scootz
|
| posted on 15/8/17 at 07:03 PM |
|
|
Spinning a BEC and Going Backwards...
Was thinking of mounting a (cable) hand clutch on my BEC shift-lever, but then I thought that this might present a bit of a challenge if I spun the
car and started going backwards (would probably want to keep both hands on the wheel for as long as possible... and might not get to that clutch in
time to save the engine from damage).
Or are there any systems on the market that sense you are about to go backwards and will disengage the drive for you?
Cheers
It's Evolution Baby!
|
|
|
|
|
BenB
|
| posted on 15/8/17 at 07:19 PM |
|
|
Is it necessary? I spun my ST1100 BEC at the North Wield track day a number of times. Sat for a few seconds to get my stuff together then fired up
first time.....
|
|
|
ReMan
|
| posted on 15/8/17 at 07:43 PM |
|
|
There's an expensive mod for this on Hayabsa, to avoid starter AND engine damage in this event.
I'm guessing it's a one way clutch/bearing in the starter to engine link
Maybe a possible mod on your engine?
www.plusnine.co.uk
|
|
|
CosKev3
|
| posted on 15/8/17 at 08:24 PM |
|
|
quote:
Originally posted by BenB
Is it necessary? I spun my ST1100 BEC at the North Wield track day a number of times. Sat for a few seconds to get my stuff together then fired up
first time.....
Yeah but did you get your foot on the clutch before the engine was driven backwards by the wheels?
If so that's why it did no damage! !!!
You can spin as many times as you want if you get your foot on the clutch fast enough.
A m8 of mine sold a Jedi single seater with a Gsxr1000 engine in it to someone that had never had a BEC before,went through 5 starter motors on his
first drive of the car due to not clutching it fast enough when spinning!
|
|
|
scootz
|
| posted on 15/8/17 at 08:29 PM |
|
|
Sorry - it's an 09 CBR1000RR
It's Evolution Baby!
|
|
|
gremlin1234
|
| posted on 15/8/17 at 08:40 PM |
|
|
never having had a bec etc,
apparently what you want is a sprag clutch
https://en.wikipedia.org/wiki/Sprag_clutch
|
|
|
phelpsa
|
| posted on 15/8/17 at 09:19 PM |
|
|
quote:
Originally posted by gremlin1234
never having had a bec etc,
apparently what you want is a sprag clutch
https://en.wikipedia.org/wiki/Sprag_clutch
The sprag clutch is what causes the problem (engages in reverse). What you need is a torque limiting clutch which most modern bike engines have to
avoid kickback issues . Problems mainly occurred with 99-02 busa engines which did not have one.
|
|
|
CosKev3
|
| posted on 15/8/17 at 09:37 PM |
|
|
quote:
Originally posted by phelpsa
quote:
Originally posted by gremlin1234
never having had a bec etc,
apparently what you want is a sprag clutch
https://en.wikipedia.org/wiki/Sprag_clutch
The sprag clutch is what causes the problem (engages in reverse). What you need is a torque limiting clutch which most modern bike engines have to
avoid kickback issues . Problems mainly occurred with 99-02 busa engines which did not have one.
K5 and K6 Gsxr1000''s can't have them fitted either
|
|
|
scootz
|
| posted on 16/8/17 at 10:14 AM |
|
|
Cheers - is a torque limiting clutch the same as a slipper clutch?
It's Evolution Baby!
|
|
|
LBMEFM
|
| posted on 16/8/17 at 03:12 PM |
|
|
Spun on occasions in my MK Indyblade at track days, as the car losses grip and goes round the natural instinct is to dip the clutch. Never been a
problem for me over many years of track driving.
|
|
|
scootz
|
| posted on 16/8/17 at 04:36 PM |
|
|
Cheers.
Dipping the clutch would be my natural reaction as well.
Easy with a foot-clutch... but might take some getting used to with a lever-clutch on the shifter stick. And made all the more difficult with both
hands staying on the wheel trying to correct the slide until the very last minute - hence why I was wondering if there were any gizmo's on the
market that can help with such situations.
It's Evolution Baby!
|
|
|
deanspoors
|
| posted on 10/10/17 at 07:18 AM |
|
|
How about having both? or are you wanting the clutch pedal space for your foot?
I have a busa and managed to destroy a starter after spinning my car in the wet, dipped the clutch as quick as I could too.
|
|
|
motorcycle_mayhem
|
| posted on 10/10/17 at 09:35 AM |
|
|
No, a slipper clutch won't help.
Engage brain, as soon as you get into a 'passenger' situation, hit the clutch pedal (or hand device). Recover car to the paddock, remove
starter motor, remove end cap and wonder how something could destroy itself that badly and where all that brown dust has come from....
|
|
|
coyoteboy
|
| posted on 10/10/17 at 04:26 PM |
|
|
What makes this more damaging on a bec than a cec?
|
|
|
CosKev3
|
| posted on 10/10/17 at 04:33 PM |
|
|
quote:
Originally posted by coyoteboy
What makes this more damaging on a bec than a cec?
Pre-engaged starter motor on a bike engine doesn't like being spun at circa 10k times its normal speed!
|
|
|
coyoteboy
|
| posted on 10/10/17 at 05:38 PM |
|
|
Hmm preengaged starters I've seen don't automatically engage the gear in a stall or reverse scenario, and retract it after start. Only
during a start (solenoid on, gear moves, starting current supplied). You learn something new every day.
|
|
|
LBMEFM
|
| posted on 10/10/17 at 06:06 PM |
|
|
I am surprised like coyoteboy, is that really why bike engines don't like going backwards
|
|
|
CosKev3
|
| posted on 10/10/17 at 06:13 PM |
|
|
Perhaps pre-engaged is the wrong word?
The starter on a bike is engaged permanently, but will only freely turn one way due to the sprag gear as mentioned above.
So when the transmission is turned the opposite way to normal running the starter is spun at a massive amount of turns more than designed due to the
gearing.
So if you are lucky it just destroys the starter,but has been known on Busas iirc to destroy the engine if the starter seizes.
|
|
|
adithorp
|
| posted on 10/10/17 at 08:01 PM |
|
|
The starter isn't pre-engaged, it's permanently engaged via a sprag gear. Think of it like the free-wheel on a bike. Turn the starter
motor and it drives the engine, once the engine starts (and the starter isn't driven the sprag gear free wheels. However turn it backwards and
it forces the starter backwards... just like rolling a bike backwards forces the pedals around.
The damage is caused by the brushes getting worn from rotating in one direction and getting a slight angle on their ends. When it goes the other way
they dig in and smash the com' etc to bits.
I went 7 years and quite a lot of spins before I was a bit late getting the clutch in and buggered a starter. I take a spare to track days (and tours)
now.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
|
|
|
bg0013
|
| posted on 10/10/17 at 11:20 PM |
|
|
quote:
Originally posted by scootz
Cheers.
Dipping the clutch would be my natural reaction as well.
Easy with a foot-clutch... but might take some getting used to with a lever-clutch on the shifter stick. And made all the more difficult with both
hands staying on the wheel trying to correct the slide until the very last minute - hence why I was wondering if there were any gizmo's on the
market that can help with such situations.
I have to do the same set up due to a license condition limiting me to an automatic vehicle (the only definition I could get out of our authorities in
Australia was that an automatic vehicle only had 2 pedals).
my car will be primarily a road car, so apart from developing the technic to make it all smooth, I cant see it being an issue.
track use might be another issue when/if I spin it.
|
|
|
mangogrooveworkshop
|
| posted on 11/10/17 at 04:06 AM |
|
|
quote:
Originally posted by scootz
Was thinking of mounting a (cable) hand clutch on my BEC shift-lever, but then I thought that this might present a bit of a challenge if I spun the
car and started going backwards (would probably want to keep both hands on the wheel for as long as possible... and might not get to that clutch in
time to save the engine from damage).
Or are there any systems on the market that sense you are about to go backwards and will disengage the drive for you?
Cheers
You are worrying about something that is a no issue. stick with a foot clutch and design to KISS engineering principles
With a bike motor it tends to stall in a spin . The challenge is to get it back into the lower range of the box and restart it.
Been there done that and bought the T-shirt and changed the pants.
There is several guys who for health reasons have full hand controls in their sevens perhaps they may help you in that field
Get on and build and stop over thinking the engineering.
Yes I have that TShirt too .....with all the side symptoms 
|
|
|
phelpsa
|
| posted on 11/10/17 at 06:23 PM |
|
|
You might not get your foot on the clutch, but you will generally keep it firmly on the brake! That is usually enough to prevent damage.
|
|
|
LBMEFM
|
| posted on 12/10/17 at 08:33 AM |
|
|
quote:
Originally posted by phelpsa
You might not get your foot on the clutch, but you will generally keep it firmly on the brake! That is usually enough to prevent damage.
Well done phelpsa, simple but of course the obvious thing to say i.e. wheel not turning engine not turning, brilliant.
|
|
|
ReMan
|
| posted on 12/10/17 at 10:32 AM |
|
|
It is obvious! 
I agree that you should not over worry , else you'll never drive it
However in the heat of a few millisecond, just as your grip/skill runs out, on the track, going backwards, bouncing over the kerbs, into the infield,
I lost all sense of what pedals I was pressing
And blew the starter!
Only a cheap fireblade, and only the starter damaged.
If it was Busa motor, then you'd want to take out that insurance with the mod
www.plusnine.co.uk
|
|
|
