Just Bought Some Torsion Bars. Do They Need To Be Heat Treated?

[Mad Scientist 106]

Picked up some torsion bars today from a supplier who will remain anonymous!

 

They aren't heat treated................ Should they be???

[stu8v 68 1 Cars]

Yup

[GTI6BOY 29]

Been using non heat treated bars for years and I've personally not had a problem, neither has my best buddy

[petert 585]

I had three sets of 21mm bars made once, which they forgot to H/T. The ones used in a rally car sagged on the first stage. Once H/T'd however, they've been in service ever since.

 

They're the same as a spring.

[Mad Scientist 106]

Well I know they are made of en47 steel, which is correct, but they haven't been hardened. This hasn't been confirmed by the manufacturer yet, but they are still shiny steel coloured!

 

I suppose I could have them heat treated myself, before I powder coat them. Wonder what that would cost?

[allanallen 528 2 Cars]

If they're where everyone gets them from the place in Leicester I wouldn't worry. There's loads and loads of them about with no probs whatsoever, they're not heat treated.

[welshpug 1,655]

Why do others bother heat treating in that case? or are they a different material?

[allanallen 528 2 Cars]

Chris penrose's are heat treated afaik, the Leicester ones aren't, who else makes them? I'm no metallurgist but I know oe bars are hardened or at least the splines are. Why are they hardened? Is it just for the integrity of the splines?

What I do know is I've had no issues whatsoever with non hardened bars as have several friends as well as every other Tom, d*ck and Harry who's bought them from all the group buys across forums, not to mention ones supplied by pug1off, 205parts(deceassed),Anthony, Paul etc

 

Haven't you got some welshpug?

[welshpug 1,655]

yup, one set on my 205 that came from Anthony, which were shiny metal coloured, from whichever source he uses and another set on my ZX that came from a different source that were a dark matt grey finish.

 

same price as it happens, and significantly less than ta certain peugeot specialist in leicester, who I dont know if they get them from Leicester or chris, or Chris penrose's items (which were available through shenpar and special tuning IIRC)

 

just curious that's all !

Edited August 3, 2013 by welshpug

[allanallen 528 2 Cars]

I'm curious really as this topic often comes up and petert is the only person to have a problem but his bars aren't the same as what we're all using anyway.

As far as I'm aware Chris and the place in Leicester (or wherever it is) are the only folk making them.

 

As for heat treating them, can you even do it after they've been made? I know alot of the materials I work with grow considerably after treatment! What does heat treating do to the properties of the spring steel? I'm sure the correct spec of spring steel shouldn't sag, hence the 'spring' bit?!

[Mad Scientist 106]

Well these are indeed from Leicestershire, so I would assume they are from the same place. If they are tried and tested, then ill use them and see how I get on.

 

To be fair to Spoox (oops!) I got a cracking deal. People should realise that just because something is advertised a bit on the steep side, doesn't mean that's what you should pay! The only place I don't barter is the supermarket!

[205turbo 32 2 Cars]

If they're where everyone gets them from the place in Leicester I wouldn't worry. There's loads and loads of them about with no probs whatsoever, they're not heat treated.

 

nothing to do with me or the company that I get them from in leicester

Edited August 3, 2013 by 205turbo

[allanallen 528 2 Cars]

Where are yours from then Paul? I was under the impression you got then off the guy in Leicester who used to sell them on eBay and supplies pug1off, Spoox etc?

Edited August 3, 2013 by allanallen

[205turbo 32 2 Cars]

He never supplied to spoox he has them made else ware

[allanallen 528 2 Cars]

But it's the same guy off eBay and supplies pug1off?

[Miles 331 1 Cars]

I've had non treated ones sag as well on the old 309, I don;t use the company in Leic as I've never been keen on the splines, some are OK others are not

[petert 585]

With your non-heat treated bars, it's possible that you're not getting near the elastic limit of the material. The heat treatment process increases the point of elasticity. Driving down the street to buy a packet of Rothmans is not the same loading as a motorsport application. Additionally, a bigger 23mm bar probably has enough cross sectional area to stay under the elastic limit better than a 21mm bar. However, just like bending a piece of wire backwards and forwards, cycling the bars through normal use is work hardening them, to the point were they will eventually loose their elasticity. An un-heat treated 19mm bar would fail dismally.

 

Hardening and tempering is the last process, done after all the machining is completed. The bars are also stress relieved between roughing and final machining, at least my locally made bars were. If company A is selling non H/T'd bars for the same price as company B, then someone is making serious coin. The H/T process is probably something like 1/3-1/2 the cost of production. I only buy Chris's bars now, preferring them over locally made bars, despite the postage.

[allanallen 528 2 Cars]

Not getting near the elastic limit of the material?? That's a good thing surely?

I personally only have experience with larger bars but I know of 21mm bars on a cars with no problems. Oh and none of us smoke

The non heat treated bars are cheap, very cheap in fact!

[petert 585]

Not getting near the elastic limit of the material?? That's a good thing surely?

 

Maybe I didn't explain it properly. The H/T process typically takes the yield point from 250-300MPa to 900-1000MPa.

[allanallen 528 2 Cars]

That makes more sense cheers! I read it as the elastic limit isn't being reached during use, which obviously you don't want.

[Mad Scientist 106]

Sparked a bit of debate here. Not being an engineer, this is a little confusing to me. My options are:

 

1. Use them as they are, with the reassurance that if there's a problem, I'll return them.

2. Get them heat treated myself, but not knowing what to ask for, that's a little tricky.

 

 

Problem is, if I start having problems on an event, then I'll be fairly annoyed. Entry fees, travel, etc etc would all be wasted.

[petert 585]

... but not knowing what to ask for, .......

 

Harden and temper please.

[Mad Scientist 106]

If its as simple as that, then I might make some enquiries. We aren't aiming for any specific Rockwell grade or anything then? No problem doing it all post machining?

[petert 585]

Simple as that. The Rockwell number is mostly determined by the material it is made from. It should finish at 44Rc min from memory.

Edited August 4, 2013 by petert

[welshpug 1,655]

I doubt you would want to do it before machining, would start to get a bit expensive on replacing machine tools surely?