Shock advice

[fontana]

Banging my head against the wall'
Does anyone know anywhere I can find standard shock length measurements for BMW's
I am pretty sure that a shorter rear shock has been fitted to my RS.
It grounds the centre stand on bumpy left hand bends with a passenger at fairly moderate lean angles.
I found a replacement on ebay, and asked the seller to measure, eye to eye, it's length.
He told me it's 360mm.
So the only way to measure mine properly is to remove it.
So mine measures 350mm.
Would 1cm really make that much difference.
Do you think winding up the spring a little would help.
I assume that's the adjuster ring at the top, which you can't get too when it's in situ

My shock is an aftermarket WP unit and appears as new.
I don't suppose it was cheap
Seems a shame to have to junk it but need to sort this before mid next month, when I'll be in the Alps with all those hairpins

[milleplod]

Does this help? I'm assuming Ohlins don't vary from stock dimensions, they certainly don't in respect of the shocks for my ST.

ShockInfo.PNG (98.98 KiB) Viewed 11001 times

Pete

[fontana]

Yes that is a help.
So the YSS shock I've seen is 360mm, and the Ohlins 358mm.
The WP shock I have is 350mm.
So it's between 10-8mm shorter.
Seems hard to believe that would make a huge difference, but I'm really not happy about the way my bikes centre stand is grounding on left handers.
I'm starting to think the answer may be just to take it off (the centre stand that is)

[milleplod]

Wonder if a shorter rider had it done? Yep, easy way is to get rid of the stand, not much call for it on hol really.

Pete

[Herb]

Couple of things.

10mm at the shock, will equate to more than that at the wheel (or height of the bike if you like). I don't know the ratio, but it will be significant.

The WP shock looks like it is adjustabke for length, and is currently set short. You should be able to get that 10mm (or 16 if the Ohlins table is anything to go by) by adjusting the length. (Right hand end of your picture).

[Herb]

Couple of things.

10mm at the shock, will equate to more than that at the wheel (or height of the bike if you like). I don't know the ratio, but it will be significant.

The WP shock looks like it is adjustabke for length, and is currently set short. You should be able to get that 10mm (or 16 if the Ohlins table is anything to go by) by adjusting the length. (Right hand end of your picture).

(Edited: I thought you had the 1150 RS??? 8mm for the 1100 rather than 16).

[fontana]

Wonder if a shorter rider had it done? Yep, easy way is to get rid of the stand, not much call for it on hol really.

Pete

Yes he must have been a real shorty.
When I got the bike (Japanese import from James Sherlock), the seat was set in the lowest of it's three positions, but clearly it still wasn't low enough, hence the rear shock mod.
I never noticed it till I started carrying my Wife about on the back recently.

The WP shock looks like it is adjustabke for length, and is currently set short

Do you think so

That would make life so simple if I could give it about 10mm.
How can you tell.
Don't worry, you can tell me.
I'm not going to start spannering it and have the thing blow up in my face

[Herb]

If you look at the right hand side, by the U bracket, there is a locknut. Undo this and you should be able to wind out the U bracket. Thread will be marked showing the maximum length. A bit like a bicycle saddle.

[fontana]

If you look at the right hand side, by the U bracket, there is a locknut. Undo this and you should be able to wind out the U bracket. Thread will be marked showing the maximum length. A bit like a bicycle saddle.

If you're right you just saved me about £150
I hate being such a plank, but I don't know anything about shocks.
To me they're just big springs that bounce up and down when you go over bumps.
I'll give it a go tomorrow.

[Herb]

If you can find a part number, the manual should be available on line. You can then make sure it's set up properly for your combined 2 up weight.

[SP250]

Herb is spot on

The thread should be marked so that you shouldn't lengthen (wind it out) it any more.
If that is not the case, then unscrew it (the U bracket) fully and measure the total length of thread available.
Measure the diameter of the thread.
Wind the U bracket back into the shock and stop at 1.5 times the thread diameter (don't include the thickness of the locknut).
This is the minimum thread engagement for safety, includes a factor of 50% ie. (min thread engagement should be 1 x thread dia).
Then wind down the lock nut and tighten against shock body.

You can then see how much longer the OA length is.
If longer that your needed 10mm, then wind it in a bit more to suit.
If shorter than needed 10mm, then just get a U bracket from the shock supplier with a longer threaded bit.

Simples!

[fontana]

Herb is spot on

The thread should be marked so that you shouldn't lengthen (wind it out) it any more!

I can't see any marks on the thread.
I'm a bit unclear.
Could you elaborate.

[Jeff Highland]

I have a standard r1100rt shock here that measures 360 centre to centre
The extra 10mm at the shock will give you about 30mm at the axle
As Herb said, loosen the locknut and wind it out (the bottom yoke) by 10mm , then mark it and wind it out fully just to make sure there is sufficient thread still engaged in the body then Wind back in to the plus 10mm position and tighten the lock nut,

[fontana]

The extra 10mm at the shock will give you about 30mm at the axle

Right so now this is all making sense,
From day one I've felt that the bike is far too upright on the sidestand.
Taking the above into account, it's no wonder if it's sitting that much lower at the back than it should be.
So tomorrow I'll give the length adjustment a go as per advice.
The solution to my problem surely couldn't be that simple could it ?

[Topcat]

I've got WP on my bike and the length can be adjusted as has been described, there is a mark ( a thin section of no thread) that shows max extension.

Just a word of warning, I'm sure mine has two lock nuts on the thread, yours has only one by the looks of it? Has the previous owner taken one off to get it even shorter?

I would get the manual or phone WP to be safe.


Cheers


Dave