Oh yea, I glazed over the projected length part, that makes it much easier.
As for the heat treating / stress relieving, there is good evidence that
stress relieving of commonly available metals like steel and many aluminums,
is detrimental to the integrity of the material. I would say that if you are
going to do this you should look into different alloys and pick one based on
its match to your needs, you will then be able to lookup exactly how that
metal should be worked for maximum strength and durability. I doubt that you
would find any commercial steel that would have to be stress relieved,
chromoly is a different story though. Any knowledgeable welding shop or
supplier should be able to help you do this. If they don't know what to
recommend, then you aren't talking to the right people, maybe try a race shop,
they are used to fabricating stuff. It can be difficult to find small
quantities of quality metals, the shop that you consult with should be able to
help you. Just recently I found a section on ebay in the business/industrial
section that is called scrap metal. If you know what you are looking for,
there are some good deals there, and also some good small volume suppliers.
best of luck,
James
BTW, I'm still in school, taking Calc III, so cosines are the least of my
problems.
----- Original Message -----
From: James J.
James,
Thanks for the reply. The upper arms wouldn't have to be considerably
"longer", per say (or at least there length projected against the horizon
wouldn't have to be longer (go tell your old math teacher, we're using Cosines
in real life!!!)), but their mounting point on the x-member would have to be
lowered. I understand that most kit-manufacturers would like to use stock
mounting points and therefore make a bracket that mounts to where the old
Armstrong shock would attach, but many of those kits also require you to cut
the ends off the x-mount so that the coil-over could fit. That being said, it
shouldn't be too much harder to mount the upper A-arm pivot-points lower on
the x-member. Ideally, I'd like to buy a post 74 x-member and some mustang II
parts and just muck around until I get a decent geometry. There are some
relatively cheap design packages for PC out there, too. One can use them to
find roll-center, etc. With a little inspiration, we could also build in some
anti-dive on the front end.
I've done some welding (even took a course once), but I wonder if I
would have to do any fancy heat-treating (stress relieving if I made any of
the new linkages? Thoughts from anyone??? I promise I won't hold anyone
liable for their welding advice if one of my a-arms flys off at 65 mph ;-)
James J.
james wrote:
James, that is an interesting observation. I'd certainly be interested in
anything that you find out. I haven't put a lot of work into suspension
design because I've never really been at a point to do it all over. It is
something I plan to do but not for a few years. I can, however, offer you
two things. One, I have been told that the negative camber a-arms don't
adversely effect tire wear if you are a spirited driver. Two, a whole lot
of things get built but few ever really get designed. I think that the
intention of many of the kits is to move the shocking and springing into the
modern era with coil overs or with tube shocks. I would also guess that
people have shied away from complete redesign because of development cost
versus saleable cost and quantity.
I suspect that one of the problems in making the upper a-arms longer then
the lowers is the shape of the body. I think that in order to make the
upper a-arms substantially longer, they would have to be mounted on the
other side of the inner fender, perhaps on the frame rail. Just a couple of
things off the top of my head.
James Nazarian
71 B tourer
71 BGT V8
85 Dodge Ram
----- Original Message -----
From: James J. <m1garand@speakeasy.net>
To: <mgb-v8@autox.team.net>
Sent: 26 January, 2003 7:25 PM
Subject: test, e-mail notice, and suspension question
First, to my DC area friends, my e-mail is now m1garand@speakeasy.net
now that DirecTV has shut down their DSL service.
Now to the group: (and answer me directly if you think it is off-topic
enough that the group wouldn't be interested) I've been reading up on
suspension design, primarily to see about options for the back-end, but
I also started looking at front-end design. What I noticed, is that
every author that I read said that un-even length, non-parallel a-arms
are the way to go in nearly evey case (so far, so good, for the MGB),
however they all suggest that the upper a-arm should be higher at the
wheel than at the cross-member. The reason being that when a car rolls
to the right (for example) the wheel on the right side also leans to the
right, reducing the size of the tire contact patch. With the MGB, as
that side of the suspension compresses, the upper a-arm travels up
through it's arc, becoming longer relative to the hub, pushing the top
of the wheel even further out and reducing the tire contact patch even
more. If the upper a-arm (in its static position) was angled upward
from the x-member to the king-pin, then any roll to that side would
compress the suspension and make the upper arm SHORTER relative to the
lower arm, and bring the top of the tire back in to reduce the camber
effect of the roll, and increase the size of the tire contact patch,
improving handling.
First, I wonder what the MG guys were trying to achieve with that
design, and second, I've seen at least four new coil-over designs for
the MGB, where the old a-arms are dismissed with, yet none of them
change the geometry to "fix" the upper a-arm issue. The car can be
designed with some built-in static camber to compensate for this, but
that method increases uneven tire wear on the inside edge. Has anyone
here used a front-end design that corrects the camber issue? Most of
the kit/muscle/street-rod crowd have adopted the Mustang II front-end,
and the parts for this are plentiful and relatively cheap (Including 2"
dropped spindles). (remember that this car was the same platform as the
Pinto/Bobcat.......Kaboom!!!!!)
So if anyone has any experience, I'd love to hear from them. Also, if
anyone is interested in working with me in trying to adapt the mustang
II front end to the MGB, let me know. When things get a little quieter
around my house this spring, I want to start taking dimensions off the
MGB for the front-end and back end and putting them into CAD, and
playing around with them. TurboCAD is cheap and powerfull. If anyone
has done something similar, and would like to share their files, please
let me know, too.
Thanks, and my apollogies to those who don't want to read about
suspension design.
James J.
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