Just fitting RC51 gearbox to VTR.

[John Orchard]

I HATE the low 1st on the VTR1000F, so l am just fitting an RC51 gearbox, the mainshaft pokes out 3mm longer on the clutch end, l could probably just make a spacer, but what the hell, RC51 clutch didn't cost much :-) l'll let you know how the whole job ends up.

[tony.mon]

Interesting, let us know how it goes.
One of the 3rd gear set is drilled, this is a known weak point on SP's when used for clumsy clutch-free upshifts or with a quick shifter fitted.
For this reason I only use the qs on mine above 3rd.
As the storm puts out less power it should be fine.

[fabiostar]

this will be worth watching to see how it goes

[sirch345]

That is interesting I agree, please do keep us posted

Chris.

[John Orchard]

Interesting, let us know how it goes.
One of the 3rd gear set is drilled, this is a known weak point on SP's when used for clumsy clutch-free upshifts or with a quick shifter fitted.
For this reason I only use the qs on mine above 3rd.
As the storm puts out less power it should be fine.

I am doing cams & upping the comp for the racetrack, so it could get a hard time ;-) But thanks l will look at 3rd, maybe l could use the Firestorm 3rd? Much of the gearbox interchanges, both use the same countershaft, shift forks interchange, same clutch push-rod, if you look at the ratios, only 1st & 4th are different.

The good thing about doing this swap is, with the sump off you can go through all the gears and see how much engagement each gear has. I recently swapped gearbox internals on my vintage motocross bike (vertically split), mixing KDX400, KX420 & KX500 gears.

So far it looks like a 'drop in' job with complete shaft clusters and clutch. But l will evaluate the possibility of just changing the mainshaft (1st drive), 1st gear (driven) on the countershaft, the slider next to it (has an extra engaging dog) and a 3mm spacer for the clutch.

[John Orchard]

Interesting, let us know how it goes.
One of the 3rd gear set is drilled, this is a known weak point on SP's when used for clumsy clutch-free upshifts or with a quick shifter fitted.

Nope won't interchange, 3rd on RC51 is a 4 dog, Firestorm is 6 dog (!). I'll look at various combinations now :-)

[John Orchard]

I don't have my engine split yet, I have complete Firestorm and RC51 gearboxes on the bench.

[John Orchard]

I've been going through all gear combinations, bloody Honda, getting tripped-up by number of engaging dogs :-( , looks like I'll have to use the complete RC51 gear clusters. I wonder if I could get a stronger 3rd driven (countershaft) gear made?

[freeridenick]

I've been going through all gear combinations, bloody Honda, getting tripped-up by number of engaging dogs :-( , looks like I'll have to use the complete RC51 gear clusters. I wonder if I could get a stronger 3rd driven (countershaft) gear made?

Speak to Nova Transmissions. They produce a close ratio 'box for the SP so will be able to sort something I'm sure.

Very interesting thread. I posed this question a while back but no-one came back saying they'd tried. When you look at the parts diagram the VTR and SP ones look near identical. I was going to try it last time I split my cases but never found and SP 'box at the right price to take the risk. Good to know they fit. A Nova 'box came up a while back for £700 which would be worth a go for the track.

Are you planning on racing?

[tony.mon]

I have a spare SP cluster and shafts if anyone else fancies a go.
They were from an SP1 motor, but I think they are the same.

[John Orchard]

Are you planning on racing?

I'll do some track days for sure, pending how that goes as to whether l race it.

I raced a Firestorm in the Australian Superbike Championship and at the World Superbike event at Phillip Island (bad crash in qualifying) back in '98.

I held a couple of Thunderbike (singles, twins & triples) lap records on my old VTR, still couldn't match those times on my 200 hp 2006 GSXR1000 !!!

[John Orchard]

Ok l'm still waiting for the RC51 clutch assembly to arrive, also an RC51 primary drive gear, the primary drive gear on the Firestorm is 44 teeth, the gear from RC51 is 40 teeth, so depending on how many teeth are on the clutch basket, l won't know the primary ratio, but it is looking lower, which would give a closer ratio gear sequence. I'm also hoping that the distance between the crankshaft and mainshaft is the same in both the RC51 and Firestorm.

[John Orchard]

Finished ! RC51 complete gear shafts & RC51 stator flywheel, took it for my first blast up the hills today ..... awesome !

RC51 stator is 1 kg lighter than the Firestorm, bolted straight in.

With the gearbox l used the Firestorm clutch, l had to run a 3mm spacer under the original clutch hub nut & spacer, and grind 1mm off the clutch end of the RC51 mainshaft so the pressure plate does not bottom-out on it. Kept the original Firestorm shift forks.

I usually run 15/43 gearing, will go to 15/44 now :-)

Took one day to strip it down, one day to rebuild it, third day test ride :-)

[tony.mon]

Well done! Shame you still had to use the clutch from the firestorm; it hurts quick launches. I've never had that problem on my SP2, so whatever they changed, it worked- can't comment about the SP1, but I haven't read any bad reports of the clutch, so I assume that's ok, too.

The clutch outer diameter is physically bigger though, as I recall, so it would mean modifying the clutch casing- not too difficult, I would have thought, especially if you fitted an electric coolant pump so could dispense with the water pump part of the casing while you were there.

It'll be interesting to see what you standing quarter times are.....

[John Orchard]

Thanks :-)

Yeh l always had that problem with the clutch take-up on my '97 racebike, l just dumped the clutch at 3 grand and then just powered through the midrange, worked ok at the time.

I think l have fixed it this time, l'll test it a couple more times and report back. I had a GSXR1000 that had the same problem, so l did the same things to the VTR that l did to the GSXR, l drilled a couple more holes in the clutch hub, to let more out to the plates, l also enlarged the machined flat on the push-rod end piece, and ground another flat on the opposite side, to let more oil into the clutch.

I run 15/50 semi synthetic oil (l only ride on warm days here in Australia, and l let it warm up before riding), l am also going to try some 20/50.