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Goo'Roo

GSF1200 gearbox issues

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Hello,

I used two different 1157cc engines on my bikes, the one I'm using now is turbocharged, and now a customer with a 96 bandit came to my workshop with the same problem.

3rd and 4th gear whining. The turbo now is starting to whine just in 3rd at low revs but I know how it'll end soon. I had lots of other sacs engines, but I never had this problem before. Is it so common on that engine?

Is there a definitive solution? Because I'm thinking about custom gears

Edited by Goo'Roo

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1 hour ago, Mark28 said:

Is there a reliable replacement? About to build a turbo motor myself.

There isn't - the Blandit has essentially the same gear cluster as the last GSXR M / N's having a slightly better undercut on the dogs.

They can be improved with a specialist 'pro cut' undercut which changes the angles to lock them better but a worn dog is still a worn dog and replacement will only improve the gears that get replaced...... 2nd is the usual one that normally needs 5th replaced as well as they run together as a pair.

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I 've seen a lot of bandit gearboxes where 3rd and 4th gears are pitted on the teeth. 

Gsxrs don t seem to suffer as badly.

Fit a Nova 6 speed box if you have deep pockets 

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Ian dont forget m and n have double row output bearing I'm sure Bandit has single but I may be wrong here.

 

Edited by jonny1bump

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On drag race engines you can get real good gears from the states I've really forgotten the contact but can find out.

Mega money thou and they work in completely different manner as you almost have two gears engaged at same time when you change and it throws the previous gear out. Bad explanation there.

I've got got shed loads of spares and Roger undercut loads of gears for me.

Once I even had dog snap off that was quite scary experience changing down to find whole transmission locked and pulling in clutch not helping. I'm quite calm person but believe me that was panic moment.

 

Edited by jonny1bump

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On my builds I spends hours fettling gearbox makes quite difference. Got feeling mention this in my build thread. Basically first thing I do is shim all that play out of selector drum. (On the stocker there is pusher on the drum). Then I'll die grind selector drum so gear dogs are all equal when in position. Takes hours, Normally spend whole weekend on gearbox. 

A friend had stock Bandit commuter bike not ridden hard output shaft snapped????

Real budget build so had to repair cases I had shaft I gave him, he was not happy with time I was taken to fettle box, did not go over to top just moderate play. But with end result said felt so much better and smoother and glad I did it.

Edited by jonny1bump

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The Suzuki gearbox I'm sure is copy of Villiers design the Kwak gearbox design of this period is so superior.

Edited by jonny1bump

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11 minutes ago, jonny1bump said:

On my builds I spends hours fettling gearbox makes quite difference. Got feeling mention this in my build thread. Basically first thing I do is shim all that play out of selector drum. Then I'll die grind selector drum so gear dogs are all equal when in position. Takes hours, Normally spend whole weekend on gearbox. 

 

That is really good information, thank you.

This is the best explanation that I have ever read.

 

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Think put pics in my build thread, but did it backwards as finished bike the talked about it. Oh well lol.

Edited by jonny1bump

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59 minutes ago, jonny1bump said:

Ian dont forget m and n have double row output bearing I'm sure Bandit has single but I may be wrong here.

 

Just checked on fiche bandit is indeed single row.

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There is quite bit play with 16 in housing you need to check dog alignment to check which side you shim it. May have to do both sides. You may  need to shim behind 25 too everyone is different. I got flat piece shim steel of various thicknesses and almost make round washer the same size of outer race only ( for 16 for 25 then vice versa inner only but not so important) They quite difficult to make. Good start sandwich between wood drill hole with carbide or diamond tip hole saw, tin snip outer diameter and gentle grind and spike bits with fine grinding wheel been very careful not to ruin your fingers.

Mock build it and you see it move back and forth.

You got to be really careful that you basically don't f**k it up and jam mechanism or push dog engagement to one side, that would be a bad day first time you do flat stick change. Also don't make shim too big and stop oil getting to bearing. I thought long and hard if I was going to post this information. If you not an expert building stuff don't do it.

Talking about good quality oil with regular changes also will help gearbox not just engine. I use the expensive Motul and change 1000 to 1500 miles max. But not starting oil debate please that's been done many times and everyone got preference.

Edited by jonny1bump
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Disclaimer - If you follow this modification it is completely at your own risk and no one other than yourself can be held accountable for any mistakes, actions or accidents which could occur from any implemented modifications and from riding in an unsafe or dangerous manner.

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I'm starting to think Suzuki did the sloppy tolerating on purpose to allow for build variation and they are relying on the undercut dogs to pull themselves into place. But it's all about that whole blue printing thing getting everything as good as it can be.

Also not mention selectors pawls these should be smooth most rebuilds end up stoning these. Also selector forks, any damage and burning bin them simple. After having box lock myself and seeing shafts snap it needs to be right don't be cheap.

Edited by jonny1bump
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2 minutes ago, clivegto said:

I am getting a gear box super finished for my latest engine build.

Whose doing that Clive and what they do sounds very interesting.

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1 hour ago, jonny1bump said:

Disclaimer - If you follow this modification it is completely at your own risk and no one other than yourself can be held accountable for any mistakes, actions or accidents which could occur from any implemented modifications and from riding in an unsafe or dangerous manner.

Oiy - i've got copyright on that ! LOL!

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Thanks for the info Jonny. As always with anything on this site it's proceed at ones own risk. Just was curious what you have found with boxes you had done in the past. 

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7 hours ago, clivegto said:

I am getting a gear box super finished for my latest engine build.

I have used this on a few ( Starts with a Y ) race bikes and it really does work. It is worth having the cams and followers done at the same time and maybe even the rods to help reduce stress.

I had a full engine done once and it was sooooo smooth afterwards.

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1 hour ago, Mark28 said:

I have used this on a few ( Starts with a Y ) race bikes and it really does work. It is worth having the cams and followers done at the same time and maybe even the rods to help reduce stress.

I had a full engine done once and it was sooooo smooth afterwards.

Already had the cams done, am getting most the engine internals done.

20190301_185029.jpg

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42 minutes ago, Mark28 said:

Excellent.who are you using?

As in the link above lol.

20190301_195132.jpg

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