At 08:24 AM 9/6/01 -0700, Steve Petrosky wrote:
>While rebuilding the front end of my 58 mga I am interested in the
possibilites of adding a front sway bar. Moss lists three sizes, but which
is best for spirited street driving with standard sized radial tires?
The short and simple answer is 3/4".
>Moss mentions that with slight modification the bars can be fitted to the
A, what exactly do they mean "modification", welding? drilling? or....
For installing STOCK TYPE front sway bar on the MGA you need the newer type
spring pans and front lower a-arms with the reinforced holes to accept the
bottoom end of the sway bar link. You also need the later type front frame
extension that has the indentation in the top to accept the sway bar mount
on the frame. The MGA front frame extention and sway bar mounts were only
designed to accept the optional factory supplied 5/8" bar. Those mounting
brackets are currently as scarce as hen's teeth, as are complete original
type sway bar kits with the frame top mounts.
For any other size bar you would need to fabricate brackets to hold the bar
on top of the front frame. The original type brackets do not include any
rubber bushing, and there is precious little space allowed there for
increasing the diameter of the bar. Any bar larger than about 3/4" would
be a tight squeeze without some "adjustment" to the frame or body. Also
bear in mind that to install the bar in the original location you need to
remove the front bumper, the valance panel, and the front frame extention
(unless the body is currently off the frame).
The MGB sway bar mounting is considerably different, in that the bar mounts
underneath the frame (unibody structure) on the MGB. The bottom surface of
the front frame on the MGA is considerably lower. Attempting to mount the
MGB bar below the MGA front frame with the original type end links will
likely result in interference of the parts (particularly the arms of the
bar) with the steering tie rods and/or rack rubber boots. Cutting and
shortening (with welding) of the end links could be a solution to that
problem by positioning the bar below the tie rods.
Aftermarket front sway bars designed for the MGA will usually mount
underneath the front frame with drilling and bolting of supplied brackets.
This "kit" will also have shorter end links of a different design, which
may be attached to the original type lower a-arms by simple drilling and
bolting of a supplied bracket. The frame mount will incorporate an
elastomer bushing. The sway bar will have a vertical hole at the end
rather than horizontal. The bracket to be attached to the a-arm will
likely be a piece of angle iron presenting a flat top surface for the link
attachment. The end links will generally be the common variety you can buy
at any local auto parts store, comprised of a long bolt and a self-locking
nut, four rubber grommets, four steel cup washers, and a tube spacer. A
picture of this type mounting can be see here:
http://www.chicagolandmgclub.com/photos/tune2001/1220.jpg
There may possibly be a short tube spacer between the 2nd and 3rd rubber
grommets to set the end arm of the bar at right angles to the link with the
suspension at loaded height.
>Also, is there any one out there that offers a rear sway bar?
Yes. You can buy both front and rear aftermarket sway bar kits for the
MGA. These are made by ADDCO (in Florida), the largest manufacture of auto
sway bars. They can be purcahsed at a substantial discount through
J.C.Whitney <http://www.jcwhitney.com>. Unless otherwise specified you
would receive a 3/4" bar for the front and a 5/8" bar for the rear. Unless
you have a special racing application with lowered suspension you should
not install a rear sway bar on your MGA.
The original (late production) factory optional 5/8" front sway bar for the
MGA is about right for use with original type and size bias ply tires.
These tires are okay for a show car, but by current tire standards they
have fairly poor grip for daily driving. Modern radial tires have much
better grip, which will also cause additional body roll forces when
cornering hard. As such, a 3/4" front sway bar is much better for street
use with radial tires.
If you're bold enough to use sticky racing tires for competition, then even
the 3/4" bar will be marginally inadequate. See here:
http://www.ntsource.com/~barneymg/recent/siemens.htm
In this case a 7/8" front sway bar is much more desireable. This picture
also illustrates why you don't want to install a rear sway bar, as one rear
tires is already off the ground.
If you go so far as to lower the suspension height for competition use,
then you can ignore all notes above and start from scratch to figure out
the best combination of sway bars. In general lowering the body and frame
height in relation to the axle height will reduce body roll, and smaller
sway bars can be used. Lowering the ride height and/or changing front
and/or rear spring rates will change the front and/or rear roll centers,
which will dramatically affect the steering characteristics, which will
change the requirements for sway bars. Stickier tires increase body roll
and sway bar requirements. Driver technique can affect the outcome of
certain types of manuvers, so the final selection of sway bars may depend
some on who's driving.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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