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Prop catchers
mangogrooveworkshop - 7/4/10 at 08:06 PM

Do you have one or more fitted.?

mcerd1 - 7/4/10 at 08:12 PM

not yet, but I will do

I recon a pair near the front and back should do it on mine

flak monkey - 7/4/10 at 08:14 PM

The tunnel is all 20mm tube...so i figured that would work well enough should the worst happen.....

mangogrooveworkshop - 7/4/10 at 08:19 PM

Im in the process of rejiging the footwells so we have stuck one right at the front where it comes off the adapter.

I was reading dave walkers article where a prop came off on his rolling road on a westfield.....enough evidence for fitting one

mads - 7/4/10 at 08:31 PM

please excuse my ignorance but what is a prop catcher (besides the obvious) and how does it work?

adithorp - 7/4/10 at 08:50 PM

It's a hoop that sits around the propshaft near it's end so that should the UJ/weld fail, the prop hasn't got room to flail around and take out your fuel lines, loom or worse still, tunnel panels and your legs.
Ideally it should sit as close as possible to the prop so as to retain it close to it's original line in order to be effective.

Not got one yet but do intend to add one.

adrian

Dangle_kt - 7/4/10 at 08:59 PM

not got one either, but it is on my imaginary "to do" list

Bluemoon - 7/4/10 at 09:00 PM

Yep I also "intend" to fit one, but am looking for a good way to retrofit without welding..

minitici - 7/4/10 at 09:00 PM

I've just added (3) prop catchers - fabricated from 5mm steel split rings.


Steve Hignett - 7/4/10 at 09:32 PM

The locost I'm building will have two, very very similar to the car above (although a bit less hefty!!!)

minitici - 7/4/10 at 09:40 PM

quote:
Originally posted by Steve Hignett
The locost I'm building will have two, very very similar to the car above (although a bit less hefty!!!)


Perhaps I should have used 3mm
I suppose I could always drill the rings to loose some weight.

craig1410 - 7/4/10 at 09:54 PM

I just got a propshaft made professionally from a reputable manufacturer (Autoprop UK) and to a spec well beyond what I needed for my Rover V8 engine.

I also have a pretty sturdy tunnel with a floor beneath the prop to avoid any pole vaulting action and I used brand new 10.9 grade bolts with nyloc's, thread lock and painted lines across the joints to ensure nothing comes loose. I feel pretty safe.

rick q - 7/4/10 at 11:56 PM

I had the weld on the rear uni fail on mine at speed. The hoops took a hiding but kept it in the tunnel. All wiring and fuel lines run inside a steel pipe inside the tunnel - it was dented by the flailing end of the propshaft as well.

Having had that happen, I wouldn't ever be without one - the thing is only mm from your hip afterall.


Danozeman - 8/4/10 at 05:32 AM

iv welded in extra tubes to my tunnel to stop it hitting me but not a hoop.

speedyxjs - 8/4/10 at 06:22 AM

quote:
Originally posted by Danozeman
iv welded in extra tubes to my tunnel to stop it hitting me but not a hoop.


Thats what i have also done but im still tempted by a prop catcher having seen a few pics of failures on here

snapper - 8/4/10 at 08:52 AM

I retro fitted double thickness steel plates either side of the front UJ as my car is a monocoque.
Rear joint hangs out the rear of the tub

alistairolsen - 8/4/10 at 08:58 AM

People seem to be missing the point of these somewhat!

The idea is not to make them mega hefty, nor to fit armour plating inside your tunnel! A prop can break anywhere along its length, but most break at the joins, but even if the rear join is out the back its still not safe if it goes out of line. If anything gets out of line enough to reach the sides of the tunnel then 20mm tube wont stop it.

The principle is by fitting a close running hoop around the shaft int he even of a failure it becomes a slack bearing and keeps the remains of the shaft inline to stop it flailing and causing damage.

They need only be 2 or 3mm plate, but they need to be CLOSE!

Julian B - 8/4/10 at 07:46 PM

I'm in the "let it be camp"

For this reason

how many time have you had a prop fail?

how many times have you had a side impact?

perhaps its worth realising that a car without all the safetey features is a car thats driven with more care

mcerd1 - 8/4/10 at 08:23 PM

^^ think about it - its a fairly light, simple saftey feature that you can easily make yourself and protects you and your chassis/ fuel lines/ wiring - I'd rather have it than not (the close fitting type that is)

mangogrooveworkshop - 8/4/10 at 10:51 PM

My take on this is we do a lot of hard starts at events like Crail or Forresburn.
Its the fact we are sharing the space with a super fast rotational shaft that is twisted repeatedly. If it lets go you have no where to go. In a production car its got a floor pan between you and the shaft.......as Robert says its cheap and easy to achieve giving you a degree of safety.

Steve Hignett - 8/4/10 at 10:55 PM

You're right Pat, but I wouldn't be bothered about taking my old car apart to fit one, but also would not consider in any way, not fitting one to this race car...

Liam - 9/4/10 at 09:35 AM

quote:
Originally posted by Julian B
I'm in the "let it be camp"

For this reason

how many time have you had a prop fail?

how many times have you had a side impact?

perhaps its worth realising that a car without all the safetey features is a car thats driven with more care


LOL! Side impact fair enough - drive with care to avoid. Prop failure - could happen anytime no matter how you drive. Completely different matter.

You may also have noticed when assembling your Dax Rush that it has rather less structure in the transmission tunnel than most other chassis. A standard locost chassis, and most others, at least have a fully enclosed tunnel for some protection.

Still 'it'll never happen to you', right?

craig1410 - 9/4/10 at 12:12 PM

quote:
Originally posted by rick q
I had the weld on the rear uni fail on mine at speed. The hoops took a hiding but kept it in the tunnel. All wiring and fuel lines run inside a steel pipe inside the tunnel - it was dented by the flailing end of the propshaft as well.


How did you get away with having your wiring and fuel lines in the same steel conduit? Are they just lying loose inside the conduit or are they secured every 9" or so as required by SVA? I though that wiring and fuel lines had to be kept a certain distance apart, ideally on opposite sides of the tunnel.

As a few others on here have said, I think there are more important things to worry about from a safety point of view than propshaft failure unless the propshaft is under spec'd or poorly made.

It's more likely that my 170BHP engine will propel me into a hedgerow backwards than break my 400BHP+ rated propshaft!

iank - 10/4/10 at 02:41 PM

quote:
Originally posted by Julian B
I'm in the "let it be camp"

For this reason

how many time have you had a prop fail?

how many times have you had a side impact?

perhaps its worth realising that a car without all the safetey features is a car thats driven with more care


I can remember around 3 being reported on here over the last few years every time the pictures posted showed a lucky escape with holes in the tunnel ally caused by the flailing prop battering.

But as with any risk assessment you need to take into account how serious the impact of it happening (worst case is death/wheelchair for the rest of your life) and the cost/impact of preventing the risk - a couple of 2-3mm hoops mounted close to the shaft isn't going to add much to the build cost/weight if done at chassis construction time.

iank - 10/4/10 at 02:45 PM

quote:
Originally posted by craig1410

As a few others on here have said, I think there are more important things to worry about from a safety point of view than propshaft failure unless the propshaft is under spec'd or poorly made.

It's more likely that my 170BHP engine will propel me into a hedgerow backwards than break my 400BHP+ rated propshaft!


Props don't break due to the torque being put through them (except on the drag strip). They break due to them going out of balance often due to one of the little weights coming off and the vibration causing a welds to fail or the prop u-j to come off. The problem is once free they are pretty much equivalent to a sledge hammer being smashed into the tunnel.