Sharp suspension feeling

[Joepi5]

Hello!

The title I out up there is a little vague, but bear with me. For about two weeks I'm the owner of a 2010 GS with 33k miles on the clock, complete with ESA. Over the past weeks I have done a big service round, (all fluids/all serviceable items, greased shaft splines, replaced rubber gearbox boot, etc.).

All seems well, but what I notice during riding is that occasionally the suspension feels like it bottoms out. Or at least that is how it feels, kind of a sharp kick so to speak. The strange part is that it seems the be dependent on road surface, and only on abrupt unevenness. It sometimes feels like you can feel even rock on the road/road lines, but as a sharp hit. On cobblestone roads it feels smoother, less sharp so to speak.
This is my first bike with telelever/paralever and first shaft driven bike. Is it supposed to feel like this? If not, what could cause this? Does my vague description raise any questions with anyone?

Now I do have to change tyres as that can be a cause for this (and they are getting too near the end for an upcoming trip). Current tyres are Bridgestone T32's which are stiff (but really you can almost run it without air stiff). So it might just be that, I don't know.

 

[landmarkjohn]

I guess you've been through all the ESA settings to try and find the best match. Try jacking up the pre load to big mountains and see if it bottoms out.

At the bikes age and mileage a suspension refurb with T Tech Suspension is the most cost effective option. I've ridden mine with worn suspension for too long before getting refurb and it really does take from the enjoyment.

 

[Joepi5]

I don't think it actually bottoms out, it just feels that way. On big more gradual dips in the road surface it's really smooth and doesn't fel underdamped at all

Also because it happens at random times. Going over speed bumps at speed doesn't produce this feeling for instance, while train tracks might.

 

[Pukmeister]

Put the bike on its centrestand then try to twist the final drive knuckle sideways on its paralever trunnions, then do the same for the swingarm and its bearings. Just make sure there isn’t any play/wear.

Look under the gearbox by the right hand foot peg and check the long frame mounting bolt that connects the frame to the gearbox casing hasn’t fallen out.

I had both these faults when I owned a Hexhead, the missing frame to gearbox bolt caused slightly vague handling with an intermittent clunk/knock.

 

[Joepi5]

Put the bike on its centrestand then try to twist the final drive knuckle sideways on its paralever trunnions, then do the same for the swingarm and its bearings. Just make sure there isn’t any play/wear.

Look under the gearbox by the right hand foot peg and check the long frame mounting bolt that connects the frame to the gearbox casing hasn’t fallen out.

I had both these faults when I owned a Hexhead, the missing frame to gearbox bolt caused slightly vague handling with an intermittent clunk/knock.

Thanks for the reply!

Checked all the suggested points before riding to work today. I feel no play in the swingarm bearings, or FD bearings.

Also checked the frame mounting bolt, they are all there. Haven't checked their tightness with a wrench/rachet, but only with my fingers. So that seems good as well.

Maybe I'm just over sensitive towards my new bike and it's just supposed to be like this. I'm going to change tyres to something with a softer carcass to see if that changes anything.

 

[ShakeyGS]

That happened to my 2016 1200 LC at about the same mileage and it turned out to be failed seals in the front shock. There was fork oil on the lower part of the shock.

I sent both shocks to Lukas at T-Tecj suspension and he did a superb reconditioning job for me.

 

[Joepi5]

That happened to my 2016 1200 LC at about the same mileage and it turned out to be failed seals in the front shock. There was fork oil on the lower part of the shock.

I sent both shocks to Lukas at T-Tecj suspension and he did a superb reconditioning job for me.

Thanks for the suggestion!
Just checked this, both front and rear shock are completely dry. This could mean they leak and are empty or not leaking at all. I'm guessing the latter since there is damping at the front and rear.

 

[Joepi5]

I guess you've been through all the ESA settings to try and find the best match. Try jacking up the pre load to big mountains and see if it bottoms out.

At the bikes age and mileage a suspension refurb with T Tech Suspension is the most cost effective option. I've ridden mine with worn suspension for too long before getting refurb and it really does take from the enjoyment.

I'm going to a local BMW specialist (I'm not located in the UK so T Tech is not really an option). But I have found general specialist near me to get opinion from them.

I'm starting to believe it is in fact a problem with the front shock, which was not what I was hoping for...

 

[Joepi5]

You were all right, both the BMW specialist and an ESA repair guy I went to yesterday both said that my shocks are nearing there end of life and need servicing.

But the biggest issue isy weight vs the springs. I have to set preload to 2 persons to have the right amount of sag.

Course of action for now is to ride this season as is, have the shocks rebuild and stiffer springs installed after the season.

 

[Pukmeister]

T-Tech does much of his business via parcel post.

If you can remove your shocks yourself and get them mailed to him, he can do them by return postal service.

You will no doubt incur import/export paperwork and shipping costs but it’s an option if you have nobody in the Netherlands that can repair/service them.

It will be like riding a new bike after, or better than new if you have the spring rate and valving adjusted to suit you.

 

[Joepi5]

T-Tech does much of his business via parcel post.

If you can remove your shocks yourself and get them mailed to him, he can do them by return postal service.

You will no doubt incur import/export paperwork and shipping costs but it’s an option if you have nobody in the Netherlands that can repair/service them.

It will be like riding a new bike after, or better than new if you have the spring rate and valving adjusted to suit you.

There is a service in the Netherlands like that as well, called esarepair.com due to import and export difficulties (and time) that will be my go to. They are also the ones that gave the advice yesterday.

 

[Mistacat]

Springs often appear to go weak when in fact it is the lost nitrogen that makes the difference.
I machined 7mm spacers for my Wilbers shocks as they needed more preload over time, when I received them back from T tech suspension they did not need the spacers, I now have them serviced every 30K miles.
The lost Nitrogen pressure makes a difference.

 

[Joepi5]

Springs often appear to go weak when in fact it is the lost nitrogen that makes the difference.
I machined 7mm spacers for my Wilbers shocks as they needed more preload over time, when I received them back from T tech suspension they did not need the spacers, I now have them serviced every 30K miles.
The lost Nitrogen pressure makes a difference.

This loss in nitrogen was indeed the cause identified by the ESA repair shop.

My weight of 125kg or 19.7 stone is simply to much for the springs (switch to two helmet preload for just me) seems to work for now. At least for this season.

 

[Joepi5]

Replaced the tyres the bike came with (Bridgestone T32's) to Continental Trail attack 3. This made a huge difference on how smooth everything feels. The things I felt too harsh (in my opnion) are now smoother and better damped.

Maybe because the tyres are softer in construction, maybe because there was an awful lot of self balancing/sealing gunk in the old tyres (rotating unsprung mass). I'm not sure, but it now feels like everything is working correctly. Will still do the suspension overhaul at the end of the year, so it will only get better .

One nice thing I learned about the place I'm going to sent my shocks to is that the owner is an Engineer who worked at WP suspension when the ESA system was developed, in fact he worked on that exact project. They are able to fill and pressurize the shock without the need for drilling in the body and installing external valves.

 

[botus]

This loss in nitrogen was indeed the cause identified by the ESA repair shop.

My weight of 125kg or 19.7 stone is simply to much for the springs (switch to two helmet preload for just me) seems to work for now. At least for this season.

... buy a spring (or two)...

std OEM spring is 140nm at the back and its OK for 80kg - I'm about 115kg and I run a 175nm rear and its like a pillow - both WP and Ohlins supply 120nm out of the box yet that can't even hold the bikes weight

and whatever mumbo-jumbo this means on the front - I think Mistacat's point is correct, this front used to be way too stiff but these days it seems to dive quite a bit and both ends due a service

 

[Joepi5]

... buy a spring (or two)...

140nm at the back is OK for 80kg - I'm about 115kg and I run a 175nm rear
and whatever mumbo-jumbo this means on the front - I think Mistacat's point is correct, this used to be way too stiff but these days it seems to dive quite a bit and both end due a service

Springs will be part of the overhaul after season. Going for hyperpro ones

 

[SnowMec]

The BMW R1200GS(A) has coil over shocks both front and rear. The telelevel front end takes some getting used to and at the rear, BMW has no linkage that helps the shock absorber at the end of the suspension travel with a progressive ratio.
They also do not have double shock pistons + needle at the rear that gives a progressive damping like KTM without linkage often have.
These technical solutions mean that the BMW R1200GS(A) K25 always has a special suspension character, it can feel like you are bottoming out the rear shock too easily if you ride actively off-road if the shock i a little bit to weak/soft.

But if the motorcycle is starting to get a few years old and or has driven a lot of kilometers, you can expect the shock absorbers to be so in need for service that they no longer work as they should, that is probably the problem.

The oil is broken down and contaminated by moisture, dirt and teflon. And nitrogen gas has leaked between the floating piston seal and mixed with the oil.
In other words, it's time for service!

The oil volume is very small in the original shock absorbers and if the bike has WP at the front, it does not have an external reservoir for gas/oil but an IFP piston, just like the rear shock absorber (Showa has an external gas/oil reservoir at the front). This means that you should service these shock absorbers quite often if you drive actively and have high demands.
ESA adjusts spring preload and low-speed damping (the bleed hole in the shock absorber piston), so it does the same thing as when you turn the damping knob at the piston rod's mount side on an adjustable shock absorber. If the shock absorber needs service, it doesn't matter what the ESA does, the shock absorber simply doesn't work well enough.
You can shim the shock absorber damping piston during service and change the spring to suit your own needs.
Then, of course, there is an almost endless aftermarket for those who want to buy new shock absorbers.