Gearbox swap

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longandlow
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Joined: Tue Jan 17, 2017 9:36 pm

Gearbox swap

Post by longandlow »

The gearbox on my sprint storm has started playing up, not selecting gear and jumping out of gear. The air shifter gives the box a hard time so it was only a matter of time. I am going to whip the motor out and change the gears, drum and forks. I have the tools covered, but what parts gaskets etc am I going to need? I don’t intend stripping the whole engine, just removing the lowers case.
Thanks in advance.
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freeridenick
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Location: Derbyshire

Re: Gearbox swap

Post by freeridenick »

I can't see that being and easy job for you doing it like that. I assume you've looked at the service manual so your going to need some way to rest the engine on its heads and make it stable. Or use an engine stand that will rotate. Even so it's a heavy old lump.

Gaskets should just be the two engine covers if you don't take the heads off. Plus other parts like a new clutch lock nut.
tony.mon
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Re: Gearbox swap

Post by tony.mon »

I've always thought that you could pull off the lower case with the engine still in the frame if you simply turn the bike upside down.
If the cases don't separate easily you will have missed one of the crankcase bolts, there's a sneaky one above the clutch, so you need the clutch off first.
It's also going to need selector forks, I would have thought.
It's not falling off, it's an upgrade opportunity.
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longandlow
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Re: Gearbox swap

Post by longandlow »

Thanks guys.
I might try turning the bike upside down, but the engine bolts are all free so it might be just as easy to remove it. I intend to change everything in the gearbox as it's had a hard life. Just hope changing it and freshening up the clutch doesn't start the hope skip and jump issue, it launches great at the moment :eh:
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longandlow
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Re: Gearbox swap

Post by longandlow »

Well to update this post. I have now changed the complete gearbox, complete with selector forks and drum. I took the engine out in the end. What a pain that was, had to strip most of the bike down to do it. I turned the motor upside down leaving the heads etc on. Due to the chain guides being bolted to the lower case the tensioners had to be loosened, and timing reset after refitting. The gearbox swap was pretty straight forward, but again a lot had to be removed from the motor. Not a job for the novice, but it is doable with some mechanical ability and knowledge.
Found the 1st/2nd gear selector fork to be very badly worn.
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Kev L
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Re: Gearbox swap

Post by Kev L »

Well done on completing the job, here’s hoping all your hard work is rewarded when you test it :thumbup:
Carpe diem, quam minimum credula postero
F3, 954 USD front, K Tech springs, Braced swinger, Penske shock, Six spoke Mockesini wheels, Harris rearsets, QaT, Flywheel diet!, A&L stacks, stick coils, K&N, FP Ti jets, lashings of Ti & CF
tony.mon
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Re: Gearbox swap

Post by tony.mon »

New parts, I hope.
It's not worth taking a chance on 2nd hand parts when it's that much if a faff to get it redone if the 2nd hand parts aren't good enough.
It's not falling off, it's an upgrade opportunity.
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longandlow
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Re: Gearbox swap

Post by longandlow »

I put a low millage gear cluster in, and new selector forks. :thumbup:
tony.mon
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Re: Gearbox swap

Post by tony.mon »

That should do it.
What times are you getting on the 1/4?
It's not falling off, it's an upgrade opportunity.
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longandlow
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Re: Gearbox swap

Post by longandlow »

Had to do a mod to the gear linkage to get the shifter to work. Ran 10.972 this weekend :D
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lloydie
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Re: Gearbox swap

Post by lloydie »

Well done .
I did a gearbox swap (ride in ride out in 7 hours once but I had just built the bike so everything came off easy .
kemes
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Location: Vantaa, Finland

Re: Gearbox swap

Post by kemes »

longandlow wrote: Wed Jun 27, 2018 8:53 pm The air shifter gives the box a hard time ...
May I ask what kind of parts have you used to build the air shifter?
2000' VTR1000 Firestrom
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