Would the Mustang ll front end lower the height of my truck and if so, is
there any way I can mount the Mustang front end and keep the height of my
truck? I have a 55 2nd 3100 and still in the decision process.
Friendly regards from the Carolinas,
Tom
55 2nd 3100
1997 -2000 Racing Seasons
http://home.earthlink.net/~tomntam/index.html
Don't crush em, restore em!!
-----Original Message-----
From: owner-oletrucks@autox.team.net
[mailto:owner-oletrucks@autox.team.net]On Behalf Of Bill & Pam Whittaker
Sent: Friday, August 10, 2001 6:51 PM
To: OleTrucks
Subject: [oletrucks] Thoughts on suspensions
The ongoing discussion surrounding the virtues of IFS made me think (and
that's dangerous) that maybe a broader discussion of all the options is
in order. The following are my personal observations and I'm not going
to make any judgments one way or the other about which is better. Ill
just offer them up to stimulate thinking and a discussion of some of the
options that are available to the average backyard mechanic.
Ive always felt that when making the decision on what type of front (or
rear) suspension to use one must first decide how they intend to use
their car or truck once its on the road. In the case of old trucks, if
you want an original truck that rides like an original truck then the
solid axle is the obvious choice. Once rebuilt they will provide more
than adequate service. If you're going to upgrade to a modern V-8 and
still want to keep the original axle then common sense dictates at least
a brake upgrade, dual master cylinder, and if the owner is so inclined
power steering. Many would consider these modifications to be perhaps
the best compromise between the old and the new, however others may want
a bit more comfort. If this is the case there are several options.
If you're going to use your truck as a daily driver or as a cruiser an
IFS system presents several advantages. Remember there is a very good
reason why modern 2WD pickups use an IFS. It's because this system rides
and handles much better than a straight axle. If you want your truck to
ride like a modern pickup then an IFS should be on your list of things
to do, especially if you're upgrading the drive train. Now days custom
kits specifically manufactured for these trucks are available from
literally dozens of sources with a wide choice of brake systems and of
course power steering. Some are better than others, and the old adage
that you generally get what you pay for still applies, but none the less
there are a myriad of choices available.
The most popular of all these options seems to be the venerable Mustang
II IFS. It has been suggested in a previous post that this suspension
was designed for a light weight car and isn't really suited for a
truck. Although designed for a car the Mustang unit is more than
capable of handling the weight and stress of almost any street rod
including trucks. When evaluating a suspension for suitability you have
to look at what the system was originally designed to do and what loads
it was designed to carry. Without going into a dissertation on the
details of the design, let me just say this... the Mustang suspension is
very strong. It was designed to carry the weight of a modern V8 mounted
directly over the centerline of the suspension. This gives the Mustang
suspension much more strength than you would think. As an example, the
first time I used a Mustang II suspension system I was absolutely
convinced that I needed the heavy duty V8 with air springs to handle the
weight of the 454 I was going to install. As it turned out I couldn't
have been more wrong. All that was required were light weight (4 cyl.
Pinto) springs just as the manufacturer of the kit had suggested. Why?
Because in most street rods as well as in our trucks the motor is
mounted behind the centerline of the suspension. Every inch the center
of the mass of the motor is behind the center of the suspension shifts a
surprising amount of weight to the rear of the vehicle. Therefore the
Mustang suspension winds up only seeing a fraction of the stress and
weight it was designed to handle. Here's another example. I keep a
spare set of the V8 springs (the ones mentioned earlier) around the shop
to use in projects while they are under construction. In my '53 3100
with a 354 hemi and TH-350 transmission in place, even my 250 lbs
jumping up and down on the front of the frame barely forces the
suspension to move. Additionally the springs are so strong that the
lower "A" arms are at an extreme angle. Because the center of the mass
of the motor is significantly behind the centerline of the suspension
there just isn't enough weight to compress these springs more than an
inch or two. For this truck (750 lbs of Hemi with air conditioning) a
simple set of 6 cylinder without air Mustang springs will be more than
adequate. So much for the strength of the Mustang II suspension.
There are of course other IFS options if you don't like the Mustang
setup. The Jag as mentioned in an earlier post is definitely a viable
one. It's just not as easy to install and repair and you can't go into
your local parts house and pickup new bushings or ball joints for the
Jag suspension like you can for the Mustang unit. This is one of the
drawbacks of using something different. On the other hand the Jag
suspension definitely has more sex appeal than most any other conversion
I can think of. Yet another option is the Pacer front suspension. But
this unit has the same problems as the Jag when it comes to parts. You
just can't get parts easily and I think everyone would agree that the
Pacer system certainly lacks any kind of sex appeal. There are other
options such as torsion bar suspension etc., but these require
fabrication skills which are beyond most backyard mechanics abilities
and I'm not going to go there.
The next option is the sub frame. This isn't my cup of tea but for some
people this is the only way to go. The sub frame has the advantages of
a modern suspension system, good brakes, and all the mountings necessary
for a V8 all packaged into a single unit. The drawbacks are that
extreme care must be used in mounting a sub frame both for overall
safety and proper suspension geometry. Also one must exercise good
judgment in choosing a sub frame in order to end up with something that
fits well and looks good. Nothing will lower the value of an old truck
more than an amateurish sub frame installation. If you must go this
route, pick carefully and have the welding done by a certified welder.
Do not pick a sub frame that requires narrowing. The amount of problems
you'll create by narrowing a sub frame are directly proportionate to
every millimeter it's narrowed. You just don't want to go there. Keep
in mind also that a using a sub frame will require significant
fabrication when it comes time to remount the front sheet metal. Very
often people seem to forget this little but significant fact.
Perhaps the most drastic option is the complete frame swap. For me this
would be a last resort. There are just too many options available to
make an original frame ride and handle well to just throw one away.
But, when you have a truck that has significant frame damage, either
from rust, and accident, or just a previous owner's hacking with a
torch, sometimes this becomes the only option. Again careful selection
is the key. Just buying a donor car (or truck) because it's available
and cheap won't do. Take all the measurements you can and pick a frame
that closely matches your dimensions. Its not terribly difficult to
make minor adjustments when mounting the cab either forward or back to
adjust for an inch or two of wheel base difference but you want to keep
these compromises to a minimum. The last thing you want is a wheel base
that's too long or a track that's too wide, unless of course you're
looking for that East LA tires outside the fenders look. In that case
as the Pontiac add says, "Wider is better". Also just like the sub
frame option, mounting the front sheet metal (and bed in this case) may
require significant fabrication and alignment.
Before choosing a suspension system, you the owner must decide what you
want your truck to be when it grows up. Do you want an original truck
that rides like an original truck or a cruiser that rides like a new car
or something somewhere in between? You ultimately have to make that
choice and you have to live with it. If you build your truck to satisfy
everyone else, you are the one that is going to be the least satisfied
with it.
OK, I'll get down off my soapbox now.
Bill
'53 3100 Hemi
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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