WOBBLY BOTTOM

[darrsi]

So, for a little while now i've been getting a feeling of the bike feeling a tiny bit unstable when riding.
It reminds me of when my rear shock leaked before and i was literally riding on the spring around corners which became quite eventful, but not quite as bad as that this time.
I have a refurbed OEM shock, which has done approximately 9000 miles.
I've checked for any leaks and i can't see any oil anywhere this time so i think it's okay where that's concerned.


I was wondering though, if the swing arm bearings are shot, or seized, what would i be feeling on the bike when riding? Could seized swing arm bearings make the rear shock stick in a fixed position?


At the moment i do think that i'm feeling too many bumps in the road, and there's that odd slightly wobbly feeling again.
My rear tyre looks okay, with plenty of tread left in the middle, so it's not squared off at all.
When i put my weight on and off the seat the suspension doesn't really feel like it's doing too much to me, almost like it's too hard.


Can somebody enlighten me on what and how to check to determine what's at actually at fault please?


I can't do anything until tomorrow so any suggestions or help welcomed in the mean time. 

[Tmation]

First check your tyre pressures are correct and the tyres are in good order.


Put the bike on the main stand and check the rear wheel bearings (You Tube or Google to save me typing it all out)


Then check the swing arm for play, up and down plus side to side.


Get someone to lean on the rear of the seat (while on main stand) so that the front wheel is off the floor


Check front wheel bearings for play


Grab the bottom of the forks to check the steering stem bearings.


If nothing obvious check all discs for run out and sticking pistons in the calipers.

[celticdog]

I wonder if you've got wheel shimmy darrsi? Could be the tyre just needs balanced, check the condition of the rims

[darrsi]

First check your tyre pressures are correct and the tyres are in good order.


Put the bike on the main stand and check the rear wheel bearings (You Tube or Google to save me typing it all out)


Then check the swing arm for play, up and down plus side to side.


Get someone to lean on the rear of the seat (while on main stand) so that the front wheel is off the floor


Check front wheel bearings for play


Grab the bottom of the forks to check the steering stem bearings.


If nothing obvious check all discs for run out and sticking pistons in the calipers.

I know i need to check the swingarm for play, it won't be any of the other stuff though, i service the brakes twice a year, tyres are all good and pumped up, my head bearings were changed and i know the signs for iffy wheel bearings.
It's either gonna be the shock or swing arm.
Just not entirely sure how you check a dud shock when there are no obvious leaks?

[darrsi]

I wonder if you've got wheel shimmy darrsi? Could be the tyre just needs balanced, check the condition of the rims

To be honest i don't get up to much speed commuting to work, and i don't need to be moving too fast to feel it.
Unfortunately i do encounter a few roads with speed bumps to and from work every day, and with  the top box and with me not being a lightweight i reckon the OEM shocks just aren't coping.

[Graham53]

Probably a daft question but are all the shock and dogbones bolts torqued up/ tight and no cracks in the coil spring ?

[darrsi]

Probably a daft question but are all the shock and dogbones bolts torqued up/ tight and no cracks in the coil spring ?

I shall check these ideas tomorrow, cheers.
Very difficult issue to explain, but quite an unsettling experience to feel when riding the bike.
Something's certainly not right.

[Fazerider]

I'm sure a decent shock will be an improvement even if you don't find anything wrong with the linkage, but it's possible that temperature has a lot to do with it.
The first 8 miles of my commute to work is on slow twisty roads with plenty of undulations, pot holes and long shallow depressions where trenches dug for pipes have sunk after repair. It feels similar to your description: a jarring ride and I keep thinking the back end's trying to step out.
OK, I've a knackered shock and the rear tyre's beginning to square off, but in winter there's a huge difference in how the bike feels in the morning when the tyres (and shock oil) are cold and when I come back at night after a long blast down the M4 and they've had a chance to warm up.

[darrsi]

I'm sure a decent shock will be an improvement even if you don't find anything wrong with the linkage, but it's possible that temperature has a lot to do with it.
The first 8 miles of my commute to work is on slow twisty roads with plenty of undulations, pot holes and long shallow depressions where trenches dug for pipes have sunk after repair. It feels similar to your description: a jarring ride and I keep thinking the back end's trying to step out.
OK, I've a knackered shock and the rear tyre's beginning to square off, but in winter there's a huge difference in how the bike feels in the morning when the tyres (and shock oil) are cold and when I come back at night after a long blast down the M4 and they've had a chance to warm up.

Yeah i s'pose the 5.5 mile journey each way doesn't help matters at all.
In very cold weather the bike simply doesn't get 'warm' throughout.
I'll check the obvious tomorrow and report back.
The shock doesn't feel responsive to me at all so is the prime suspect, but as always these things can play mind games and are not always the real culprit.
And as shocks can empty a wallet i thought it would make sense to ask advice first.

[Dudeofrude]

Have you ridden it since? Does it still feel the same?
I had what sounds like  a very similar experience a week or two back while out for an afternoon ride.
 Sort of feels like your riding on a flat tyre? Every corner felt like the tyre was folding under the rim?
Put me off so much I had to come back home as I was convinced I had a puncture or a bearing was shot but couldn't find anything wrong and has been fine ever since? Was very strange

[darrsi]

Have you ridden it since? Does it still feel the same?
I had what sounds like  a very similar experience a week or two back while out for an afternoon ride.
 Sort of feels like your riding on a flat tyre? Every corner felt like the tyre was folding under the rim?
Put me off so much I had to come back home as I was convinced I had a puncture or a bearing was shot but couldn't find anything wrong and has been fine ever since? Was very strange

I started getting a hint of something being not right before Xmas, then i was back at work on Tuesday and have noticed it all week.
As mentioned by Fazerider, the condition of the roads are not helping either. There's a constant flow of lorries all around where i work, and my journey home consists of a few bus routes, so the roads are being totally shagged by heavy vehicles.
I'm running 36/40 psi on the tyres which i checked on Wednesday, and they were fine. I'm fortunate to have access to an airline at work, so not only can i easily monitor the pressures very regularly i also have the consistency of using the same source.

[darrsi]

So, after a lot of poking about, and jumping up and down on the bike around my friends house we both agreed that the swing arm and rear shock are behaving exactly the way they should be.
Everything else is good too, no play anywhere, nothing binding, etc, which i expected anyway. Earlier i'd even given the bike a good clean as well.


But on closer inspection there was a bit of a flat spot on the rear tyre.
It's nothing major to look at, and there is still a lot of tread left in the middle of it, but i think as there is a very slight outer edge to it, it could be where it's not gripping in the slippery conditions for a split second giving me that momentary sliding feeling.
This would simply be caused by the slow and mainly upright journeys to and from work every day.
It seems a shame to have to change a decent tyre (T30) with so much tread left on it, but the unstable feeling is more than enough reason for me to do so. 

[Graham53]

Hope that works Darrsi ,Can you keep the tyre after getting a new one just in case you change it and the problem still exists , least that way you've got a decent emergency tyre and if it cures it then you can just bin it

[Skippernick]

Find some bendy roads for an afternoon.

[darrsi]

Now i'm fairly sure what it is i might be able to ride through it with a bit more confidence, but if it gets too annoying then i will just swap it out for peace of mind.


The time before when my shock had leaked it's oil so i was riding on the spring was a horrendous feeling, and i could only anticipate what was coming as i approached a bend but the bike had its own ideas of where it wanted to to go.
This felt like the start of that, but nowhere near so bad, but obviously it does play with your head.


I've even started going a longer way home from work just to keep the bike flowing and to try and cut out the ever increasing traffic, but it's just the sheer volume of vehicles on my route that turns it into a bit of a chore.


My wallet took a big sigh of relief anyway once we realised that all the suspension was good.