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pug205rally

Rear Torsion Bars

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pug205rally

Hi,

 

I have just found some thicker torsion bars with a parts box of old 205 bits and pieces and want to fit to my beam. But having re-read the refurb guide it states the bars are handed and are marked accordingly. The bars I have found are not marked and not on a trailing arm so I have no way of knowing which way round they should go. These bars have been in a box for 3+ years

 

What if any are the likely problems if I put them in incorrectly and how can I tell. Breaking ? poor handling etc. etc.

 

I am assuming its a wear factor and they are the same on insertion but to constant load in one direction has a usage effect.

 

Cheers

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roland rat

are there any painted lines on the bars?if so i ve got a pic of a rear beam so you could work out which one goes where. :)

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pug205rally
are there any painted lines on the bars?if so i ve got a pic of a rear beam so you could work out which one goes where. :(

That the trouble no markings at all - someone have recoated the bars with red plastic paint - looks nice but has covered any marking's , tried scraping off but still no joy with any markings , guess they where rubbed back prior to painting

 

Grrrrr :)

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welshpug

there is a slightly different shoulder on one end of one of the torsion bais IIRC, like a little groove.

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Sandy

You can't fit them the wrong way round, but why they are left and right is a mystery to me, it might be to do with ageing? The 22mm bars I bought weren't sided, so I just whacked them in, seems fine so far.

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niklas

I don't see why they should be sided from a technical point of view!? To increase durability? Would Peugeot really put money into the manufacturing of them to make them last 20 years instead of 10?

Doesn't sound likely does it.. :)

 

Besides, how would it be done?

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pug205rally

Thanks for the replies - I was not sure hence the question and was only asking as the refurb guide raised the quesiton

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littlemike

One's longer than the other so you can't get them the wrong way around.

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Sandy

Are you sure??

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niklas

Err no, they are the same length!

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pug_ham
One's longer than the other so you can't get them the wrong way around.

No they aren't, they are exactly the same length & have the exact same splines on each end so they can be fitted the wrong side, look at this topic for proof & reasoning.

 

Graham.

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littlemike
No they aren't, they are exactly the same length & have the exact same splines on each end so they can be fitted the wrong side, look at this topic for proof & reasoning.

 

Graham.

 

You're correct. I've been rebuilding my 205 beam this morning and both bars are the same length.

 

I've got a Gti6 one apart that I pinched a pivot shaft out of for the 205 beam and I must've got muddled between all the torsion bars that are on the floor!

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Grim.Badger
I don't see why they should be sided from a technical point of view!? To increase durability? Would Peugeot really put money into the manufacturing of them to make them last 20 years instead of 10?

Doesn't sound likely does it.. :P

 

Besides, how would it be done?

 

As far as I understand the principles of spring steel it is all down to how the bars were manufactured. Just because a peice of spring steel can bend or twist in one direction without fatigue doesn't mean it can bend in the opposite direction. I'd suggest that they can't twist in the wrong direction because of peugeot cost cutting and not producing steel that was up to the jobs of bending in both directions.

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pug205rally
As far as I understand the principles of spring steel it is all down to how the bars were manufactured. Just because a peice of spring steel can bend or twist in one direction without fatigue doesn't mean it can bend in the opposite direction. I'd suggest that they can't twist in the wrong direction because of peugeot cost cutting and not producing steel that was up to the jobs of bending in both directions.

This would imply that the bars must be the correct / original way around or else the bars will not properly flex. This goes back to my original question about wrong handing ......

Edited by pug205rally
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niklas
As far as I understand the principles of spring steel it is all down to how the bars were manufactured. Just because a peice of spring steel can bend or twist in one direction without fatigue doesn't mean it can bend in the opposite direction. I'd suggest that they can't twist in the wrong direction because of peugeot cost cutting and not producing steel that was up to the jobs of bending in both directions.

 

And how exactly would you make a homogenious steel (like spring steel) that behaves differently depending on which way you twist it?

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Grim.Badger
And how exactly would you make a homogenious steel (like spring steel) that behaves differently depending on which way you twist it?

 

Who said it was homogenous?

As far as I know one way of making spring steel is to heat and twist a bar of steel and then rapidly cool it. This will fix the crystal structure in a sort of twisted form which will resist twisting in one direction much better than the other (imagine a bolt hand tightened into a hole).

I may be wrong about this but it's always the way that I've understood springs.

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niklas
Who said it was homogenous?

As far as I know one way of making spring steel is to heat and twist a bar of steel and then rapidly cool it. This will fix the crystal structure in a sort of twisted form which will resist twisting in one direction much better than the other (imagine a bolt hand tightened into a hole).

I may be wrong about this but it's always the way that I've understood springs.

 

Never heard of twisting the the spring steel during heat treatment...

 

I heard a suggestion that the colour codes is a way of marking the stiffness of the springs, just like they do on the front springs. Sounds plausible!?

Besides my aftermarket torsion bars are not marked in any way...

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Guest Pär Hansson

Twisting the bar during hardening to achieve a directional apt for torsional stiffness would be a cumbersome and expensive affair, that I doubt would work at all. It would incorporate a partly cold tensioning of the material which I doubt can be managed process-wise in torsion, a process which is hard enough to manage in pure tension.

 

The Peugeot torsion bars have the same elastic and durability properties both ways. My c2. :blink:

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Sandy

I reckon it's probably to do with settling, to make sure they go back the same way if dismantled?

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Grim.Badger
Twisting the bar during hardening to achieve a directional apt for torsional stiffness would be a cumbersome and expensive affair, that I doubt would work at all. It would incorporate a partly cold tensioning of the material which I doubt can be managed process-wise in torsion, a process which is hard enough to manage in pure tension.

 

The Peugeot torsion bars have the same elastic and durability properties both ways. My c2. :(

 

Fair enough, I've only ever been told "lies for children" physics and my knowledge of metalurgy is all based on ancient forged and cast metals :blink:

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pug_ham
Besides my aftermarket torsion bars are not marked in any way...

Neither are mine but I will mark them when I fit them in the same way as standard ones.

 

Metal has a memory though so fitting them on opposite sides after years of being twisted one way can't be a good thing imo.

 

Graham.

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