Larry - I would suggest you check the tensile strength of ordinary mild
steel as well as what the book says for 4140. When you weld the 4140 (or
most other high tensile steels) the heat from the welding will anneal the
4140 so the roll bar (around the welds) is only the strength (or close to)
the strength value for ordinary Mild Steel (1010).
Heat treating the roll bar will put the strength you quoted back in - and it
will be that strength all over. A stronger roll bar will not only add
rigidity to the frame of your TR3A, but it will stay where you want it to
stay, if the day ever comes where you .......... heaven forbid.
Talk it over with a friendly heat treat shop. They will be able to explain
it.
Don Elliott, 1958 TR3A, Montreal, Canada
----- Original Message -----
From: "Larry Young" <cartravel@pobox.com>
To: <fot@autox.team.net>
Sent: Monday, March 17, 2003 3:45 PM
Subject: Anti-Roll Bar Materials Question
> After looking at the bars made by Saner, I decided to make an adjustable
> anti-roll bar for my TR3A. The Fred Puhn book says to use 4130 steel
> for bars up to 1 inch and 4340 for larger bars. I used 4140 steel for
> mine. Fred Puhn also says to have the bar heat treated to 160-180,000
> psi. I've been running mine without the heat treat. I assume the heat
> treating will increase the stiffness of the bar. Can someone tell me how
> much it will change the stiffness of the bar?
>
> In the archives, I've seen past discussions about the effect of
> anti-roll bars on understeer of solid axle TRs. On the top of p. 149,
> Fred Puhn describes how a stiffer anti-roll bar can reduce understeer.
> Larry Young
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