F2 rear end

[marjay]

Hello,

After finally getting my F2 working to the point where I can ride it without it spitting me off due to random powervalve opening, I've found that the springs and racetech cartridge emulators that I installed in the forks are doing an excellent job, especially considering the crossply tyres.

However, the back end feels... loose... for want of a better word? Over about 60mph it weaves left to right a little. Nothing dangerous, just disconcerting. The shock appears to have enough damping and there doesn't appear to be any wheel bearing movement, nor swingarm bearing movement, nor shock bush movement... But I can't be certain. The bike passed an MOT fine.

Anyone any ideas what could be causing it? Is it just that the back end is too soft, and I need to invest in a new shock? Or could it be swingarm or shock bushes or linkage bearings?

The rear end feels surprisingly soft when I sit on the bike and take it off of the centrestand... Wonder if that is relevant? There is definitely damping in the rear shock though...

[marjay]

Nobody?

I just want someone to tell me what is most likely to cause a vague back end on an F2. Bushes, shock, bearings... rusty swingarm even?

I added up the cost of all of the swinging arm/suspension parts in the one stop shop, and it came to £234.40... excluding a shock.

[Shytalk]

Start with the basics, tyre pressure, tyre condition, is the rear wheel in line with the front, play in linkages or bushes then shock itself, if its the original shock then it could well be past its best, lastly take your weight into consideration too.
A custom shock to suit you will set you back at least £300 I should think, I'm not sure if the original shocks are rebuild-able either else that would be an alternative to a completely new one.

[crash]

sound like a rear tyre problem that.

[marjay]

Rear tyre is a brand new Bt45 at 28psi...

I weigh 11 stone

Front pressure is 26psi (as per Haynes manual)

Wheels are perfectly aligned

Bushes seem OK.

Shock is original, but covered with a kind of rubber gaiter thing. Looks pretty mint underneath.

[midlifecrisisrd]

See what the spring preload is set at, may need turning up to max to see if it helps but as it will probably be near 20 years old probably just shagged

Steve

[Shytalk]

Shocks will always look OK unless leaking, but if the damping inside is gone they are next to useless, it would be ideal if you had someone nearby who you could borrow one off as a quick ride round the block will confirm it.

[LC_BOTT]

I think the F2 shock is still available, Norbo sells them for approx £110 (just looked £125) In case you decide on a nice Yam one?

[kickstart]

Sept 27, 2012 14:16:04 GMT 1 marjay said:

Rear tyre is a brand new Bt45 at 28psi...

I weigh 11 stone

Front pressure is 26psi (as per Haynes manual)

Just had a quick look on the Bridgestone web site and they list the pressure to use as 2.5 bar front and 2.8 rear, which is FAR higher than you are using.

All the best

Keith

[mellow]

my rear end is completely new,bushes/pivot sleeves/genuine shock etc and at 30mph mine weaves slightly. I put it down to head bearings.Got tapers fitted but its a b*****d to adjust right as when you tighten the top bolt it tightens the bearings makin them too tight.so im going back to standard i think

[Deleted]

mellow ya perfectionist, these bikes will never handle like a modern superbike, they are like a bucking bronco, love it