchgear etc. When I got the bike it only had one front brake disc, on the right hand side of the wheel.

The brakes are not great so I have sourced a left hand front disc and caliper.

For some reason I can't get the disc to mount onto the wheel, it's as if the hole in the middle of the disc isn't big enough to fit over the hub.

Can anyone shed any light on where I'm going wrong here please? Should I just bore out the disc or have I got the wrong disc? Do they come in different sizes / specs? I bought the disc from the US via ebay, whereas it is a UK bike.

Any help would be very much appreciated

[hampshirehog]

Hello mate. You must have bought the wrong disc as all the front discs from the whole GS / aircooled GSX range will fit at the hub.

[GS850bobber]

thanks for the reply, that may well be the case, although the disc fits perfectly on the right hand side and is visually identical to the right hand disc.

back to ebay for another one then!

[hampshirehog]

Hold on - if it fits on the other side then there is something wrong with your wheel. The discs on both sides are identical and interchangeable (apart from the slotted discs will have the slots the other way round)

[GS850bobber]

that would make more sense and yes the discs are identical apart from the slots being different, so I was fairly sure it was the right disc for the bike, it has L stamped on it whereas the other one has R. any ideas as to what the issue might be with the wheel, seems to be in very good condition, maybe that's why the last owner left the disc off, I just assumed he'd gone for a minimalist look!

[hampshirehog]

How much is it not fitting by?

[GS850bobber]

it's not far off, I could try some filing and a good dose of club hammer I guess, it's just that the hub doesn't look to be burred or corroded at all so I thought it should just go straight on like it does the other side. The side I'm having problems with is the speedo drive side.

[GS850bobber]

here she is......

[Big T]

here she is......

Yeah, that's the bike, but we want to see the disc and the wheel to evaluate your problem. Big pictures

[TheCafeKid]

This may sound dumb but you took the speedo drive off yeah?

[GS850bobber]

yeah, removed the speedo drive, am going to try again tonight, if no joy will take some close up pics and post them tomorrow. thanks for all the help!

[bwringer]

Has the wheel been painted or powder coated?

You'll need to remove any coatings where the rotor mounts.

[Suzuki mad]

Its going to sound daft but the PO hasn't replaced the front wheel with a single disc'd wheel from a 550 or something stupid like that? It would explain why the disc wont fit onto the wheel.

[TheCafeKid]

Its going to sound daft but the PO hasn't replaced the front wheel with a single disc'd wheel from a 550 or something stupid like that? It would explain why the disc wont fit onto the wheel.

Doesn't sound daft, but all of the single rotor wheels were drilled both sides for dual rotors and a plastic "cap" was put on to cover the non rotor side. I converted a single disc 77 750 to dual and only had to change the fork legs out and pop that cap off the wire spoke wheel to add the second disc.

[GS850bobber]

Believe it or not, embarrasingly it was a dust cover that was preventing the disc going on!! I blame having a garage with no light in it, either that or my general inability!!

Please see my most recent post for what is probably another very stupid question!

Thanks for all the fine suggestions, you all over-estimated me as it turns out!!!