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Vague handling

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liverpool_f_
the 900
the 900

Posts : 367

Vague handling

Post by liverpool_f_ on Wed 12 Aug 2015, 10:39 pm

Hi all,

Quick question about potential causes of vague handing, (apologies for the vague description!) My cb was handling fantastically well and all of a sudden there seems to be a discrepancy between rider input and bike output. It feels like road lines and bad surfaces are pulling it around a lot more than they used to and all in all the handling doesn't feel crisp. This all came about round about the time I hit a pot hole pretty hard.

I can't feel any play in the steering head bearings or any notches but this is all I can think could be the cause. They are rather new so I really hope I didn't mangle them. Tyre pressure is checked and fine.

Does anyone have any suggestions as to what could be the cause?

(it is rather upsetting as the bike really isn't as confidence inspiring as it once was in the twisties)
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Llewelyn1965
the 900
the 900

Posts : 340
Location : Swansea

Re: Vague handling

Post by Llewelyn1965 on Wed 12 Aug 2015, 10:55 pm

I had the same thing after a pothole smack. The fork oil started leaking from the bolt at the bottom of fork leg and the handling went dodgy. Not sure if they are connected, but handling is ok now.

muttley1
the 900
the 900

Posts : 752

Re: Vague handling

Post by muttley1 on Wed 12 Aug 2015, 11:34 pm

The handling can go off due to tyre wear, carrying loads etc but if its suddenly changed due to one thing then check the bike from the tyres up, I'd say the damage will be more likely closer to the impact:

tyre damage especially the tyrewalls, pressure still ok, wheel bearings ok, dents to rims, axle not out of line, fork oil leaks (as said), top and bottom yoke bolts still torqued up correctly. I'd also check the wheel itself, very unlikely its cracked but just in case.
Perhaps the brakes are worth a look in case a pad has been knocked loose (unlikely) or some road crud has got into the caliper area.

atb with getting it back on track

muttley1
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geoffnorfolk
Godly
Godly

Posts : 63

Re: Vague handling

Post by geoffnorfolk on Fri 14 Aug 2015, 9:36 pm

I wonder if the bearings weren't properly seated before and the pothole has shifted them slightly. Although you can't feel any play in the bearings, it's very difficult to pick up small movements when you rock the forks. Also, there's supposed to be a certain amount of "preload" on the headbearings..... basically, they should be tightened a little more than just taking up the freeplay but must still be able to move freely with no resistance. Ideally, the top bearing adjuster should be tightened down onto the bearings to a specified torque to give the correct preload but most people don't bother with that.
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liverpool_f_
the 900
the 900

Posts : 367

Re: Vague handling

Post by liverpool_f_ on Mon 17 Aug 2015, 5:16 pm

Thanks for the info guys, lots to look at there.

The front tyre is maybe past its best anyway so I think I will get a new one. That should also cover the front axle alignment and damage check. Is there a more sophisticated method of checking the quality of my steering head bearings other than the rudimentary feeling for play in all directions with the forks and checking for smooth turing left to right? 

If it needs disassembled, I think it will end up being 1 for the mechanic.
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Celt500
Mothra the Radioactive
Mothra the Radioactive

Posts : 227

Re: Vague handling

Post by Celt500 on Mon 17 Aug 2015, 5:41 pm

My one had a comically loose steering head bearing when I first picked it up, and I just had to tighten it up again the other day as I was starting to feel a slight click going over speed bumps.

Though play in the bearings obviously needs urgent attention, to me it didn't make the handling feel vague. It just added a bit of vibration and a bit of a click or clunk going over bumps or getting on the brakes hard.

What did make the handling feel vague though was a wheel bearing on the way out. And it started tram-lining over bad surfaces like you describe, so that would be my guess. Oh and it was a rear bearing on mine that made it feel like that so might be best to check both ends.
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liverpool_f_
the 900
the 900

Posts : 367

Re: Vague handling

Post by liverpool_f_ on Wed 19 Aug 2015, 12:47 pm

Interesting point about the wheel bearing. That hadn't really occurred to me and is definitely a candidate for damage after clattering into a pot hole
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eternally_troubled
Admin
Admin

Awesome!
Posts : 3656
Location : 'ere be fens. (near Cambridge)

Re: Vague handling

Post by eternally_troubled on Thu 20 Aug 2015, 8:09 am

I can vouch for that:

I didn't realise that my rear wheel (and sprocket) bearings were on the way out until the MOT man noticed the wobbling!

I replaced them and the handling got better... doh!

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