GSXR Rear Wheel on GS1150

**Billy Ricks** · 09-29-2011, 01:14 PM

Originally posted by kkernahan

Im just about finished with the Front End mods for the 1150 and working on the rear.

I used an 89 GSXR 1100 rear wheel, which is wider as many of you know, and now need to work out the caliper, spacers and front sprocket offset.

Should I use the stock GSXR bracket and caliper? I assume yes, based on previous posts. In that case ill leave the right side of the setup alone (meaning stock arrangement with spacer, and bracket for the 1100 wheel and caliper) spread the stock 1150 swingarm with a bottle jack, and add a spacer on the left side? Correct? I guess ill also need to tweak the torque arm and add a tab on the bottom of the swingarm...

Can anyone tell me what the total spread is with the GSXR wheel, and new spacer size needed to keep it centered? The total spread divided by two would tell me the offset for the front sprocket....correct?

Once I work this out, ill check in on the sprocket gear ratio needed....
Thanks-Kevin K

On my 700 which has basically the same swingarm as the 1150 I had to pick up about 1/4" for everything to squeeze in the swingarm without having to pry it apart every time. You have to spread it almost an inch because ti will try to go back to it's original dimension if you just go 1/4" when spreading. Just go a little at a time until you get the measurement you're looking for once the jack is removed. All I used was a bottle jack. You'll probably have to go with about a 1/4" offset on the sprocket to clear the tire.

My stock sprockets were a 14/44 combo. I'm running a 16/42 combo now and the rpm/mph ratio is very close to stock.

**salty_monk** · 09-29-2011, 05:30 PM

Is that the 5.5" wheel? I used that with a 170 tyre. I would guess I spread the swingarm a little more than Billy & needed to run the wheel far back in the swingarm using a longer axle I happened to have lying around (So I don't know what it came off of...)

My offset finished up at about 8mm. Others have used the 3/8" offset sprockets I think. I used a 6mm spacer & a PBI 530/520 "conversion" sprocket which has a 2mm lump on one side.

I started off at 16/42 but didn't like it. The gearing was much taller than stock on the 750 so I switched to a 47 on the rear & liked it a lot. Worked out about stock so I guess the gearbox ratio's on the 86/700 must differ to the 83/750.

If you want a 520 / 42T rear to fit a GSXR wheel with about 1,000 miles on it then let me know. It's gathering dust so will go cheap. It's a black one.

**Billy Ricks** · 09-29-2011, 06:40 PM

The 700 and the 750 did have different gearing. I think the 750 has a 15 tooth front vs 14 for the 700.

**salty_monk** · 09-30-2011, 02:08 AM

I would think they must also have different ratios in the box as well - either that or your bike has a lot more power than mine did (or no hills where you live

)

**KC1908** · 09-30-2011, 05:19 AM

Hey Kevin,

Give me your email address and I wil send you some photos of mine. I have a 4.5 in one GS1150 and a 5.5 in another GS1150. Did my mates GS1150 as well with a 5.5. I didn't use a bottle jack and wouldn't recommend that either. I used the stock GS1150 caliper on the three of them. Made my own caliper hanger to suit them. They've been on for a couple of years now.

I will take some photos on the weekend. Had some alloy spacers machined up instead of the stock ones.

Ken

**Billy Ricks** · 09-30-2011, 05:59 AM

Originally posted by salty_monk

I would think they must also have different ratios in the box as well - either that or your bike has a lot more power than mine did (or no hills where you live

)

Same ratios in the gearbox. My bike has been breathed on a little bit, mild porting, RS flatslides, and pipe.

**Cyclepath834** · 10-03-2011, 12:08 PM

SM, its actually a 4.5 wheel. whats the better mod? 4.5 or 5.5? I imaging more clearance issues with the larger wheel....

**Cyclepath834** · 10-28-2011, 01:21 PM

Hey Ken, I hope your well. I was wondering if I could see how you accomplished the 4.5 rear wheel changes to the gs swingarm?
Kevin

**Agemax** · 10-28-2011, 01:28 PM

good luck if you want to spread the swing arm apart by an inch?????
who knows where that is gonna stress the arm and cause catastrophic failure!

**salty_monk** · 10-28-2011, 03:48 PM

4.5" wheel is much easier....

Agemax, stress points would be mainly the welded gusset that goes between the two arms. You can examine the welds after you jack it apart to make sure there are no cracks but you are correct that you can never be sure without an ultrasound or X ray or something.
It sounds worse than it is, opening the wheel end of the swingarm by an inch requires very little force (you could do at least 1/2" by hand for example) & is about 20" away from the point that is actually deforming so by the time you get down there the actual amount of deformation is pretty tiny.

VERY IMPORTANT - Spread the swingarm on the bike not on the bench... It's effectively an X shape so if you spread the wheel end without supporting the pivot end you will just deform the pivot end & it will no longer fit!

I think you will need either a 3/8" offset sprocket or spacers to suit.
I ended up with 8mm of spacers on a 520 setup but the sprocket I used was a 530-520 conversion sprocket which had an additional lump on it so you still got good spline contact.

You are going to need to convert to a 530 chain at a minimum for clearance. Not all chains are the same width, 520 chains for example go from 18mm to 25mm even though the inner spacing that the sprocket runs on is identical. Side plates are thicker/thinner, X rings tend to be thicker than simple O rings etc etc.

As far as rear brakes - I used the stock GSXR rotor with a custom CNC bracket plus a custom torque arm & fitted a caliper from a GS1000 as I needed the brake line to exit out the back not the side like the 750 one did.

As for wheel spacers - you are going to have to calculate that as you go. You may need to adjust some of them. I had some ground down to make it all work.
I also found some hardened washers at the Truvalue store that fit the axle perfectly with just a touch of the dremel to clean out manufacturing marks. They were about 2.5mm or 3mm each from memory & I used a couple on the brake side to make up what I needed.

**Agemax** · 10-28-2011, 04:31 PM

surely if you jack it apart you cannot be sure that either side will extend the same amount. if one side of the arm is slightly weaker than the other for what ever reason then the rear wheel mounts will be very skew?
i would not trust an arm that has been modded this way but thats just me!

**salty_monk** · 10-28-2011, 07:06 PM

What we don't have measuring equipment in the UK now?

I could have sworn there were a few rulers, tapes & the likes around when I left

You really aren't widening it very much. 1/4" at the wheel end is not very much at all. I suspect the tolerance on the swingarm in the first place allows for a couple of mm of displacement at that end if not more.... I had an idea you worked in manufacturing but maybe I was wrong? Real world manufacturing tolerances on this stuff are rarely "spot on" & that was even more true 30 years ago.

Personally I wouldn't want a plastic panel on a side cover that holds oil in the engine... but each to their own eh

Billy & Dee have a lot of miles on this particular mod so I suspect it is one of the better tested mods that people have done to their bikes on this forum...

**Guest** · 10-28-2011, 09:33 PM

Mine was spread out so little that i was still using the original stock axle. I don't think it hurt the swingarm at all.

**Carter Turk** · 10-29-2011, 11:03 AM

What about a Bandit swinger?

GSXR Rear Wheel on GS1150

GSXR Rear Wheel on GS1150

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment