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BiKenG

Swing-Arms

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I was under the impression that the 3rd and 4th Gen S/As were basically the same apart from the suspension mount. But just looking at some specs and according to them, the 3rd Gen is 5mm longer @ 565 and 15  mm wider @ 250 mm. But a rough measure of a 4th Gen frame suggests a 3rd Gen S/A would in fact fit no problem. Can anyone confirm this difference, or are the specs that I looked at wrong and more specifically, can a 3rd Gen S/A be used in a 4th Gen frame?

 

I had thought they were interchangeable, but maybe that's not the case. So would be good to hear from anyone who's done the swap.

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Sorry to have to bump this, but surely someone has a 4th Gen S/A to measure? I have a 3rd Gen so I can confirm those specs, but no idea if the 4th Gen data I have is correct. In particular I find it hard to believe the 4th Gen S/A is 15mm narrower at the pivot than the 3rd Gen.

 

Could someone with a 4th Gen S/A please measure it for me. Length (centre to centre, eccentric hub to pivot) and especially the width across the pivot. Just the actual cast Al part would suffice.

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I may have one.  I will check tomorrow.

 

Ciao,

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Great. I await your report.

 

I measured the 3rd Gen I have here and it is 242 (maybe 243) across at the pivot. That's just the actual Al casting. The collars will add about 7mm to that.

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On 5/17/2018 at 11:22 AM, BiKenG said:

Sorry to have to bump this, but surely someone has a 4th Gen S/A to measure? I have a 3rd Gen so I can confirm those specs, but no idea if the 4th Gen data I have is correct. In particular I find it hard to believe the 4th Gen S/A is 15mm narrower at the pivot than the 3rd Gen.

 

Could someone with a 4th Gen S/A please measure it for me. Length (centre to centre, eccentric hub to pivot) and especially the width across the pivot. Just the actual cast Al part would suffice.

 

My eyeball, calculations & steel rule measurements yielded 228mm across the casting at the pivot (I am more certain of this measure than the length), and 560mm centre-to-centre between the eccentric and the pivot.  HTH.

 

Ciao,

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8 hours ago, JZH said:

 

My eyeball, calculations & steel rule measurements yielded 228mm across the casting at the pivot (I am more certain of this measure than the length), and 560mm centre-to-centre between the eccentric and the pivot.  HTH.

 

Ciao,

 

Hmm, thanks for those measurements, but I am very surprised to have confirmation that the 4th Gen S/A is 5mm shorter and 15mm narrower at the pivot than the 4th Gen. I really thought they had the same basic dimensions.

 

Looking at the 4th Gen frame however, I'm sure a 3rd Gen S/A could be mounted in there. Has anyone tried this, squeezing a 3rd Gen S/A into a 4th Gen frame?

 

Guess I need to get hold of a 4th Gen S/A. Anyone got a spare one?

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There is also the ultimate location of the sprocket to consider.  With the RC30 swing arm in my RC36-I frame I needed to use a 5mm spacer on the LHS of the swing arm pivot and also space the sprocket out by 3mm (although part of this was necessary in order to get the 530 chain to be centred over the RC30 (525 pitch) chain guide).  I am also using a custom rear sprocket and a modified front sprocket, so the measurements above should only be regarded as an illustration of the considerations necessary.  There are also at least three different lengths of Honda RHS swing arm pivot bushing nuts (whatever those fully-threaded adjusters are called), so there is often room to move the swing arm to the right.  Now that my 3rd gen is sorted, I have no real need of my spare 4th gen swing arm...

 

Ciao,

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Well let me know what it would take to relieve you of that 4th Gen S/A.

 

In the meantime, I should probably offer up the 3rd Gen S/A and see if it will fit between the adjusters in the 4th Gen frame.

 

As you say though, who knows if the alignment will be correct. The good part is that all these Honda wheels use the same offset and the eccentric hub of the RC36s is the same. At least, I think it is. I'm pretty sure the dimensions are the same. So the rear of the S/As must be the same. I wonder how the lateral location of the pivot compares between the RC36 models.

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Not much, really.  I'm sure we can work something out.  Let me know if you need it.

 

Ciao,

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