NC30 - How to Rose Joint rear suspension

[tigerclaw]

Hi, I am going to rose joint the rear suspension (dogbone section) to make it adjustable. Can someone share some wisdom and possibly pictures - I can see that I can either set it up to run exactly as the dogbone currently does or I can but a long bolt through the frame mount and make the links run outside the dogbone mounts on the frame, this may be necessary to avoid the shocks lower mounting bolt? (the dogbones are flat and miss the mounting bolt whereas a rose joint may foul it)

What I am wondering is

a) What size / strength rose joint is suggested (or is it fine to use whatever size will go over the new mounting bolt that is going to run through the frame?)
b) I was thinking that having the rose joints running outside of the frame mounts (ie legs open) may increase the force placed on the rose joints - is this a concern or a problem?

That all said, I have a car with an anti rollbar that is mounted on rose joints (which they mostly are) and it takes huge strain with no problem but on the bike I dont want the suspension to collapse while I am heading on down the road (bit more of a high risk application) - thanks for the input

[The Novice]

Just get a set of dog bones made up at the size you want. Otherwise, eBay will sort you out, there is an eBay store selling all diff sized Rose joints. I was going to make up some adjustable links for my crm. It was as cheap to get a pair of stainless dogbones made up. I just used a piece of galv to try out how long to make the new dogbones. Longer will lower the bike, shorter will raise it.

[tigerclaw]

Thanks Novice, I hear what you are saying and its probably stronger and lighter, but doesnt this look pretty
viewtopic.php?f=24&t=391&p=2060&hilit=dogbone#p2060

[The Novice]

Looks ok but once you have the right height when will you ever see them!

[tigerclaw]

You're probably right... not sure what I am actually going to do... could do either with about the same effort... a solid dogbone is probably lighter and stronger, but being able to play with the adjustment is also cool... did i mention I wire brushed and buffed the bolts which mount the subframe so common sense may not win through

[Cammo]

You can certainly notice a difference between standard and maximum raised ride height (before suspension hits exhaust - that's the limit to how far it can be raised), but really there's not much difference to handling in between these extremes in my opinion.

Adjustable sounds nice to have, but far easier and simpler to just shorten the dogbone length.

[speedy231278]

If you want to alter the ride height but be able to fiddle with the setting, would it not be easier just to have an adjustable shock? Or does changing the linkage length have a subtly different effect than changing the length of the shock?

[Neosophist]

You can certainly notice a difference between standard and maximum raised ride height (before suspension hits exhaust - that's the limit to how far it can be raised), but really there's not much difference to handling in between these extremes in my opinion.

Adjustable sounds nice to have, but far easier and simpler to just shorten the dogbone length.

I concur.

I've tried a few settings and it didnt make worlds of difference (although im only riding on the road). Currently im using the RC30 dogbone and triangle piece, forgot the name of it and the suspension is really close to the exhaut but working fine.

Hopefully take it to the track this year and give it a good testing now its all overhauled.

My best advice would be that if your not already sure on how to get it sweet then spend the money you would on some rose joints and what not and visit a professional suspension guru who will help you set the bike up to its best settings and advise you if you need the ride height done and where it needs to go.

The amount of time it saves getting a guru to look at it pays for the job itself if you value your time, it also gives you a good base setting.

If you already have it nailed down pretty well get some pictures up after fabrication.

[tigerclaw]

Hi Nesophist - No, nothing is final yet, I am soaking up the input.. I am trying to stick to the standard shock at the moment (partly because I would like to keep the original parts as much as possible and I dont want to spend too much cash, partly because I dont have much knowledge on good shocks / bad shocks and shock setups so I thought it would be a good plan to adjust what I know instead of throwing the cat completely among the pigeons) - I definately hear you about speaking to a professional, I actually know someone who races and I will have a chat with him.

Speedy - I dont have the experience or skill to know the difference but I suspect an adjustable shock is probably the right way to go because moving the "rocker" point by shortening the dogbone cant be as good as leaving all the stuff at its correct design angles so that X movement on the swingarm results in Y movement on the shock...

But I'm learning and you guys have got me thinking (which is good :))

[Cammo]

Raising the rear really transforms the handling on these bikes for the better.

Below is a pic of a drilled dogbone the previous owner did on one of my nc30's (new hole not being used).



The numpty drilled the new hole too far from the standard hole (from memory it was around 14mm) and so if it were used it would foul the exhaust. I got both holes welded up and drilled a new one 8mm from the centre of the standard hole now it's a good un. This part is cheap and plentiful if you ask in the wanted section, hence my suggestion to just get hold of a couple and drill one at the maximum ride height (8mm) and one in between (perhaps 5mm) to see which you like it.


Or... you could fit the dogbone from an rvf. These do exactly the same thing as a drilled (shortened) nc30 dogbone but are usually more expensive an in demand, go figure

rvf link on the left, vfr on the right:




As you raise the rear ride height by this method it firms up the spring rate of the shock slightly due to the change in geometry, usually beneficial if you're using the standard shock.

Rvf owners have it easy and can simply insert a shim at the top of their shock which raises the ride height without changing the shock spring rate (Rick Oliver sells the shim for rvf owners).

If you want to alter the ride height but be able to fiddle with the setting, would it not be easier just to have an adjustable shock?

That would certainly be an easier option, but much more expensive!