morfy
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| posted on 19/10/07 at 04:40 PM |
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bec prop shaft
has any one made there own prop for a bec if so could you tell me which one they used and on the expanding joint (where is slides in and out) should
there be any back lash
cheers
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mark chandler
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| posted on 19/10/07 at 05:27 PM |
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I did after looking around my scrap bin.
Did as follows:
Escort jointed prop, hacksaw around the welds on the front prop by the donut, then knocked of the end, Its a 2" OD tube that the end plugs
into.
Landrover propdshaft has a slide on one end, tube is the same size so had a measure up and cut the tube so it would push over the stub, lined up and
welded.
For the engine side, grabbed an old landrover diff and took off the pinion flange, stuck it in lathe and turn down the middle so I had a flat plate
with holes that match the prop end and a tapered hole in the middle.
Sprocket off the engine, ground off the teeth etc to fit inside the new flange adaptor (I machined a taper on the sprocket) with the matching taper
on the flange two went together squarely so welded up.
Put it all in, been good for a few hundred miles now, no vibration or anything nasty.
Total cost ~ £20, 1/2 day to do.
Get a later RR propshaft they have plastic sleeved sliders, you need one without slack that slides smoothly.
Ebays your friend here, old landrover stuff is pennies and everywhere.
Regards Mark
[Edited on 19/10/07 by mark chandler]
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daviep
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| posted on 19/10/07 at 11:26 PM |
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I used a standard 2 piece prop like this
 :
And then bought 1 of these: 1140 series slip joint (£27)
and 1 of these: Slip stub (£10)
These replaced the normal gearbox slider.
Standard escort propshaft tubing is 2" od x 0.064" wall.
Press new slip stub in to old prop, tack weld up checking it's still true in between each tack and then weld.
The standard 1140 series flange(small ford)fits most of the common sprocket adapters such as this:
Supplied by "Attitude Roadsters" £55 (I'm impressed with mine)
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Hellfire
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| posted on 20/10/07 at 08:06 AM |
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Personally, I'd rather get one professionally built or modified and balanced. Don't forget it will be spinning around in excess of 11,000
rpm in some cases and within a few inches of your legs.  The slightest imbalance could lead to premature engine wear and could also have some far
more serious consequences.
They are however your legs, not mine. At least consider the risks before deciding whether to make your own or not and if you still decide to diy, at
least incorporate some type of fail-safe around the prop to ensure it never gets near your legs if it fails.
Phil
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PhilCross66
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| posted on 20/10/07 at 11:50 AM |
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I've just been working out prop speed and only get about 6500 rpm, am I working it out wrong.
I used 120mph=192000metres/h as top speed, my 15" wheels have about 1.8metre circumference and 3.62 diff so ..
192000/60=3200 metres per minute
3200/1.8=1777.8 wheel revolutions per minute
1777.8*3.62=6436 propshaft revolutions per minute at 120mph
Im only asking since I made my own prop too and I didnt think it was reving too hard
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Peteff
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| posted on 20/10/07 at 12:36 PM |
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it will be spinning around in excess of 11,000 rpm
There's a reduction gear between the engine and the sprocket output 
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Jimbob
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| posted on 21/10/07 at 05:22 PM |
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quote:
Originally posted by Hellfire
Personally, I'd rather get one professionally built or modified and balanced. Don't forget it will be spinning around in excess of 11,000
rpm in some cases and within a few inches of your legs. The slightest imbalance could lead to premature engine wear and could also have some far
more serious consequences.
They are however your legs, not mine. At least consider the risks before deciding whether to make your own or not and if you still decide to diy, at
least incorporate some type of fail-safe around the prop to ensure it never gets near your legs if it fails.
Phil
I agree, would def have one made and balanced properly, most def NOT something to skimp on and personally i would use Dunning & Fairbank,
affordable quality
James
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Hellfire
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| posted on 21/10/07 at 08:07 PM |
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quote:
Originally posted by Peteff
There's a reduction gear between the engine and the sprocket output
You're quite right Pete but in my defence, I did say "in some cases" (I just can't think of any right now  )
The 2007 Fireblade has a rev limit of 12,200 rpm. With a primary reduction of 1.604 and a 6th gear reduction of 1.116 that gives approximately 6,557
rpm at the output.
Phil
[Edited on 21-10-07 by Hellfire]
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