Can I move Mustang II rack out 3/4"

Since you don't even have a basic understanding of suspension geometry, you really shouldn't try to give any advise on it...

 

If you look at an assembled MustangII cross member kit from the front, you'll see both the upper and lower pivot points for the inner suspension joints. If you draw an imaginary line between those inner points from top to bottom on both sides, they from a "V" shape pointing to the road below. the rack's inner pivot points HAVE to land on those lines so that the tie rods can move in the same arc as the upper and lower control arms.

So, for instance, lets say the upper inner pivots are 29" apart, and that is the top of our "V". The lower inner pivots are, say 24" inches apart, and that is towards the lower part of our "V". Let's say our steering rack's inner pivots are 26" apart. The point on our imaginary "V"s lines that is 26" is the only geometrically correct point to mount that rack. Go lower and the conflicting arc is going to make the tire toe out every time the suspension compresses, going higher on that imaginary "V" and bringing the rack's pivots inside that line will create another conflicting arc that has the opposite effect. Try drawing it on a sheet of paper and you'll see what I'm talking about. Even better, What ElPolacko and I did years ago to test theories before he became a computer god, was to use my giant drawing board with a sheet of cork over it, cut cardboard suspension parts life sized, and thumb tack the joints so it could all be moved. I learned more about suspension movements that way than any other.

 

need louvers, I agree that there is a lot of scary stuff running around because making it fit is more important than making it work/safe.
One thing no one has suggested is to move the rack forward the required amount and after all is said and done fix the ackerman problem by bending the steering arms. We already know it is screwed up anytime you change the wheelbase.
Bending steering arms is done all the time on trucks when WB is changed.
To those of you who think this is not a viable alternative, take up stamp collecting!

 

The only problem with that is if you are moving the rack forward from the cross member, the steering arms would need to get Longer and I'm pretty sure you can't "Bend" them longer and I have yet to see a metal stretcher that works.
On top of that, most of the Mustang II spindles have the steering arm built in and many are cast

 

Moving the rack down isn't the same as lowering the entire car.
Lowering the car by modifying the springs or what have you doesnt change the relationship of the inner pivot points of the rack and the control arms.

Lowering the rack alone does alter that relationship and this makes things move in conflicting arcs etc.

From personal experience, I would move a rack forward 3/4" LONG before I'd even consider dropping it 3/4" by itself.

You would be amazed how fast bumpsteer enters the equation when you raise or drop a rack out of alignment!
Slightly changing the Ackerman isn't nearly as big an issue...although its better to avoid any changes if at all possible.

 

What a bunch of Bull s**t These are 30s and fortys hotrods. Did Henry even know what Ackerman was back than?

 

Ahhhhhh, ya, he did. It's in the angle of every early Ford steering arm ever forged. Any other stupid questions today?

 

The understanding of Ackermann Angle was around Long before Henry, and every auto maker used the principle
It was invented by the German carriage builder Georg Lankensperger in Munich in 1817, then patented by his agent in England, Rudolph Ackermann (1764–1834) in 1818 for horse drawn carriages. Erasmus Darwin may have a prior claim as the inventor dating from 1758.

So really - no Bullshit involved.

 

Absolutely.

The builders of of horse drawn carriages knew what Ackermann was.

In fact, if was patented by Rudolph Ackerman in 1818, for horse drawn carriages...

Edit.

Don types faster...

 

Thank-you for a very rational explanation and informative answer for my question, no insults or anything else just a good answer to a legit question

 

I don't think moving the rack out 3/4 would be that much of an issue in normal turns, normal roads..More than 1/2 lock you may start seeing/feeling some ackerman change and at full lock in a power slide there will be the most change...

 

Seems to me, that if the oil pan can be removed without pulling the motor, then it's a no-brainer to notch it.
If not, then you may need to lift the engine and then drop it out. Seems much easier to me than messing with these angles that should be left alone.
But I like to keep things simple.

 

You are very welcome sir.

 

You missed my point, you don't have to make them longer just bend them to the right angle. And if you can't bend them because they are cast iron, throw them in the trash, cast steel you can bend with heat!

 

you do have the steering rack on the front of the cross member, right? engine is rear sump, right? or is there a rear steer m2 i don't know of? stove bolt with mII

 

I'll try to get some pictures up when I can.

Thanks to eveyone for all the help on this.