Girvin Vectors

[NAILTRAIL96]

Is there a lot of work involved in changing the shock from elastomers to something more modern?.
I've seen pics of it done but is it worth the cost and effort?.

 

[apache]

It's dead easy. The hardest bit is making sure you buy a shock that will fit.

The elastomer one has a rather large lower pivot diameter, and as it's a steel tube, you can't turn it down to the smaller diameter of typical shock bushes (12mm? Can't remember...)

Sooo, you need to make a new pivot to with large ends to suit the original clamping arrangement, and a smaller centre. You need to do this in two pieces. I made one piece with the large end and smaller diameter part to slide through the new shock, then a shim to slide over it for the clamp at the other end. I made a couple of nylon washers for the sides of the shock eye, but I don't think this is necessary given the very low angular movement at the eye.

The top pivot is very close to that of a modern shock eye and only needs something like 0.5mm skimming off it in the lathe.

Probably an hour's work and a couple of quid's worth of a structural alu grade rod - 6082T6 or the like.

 

[NAILTRAIL96]

So a set with wrecked elastomers is not the end of the world.
How does a shock conversion compare to a new set of elastomers?.

 

[apache]

Definitely not the end of the world. Its an easy conversion.

The ride difference is a difficult question for me to answer. The last time I rode an eleastomer equipped Proflex was in 1995-ish. I haven't finished building this one yet. However, the work to convert the rear of a 656 to air shock looks to be difficult due to the short length requirement, so I might end up with an elastomer back end.

I did buy a CF swingarm off a later model thinking I might be able to cobble something together, but the main pivot on the CF swing arm equipped versions is further forward on the main triangle, so whilst the CF arm will physically fit onto a 656, it will result in an unacceptably long back end and I imagine pretty dull handling! Stretch-Limo-Flex anyone?

I'm not paying $50 for a bit of rubber sold as an elastomer replacement, so I'm busy reading up on shore hardness and pestering my usual plastic suppliers for urethane bar samples

 

[NAILTRAIL96]

That does sound like an expensive bit of rubber!.

I guess I'll know better when I aquire all the parts and can take some measurements.

If you post up some pics of the shock and the space you're trying to squeeze it into maybe the collective could make suggestions.

 

[andrewl]

I'd have top say I found the suspension action on the carbon ones I have was pretty awful and didn't inspire any real confidence in the bike I had them on.

They look great on the wall though and a are a good conversation starter...

 

[NAILTRAIL96]

Ooh, carbon you say?

 

[apache]

Like this...

http://www.ebay.co.uk/itm/190588573467? ... 500wt_1156

 

[Raging_Bulls]

I did buy a CF swingarm off a later model thinking I might be able to cobble something together, but the main pivot on the CF swing arm equipped versions is further forward on the main triangle, so whilst the CF arm will physically fit onto a 656, it will result in an unacceptably long back end and I imagine pretty dull handling!

Nothing wrong with long swingarms. Fit a very hard shock, lower the fork and you can go dragracing.

 

[paininthe]

@ nailtrail96 I have some i'll package up for you if you want to try them. Doing nothing with them at the moment. Later ones with separate stem and coil spring. Just cost you postage to see what you think.