DarrenW
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| posted on 20/8/09 at 07:44 AM |
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Prop catcher idea
Following on from Pif's nightmare (albeit extremely lucky too) i was thinking of how someone could retrofit a prop catcher. Landrovers use big
U-bolts to secure (i think) the rear leaf springs to the axle. Although i havent measured them up etc im pretty sure a couple of those could be bolted
in around the prop to add some security in case it was ever to let go.
What do you reckon?
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Mr Whippy
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| posted on 20/8/09 at 07:53 AM |
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yip, sounds a good plan. Was thinking about this issue and my falcons GRP tunnel 
was also looking at getting a switch that would kill the electrics to the engine (just a carbed pinto) in the event of a crash. Could I use a switch
from an injected car? If so which one?
[Edited on 20/8/09 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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Bluemoon
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| posted on 20/8/09 at 07:55 AM |
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Thinking the same, ideas welcome!
Dan
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adithorp
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| posted on 20/8/09 at 07:56 AM |
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Should work as long as you've got something convenient to bolt it to.
What ever you use you want it to be as close as posible to the shaft as possible. That way it's more restricted, should it break. It's the
flailing that causes problems. Keep it almost in line and it should still spin rather than batter everything in sight. The more out of line the more
energy it's got.
Going to be looking at mine sometime!
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Guinness
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| posted on 20/8/09 at 07:59 AM |
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I thought about a steel wire rope loop around it? It would be fixed at both ends to the top of the chassis and wrapped loosely around the prop?
Mike
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r1_pete
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| posted on 20/8/09 at 08:00 AM |
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Couldn't you fit a tunnel liner in something like 3mm ally plate in the first 300mm or so of the tunnel? if it was made in a bowler hat section
it could be screwed into the floorpan or chassis at either side.
Sure it would be damaged if the uj lets go, but, it deforming would take the stress off the fixings, prevent it getting ripped out, and protect
passengers in such an event, think of it as a crumple zone....
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DarrenW
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| posted on 20/8/09 at 08:02 AM |
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Maybe using 4 u bolts would work, 2 pointing down, 2 pointing up. All spaced out accordingly. Might need brackets adding to the tunnel frame but at
least the bolts are easily available to reduce fabrication time.
My mate is a LR independant specialist and gets the bolts at reasonable cost from the likes of Britpart, but of course he has an account and spends a
fortune with them.
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DarrenW
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| posted on 20/8/09 at 08:07 AM |
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There are loads of ways to make a prop catcher, i was just thinking of using something easily available off the shelf. Another advantage of the u bolt
idea is that they should be easy to take out if you want to change the prop for some reason.
Maybe we should make more use of centre bearings, not so much for support in normal use but to control them in event of emergency.
Automotive engineering principles would suggest more effort is made to stop them failing in the first place of course, so catchers should only be
thought of as redundancy.
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procomp
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| posted on 20/8/09 at 08:08 AM |
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Hi
well believe it or not EVERY front engine rear wheel drive car that competes under MSA regulations HAS to be equipped with a full 360deg capture
device. Not that anyone seems to pay any attention to that regulation. On all the LA's as standard we have prevision for a simple bolt in from
above 25mm x 5mm steel strip to surround the prop shafts this works well And meets all the MSA specifications.
Cheers Matt
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Mr Whippy
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| posted on 20/8/09 at 08:19 AM |
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for the falcon I was planning on using two of these simple split hardwood blocks bolted to the GRP tunnel with coach bolts. Very light even if I make
the blocks 2 inches thick and their easy for me to make. I have a live axle hence the slot for movement.
 
Description
[Edited on 20/8/09 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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tegwin
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| posted on 20/8/09 at 08:31 AM |
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I made one for my hovercraft years ago..
Got a piece of 4mm wall pipe about 60mmID... Cut it in half...
Welded steel bars to each half... bolted together.... perfect..
The idea of it was that should the prop fail, it could still spin freely inside the restraint without locking up or snatching...
------------------------------------------------------------------------------------------------------------------------
Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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procomp
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| posted on 20/8/09 at 08:38 AM |
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Hi
You need to take into account the gearbox's horizontal movement under acceleration and hard cornering on the front device.
Cheers Matt
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James
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| posted on 20/8/09 at 09:19 AM |
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This is so 2004! 
When I did mine, I just bolted (so as to be removeable for prop/tunnel access) a couple of 19mm square tubes horizontally to the vertical 19mm tubing
of the prop tunnel. Two pieces one above and one below the prop near the front UJ and the same near the rear of the prop.
The prop is then contained in a 'box' of 19mm tubing... hopefully strong enough!
I was more concerned about the prop taking off my leg or pogo-ing the car than fuel/electrics/brakes but I think it'll still work to protect
these too.
Don't have a picture AFAIK but it's light, cheap and easy to do!
HTH,
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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pewe
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| posted on 20/8/09 at 10:16 AM |
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Mine is flat strip steel 50mm x 4mm bent into an elongated horseshoe shape with 90 degree bends on each end drilled to take M10 bolts.
Chassis mounting below the prop is via two 50mm x 25mm SST welded to the chassis with spacer inserts to prevent crush when bolts are tightened.
The horseshoe shape is actually nipped in at the lower end to prevent the shaft dropping down and digging into the road surface if it ever failed -
anyone who has ever over turned a milk-float will know that's how that happens!
Cheers, Pewe
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Canada EH!
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| posted on 20/8/09 at 03:05 PM |
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Tegwin has the right idea, but the loop needs to be an oval to allow for up and down movement of the diff in solid axle car and transmission movement
in all cars.
The original Locost chassis will hold the prop shaft in place as it is fully enclosed, but you need protection from the possibility of the front
U-joint breaking.
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blakep82
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| posted on 20/8/09 at 03:42 PM |
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race cars (my pick up included) just have a steel bar loop in the tunnel, say 3-5mm steel, welded to the bottom of the tunnel on the chassis, and
hooped over the top
dead simple. doesn't stop if flailing about much, but shoul keep it inside the tunnel ok
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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snapper
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| posted on 20/8/09 at 05:26 PM |
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2 X 100mm square by 3mm thick plate bolted to the tunnel sides with spreader washers.
retro fitted so on the outside not the inside but should stop penetration.
The rear prop UJ is behind the rear bulkhead.
I would have thought that some extra box section at strategic positions along the tunnel would be adequate but liked the idea of some plate in case
some shrapnel flew about.
I have been badgering our stores for old kevlar flack jackets, light and strong could be used as a flywheel shatter blanket as well but they re
certificate them so may be 5 years time.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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