Honda RC31 (Bros) Site

I plan to modify my Bros over the winter of 2002 to provide:-

CBR600 front end (forks and wheel/disks/calipers)

Purchased - 30/10/2002
 cbr_front_end1.jpg (29775 bytes)
VFR750 single sided rear end complete Purchased - 1/12/2002  vfr750fm_complete_rear3.jpg (31117 bytes)    vfr750fm_complete_rear4.jpg (32405 bytes)
CBR900R rear shock Purchased - 13/11/2002  cbr900_rear_shock2.jpg (25480 bytes)
Solo tailpiece.
I know it looks terrible but look here for conversion.
Purchased - 10/04/2003 seat_original.jpg (9101 bytes)

I rebuilt the front forks with new bushes, seals etc.  They are now ready to fit.

After stripping down the VFR rear end I checked all the dimensions and calculated that if I took the VFR rear hub complete with disk/caliper I could remove the Bros hub disk/caliper and bolt the VFR straight on.  This would then eliminate the need to machine the Bros spindle to accept the VFR rear wheel with it's 4 bolt method of fixing as opposed to the Bros' single centre bolt.  The machining of the Bros spindle is a common method of getting the VFR wheel to fit the Bros assembly.
I reckon you would only need the VFR wheel and centre spindle providing you can get/make a spacer that slips on the VFR spindle behind the cush drive assembly as the VFR splines protrude through the hub by approx 2mm, also another spacer of approx 5mm would be required behind the 46mm A/F nut.

I fitted the entire VFR750 hub/spindle including disk and caliper but used the Bros cush drive because the VFR cush drive takes the VFR sprocket - a 530 chain and the Bros is a 520 and the Bros' wont fit on the VFR's either.
I don't like the setup (purely cosmetic) and will probably have the Bros spindle machined and fitted with the 4 VFR wheel bolts so as to retain the existing Bros rear hub assembly - it's quite a bit lighter than the VFR too.

The VFR spindle sticks out more than I like, just too many spacers/washers and looks like this
 vfr750 spindle in Bros hub_2.jpg (87004 bytes)

The VFR hub assembly

 vfr750fm_rear_hub_assembly1.jpg (29394 bytes)   vfr750fm_rear_hub_assembly2.jpg (27234 bytes)

The Bros hub assembly

No pictures yet.

I noticed a lot of web sites detailing the mod to fit a 'blade' rear shock to the Bros and all indicate filing/grinding the top eye to fit in the frame.
I machined mine down to fit BUT also relieved the eye width itself by approx 0.5mm on each side to allow just the centre spindle to protude and therefore be clamped in the frame correctly.
Whilst the shock was in the milling machine I also offset bored the centre hole to 12mm (shifting the hole up by 1mm).  I will get a photo of it to better explain what I mean, but just at the moment it is fitted to the bike.

I have also fitted some K&N air filters and modded the carbs to provide main jets of 142 front and 138 rear, left everything else as was.  Adds a feeling of more 'get up and go', haven't had time to properly check it under ride conditions as it has been persistently raining !!  The inlet noise is pretty loud but I have a cure for that - earplugs !!

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