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Gsxr750F swing arm. Good Idea for track work?


dupersunc

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Anyone run  the Short GSXR 750F  swing arm on a Slabbie on track?

I've just acquired one, and I'm looking at trying it on my 7/11 race bike.    Now I know the history,  and supposedly the GSXR 750F was a widow maker, hence the longer arm on the G and H models.

However tyres have changed in all but colour and shape in the last 30years.  I'm hoping shorter wheel base, and a little more rear weight bias would help turn the bike quicker and help my front end problems.

Anyone gone down this route?   Or am I mad?

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I'm with modern rubber and suspension calming the F down. A mate of mine bought an F when they came out (I was very envious !), he was so concerned about the bike's handling when pushed  - he traded it in for an RG500 ! which he loved, apart from the shocking fuel consumption..

If you have any problems it'll probably be due to s.arm flex, which was noticed with the tyres when racing, even back then, some fitted 1100  s.arms, which are 1.6 times stiffer (from a P.Bikes article by John Robinson ).

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7 hours ago, Oilyspanner said:

I'm with modern rubber and suspension calming the F down. A mate of mine bought an F when they came out (I was very envious !), he was so concerned about the bike's handling when pushed  - he traded it in for an RG500 ! which he loved, apart from the shocking fuel consumption..

If you have any problems it'll probably be due to s.arm flex, which was noticed with the tyres when racing, even back then, some fitted 1100  s.arms, which are 1.6 times stiffer (from a P.Bikes article by John Robinson ).

Short swing arm never bothered these below

img155.jpg

img154.jpg

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7 minutes ago, dupersunc said:

I'm not racing at the TT sadly.

Didn't say you was, what I was trying to point out was most of those bikes were the ones with short swingarms and they had very good results. this is on the most demanding circuit in the world on both man and machinery and being ridden by some of the best riders of the time and believe me you don't win races on the IOM  with a substandard bike.. I have had oil cooled gsxr's from when they were first released and raced them continually to this day and have to say that there is such a load of negative shit printed about them it makes you laugh, they were pritty much the first jap bike that you could buy to go racing with that you didn't have to go looking for a aftermarket frame. back to your swingarm why don't you just elongate the adjusters in the swingarm to move the wheel forward.

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50 minutes ago, cregnybaa said:

Didn't say you was, what I was trying to point out was most of those bikes were the ones with short swingarms and they had very good results. this is on the most demanding circuit in the world on both man and machinery and being ridden by some of the best riders of the time and believe me you don't win races on the IOM  with a substandard bike.. I have had oil cooled gsxr's from when they were first released and raced them continually to this day and have to say that there is such a load of negative shit printed about them it makes you laugh, they were pritty much the first jap bike that you could buy to go racing with that you didn't have to go looking for a aftermarket frame. back to your swingarm why don't you just elongate the adjusters in the swingarm to move the wheel forward.

Gotcha. :)

So the short F arm is the arm of choice at the TT?

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2 hours ago, dupersunc said:

Gotcha. :)

So the short F arm is the arm of choice at the TT?

I don't know what most of the others run today, but I have got one 1100 with elongated chain adjusters and it does turn quicker with no side effects and I have used the short swingarm in the 750 with no problems.

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I did Donington last year on my Slabby 7/11; healthy motor, 750k frontend, R1 shock and Slingshot wheels with sticky tyres. 

I’m anything but a fast guy on track, but even I could feel the limiting factor was the swingarm. At some point I even pulled of to see if the wheel was actually tightened up (it was) 

I’m in the process of turning this bike into a dedicated trackbike and the first mod will be bracing the swingarm. 

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On 1/4/2018 at 10:09 PM, cregnybaa said:

I don't know what most of the others run today, but I have got one 1100 with elongated chain adjusters and it does turn quicker with no side effects and I have used the short swingarm in the 750 with no problems.

CregNyBaa has had quite a bit of input into my bikes helping me with running them in the Manx and Classic TT.  Both now have longer swingarms but originally one was long and one short.  The differences to me were so small that other factors such as the suspension unit, settings, going from 18 inch to 17 inch wheels, and even the seat foam (swapped seats between bikes) had as much effect on the feel.  Currently both 750s have the longer swingarm,  simply because that was what I could find when I needed to change the shorter one.

Those 750s in the Production TTs above were on 18 inch wheels on a course that was slower than the one today.  Can't remember the weather but I can't see the longer swingarm knocking a minute off the laptime.

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2 hours ago, Rene EFE said:

When I got used to it, it didn’t really slow me down anymore, it was just a bit different from what I’m used to. 

Still gonna brace my swingarm though, just because I can :) 

That's the problem with this whole issue.  It's comparing a slabby with what people are used to.  Slabbies are a product of what was raced at the time,  by the technology  and manufacturing processes available at the time, not to mention rider expectations too.  They looked like F1 bikes and performed exactly like F1 bikes of the time.  My racing partner happens to work with Roger Marshall, and when we were converting the slabbies for FE racing in the early 2000s he had a good chat with Roger about them and what we could expect out of them.  Roger told him that he was initially hesitant about riding the 750s at the TT as he didn't like "road" bikes.  To cut a long story short by the time he'd got to the bottom of Bray Hill on the thing he was convinced it was a race bike.  So they do handle like race bikes of the time, different to the big heavy 1000cc F1 bikes that went before, and the stiffer beam framed bikes that followed.  We just need to remember that they perform flawlessly for what they are. 

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