GSX-R1127 Gearbox compatibility with Bandit 1200?

[dr_thirsty]

I found a Close-ratio 6-speed, drop-in gearbox for 1200 Bandit and I was wondering if anyone knows if Bandit 1200 gearbox is compatible with the 1127 GSX-R?

Here is the link to the kit from Nova Racing Transmissions: http://www.novaracing.co.uk/ProductSuzukiGSF1200CloseRatio6SpeedGearbox.html

[Gixer1460]

Wouldn't it be best to ask Nova? As far as i'm aware the 'M' GSXR 11 box is swappable with a GSF, but don't know for a fact! 

[dr_thirsty]

Yes, I already asked Nova and they didn’t know? 

[Dezza]

Relative to the astronomical cost of that gearbox, finding a decent Blandit 12 engine and going from there will be minimal and then you'd know it would all fit.

[no class]

I recal that the output shafts on the m/n models had double row bearings such as the b12. The 1052 models have single row outputshaft bearings as well as the 89-90 1127’s . there is a “C” groove on the lower cases that keep the bearing secure.... this will vary on the models with single row bearings compared to double row . lower crankcase 89-90 have different part number from 91-92 ..... possibly due to the double row bearing groove ?

Edited April 22, 2020 by no class

[dupersunc]

The only real difference is the output bearing behind the Sprocket. Use the correct bearing for your cases and you'll be grand. The later Bandits and GSXR1100 have a longer output shaft and double row bearing to allow for wider rear tyres, the Nova shafts are the same length as these, but you can use the early out put shaft bearings.

Personally I'd start with a good GSXR motor rather than a Bandit lump. The GSXR motors are better finished, and little things like the clutch sprag are lightened on the GSXR, the Bandit isn't.

[dr_thirsty]

Thanks for the advice. I am starting with a 89-90 GSX-R motor, so no Bandit. I am installing it in a 91 750, for a TrackDay only focused bike. The 6-speed is an interesting option, but won’t know if I need it Yet? 

[Gixer1460]

Don't 750's have 6 speed boxes anyway - obviously not close ratio though? As there were lots of 750 race bike classes, I would have thought suzuki kit gearboxes would be available and cheaper second hand?

[dr_thirsty]

There is a thread here somewhere, that explains using the 750 gearbox. But, it is not without work and apparently, I have heard that the 750 gearbox can be fragile, in a tuned 1100. Plus ratios are meant for the higher rev-ing 750s. Nova gearbox if it drops in, would be tough and have the right ratios to match. It’s a wishlist item at the moment anyway. 

[dupersunc]

9 hours ago, dr_thirsty said:

There is a thread here somewhere, that explains using the 750 gearbox. But, it is not without work and apparently, I have heard that the 750 gearbox can be fragile, in a tuned 1100. Plus ratios are meant for the higher rev-ing 750s. Nova gearbox if it drops in, would be tough and have the right ratios to match. It’s a wishlist item at the moment anyway. 

750 gearbox swap needs a bit of faffing with the clutch. Its not that tricky but you are correct they are not going to last with a tuned 1100 motor.

The 1100 ratios are not Ideal for track work, 1,2,3 are too close, 3,4,5  too far apart.  But they still work well enough. I run mid/ front of Fast group on my mildly tuned 1127 woth a five speed. I run 14/48 or 15/48 depending on the circuit.

[dr_thirsty]

That's good to know thanks. Do you happen to know if there are any problems running a wider rear-wheel with the 89-90 1127 motor. I've worked out I need an offset front sprocket, but this dimension was based on my original 91 750 motor and that had the 5.5 inch rear wheel anyway. I'm going to stick with a 180 rear, that way I can use modern lighter GSX-R wheels and not need a second mortgage for special wheels.

[dr_thirsty]

14 hours ago, Gixer1460 said:

Don't 750's have 6 speed boxes anyway - obviously not close ratio though? As there were lots of 750 race bike classes, I would have thought suzuki kit gearboxes would be available and cheaper second hand?

The only `Suzuki gearbox' I've heard of is the one Guy Martin used in this GSX-R1100 Turbo and he probably has contacts I don't have? 

[dr_thirsty]

16 hours ago, Dezza said:

Relative to the astronomical cost of that gearbox, finding a decent Blandit 12 engine and going from there will be minimal and then you'd know it would all fit.

Yes, when I come across a cheap Blandit motor, I will use it to check. I am going to get a 91-92 1127 too, to see the differences with my 89-90 motor.

[dupersunc]

28 minutes ago, dr_thirsty said:

That's good to know thanks. Do you happen to know if there are any problems running a wider rear-wheel with the 89-90 1127 motor. I've worked out I need an offset front sprocket, but this dimension was based on my original 91 750 motor and that had the 5.5 inch rear wheel anyway. I'm going to stick with a 180 rear, that way I can use modern lighter GSX-R wheels and not need a second mortgage for special wheels.

There are different spacers for the front sprocket, The 750 spacer will put the chain where you want it for the 750 wheel.  chain will be very, very close if you use a 180/60 rear tyre, and you will find a 180/60 works best.

Later Suzuki wheels have the rear sprocket 10mm further from the centre line,  most people machine the sprocket carrier down 5-6mm  and fit an offset front sprocket.  when I did mine I went 6mm off the sprocket carrier, moved the wheel across 1mm, and used a 3mm offset front sprocket of a zx6f,  can't remember which model, but they have an offset as stock.

I'm convinced Triumph 675 wheels are a good option, the sprocket alignment is much closer, but I'm told getting the rear brake to line up is awkward.  675 wheels are some of the lightest  oem wheels available, but anything is lighter than the 89-91 Suzuki wheels.

[dr_thirsty]

On 4/23/2020 at 11:16 AM, dupersunc said:

There are different spacers for the front sprocket, The 750 spacer will put the chain where you want it for the 750 wheel.  chain will be very, very close if you use a 180/60 rear tyre, and you will find a 180/60 works best.

Later Suzuki wheels have the rear sprocket 10mm further from the centre line,  most people machine the sprocket carrier down 5-6mm  and fit an offset front sprocket.  when I did mine I went 6mm off the sprocket carrier, moved the wheel across 1mm, and used a 3mm offset front sprocket of a zx6f,  can't remember which model, but they have an offset as stock.

I'm convinced Triumph 675 wheels are a good option, the sprocket alignment is much closer, but I'm told getting the rear brake to line up is awkward.  675 wheels are some of the lightest  oem wheels available, but anything is lighter than the 89-91 Suzuki wheels.

I am using the 94-95 750W swing-arm and to get that to line up perfectly, I needed a 3mm spacer on the clutch side of the swing-arm. Now a 750W wheel lines up perfectly with the front. I'm using L1 750 wheels I will need either a 5mm, 1/4", 3/8"or 10mm offset front sprocket. I want to go to a 520 chain, as that will give a bit more room, also may limit the sizes I can get on the front sprocket, but I will have to come to that later. With 530 size those are the sizes available, so no problem. On the sprocket side of the wheel, 10mm is the problem correct, might have to run without the seal on the sprocket carrier (use a sealed bearing instead). Tap the studs deeper, so they don't stick out so far and hit the weld on the inside of the swing-arm. I first tried with a 1000 K5 rear, wow that is even worse (an extra 5mm to get rid of). I was looking through the parts catalog and it looks like for 90 there is a 3mm wider sprocket spacer. Good way to check which model mine is? If it turns out I have an 89, I can use spacer from the 90. If I remember correctly from 90 they used a 5.5” rim on the rear. Spacers from 91-92 are smaller, most likely because of the double row bearing on the output shaft. 

Edited April 25, 2020 by dr_thirsty

[coombehouse]

On 4/23/2020 at 10:47 AM, dr_thirsty said:

I am using the 94-95 750W swing-arm and to get that to line up perfectly, I needed a 3mm spacer on the clutch side of the swing-arm. Now a 750W wheel lines up perfectly with the front. I'm using L1 750 wheels I will need either a 5mm, 1/4", 3/8"or 10mm offset front sprocket. I want to go to a 520 chain, as that will give a bit more room, also may limit the sizes I can get on the front sprocket, but I will have to come to that later. With 530 size those are the sizes available, so no problem. On the sprocket side of the wheel, 10mm is the problem correct, might have to run without the seal on the sprocket carrier (use a sealed bearing instead). Tap the studs deeper, so they don't stick out so far and hit the weld on the inside of the swing-arm. I first tried with a 1000 K5 rear, wow that is even worse (an extra 5mm to get rid of).

You can make 530 sprockets fit 520 chain by reducing the sprocket thickness. 520, 525 & 530 are all the same pitch.

[dr_thirsty]

8 hours ago, coombehouse said:

You can make 530 sprockets fit 520 chain by reducing the sprocket thickness. 520, 525 & 530 are all the same pitch.

Yes that’s correct, but you will have some trouble due to the fact that the good quality front sprockets are hardened. And also you are limited to the least number of teeth you can have. If I need huge sprockets, chain will be longer, heavier and that defies all I’m trying to do. 

[dr_thirsty]

I also got conformation from Team York Suzuki, they race at the TT and Nova Racing Transmissions said I should contact them. So as mentioned in this thread, yes it will fit and it will also fit the 1052 motor too. Just use the original gearbox output bearing for each type. Now all I need is to save up a bit longer !