Rear wheel lock up

[brianski]

Have any of you guys experienced the back wheel locking up while down shifting. This has happened to me a few times now when changing down from fourth to third or third to second at about 30mph. I give a quick blip on the throttle with the clutch in to match the revs let the clutch out & the back wheel locks up momentarily, Battery & oil lights come on back end steps out & then the motor picks up again.Not very pleasant.
I'm wondering if this is anything to do with the Y piece & remus fitted to my 1150 gs. Your thoughts would be appreciated.

 

[DrAlf]

I experienced a huge rear wheel lock up when my gearbox went bang – that was fun. Other than that I’ve never had it happen on the GS – had it a few times when I was a noob rider, downshifting too many gears and not matching the revs but it doesn’t sound like this is the case here. I’d suspect the gearbox but then I always do.

 

[Spout]

If the battery and oil lights come on doesn't this mean the engine has stopped running momentarily?
That would explain the 'lock up' of the bump start when you release the clutch.

Do you have tickover problems?

Just had a thought. Could it be a wonky electrical connector in the sidestand/clutch/in gear/can't start loom? For some reason when you pull the clutch in the engines cutting out cos it thinks the sidestand is down?

Good luck, and I hope someone comes up with a plausible answer.............

 

[Commuter]

No sure

The only time I have had this happen to me is when driving "Enthusiastically" Normally when I have been trying to knock speed off with the engine or when the ABS kicks in.

Is this during regular or excessive ridiing? If the latter then likely to be ABS (if you have) kicking in, the red light comes on then.

 

[brianski]

I do have ABS, and the bike seems to tick over without any problems. Idle speed is about 1000rpm does this sound about right?
The problem does seem occur after i've been riding - enthusiastically!

 

[brianski]

Can't say I've noticed that twitch but I'm takin the bike back to the dealer to get them to have a look.
As this is my first experience with BMW I'm wondering how good their service bods are, although they seemed pretty good on the car side when i last had one.
Thanks for the input so far.

 

[The Mechanic]

Idle speed too low!

Sorry but you didn't say if you have an 1100 or the 1150, but that idle is too low it should be more like 1200rpm. Its possible that if you are new to owning a BMW that you're experiencing shaft torque reaction rather than rear wheel lock up (I stand corrected if you are leaving black lines every where) this can be a bit unsettling to start with, also you have to appreciate that there are some big pistons in these engines and if compression is good then it would be quite easy to lock the rear wheel by too enthusiastic application of the lower gears for slowing down. Anyone that has ridden a Ducati will tell you just how easy it is to do, thats why Aprilia's Vee twins all have pneumatic slipper clutches to prevent this. So as the Beemers pistons are just a bit bigger I think this could be your problem....perhaps experimenting with a little more delayed clutch release might smooth things out for you .

 

[nleader]

I think Spout has a most likely sounding answer - although everything the Mechanic says is good too (as usual).

(Using guesswork figures just to illustrate). In 3rd at 30mph, your engine speed is 3,500 rpm. You blip the throttle, pull in clutch and select 2nd. Whilst the engine is detached from the rear wheel it cuts out (idiot lights go on) and revs drop to 0 rpm instead of the 4,500 rpm you were looking for. As you feed out the clutch the big difference between engine speed and road speed cause the rear wheel to slide as you inadvertently bump start the engine.

Here's a simple test for that hypothesis. If you pull in the clutch and freewheel - rather than feeding out the clutch, does the engine stop running?

Cheers, Norman

 

[hypoid]

I could always downship with blipping throttle, etc for engine braking much easier and more naturally on the Bandit 1200, due to the smaller pistons, less flywheel effect and easier reving nature or the inline four. On the Beemer I have to confess I'm a bit squeemish in using so much engine braking while riding briskly. I remind myself that brake pads are sooooo much cheaper than a new tranny!

 

[nleader]

Hello Hypoid,

Over here new riders are no longer taught to use a change down of gears to help slow the bike. There's a saying that goes "Brakes to slow, gears to go". What they're taught now is to slow down using the brakes and then select the new correct gear for their road speed. There's another saying I remember that goes "If you brake with your gears then your gears will break".

Cheers, Norman

 

[brianski]

If I pull the clutch in & freewheel the engine doesn't stall and it's not a case of using the gears to slow down it's a case of selecting the right gear for that particular situation with a blip of the throttle in between gear changes for a smooth change. It may well be that I'm not used these big pistons and the amount of compression produced, after all I've been riding Jap sportsbikes for years.

 

[jimbo]

brianski,
As a couple of people have said before, if you really get getting the charge and oil pressure light coming on, then something funny is happening. either there is something very odd happening with the electrics or the engine speed has dropped to below 750ish RPM if not lower.
I have to admit I'm baffled as to how this could be happening. Given your description you seem sure that the rev aren't dropping that low, so that suggest something weird with the electrics. The rev counter is still showing revs (which suggests sparks at the plugs?), but the charge light suggests not. Don't know about BMs, but usually the oil pressure light is a fairly basic circuit.
Are you sure about the lights coming on?

I am baffled

 

[Keith Chapman]

Is it the blip that is causing the problem? a quick blip can stall or nearly stall the engine as you try to get the pistons moving. that would explain why you keep ticking over if you just pull in the clutch and free wheel.

Try a slower blip or no blip at all.

 

[The Mechanic]

Without a test ride!!!!!

We're all just guessing now and the only way to really pin this one down is to get some one who is familiar with the breed to actually test ride your bike, maybe even a BMW dealer chap.

If the engine idles ok while coasting in gear with the clutch disengaged, then its probably something that the pilot is doing to cause this problem......unless there is (as has already been suggested) a fault with the transmission system....but now I'm just guessing.

I want to help but I'm scratching at an already thinning head of hair!

 

[brianski]

Thanks guys I'm begining to think its something I'm doing rather than the bike, as Keith mentioned it could happen with a quick blip of the throttle which is probably what I'm doing. Still 'ill get it checked out.

 

[The Mechanic]

I wonder.....

How long do you reckon it would take to sort this one out if we were all in a pub? 3 pints each, 4 or more! And would we have reached a conclusion do you think ....hic!