installation tips on putting 18" GSXR wheels on a '78 GS1000

[triffecpa]

A buddy and I are building a vintage race bike from a '78 GS1000. We're using '85-86 GSXR750 wheels so that we can use 18" Dunlop bias ply race tires and still remain eligible for the Superbike class in our local club.

We've installed the entire front end, so no problems there. The rear has a GS1100 aluminum swing arm and when we installed the rear wheel, we ended up with some sprocket alignment problems. I've searched the site, but most people seem to be installing 17" wheels instead of the old skool 18's. Has anyone else done this conversion? Do we just need an offset front sprocket?

Thanks for the help.

Tracy

 

[80GS1000]

How much off the mark is the sprocket alignment, and what size chain are you using?

 

[irwnn]

RE: How much off the mark...

RE: How much off the mark...

howdy, I'm the other half of the "build"

... right now the wheel is off center, but once we get the spacers made, it appears that we'll be off by about an inch.

I figure we'll probably use a stock chain (530?).

 

[Guest]

your stock chain is 630? or can you run the newer samller chain in your class?

the rear wheel shouldn't be off an inch. The 5.5 wheels are only off 5/8 of an inch. Yours should be less than that. Something is telling me 3/8" maybe. Those 18's are 4" rims aren't they?

If I remember correctly the gixxer swing that goes with that wheel is 260mm wide at the forks same as the gs1100 swing its going in.

I have a buddy with a stock 86 1100. He is out of country right now but will be back in a week or so. I can get the size of the sprocket side spacer for you and then you just need to fill in the gap on the rotor side and it should be aligned in the swingarm. Then just subtract the gixxer spacer from the stock gs spacer (28.5mm / 1.122") and you will have your offset.

I will be posting this info on my new website in the tech section.

cheers,

 

[triffecpa]

Thanks guys.

Just to clarify. We're running a '78 GS1000. We've got the GS1100 box section aluminum swing arm installed. We're running GSXR750 wheels. ('85-86 vintage). The rear wheel is 3.5"x18". We're currently running the GSXR cush drive from a similar year GSXR1100 wheel. I think that the rear sprocket that is currently mounted to the cush drive is for a 530 chain, hence Pete's statement. He hasn't done quite as much work with the GS bikes as me. He's got a mid 80's GSXR750 drag bike though.

He's back home again later today and can make some more detailed measurements. I gave him the dimensions from a stock GS750 wheel and cush drive, so we can compare them and see what it takes to get the same sprocket offset on teh GSXR wheel as exists on a GS750 wheel.

Thanks
Tracy

 

[Guest]

I have a couple 3/8" offset 630 pitch front sprockets (brand new) if that is what you end up needing. I haven't got the stock measurement yet from the stock 86 wheel spacer but when I do or if you can find it you will have the offset number you need to align the sprogs...........

 

[Guest]

Yeah, an inch sounds a bit much. I did the gsxr mod on my 82 EZ, and was off 5/8". I used rims off an 88 gsxr1100.

 

[Guest]

I have checked the part numbers for 86 and the spacer is the same up to 90. I know that the 90 rear wheel needs a 5/8 offset counter sprocket.

The spacer you need info is on my site http://www.robwilton.com/xtech.html

You need a 12.75mm / 0.501" spacer to line it all up with a 5/8 off set sprocket.

You should however mill down the sprocket face of the carrier so you can take advantage of the narrower tire. If you try to use a 630 chain (if regs require that for racing your class) the chain will not clear the frame.

Milling the carrier down a couple mm's will allow a 10mm offset. You can use an old sprocket as a spacer and weld them together or buy a 3/8 offset.

IF you are using the 530 chain it is still a good idea to mill a bit off and adjust the front counter shaft sprocket spacer accordingly to give you a little more clearence.

 

[irwnn]

Yup, 5/8"

Yup, 5/8"

So, I made it home for a day, took better measurements, and voila; 5/8".

Next question: will a GS cush drive/sprocket carrier slide into a GSXR wheel?

p

ps "the spacer is the same up to 90"... good info, thanks

 

[tone]

Next question: will a GS cush drive/sprocket carrier slide into a GSXR wheel?

yup it fits but one is 5 bolt fitting for the sprocket & the other is 6 so you may have a little trouble locating a sprocket for a 530 chain on the gs carrier

they are available but not always off the shelf here in the uk anyway

 

[8trackmind]

The GS450's and GS550's use the same carrier as their larger brothers. They also use a 530 chain. J.T. sprockets makes what you need. Z1 enterprises is where I would get them.
http://www.z1enterprises.com/catalog.aspx?pid=GS550ET-1980-MP0

 

[Guest]

So, I made it home for a day, took better measurements, and voila; 5/8".

Next question: will a GS cush drive/sprocket carrier slide into a GSXR wheel?

p

ps "the spacer is the same up to 90"... good info, thanks

you can't put a 6 cush hub into a 5 cush wheel or vise/versa.

Here is a little "tidbit"

the 6 bolt gs hubs fit all the 6 bolt gsxr hubs up to 95 750 and 98 1100..and the bandit 1200's....BUT!!

The inner hub spacer is a diff size so if you try to use one for the other you either have a hub that won't seat properly on worse you will explode your hub bearing cuz of the lateral forces due to it not being in contact with the inner spacer behind it.

So that being said. if you swap the hub swap the inner spacer too.

 

[tone]

you can't put a 6 cush hub into a 5 cush wheel or vise/versa.

Here is a little "tidbit"

the 6 bolt gs hubs fit all the 6 bolt gsxr hubs up to 95 750 and 98 1100..and the bandit 1200's....BUT!!

The inner hub spacer is a diff size so if you try to use one for the other you either have a hub that won't seat properly on worse you will explode your hub bearing cuz of the lateral forces due to it not being in contact with the inner spacer behind it.

So that being said. if you swap the hub swap the inner spacer too.

hmm good point on the spacer katman :-D it needs checking but not always changing or it might even need changing for something completely different, this is due to the bearings being set into the hubs & carriers at different depths
its the carriers that have bolts though not the hubs :-D
5 bolt carriers (7"dia from memory) fit early oil cooled gsxr wheels but some of the smaller stuff has a 6" dia carrier, 600's & the like, a lot of the water cooled bikes also use the smaller hub & carrier

please dont set too much store by part numbers etc when doing these swaps do it with the metal & measure carefully is the best advice anyone can give :-D

 

[Guest]

sorry,,, I call the carrier the hub..

I just measured the inner spacers for the "carrier"

82/83gs is 31.75mm from bearing face to bearing face
92/93 gsxr 750/1100 34.75.

from carrier seated position to sprocket face the gsxr carrier is 2mm further out from wheel center than the gs. SO! good idea to use the GS carrier (for early 90's gsxr wheels) to gain the 2mm extra clearence between chain and frame.

 

[irwnn]

sprockets

sprockets

yup it fits but one is 5 bolt fitting for the sprocket & the other is 6 so you may have a little trouble locating a sprocket for a 530 chain on the gs carrier

they are available but not always off the shelf here in the uk anyway

always something... I'll bet Sprocket Specialists can hook us up.

p

 

[Diamondj]

Sprocket Specialists should be able to hook you up. I had to machine the sprocket carrier face on mine down by about 1.5 mm and use a spacer behind the engine sprocket to get everything to line up when converting it to a 530 chain. The 630 countershaft sprocket is superwide on the GS1000 as it's got that rubber damper in it. I used CBR600F2 wheels on mine with a Metmachex swingarm for a GS1000 as I was going for a Marchesini 5 spoke look without spending $2000.... The rear rim on mine is 17 x 4.5"

Jim

 

[Steveb64]

18" wheels

18" wheels

Can't help you with the spacer problems - BUT I have been running 18" wheels on my old GSX for years (even before it got stored) - though mine were spoked rims (Akront and Borrani), laced up to early GS(2v)750 spoked hubs, with 2.5" front rim width, and 3.5" rear. Bolted straight in, and turned the old girl into a turning demon! Could get up the inside of (early) GSXR's on tight twisty corners!:-D The main thing I HAD to do, was get the front suspension stretched out as much as possible, as having the rear raised with 18", and the front lowered with 18" - it got kinda twitchy. Ended up with the forks on max preload, oil height raised by 2-3cm (can't remember exactly) AND 10psi of air!

One thing I was wondering about - why use cross-ply tyres? I started off running Pirelli sportscomp Phantoms (the original cross-ply ones) which worked well enough, but the bike would still get the 'weaves' if I hit a sudden dip/bump in mid corner. Then the first radials came out - and a mate who was racing at the time did a big rave about them - so next tyre change (after two sets of the Pirellis) was to Michelin A/M59X's (with tubes in, due to spokes). MAN what a difference. It was still a little twitchy in a straight line - but pitch it into a corner, and it was like it was on rails! NO wobbles, weaves, headshakes, ANYTHING! One example I remember well (for some reason), I was blasting downhill at 180k into a FAST LH sweeper, and hit a patch of loose gravel mid corner. Back stepped out. :shock: Well out. Then it hit the tar again, kicked straight and just continued on as if nothing had ever happened! NO twitch or wobble!

Errrm - one odd thing I remember now - the countersteering went kind of weird. I'd give a shove on the bars to get the bike tipping in and control the first part of the lean - but the more lean - the less countersteer - until I was actively turning IN to the corners when really peeled over! Never worked out exactly why, just rode around it...
Mind you - this was also the bike I learned to rear wheel steer with too - just start feeding the power on as you apex - but use some proper slide carbs - NOT CV's, as they don't really give a quick enough response when you need it...

 

[irwnn]

... why use cross-ply tyres? ...

... comes down to availability of race compound rubber in a size and style allowed by the rules.

p

 

[Steveb64]

... comes down to availability of race compound rubber in a size and style allowed by the rules.

p

Thought that might be the case. ...just been looking at what IS available in 18" sizes - bugger all these days! Though Michelin do a Pilot Road that's a 160 - but that's going to be a tight fit, as I had to squash the rear caliper stay arm to fit the old 150/? x18 M59x that's on it at the moment.

Damn. ...(I'm planning on taking mine out in the pre '82 post-classic class here in NZ)... At least our class here doesn't have too many rules regarding tyres... :-D