GS tranny in a GT750 box

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MikeD
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Re: GS tranny in a GT750 box

Post by MikeD »

tz375 wrote:Please measure it across the gears on both shafts and I'll see if it can fit without resorting to conversion to full cassette style trans.
both are ~116mm +/- .5mm
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tz375
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Re: GS tranny in a GT750 box

Post by tz375 »

That unfortunately is the same as a GSXR six speed that won't fit without more significant modification such as moving the side of the crankcase out by 7mm.

Grab a GS1100, 1000, 750 etc or GSX as they were known in other markets. SOHC or DOHC (16v) models will work but not the later 6 speed bandit/Gixxer type.
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Re: GS tranny in a GT750 box

Post by ja-moo »

This thread is so long, I have forgotten why one would need a 6 speed in a GT?
Visiting from the "K" camp...........
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Suzukidave
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Re: GS tranny in a GT750 box

Post by Suzukidave »

I dont think we have found a 6 speed that will work yet ?
the older i get the faster i was
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tz375
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Re: GS tranny in a GT750 box

Post by tz375 »

ja-moo wrote:This thread is so long, I have forgotten why one would need a 6 speed in a GT?
That's because they are so highly tuned with a very narrow powerband. OK so that's not close to being true, but don't let facts get in the way of a good story.

The thread was about changing 5 speed trans for one with better ratios. Stock JKL are awful, MA are a little better, B is almost OK and GS750 etc are better again in choice of ratios.
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Re: GS tranny in a GT750 box

Post by ja-moo »

Thanks for the answer!
Visiting from the "K" camp...........
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Suzukidave
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Re: GS tranny in a GT750 box

Post by Suzukidave »

File with missing pictures http://suzukidave.com/index.php?sfpg=R1 ... OGJkZmI4MA" onclick="window.open(this.href);return false;
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Re: GS tranny in a GT750 box

Post by Suzukidave »

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Re: GS tranny in a GT750 box

Post by Suzsmokeyallan »

Going back to the comment about the GSX gearbox being just 7mm too wide between the gears, I believe it can be made to work by slimming some material from the outer faces of the gears and also some work to the bearing inner faces to get the shafts into the bearing supports without modifying the cases.
I'm more concerned with the drum and selector forks distance from the gears and shifter drum fork pin locations.
If one one you bought MikeD has not worked let me know and send some photos of the problem area
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MikeD
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Re: GS tranny in a GT750 box

Post by MikeD »

I don't have the cases split yet to try it
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tz375
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Re: GS tranny in a GT750 box

Post by tz375 »

A GS750 trans will fit without too much effort and so will a GSX750. The output shaft of the latter is longer but distances internally are the same as the earlier GS.

Both shafts need to be machined for oil seals and the clutch side of the input shaft has to be shortened to allow the clutch to lift. The output shaft can be machined on the flange or the bearing to allow for the extra 1.5mm to slot in between the case walls.

The GS trans is somewhat different to the GT even though most of the gears appear to be the same as a late GT box, but they are not. Some use different dogs and others are different diameters and some are longer.

Withe GSX750 5 speed, some of the gears are different to the earlier GS but the same modifications work.

When using a GS or GSX transmission with a stock GT rear wheel, you need to obtain an offset sprocket and fit it inside out.

A GSX1100 (GS1100E) trans is very similar to a GSX750 but two gears are wider and the shafts are 2mm longer to fit them. The flange which has to be machined on a GS trans to make it fit is already thinner on an 1100 than it is on a GT or 750, so machining it thinner is not an option. The bearing has to be machined to fit an 1100 trans.

In all cases, it is essential to remember that the input shaft is located to the clutch side and the output shaft is located to the sprocket. The shafts can float inside the small bearings and on the 1100 has wave washers to take up the slack. The trans must be assembled in the lower case and the locating nuts tightened before checking for clearance between gears. The moving gears should have similar clearance from the fixed gears on both sides. Cycle through the gears and check that the dogs are clear of each other.

Failure to get clearances right could be very serious.

There is currently no known was to fit a six speed trans into a GT without substantial modifications.
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Re: GS tranny in a GT750 box

Post by MikeD »

if someone wants this 2001 Suzuki Katana GSX750 trans as a donor to try to machine up a known fix I'd be happy to donate it to the cause and send it along in the hopes that there is a 6sp solution that can be developed
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tz375
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Re: GS tranny in a GT750 box

Post by tz375 »

Allan, jumped in earlier, so if he wants to try it, that's good. If not please send the cluster plus forks and shift drum and I'll see what I can come up with.

I'm still trying to slam a set of cases closed on a set of 1100 gears that are a touch to fat for the outfit. Getting really close now and it looks like the upper oil guide needs the same modifications that SuzukiDave came up with for the 750. I'll loctite the screw before I cut half its head off in situ.

And of course the cases sometimes need to be relieved on the inner cheeks to clear the new, larger gears which are now closer to the cases and rub.
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tz375
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Re: GS tranny in a GT750 box

Post by tz375 »

Funny thing happened yesterday. I was playing with some RD400 and RD350 transmissions and realized that TZ250 and 350 have the same sprocket splines as an RD350 and they are teh same as a GS750/1000/1100 and some GSXRs.

RD400 transmission has a different spline and it happens to be the same as a GT750.

So feel free to order an RD400 sprocket for that 520 chain conversion on your GT750 and for anyone with a GS750 up they can use a TZ or RD350 520 sprocket.
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Suzukidave
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Re: GS tranny in a GT750 box

Post by Suzukidave »

Off set sprockets for the rd400 seem easier to find to for those with a stock transmission but need to work around a wider rear tire .
the older i get the faster i was
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