Suspension Overhaul - now feels worse!

[Jamieboy]

Thanks for the replies.

I don't think it is a set-up issue. As a couple of people have said, it feels like the shock is too reactive, but only to tiny forces, it does not feel like the spring is too hard when going over larger bumps and I have tried reducing preload setting and it didn't change the juddering feeling.

It feels more like the tiny bit of movement in the shock that must take place when travelling over an essentially smoothish road is not happening, so the little imperfections are being felt in the bars more than I would expect - so I am wondering if it is possible that it has been over-pressured when put back together thus impeding initial shock travel. Anyone hear of this happening?

I will however set the sag etc this weekend and see if it has a positive effect.

 

[monkeyboy]

Thanks for the replies.

I don't think it is a set-up issue. As a couple of people have said, it feels like the shock is too reactive, but only to tiny forces, it does not feel like the spring is too hard when going over larger bumps and I have tried reducing preload setting and it didn't change the juddering feeling.

It feels more like the tiny bit of movement in the shock that must take place when travelling over an essentially smoothish road is not happening, so the little imperfections are being felt in the bars more than I would expect - so I am wondering if it is possible that it has been over-pressured when put back together thus impeding initial shock travel. Anyone hear of this happening?

I will however set the sag etc this weekend and see if it has a positive effect.

Forget fiddling with the little preload adjuster knob - that's for fine tuning really. Imagine a spring held between your fingers - if you put no preload (compression) on it, then tap one of your fingers and the spring will move quite a bit because the spring isn't very hard and no force will come through to the other finger. Now bring your fingers much closer together (more preload) and do the same tap and your fingers might not move at all as the spring is much harder, and more force will come to the other finger. Take it to the absolute max and compress it completely and all the tap is transferred straight through. The damping just slows the reaction of the spring to the force. Depends very much on the speed of the force too though when applied to the bike.

Anyway - if you're happy and you have a CSpanner - take the front shock off and wind off the preload a couple of rings and see what effect that has. It may be that they assembled it and wound it down too far/more than you're used to. The front shock isn't pressurised as far as I know - its just oil flowing through a hole - so as it seems to be damping the bigger bumps ok it would seem to me that the damping isnt the problem. It just sounds like the front spring is to hard - ie too much preload.

 

[Flipfly]

Forget fiddling with the little preload adjuster knob - that's for fine tuning really. Imagine a spring held between your fingers - if you put no preload (compression) on it, then tap one of your fingers and the spring will move quite a bit because the spring isn't very hard and no force will come through to the other finger. Now bring your fingers much closer together (more preload) and do the same tap and your fingers might not move at all as the spring is much harder, and more force will come to the other finger. Take it to the absolute max and compress it completely and all the tap is transferred straight through. The damping just slows the reaction of the spring to the force. Depends very much on the speed of the force too though when applied to the bike.

Anyway - if you're happy and you have a CSpanner - take the front shock off and wind off the preload a couple of rings and see what effect that has. It may be that they assembled it and wound it down too far/more than you're used to. The front shock isn't pressurised as far as I know - its just oil flowing through a hole - so as it seems to be damping the bigger bumps ok it would seem to me that the damping isnt the problem. It just sounds like the front spring is to hard - ie too much preload.

The 1150GS range have a set number of preload settings, they are not on a ring adjuster like Ohlins, Wilbers, Nitron etc.

 

[monkeyboy]

Ohh yea - what an idiot! It's been ages since I had the originals on. You still need a C-Spanner though don't you to spin the adjuster round and step it up and down the settings?

 

[Neil W]

Sounds a lot like the front shock has been overfilled with oil when it was rebuilt , when ABE refurbed the shocks on my old 1150 about 5 years ago it was amazing how much difference it made to both the front and rear.

 

[Nick591]

If you wind preload off to the lowest setting and you still have the problem it's because there's too much resistance to initial movement in the damper rod. That can be caused by too much damping (not sure if these have adjustable damping) or by too much 'stiction' on the damper rod. If the refurb company replaced the damper rod seals they will be much tighter than before. May just need more miles on bumpy roads to bed them in. Either that or its overfilled with oil. If the shock is also gas filled the gas pressure could be too high. I'd talk to the refurb company.

 

[Slipperyeel]

I really don't think much can be done to the front OEM shock. Only an oil change and then to do that the damper unit need to be drilled to drain it, then plugged with a valve. ABE are one of the few outfits who will tackle this job. And after that, it's just a fresh oil and air mix, no new seals... I know all this because I went through a while suspension refurb back in Feb this year.

Sounds like one of two things. The OP now has a properly functioning shock and needs to get used to it . Or it's been over pressured and now need it backing off a little.

 

[wust588]

I think you are flying in the face of the laws of physics by saying that adjusting the
preload alters the "hardness" or "softness" of a spring.

All the preload does is er preload the spring, it doesn't change the spring rate.

The damping alters the "hardness" or "softness" of the shock absorber. Not the spring.

 

[DutchBryn]

Some good, thoughtful input (above) about the way suspension works together.

Obvious ways to check your suspicions would be swapping yours with a known 'good' front shock.
Further, there are such things as suspension dynamometers. Not sure where you had yours worked on, but when Maxton did some work for me a few years back, they had one.

 

[Sneakybiker]

Presuming that the suspension overhaul is in good order (and better than before one would hope) I have a point of curiosity that might be contributing to the knocking sensation. Have you had the front suspension back out of the bike since the rebuild...it might be worth checking that the 2 rubber bushings are present along with the metal guidance tube at the top of the shock where it attaches to the frame under the tank.

Might be worth a look as the little suckers are easily misplaced, in case they still reside with the suspension company or are rolling around your garage floor!! ;-)

 

[Jamieboy]

Thanks all for the replies.

It appears Sneakybiker may have nailed this with their first post on the forum! There appears to be no lower rubber on the top of the shock. Can only guess it fell off when I was fitting it - what a tit!

Thinking about it, that not being there means the top of the shock is sitting against the frame - which could be exactly why i'm feeling small forces so 'directly'.

Thanks very much. Glad I didn't name the suspension outfit at the start now. Weakest link in the whole system was clearly me!

 

[Deleted account 211025001]

Nice one and good to have a definitive answer

Andres

 

[Comfy Old Boots]

Thanks all for the replies.

It appears Sneakybiker may have nailed this with their first post on the forum! There appears to be no lower rubber on the top of the shock. Can only guess it fell off when I was fitting it - what a tit!

Thinking about it, that not being there means the top of the shock is sitting against the frame - which could be exactly why i'm feeling small forces so 'directly'.

Thanks very much. Glad I didn't name the suspension outfit at the start now. Weakest link in the whole system was clearly me!

Part number or it never happened

PLease and thank you

 

[Jamieboy]

Right! Looked it up: 31422311994. There should be two of them. I have one.

 

[Comfy Old Boots]

Right! Looked it up: 31422311994. There should be two of them. I have one.

That'll do it!