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John - 23/10/02 at 12:02 AM

I am using a sierra for running gear including IRS as per Avon. I was wondering if it is necessary to cut down propshaft? Is it not possible to increase length of car to match sierra prop shaft length exactly.

If I do have to cut down the propshaft is it really necessary to have it done professionally, as advised by Tiger book, and balanced? Or can this be done in my own workshop with care (no lathe but do have 14in chop saw)?

Thanks for any advice on this.

John.

David Jenkins - 23/10/02 at 07:44 AM

quote:

If I do have to cut down the propshaft is it really necessary to have it done professionally, as advised by Tiger book, and balanced? Or can this be done in my own workshop with care (no lathe but do have 14in chop saw)?


John,

I'm not going to tell you not to do your own propshaft - but consider the following:

The propshaft is around 2.5 feet long, weighs around 5 - 10 lbs, and at full speed is going to be spinning at 7000rpm. Just consider what will happen to the propshaft tunnel if your welding lets go - and your legs are just alongside.

Even if your work holds together OK, there is still the problem of balancing - a small imbalance will cause a fair amount of vibration.

Many have modified their own propshafts, and I'm sure that many are working really well and have given their owners good service... but this was one component that I decided to buy in ready-made!

regards,

David

(who lowers his head behind the parapet and waits for the missiles!)

James - 23/10/02 at 09:34 AM

quote:
Is it not possible to increase length of car to match sierra prop shaft length exactly.



Hi John,

If you want it to be long enough to be a 4 seater!

From what I remember my Sierra prop is about 4/5 feet long. The Locost one needs to be about 18 inches so you're talking about adding 3 feet to the length of your chassis!

Even if you thought that a good idea then the complexity/cost/effort involved in extending the car this much is bound to be more effort than getting the prop professionally chopped I'd have thought.

HTH,

James

Reminds me of a conversation I had with a colleague the other day. I mentioned to him there's no plans for IRS around so that I was designing my own. He suggested that instead I used a cut down Sierra chassis and bolted my body panels to that!

stevedenbigh - 23/10/02 at 10:35 AM

quote:
Originally posted by James
quote:
. He suggested that instead I used a cut down Sierra chassis and bolted my body panels to that!


Isn't that what ford did with there Escort Cosworth?

chrisg - 23/10/02 at 05:15 PM

As I am 6 feet tall I estimate the length of my overalls to be about 5 feet 2inches.

Thankyou

Chris

Liam - 23/10/02 at 06:47 PM

quote:
Isn't that what ford did with there Escort Cosworth?


Yeah it is. Not sure that tactic would work for a seven replica though!

paulbeyer - 23/10/02 at 09:39 PM

Not unless you want to drive around in a Robin Hood.

stevedenbigh - 24/10/02 at 09:53 AM

Speaking of the man from sherwood forest, I seem to remember they has an add campaign asking "is this the most beutiful chassis ever". Where do I send my answer "no, and it lacks proper triangulation" to?

John - 26/10/02 at 01:14 AM

Thanks all for help.

I didn't realise there was so much difference in length of prop shaft. Leaving without cutting down is not now an option.

John.