750 gearbox in 1100 engine - Suzuki GSX-R Motorcycle Forums Gixxer.com
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post #1 of 6 (permalink) Old 10-10-2012, 08:01 AM Thread Starter
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750 gearbox in 1100 engine

Hey guys

I have searched on this toipic and i have found some people who say thet did this but its all a bit yes/no.

The case has the same number stamped on the outside, 17E so that means every distande,dimension of the 750 and 1100 engine case should be the same correct?

I have readed that when you take the 750 gearbox you need the cable operated clutch aswell, is this true?

Cant i keep the hydraulic clutch or is the primary axle way different (where the gears are that is)?

On the other hand i maybe can get a dry clutch from a 1994 wsbk, but that still a big?

Is the 750 gearbox weaker then 1100 gearbox, more componets in the same space must be smaller, thinner?

But the 6 gears offer more advantages then the 5 gears from the 1100 i reckon.


Forza Flandria!
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post #2 of 6 (permalink) Old 10-11-2012, 09:07 AM
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Re: 750 gearbox in 1100 engine

I have seen it done at my local Suzuki shop. That bike has now been sold. But they did the conversion for racing. Sorry, I don't have more details.
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post #3 of 6 (permalink) Old 10-11-2012, 07:59 PM
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Re: 750 gearbox in 1100 engine

The OSS website has a write up on this. From what I recall there has been a case of the clutch basket disintegrating under the stress. That is also on the website. The 750 clutch basket or the flywheel fouls #4 rod screw so one form an oiler has to be used for this combo of 750 tranny and cable clutch.

I have swapped 750 WC cases into my 1100 engine due to damage to the original 1100 cases. The 1100 transmission fit fine, so one assumes the converse is also true, as would apply in your case.

On a side note, the upper casing had to be trimmed to accept the larger 1100 cylinders though. along some of the inner edges. The drum, rods and all big end and needle bearings are housed identically in the cases. There are some things to be cautious of, in regards the bearings, they look similar but do have different part numbers. However in my case, I am running the 750 big end bearing on the 1100 shaft, in a 750 casing so that is a confirmed ok, can't say for the others.
Best of luck!
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post #4 of 6 (permalink) Old 11-15-2012, 11:13 PM
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Re: 750 gearbox in 1100 engine

I hear the Valvoline/EMGO suzuki guys were using race kit tranny's (6 speed) in their GSXR 1100's.....
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post #5 of 6 (permalink) Old 11-16-2012, 01:27 PM Thread Starter
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Re: 750 gearbox in 1100 engine

Will see if the 750W gearbox can be put into the 1100W cases, going to further tune the cyllinderhead and make the internal components lighter so its little effort to swap the gearboxes.

Love to have the gearbox from my 750sp, i think i might use the 750sp gearbox and use a stock 750W gearbox in the 750sp engine.

But then my 750sp isnt stock anymore, what to do?

I still use the 750sp as my daily drive and the race tranny isnt very street friendly in my opinion.

Or could one make his own close-ratio gearbox by swapping gears from a 750w/1100w or rf900?

Forza Flandria!
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post #6 of 6 (permalink) Old 11-16-2012, 02:31 PM
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Re: 750 gearbox in 1100 engine

750W gearbox willl fit in 1100W cases . . . you just need to use the selector drum, selector gear shaft, and selector forks to match. You can modify the late series hollow 750W shafts for hydraulic operation. You cannot use the 750W clutch with the 1100W, because the basket fouls the crankshaft and conrods. The 1100W clutch can be used after some machining because of the shorter clutch shaft on the 750W. The 750W gearbox is much weaker (not surprising) than the 1100W's. Some racers made the swap to get the closer ratio's for the track, but really with the high/broad torque available on the 1100W's it is not an issue. My race engines pull hard from 6000 to 11500, and all I have conceded was to get a Robinson 2nd gear ratio to reduce the split between 1/2 and increase the 2/3 split for track work.

Streetbike . . . GSXR1100WS, Yoshi RS3 pipe, Factory Pro jet kit. Hillclimb car . . . 1298cc SBM big block, Yoshi stage 2 cams, FCR41's, Dyna 2000, MTC lockup clutch, Geartronics paddle shifter. Circuit race car . . . currently 1118cc Wiseco Gixxer with Hahn turbo / Hilborn throttle bodies / Microsquirt EFI
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