Caterham Pop Shaft Strength?

[Rob Walker]

Hi,

 

I took my prop to " Chards" a well respected propshaft/driveshaft manufacturer and reconditioner today for overhaul and rebalance. When asked how much power I was putting through the prop he was most concerned ( 230bhp 160 lbs torque). He said that the prop was not designed to ever handle that sort of power and could be unsafe. 150 bhp 100lbs torque being the absolute limit and with the original light duty joints replaced still only 175 bhp 125lbs torque.

 

Anyone know anything about this subject ?????????

 

Cheers

 

Rob

 

 

 

Edited by - Rob walker on 2 Feb 2006 14:24:05

[F355GTS]

I await further comment

 

Mark

[Marius]

There have been some failures in the past so he obviously knows what he´s talking about...

 

Let´s see if the carbon one on my car will last a whole season....

[Harry Flatters]

I wonder what PS Caterham use on the CSR260 then 🤔

 

*arrowright*Harry Flatters *arrowright*

AKA Steve Mell - Surrey AO and Su77on Se7ener

[Rob Walker]

Chards are refusing to guarantee/take any resposibity for the work done on the prop, in their view its unsafe and if I use it I use it at my own risk, suggested fitting two circular hoops in the tunnel either end of the prop to save my legs if it snaps. " Paul Gibb knows about this ".

 

Trouble is if they are right and a stronger prop is necessary there is insufficient clearance within the tx tunnel to get the bigger joints past the tx tunnel tubing/bracing.

 

Rob

[Rob Walker]

Marius,

 

Out of interest I asked about carbon Fiber props and the guy told me that they had been used for years on the Renault Espace and then produced one for me to have a look at, light as a feather. He said they only fail if a stone or debris hits them whilst under load, then they have been known to shatter.

 

Rob

[Claire Voyant]

What is the weight difference between a standard propshaft and the CF ones?

I have read up on peoples' opinions on the CF shafts here but I don't think anyone has given weights.

Ed: Sorry: rereading the older threads it is about 2kg: I am suprised it is as little as that.

 

Edited by - Rollbar on 2 Feb 2006 15:58:03

[Jason Plato]

Have a word with Chris Wheeler - he fitted an uprated prop to the RSTv8 for Mike Biddle . This had uprated CV joints etc .

 

 

[Rob Walker]

2kgs sound about right, its only the tube thats CF and that a mere 24" of thin mild steel tubing. Probably only worth considering if you have a long prop .

[Rob Walker]

Dave,

 

There are no CV joints on a caterham prop. I have had the heavy duty hardy spicer joints fitted to my prop but advised its still not strong enough. To make it significantly stronger the bearing carriers or propshaft ends need to be changed to the next size up and stronger tube used to link them together and this makes the ends of the prop 12mm wider as such too big to fit into the tx tunnel.

 

Rob

 

Edited by - Rob Walker on 2 Feb 2006 16:24:53

[I reply to every thread]

So you can't have an engine over 175bhp in a Caterham?

 

Isn't this guys argument rather self defeating in practice?

 

Paul Gibb had a failure but I thought that the consensus on that was that the shock loadings induced by the sequential box were primary contributors?

[Harry Flatters]

Clearly these Chard people know their onions but it's not exactly as if the last 5 years has been littered with horrific tales of prop shafts going bang on R400, R500 and other equally & more powerful cars that clearly exceed their stated tolerances for our 'toffee' prop shafts.

 

I personally am aware of 3 incidents in recent memory of prop shafts failing. One has already been mentioned in this thread, one was on a prop shaft not made by Caterham and the third one was brain failure on the part of its owner who forgot to tighten up the flange bolts on the prop shaft.

 

Have Chard actually tested one of these to destruction?

 

 

*arrowright*Harry Flatters *arrowright*

AKA Steve Mell - Surrey AO and Su77on Se7ener

 

Edited by - Harry Flatters on 2 Feb 2006 16:41:48

[Peter T]

I am not even going there.

I have never heard such drivel, it not is about the size but the material it is made of.

 

Carbon Components Here K9 Composites

 

[I reply to every thread]

You've not had propshaft problems have you Peter?

[Dickie Normuss]

😬

 

Seek forgiveness, not permission.

Rules are for the interpretation of wise men and the obedience of fools.

[Peter T]

WHO ME........................................

 

Care to elaberate on that Mathew.

 

Carbon Components Here K9 Composites

 

[Rob Walker]

Peter T,

 

" Drivel" I am well aware that a extremely strong prop could be made out of better materials and keep the same or even smaller dimensions. The ends could be machined out of billet steel EN12 and thin walled chrome steel tube used to contect the ends. However this not F1 and these parts are not off the shelf and I am expecting to refurb my prop for cica £100 not £1000`s for a bespoke item.

 

if you know of a cost effective route other than fit HD joints to increase the strength of my prop I would be gratefull for the advise . Smartarse coments are not usefull .

 

Harry,

 

I agree there are loads running out there, however my prop is off my April 2004 car and its only done 5K miles and its worn out despite periodic regreasing and I do not sprint or give it a hard time away from the line. Could be more owners need to have a look at their props before complete failure??????? I don`t know that s why I started the thread.

 

Rob

 

 

[I reply to every thread]

You've been unlucky then - My prop is probably one of the few original components left in my 80,000 mile 94' car - It's variously had 170, 200 & 232 bhp put through it latterly through a paddle clutch with no issues - (although admittedly checking the grease nipples is on my list of things to do).

 

As far as I'm aware the R500's have the same prop as a 1400 SS don't they?

[Rob Walker]

Yup the 1400cc has the same prop as the 1800cc R500. The CSR prop looked to have the same joints on the demo chassis. I will get some facts and figures on the prop joints from either Road & Race, Raceline or Chards all of which I have to revisit in the next day or so.

 

Edited by - Rob Walker on 2 Feb 2006 17:54:58

[Harry Flatters]

Rob,

 

By worn out I assume you mean that the UJ's are US and thus need replacing. These are lifed parts and do need replacing from time to time. You may have been unlucky with yours apparently wearing so quickly. I replaced mine last year as a matter of course when I had the diff refreshed and to my knowledge they were the original as supplied in 1994. They showed absolutely no sign of wear despite having 160, 200, 225, 232 bhp and around 170lbft shoved through it over the years.

 

IMHO I just think that it's a bit dangerous a company like Chard making sweeping generalisations without carrying out a controlled analysis or perhaps first speaking to CC.

 

BTW I'm not here to fight Peter T battles for him but SmartArse is one thing he is not. I think you will find Peter has a fairly sound engineering grounding and indeed has very first hand knowledge of prop shaft failure.

 

*arrowright*Harry Flatters *arrowright*

AKA Steve Mell - Surrey AO and Su77on Se7ener

 

Edited by - Harry Flatters on 2 Feb 2006 17:58:04

[Peter T]

Well Rob if you don't think spending a few quid more on your prop to safeguard your limbs in the event of a failure, then i retract my so called smart*rse comments.

 

My current propshaft which is nothing special i can assure you, it came staright of the shelf at Redline and is standard fitment to a Ford x-flow variant, this has no problem transmitting a genuine 270 BHP, 190 LBFT from my engine.

And even more when my gearbox let go on the rolling road and the back wheels locked up at 54 MPH it showed no signs of being weak.

There are quite a few of big power boys still using the standard propshaft, and i have never seen failures even ones being used in competition.

 

Carbon Components Here K9 Composites

 

[Jason Plato]

Yes I meant UJ not CV's

 

I wonder if the supplier has changed for this part recently ?

 

 

 

 

 

 

[rgrigsby]

Just to add to the list of big power engines my car ran the original propshaft up until last year which at that point was 13 years old and had completed 40K+ miles of which at least 15k is on track and a fair amount sprinting/racing. It started life with a 1700 xflow, then 155RK spec Xflow, then a monster steel 1800xflow with a paddle clutch without any problems.

 

Admitedly when I switched to the duratec I had to change it as it was the wrong length and yes it did look pretty worn out but it's had a fairly hard life so I wasn't too worried. I will confess to not having checked the prop recently in the past 6K miles with my 250bhp duratec so I'll add to the list of things to look at next time I'm under the car.

 

Rob G

www.SpeedySeven.com

[tiddy1]

I had a chat with some guys at work re prop shafts and thier opinion is that the caterham one will be fine at all the torqure and power levels we can throw at it. It is really only the shock loading that is an issue and with such a light car you really can't geneterate enough shock load. If it was in an escort or such like you may have a problem. Some of the racers could probably shorten its life if they were constantly bouncing off the curbes whilst keeping the throtle fully planted.

 

The fatigue loads are really not going to be high enough during the normal life of a 7

 

and considering that there must be hundreds of 7s out there with 200+ bhp and I only know of one failure it seems to be bourne out.

 

I expect that the CSR uses exactly the same prop

 

Simon

 

[Paul Gibb]

Unfortunately the prop that failed on my car had been replaced only 18 months previously and had covered around 2200 miles - all on track. I am not certain of the mode of failure but it was catastrophic and involved the front uj & prop nose causing considerable damage to the adjacent tunnel. The tunnel was repaired by Arch with the addition of a substantial 3mm steel plate running along the drivers side of the transmission tunnel providing protection should the prop fail again (I am sure that Bruce would be more than happy to replicate this mod if asked).

The previous prop had covered around 17500 miles, at least 2000 over 250bhp and around 1300 with seq dog box - again all on track - the ujs are in excellent condition.

As mentioned above Russell Savoury & Chris Wheeler have installed a beefed up prop in the RST-V8 but surgery to the tunnel was required to accommodate this (and detailed available pics are on the RST-V8 website).

According to Simon to whom I spoke following the failure Caterham continue to use the standard prop in the CSR, I have no idea whether or not this is still the case.

I am now resigned to replacing the prop each winter but would be interested to know whether others have discovered at a more satisfactory solution.

 

 

L7 FUN