Prop Catcher - Demand?
FASTdan - 12/5/11 at 06:54 AM
I will be manufacturing something to do this job for our own car as below:
Would there be a demand for it as a product? material would be 5mm Mild Steel, weight of a pair as shown above 280g. Price I would hope for £10 per
pair - obviously most installations will require 2 pairs.
The plate is designed to be as wide as the standard book chassis tunnel and can therefore be fastened directly to the vertical box sections - OR as in
some cases, may need spacing off the box to position it 'inboard' of the UV joint. The hole through the middle is 70mm providing a 10mm
clearance around the prop.
The above could be done in 6mm alu to reduce weight but price would need to be £15ish per pair.
40inches - 12/5/11 at 07:08 AM
Don't like the overlap,I would prefer it if the plates butted together, to give 4 separate mounting holes, otherwise I would be interested if
they will be available in the next couple of weeks, and they fit the MK.
gavin174 - 12/5/11 at 07:21 AM
hi
I would be interested.
not sure if 2 holes in each chassis tube might weeken the chassis a bit (4 for each catcher)
FASTdan - 12/5/11 at 07:23 AM
Thanks for the response - I have only just added the overlap to eliminate 2 fasteners as I thought people might be put off by more drilling/nutserting
etc, cost wise it wont make any difference either way. What dont you like about it?
Probabyl needs a rad on the internal corner to eliminate any catch point, but I cant see any other issue?
*edit to add once I have feedback I can have these ready within 2 weeks.
[Edited on 12/5/11 by FASTdan]
40inches - 12/5/11 at 07:41 AM
My thinking is that 4 mounting points will spread the load,wouldn't a single mounting point halfway down the chassis tube be prone to buckling in
a side impact, as against 2 mounting points nearer the ends of the tube But this is just my thinking, probably talking borrocks
martyn_16v - 12/5/11 at 07:53 AM
If you have a side impact hard enough to start buckling the tunnel, you're probably already mincemeat...
FASTdan - 12/5/11 at 07:58 AM
quote:
Originally posted by martyn_16v
If you have a side impact hard enough to start buckling the tunnel, you're probably already mincemeat...
Not only that but you'd be looking at buckling both verticals - given that the plate is tying the two together.
jonrotheray - 12/5/11 at 08:17 AM
Yes please!
Bluemoon - 12/5/11 at 08:20 AM
Interested but need to measure the MK indy prop and chassis..
Not sure it would be correct for a live axel (perfect for IRS though) you might need an oval hole . If you made the over lap twice the length you
could use 2 bolt holes as suggested above but choose oval large, oval small or circular hole depending on how you mounted it?? One could the chose the
smallest hole size required for any set-up???
Dan
[Edited on 12/5/11 by Bluemoon]
jossey - 12/5/11 at 08:23 AM
same as above i would be interested but i dont like the overlap.
Let me know how you get on.
johny p - 12/5/11 at 09:02 AM
yes i will defo have 2 please
yozza - 12/5/11 at 09:23 AM
Yes
Very interested
Let me know if you go ahead.
Regards
Joe Hughes
RichardK - 12/5/11 at 09:27 AM
I personally would prefer this design
chunky2772 prop catcher 1
But maybe a bit faffy due to different tunnel width and prop diamentions.
Cheers
Rich
mcerd1 - 12/5/11 at 09:36 AM
quote:
Originally posted by FASTdan
Thanks for the response - I have only just added the overlap to eliminate 2 fasteners as I thought people might be put off by more drilling/nutserting
etc, cost wise it wont make any difference either way. What dont you like about it?
Probabyl needs a rad on the internal corner to eliminate any catch point, but I cant see any other issue?
As I see it the overlap might actually be a benafit - it'll hold the 2 halfs together better thatn bolting each half to the chassis on its own
and I don't think youd need a radius on the inside corners, just cut the 1/2 circle hole then take the strait line to the edge of the part like
this:
Prop Catcher Idea
I can't use any of these ones as they are though - my dax chassis doesn't have tubes in the right place for them 
[Edited on 12/5/2011 by mcerd1]
FASTdan - 12/5/11 at 09:36 AM
quote:
Originally posted by Bluemoon
Interested but need to measure the MK indy prop and chassis..
Not sure it would be correct for a live axel (perfect for IRS though) you might need an oval hole . If you made the over lap twice the length you
could use 2 bolt holes as suggested above but choose oval large, oval small or circular hole depending on how you mounted it?? One could the chose the
smallest hole size required for any set-up???
Dan
[Edited on 12/5/11 by Bluemoon]
Thats an excellent idea. I will look into modifying the design as per the above. This will allow the overlap to be removed by the builder if desired
and offer 2 or 4 fasteners.
This will definitely go ahead as there is enough interest in this post alone to justify the investment.
Richard, that is indeed a nice design but there is no way I could produce it for the same cost and I cannot see any benefit over and above my design
(apart from a few grams).
A few have mentioned the indy - this is designed around the indy's tunnel, overall width of the plate being a couple of mm less than the tunnels
outside dims.
I will publish a drawing to allow people to measure up anyway.
Thanks for everyones input, keep 'em coming.
[Edited on 12/5/11 by FASTdan]
Neville Jones - 12/5/11 at 09:56 AM
Make the material thickness 3mm. That's plenty big enough in the application.Otherwise, to match the strengths, the bolts will have to be 12mm!Or
more.
I could use a few of these.
Cheers,
nev.
FASTdan - 12/5/11 at 09:56 AM
quote:
Originally posted by mcerd1
I can't use any of these ones as they are though - my dax chassis doesn't have tubes in the right place for them
[Edited on 12/5/2011 by mcerd1]
How far out are the verticals though? I see no reason you couldn't space these plates off the box sections using pillars to clear the UJ as
required.
mcerd1 - 12/5/11 at 10:11 AM
quote:
Originally posted by FASTdan
quote:
Originally posted by mcerd1
I can't use any of these ones as they are though - my dax chassis doesn't have tubes in the right place for them
How far out are the verticals though? I see no reason you couldn't space these plates off the box sections using pillars to clear the UJ as
required.
the dax tunnel is a totaly different design to the locosts, there is no top rail / vericals - everything is diagonal apart from the lower rails
its hard to explain and I don't have all my pics with me, so I've nicked someone elses build pics:
[Edited on 12/5/2011 by mcerd1]
FASTdan - 12/5/11 at 10:18 AM
quote:
Originally posted by Neville Jones
Make the material thickness 3mm. That's plenty big enough in the application.Otherwise, to match the strengths, the bolts will have to be 12mm!Or
more.
I could use a few of these.
Cheers,
nev.
Agreed on the strength - I had 5mm for a peace of mind thing, it 'looks' right whereas 3mm to Joe public it might look a bit flimsy.
designer - 12/5/11 at 10:24 AM
A good idea, but vastly over-engineered.
When a UJ fails the impact is on the edge of a sheet catcher, and can be controlled by 2mm material.
Also, you have to bear in mind that you only need a prop catcher at the gearbox, power input, end.
FASTdan - 12/5/11 at 10:28 AM
quote:
Originally posted by designer
A good idea, but vastly over-engineered.
When a UJ fails the impact is on the edge of a sheet catcher, and can be controlled by 2mm material.
Also, you have to bear in mind that you only need a prop catcher at the gearbox, power input, end.
How come only the gearbox end?
Neville Jones - 12/5/11 at 10:30 AM
quote:
Originally posted by designer
A good idea, but vastly over-engineered.
When a UJ fails the impact is on the edge of a sheet catcher, and can be controlled by 2mm material.
Also, you have to bear in mind that you only need a prop catcher at the gearbox, power input, end.
You've never been on the recieving end of a rear UJ letting loose? Far worse than a front.
You need a retraint that does both ends.
Not wanting to put Dan out of work, but suitably placed uprights in the tunnel structure, with tubes across the top, will do the job. You've only
got to stop the prop taking out your legs or hips.
Cheers,
Nev.
designer - 12/5/11 at 10:41 AM
Generally the design of the transmission tunnel should stop a broken prop from entering the cockpit. A catcher is to save the prop from hitting the
floor, digging in an flipping the car.
The prop shaft should have the same quality of joint front and rear to any failure will be at the front when all the reactions are, as the rear is
'cushioned' a little by the tubular shaft.
If a rear joint fails the shaft will clatter about a lot but cannot dig into anything as it is trailing. A front failure, and the prop hitting the
floor, is exremely dangerous as it can dig into the road surface with dire results.
FASTdan - 12/5/11 at 10:43 AM
quote:
Originally posted by Neville Jones
quote:
Originally posted by designer
A good idea, but vastly over-engineered.
When a UJ fails the impact is on the edge of a sheet catcher, and can be controlled by 2mm material.
Also, you have to bear in mind that you only need a prop catcher at the gearbox, power input, end.
You've never been on the recieving end of a rear UJ letting loose? Far worse than a front.
You need a retraint that does both ends.
Not wanting to put Dan out of work, but suitably placed uprights in the tunnel structure, with tubes across the top, will do the job. You've only
got to stop the prop taking out your legs or hips.
Cheers,
Nev.
Don't worry about me, this is a product for either a standard chassis build or a retro-fit, as you say there's other ways of solving but a
bolt in item will suit some
I would also hope that such a device will also save the chassis from serious damage.
FASTdan - 12/5/11 at 10:46 AM
unless I am very much mistaken both front and rear UJ's transmit the same torque during any conditions therefore have an equal chance of
failure.
If all you are interested in is stopping the prop hitting the floor a bar across the bottom of the tunnel both front and rear will suffice.
[Edited on 12/5/11 by FASTdan]
RichardK - 12/5/11 at 10:54 AM
Thinking about it I do like your overlapping design, its growing on me! What sort of money you looking at?
R
mcerd1 - 12/5/11 at 11:27 AM
quote:
Originally posted by FASTdan
I would also hope that such a device will also save the chassis from serious damage.
thats what I always reconed..
even if the tunnel is enough to stop you getting injured, then the propcatchers will save your chassis and any wiring loom, brake or fuel lines that
are in / near the tunnel
also I'd say the rear one if anything is more important (but I'd always fit a pair)
if the front one goes you can just knock the car out of gear - if the rear goes you've got to stop the wheels 
Confused but excited. - 12/5/11 at 12:05 PM
quote:
Originally posted by gavin174
hi
I would be interested.
not sure if 2 holes in each chassis tube might weeken the chassis a bit (4 for each catcher)
I have always been lead to believe that if you drill a hole through any structural tube, you should sleeve the hole (and ideally weld the sleeve in),
to prevent weakening of the structure and any crushing of the tube.
Of course there are many guys on here with far more extensive knowledge of these matters than my humble self.
se7en - 12/5/11 at 12:06 PM
quote:
Originally posted by RichardK
I personally would prefer this design
chunky2772 prop catcher 1
But maybe a bit faffy due to different tunnel width and prop diamentions.
Cheers
Rich
Ditto Rich. I think that yours is much better than the above. It is a piece of over-engineering.
Tom
brookie - 12/5/11 at 03:09 PM
i will have a pair as well
rick q - 13/5/11 at 03:11 AM
Front and rear are essential in my view. I've had a propshaft let go at the diff end - the catchers in mine saved both the car and me from
considerable damage :- http://www.locostbuilders.co.uk/viewthread.php?tid=133580
stevegough - 13/5/11 at 05:12 AM
Just one point - if you make it one piece, it would be much harder to fit to an existing (finished) car than a two - piece one, as you could fit it
with the prop in situ - or am I stating the obvious? I quite like the idea of some protection in the tunnel, I would have one or two - you
didn't answer the question of price, though?
MikeR - 13/5/11 at 05:56 AM
i'm interesed in two please (a paranoid front and rear) :-)
40inches - 13/5/11 at 07:11 AM
quote:
Originally posted by stevegough
- you didn't answer the question of price, though?
See the OP's first post.
FASTdan - 13/5/11 at 12:25 PM
Some revisions to the design:
3mm Mild Steel
3x position options allowing oval for live back axles (30mm center distance on oval, is this enough?)
6 holes in each plate allows various mounting options, either 2 bolts or 4 bolts, overlapped or if desired can be trimmed down to be non-overlapping.
Weight 220g per assembly.
As previously mentioned I am aiming for a price of £20 for a pair of catchers (4 plates).
Description
[Edited on 13/5/11 by FASTdan]
mads - 13/5/11 at 12:51 PM
i'm interested in a pair
hucky - 13/5/11 at 12:53 PM
you have a buyer here
RichardK - 13/5/11 at 12:55 PM
I'll take a set too please mate.
Cheers
R
twybrow - 13/5/11 at 01:33 PM
Also interested in a pair... and maybe a pear...!
40inches - 13/5/11 at 01:34 PM
That will do nicely thank you, you can put me down for a pair.
FASTdan - 13/5/11 at 03:36 PM
Thanks for the responses guys, drawings are out for quote so early next week I should have a finalised price and delivery date.
adithorp - 13/5/11 at 04:02 PM
If these are made to fit the width of an MK or book tunnel, does that mean there's no scope for adjusting then for the prop being offset in the
tunnel?
The damage caused by a broken prop is because when it breaks it then flails around. That flailing can rip out fuel lines, wiring loom, start fires,
and damage paneling and the chassis tubes and some have come through and hit legs/arses! By keeping the broken prop close to in line it doesn't
flail but continues to spin. If it breaks at the rear then it'll stop when you put the clutch in, thus limiting the damage if you'relucky;
If it's at the front it'll continue to flail untill the car stops. All the damage I've heard of, has been caused by this and not by
digging in the ground.
FASTdan - 13/5/11 at 04:51 PM
No scope currently for side to side adjustment - how far offset is a prop likely to be?
Current design has a 70mm hole, therefore 10mm clearance all round. I can increase this a bit but obviously as discussed the more clearance the more
out of control the prop becomes. Another 10mm on the rad probably wouldnt hurt?
I could also make the holes into open ended slots, this would offer some scope for sideways adjustment however you will always be limited by a 20mm
box section width.
designer - 13/5/11 at 10:39 PM
quote:
if you drill a hole through any structural tube, you should sleeve the hole (and ideally weld the sleeve in), to prevent weakening of the structure
and any crushing of the tube.
100% correct.
indykid - 13/5/11 at 11:47 PM
quote:
Originally posted by designer
quote:
if you drill a hole through any structural tube, you should sleeve the hole (and ideally weld the sleeve in), to prevent weakening of the structure
and any crushing of the tube.
100% correct.
It's a god job they're going in the uprights of the transmission tunnel then....
For offset props, you could have a split circular plate with an eccentric hole. Assuming you have the vertical wiggle room, you then drill your own
holes in the mounting plate and chassis tubes, having lined it up as desired.
Probably best to stick with the current design though or you'll be iterating forever
mrwibble - 14/5/11 at 12:08 PM
i'd be interested have to measure my tunnel width though first. are you going to keep some in stock or, are you taking orders?
FASTdan - 14/5/11 at 12:40 PM
It will be a stock item so no need to pre order :-)
tony.g - 15/5/11 at 07:49 AM
I'm interested,
When do you expect to have them?
Tony
FASTdan - 15/5/11 at 08:49 AM
Should be 2 weeks, will be ordering later this week.
HowardB - 15/5/11 at 09:00 AM
will they be powder coated, painted, galvenised, or some other cunning finish?
As an aside, what if they were made of er,.... plastic? 10mm thick,....
keith777 - 15/5/11 at 09:18 AM
I'll have a pair !
cheers Keith
stevegough - 15/5/11 at 12:19 PM
quote:
Originally posted by HowardB
will they be powder coated, painted, galvenised, or some other cunning finish?
As an aside, what if they were made of er,.... plastic? 10mm thick,....
Plastic? - are you serious?
HowardB - 15/5/11 at 02:43 PM
there is plastic and there is plastic. I have an almost endless source of plastic which is 1/3 the strength of steel (100Mpa tensile 150Mpa
compressive), and approx 1/7 the density. It also needs no additional painting or anything else,.... so I was thinking, perhaps a 10mm plate, similar
to that shown.
As for serious,... well there is no point taking life seriously we'll never get out of it alive!!
FASTdan - 16/5/11 at 08:45 AM
quote:
Originally posted by HowardB
will they be powder coated, painted, galvenised, or some other cunning finish?
As an aside, what if they were made of er,.... plastic? 10mm thick,....
Yes Hopefully powder coated matt black
I suspect the correct plastic could be quite effective.
johnq - 16/5/11 at 09:02 AM
looked through the thread but didnt establish wether this would fit a live axle setup, is it me??
FASTdan - 16/5/11 at 09:18 AM
quote:
Originally posted by johnq
looked through the thread but didnt establish wether this would fit a live axle setup, is it me??
Hi John, the revised design with 3 holes allows for an oval configuration for live axle. At its longest the oval has 30mm center distance (so 30mm
prop travel) - unfortunately I do not have a live axle car to measure so if anyone can confirm the suitability (asap!) I would be grateful.
MikeR - 16/5/11 at 05:59 PM
Gut feel is its not enough. The Standard locost has about 4" of travel at the axle. This is rotating around the length of the trailing arm. The
diff nose will be moving less than the 4" - but i'd still guess you'd be close with 30mm.
tony.g - 16/5/11 at 07:56 PM
I have just checked my car and can't work out how i could fit them, so i don't think i will be needing them.
Thanks
mads - 31/5/11 at 12:18 PM
any more news on this Dan?
FASTdan - 3/6/11 at 01:42 PM
Prop Catchers now in stock
mrwibble - 3/6/11 at 02:51 PM
super, will be ordering.
foskid - 30/1/12 at 10:30 AM
I really like Dan’s concept for this, but I have some sheets of 14mm thick nylon N6, I'm thinking that the catcher plates made from this material
and could be mounted one either side of the upright members. They could then be bolted right thru all three components with a single bolt each side
without any likelihood crushing the upright members and providing a containment area of about 45-46 mm thickness. More than sufficient I would have
thought to absorb the energy of a flailing prop unless both ends of the prop separated simultaneously.
FASTdan - 30/1/12 at 01:41 PM
Bolting right through is a nice idea, one half one side the other half on the other - as you say this method eliminates the problems normally
associated with bolting through box section. This could be done with my 3mm steel ones or as you say with an alternative material.
The only downside is you are restricted then to the position, where on some chassis/gearbox/prop configurations it may be necessary to space the
plates off the box section to the best position.
[Edited on 30/1/12 by FASTdan]
