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Technically Speaking => General Technical discussion => Topic started by: vonny232 on Wednesday, 27 March 2019, 07:18 PM

Title: Rear wheel lock up
Post by: vonny232 on Wednesday, 27 March 2019, 07:18 PM
Hi,

Bit of an odd question here.

Was driving into town this morning and accelerated in a low gear (2nd/3rd) and when I changed gear the rear wheel locked up (I had a major wobble, scared the hell out of me).

Fortunately the bike then recovered and is working fine. I rode into work and its all perfect.

Thing is it happened so fast I am not totally sure whether its something dumb I did, or something more serious (I was still a bit sleepy after waking up).

I guess my question is - What things can happen which can cause the rear wheel to lockup?

Can something happen with the engine/transmission?
Brakes?
It might have been me being stupid, like knocking it down into first - I cant remember as everything happened so fast, I pulled over and knocked it into neutral and it seemed fine.


Title: Re: Rear wheel lock up
Post by: Mick_J on Wednesday, 27 March 2019, 07:41 PM
My first thought is that you had a bit of a brain fart and changed down into first.
Title: Re: Rear wheel lock up
Post by: vonny232 on Wednesday, 27 March 2019, 08:15 PM
Cheers, yes its a real possibility.

I just wanted to get an idea of any "legitimate" reasons for a rear wheel lockup, so I can rule it out.

I read that lockups can also be caused by:
Faulty wheel bearing (unlikely as there is no noise and it is perfectly smooth).
Poor gear shift (only partially shifting)??
Brake caliper stuck (dont think its this, as I dont think I touched the brake, and ive never made it lock up so fully before when jabbing the brake).
Clutch?
Engine temporarily seizing?

Any suggestions/reassurance welcome :)
Title: Re: Rear wheel lock up
Post by: seth on Wednesday, 27 March 2019, 09:02 PM
I'd go with changing down at to high a speed for the lower gear or changing down 2 years by mistake.
I've had this for the very reasons in the past.
:cheers:
Title: Re: Rear wheel lock up
Post by: Del on Wednesday, 27 March 2019, 09:33 PM
As my illustrious friends have said the only time it has ever happened to me is gearing down to 1st and that was on a ZX9r a fair few years ago - lesson learnt that day ill tell you 
Title: Re: Rear wheel lock up
Post by: Captainjashton3rd on Wednesday, 27 March 2019, 10:22 PM
Thats really hairy. Proper shit scary.
Sounds like you did well not to slide up the road.
Glad you and bike are ok.
Happened to me on a kx250 scrambler years ago and i ate dirt. Dropped an extra gear too soon, she locked back wheel and paid for it.
I was younger and bounced off the ground better than i do now!
Title: Re: Rear wheel lock up
Post by: Notty on Wednesday, 27 March 2019, 10:34 PM
My mate did that when we were teenagers in his Austin 1100 4th to first ! pissed at the time mind  :bugga:
Title: Re: Rear wheel lock up
Post by: vonny232 on Thursday, 28 March 2019, 12:06 AM
Cheers guys.

Question - If you lock up the wheel by accidentally knocking down to 1st gear, shouldnt the engine scream (as it turns over very fast) or is it possible to skid the tyre without the engine turning over?
Title: Re: Rear wheel lock up
Post by: froudy on Thursday, 28 March 2019, 12:30 AM
@vonny232

No it won't scream the engine if you knock it down too many by accident..It WILL lock the rear wheel though and it's not a nice experience!
Title: Re: Rear wheel lock up
Post by: vonny232 on Thursday, 28 March 2019, 12:59 AM
Interesting. I have knocked down to 2nd before (on a prev bike) and it did scream, same with a car.

Is there something special about 1st gear so it does not turn the engine over and will lock the wheel instead?
Title: Re: Rear wheel lock up
Post by: seth on Thursday, 28 March 2019, 01:08 AM
You'll have had the throttle closed at the time I'm guessing so the fuel injection isn't supplying lots of fuel on a closed throttle the there is a backlash/torque limiter built in to the clutch set up to help stop it stalling while the ecu sorts out the fueling.
:cheers: