Well, it depends upon which flavor of Polyurethane. It's available in
different hardnesses, anywhere from softer than the stock rubber bushings to
the "almost billet aluminum" hardness that the current brit suppliers seem
to favor. They're just about as hard as the trunnion bushings.. And about
as easy to install too.
When things calm down this winter I'm going to experiment with casting
bushings for my street Spitfire out of the compound we use at work. It
comes as a two part like an epoxy and comparable in hardness to the butyl
rubber bushings. All I need to do is form up a mold on the mill and I'm
set.
And it's in a nice bright blue, for that Gen-X look.
Cheers,
Jim
Dallas TX
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Bill Babcock
Sent: Wednesday, October 05, 2005 8:56 AM
To: 'Gerald M Van Vlack'; FOT; Triumphs
Subject: RE: Rear Trailing arm bushes IRS cars
I would think poly mounts on a street car would be hideous. I guess people
always think stiffer is better for the same reason they think bigger is
better. A certain Freudian sense of longing perhaps? In a race car we're
looking for precision and don't mind replacing bits that wear out in a year.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Gerald M Van Vlack
Sent: Wednesday, October 05, 2005 5:54 AM
To: FOT; Triumphs
Subject: Rear Trailing arm bushes IRS cars
Lists,
I recently responded to Dave Connitt's post on using some type of hard mount
on his 4A steering rack, I was against doing so on a street car. I went on
to opine on my thoughts regarding the general use of Poly mounts on street
cars etc. We all have our opinions.
I have a question for the list on the subject. Specifically the poly mounts
for the IRS Trailing Arm attachment to frame pivot point. Properly installed
rubber mounts rotate by the flex in the rubber itself and not via the
through bolt that clamps the bushing between the mounting ears. That's not
the case with the poly mounts, there is no flex in the poly hence the
bearing becomes the bolt to sleeve interface or the sleeve to poly bush
interface or maybe both. I don't recall for certain but I don't think the
metal bushings are long enough to be clamped between the mounting ears and
held stationary forcing the rotation to be between the bushing and the poly
mount and not the bolt shaft to bushing. Has anyone inspected this
installation after a few years of use?
What was observed?
To those suppliers who sell the poly bushing replacements and who read these
lists. Do you know the engineering that applies? I'm using some from a well
known "racing" supplier but I am suspect of the design input. I'm fairly
certain that I'll go back to rubber in the future if I can find an adequate
way to install new ones.
Thanks,
JVV
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