Rear 'squat' and night riding

AndrewD · Oct 23, 2009

Okay guy's I need to know if my GS should 'squat' when I feed it the berries? On our recent trip to Italy it liked to squat on acceleration and dip on braking a bit too much (so you can't see where the road is going).

I think it's all in the back end and I have the preload set high for load as it had the panniers etc on board. Normal or stuffed! :blast

Yes I'm sure a set of Ohlins would be spot on, but I ca't fork out that sort of dough!

sockpuppet · Oct 23, 2009

Mine is doing exactly the same at the moment.

Squats on acceleration (or me sitting down!). Getting what feels like fork dive on the front when braking.

The rear shock damping is fecked. Speak to Steptoe he can (or knows a man who can) rebuild them.

Alternativly if its not the damping you might just need a bigger spring on it.

AndrewD · Oct 23, 2009

sockpuppet said:
Mine is doing exactly the same at the moment.

Squats on acceleration (or me sitting down!). Getting what feels like fork dive on the front when braking.

The rear shock damping is fecked. Speak to Steptoe he can (or knows a man who can) rebuild them.

Alternativly if its not the damping you might just need a bigger spring on it.

Ah-Ha! A little searching and surfing the wisdom on the internet found this!

http://members.cox.net/slartidbartfast/bmwfix/shock-oil/shock-oil.htm

This does look like the issue I have as the knob (no not me!) does turn pretty easy, excellent if it cures it!

sproggy · Oct 23, 2009

That solution is for the hydraulic preload adjustment, while your problem sounds more like a loss of damping. Loss of preload will result in the rear sitting lower with your weight on it, but it won't result in pitching and squatting.

Loss of damping will result in pitching and squatting but won't make the back sit low.

Careful you don't choose the solution to a problem you don't have or you'll be disappointed with the result!

AndrewD · Oct 23, 2009

sproggy said:
That solution is for the hydraulic preload adjustment, while your problem sounds more like a loss of damping. Loss of preload will result in the rear sitting lower with your weight on it, but it won't result in pitching and squatting.

Loss of damping will result in pitching and squatting but won't make the back sit low.

Careful you don't choose the solution to a problem you don't have or you'll be disappointed with the result!

I never said the back was low, but I guess it is hard to decipher from a short description of a complex dynamic! :type

No the back was high enough with me (a fat git) and 100 lires of ally panniers with cloths and food for 2 weeks plus tent etc....

And it had this problem without the panniers, so I'll give it a whirl and see where we get! :bounce1

Re-reading your post it does not look good, but if there is no preload then it will not absorb changes in weight transfer......Hey it's a free try and I've won another on eBay for £10 so it's worth a shot.....or it's a new one(ouch)

sproggy · Oct 24, 2009

AndrewD said:
I never said the back was low, but I guess it is hard to decipher from a short description of a complex dynamic!

Exactly my point - if the back's not sitting low then the preload is probably fine and your problem is loss of damping.

AndrewD said:
.....but if there is no preload then it will not absorb changes in weight transfer......

Er.....no. The damping (compression and rebound) is to slow down and control the movement of the springs as the forces through them change. The preload simply determines how much the spring/damper assembly settles under a static weight. So if you had no preload at all the back of the bike might sit lower than you'd want it, but the damping would still control forward/rear pitching of the bike.

Buying a cheap used shock is still worthwhile as it give you a unit to send away for rebuild and one to keep on the bike while that's being done, but from the sound of it I wouldn't think it's worth trying to fill the preload system with oil. When you increase the preload does the back of the bike rise slightly?

MattW · Oct 24, 2009

I can see the problem.

Someone has snuck in and bolted a bank vault to the back of your bike

AndrewD · Oct 24, 2009

MattW said:
I can see the problem.

Someone has snuck in and bolted a bank vault to the back of your bike

Yes we were recreating the Italian job! :green gri

As for the shock, I'll need to have proper look. But as you said I've now got a rebuildable spare :thumb2

Any recomendations for rebuilders?

sockpuppet · Oct 24, 2009

AndrewD said:
Any recomendations for rebuilders?

Steptoe. Or do a search. This has been covered a few times.

Rear 'squat' and night riding

AndrewD

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sockpuppet

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AndrewD

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sproggy

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AndrewD

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sproggy

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MattW

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AndrewD

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sockpuppet

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