Other hobby

[88workcar]

A cousin of mine introduced me to Rat Rods. I am building my first and enjoying it quite a bit. It turns out that with the other filming that has been going on in our nice little town, some those guys asked to come to my shop too. That was flattering also. Mine should be complete in a couple more weeks.55663556645566555666

[88workcar]

55667556685566955670a few more in no certain order

[ProHydroRacer]

Very Kool!

[88workcar]

5568755686A few more

[88workcar]

The engine is a 502 GM crate motor. I bought the first one and it had two cracked heads and a washed out block (where the head was cracked) I called the seller and he said come get another one. That one had a bad crank. So between the two I had enough stuff to build a motor and a complete set to build a mock up motor. The one in the frame is all the junk parts. The front axle was not working no matter which way I had itright side up or upside down. It needed to be strait, so I cut it and welded it. My first big obstical was gone and from there it just snowballs.

[88workcar]

556895569055691more pictures

[88workcar]

5569255693last ones for now

[Yellowjacket]

I think that radiator grill is aptly named...

You really need to rethink that front suspension.

I realize what you are trying to do, but what you've got there has adverse roll steer (I would say roll oversteer, but that is usually associated with rear axles and this is a front axle) and it is going to handle really funny... With the layout you have, as the spring deflects the distance between the front mount and the spring attachment to the axle gets shorter on the outside of the turn and longer on the inside. That results in roll steer into the corner. When you move the wheel a little bit the car will want to turn more, and the more it rolls, the more it will try to turn...

There's a reason that classic rods use a dropped front axle with proper location (springs under the axle and shackles at the rear)... You've got a boat load of power there and that front end is going to result in it being darty, since the more the body rolls the more it will try to turn into the turn by itself... It's going to be strange to say the least...

You also should calculate where the roll center is for the front suspension and make sure it is equal or lower to the rear roll center. I don't see the lateral linkage for the rear suspension so I can't comment on where that is. Way back when, American cars had the front roll center lower than the back, but the Europeans stopped doing that by the late 70's and went to a horizontal roll center. The height of the roll center determines how much body roll you have and whether or not the car lifts its wheels or jacks (like an old VW) when you go around a corner.

Cars are fun, but, as I said you have a lot of power available and if you aren't careful, things can get dangerous...

[88workcar]

Thanks yellow, I was warned about this early on. When I cut and flipped the front the spindle angles were held exactly at the stock location. That part didn't change. Only the middle of the axle. I simply removed the drop and made it into a strait axle. Unless I am not understanding something here. It will have shocks and pad and ect.. when it is done. The rear is a home made 4 link. Pinion set at -3 and a cross bar on the lower arms. It will be tested quite a bit before I jump off in it. I have installed brand new disc brakes on all 4 corners. The wonderful part is that if it don't work, changing is easy. I do apreciate the advice.

[88workcar]

The cab is a 46 chevy, the back fenders are actually the front fenders from a 41 Pontiac. The tail lights are 1960 Ford. The front axle is a 50 Ford. Yellow, I keep reading your post. Do I need some type of sway bar or something to keep the axle centaly located to the frame? is that what you mean?

[Yellowjacket]

Well, yes and no....

First lets talk about roll steer. As the body rolls the springs deflect. In your design the spring is fixed at the front and arches upward. When the spring deflects further upward, on the outside of the turn side of the car, since the front of the spring is fixed, the deflection has the effect of shortening the distance from the mounting point at the front to the spring pad. The exact opposite is happening on the other side of the car, the spring is flattening out and is getting longer on the inside, and as a result of body roll, the axle will skew to point the front axle to steer towards the inside of the corner. This will result in the car turning more as the body rolls. This is bad because it is unstable, the more it rolls, the more it tries to steer into the corner. You actually want the opposite thing to happen, as the body rolls the axle should steer less, which provides stability. What you need to do at the very least is fix the rear end of the spring and put the shackles at the front, that would address the roll steer problem. As it is, if you jerk the wheel hard the car is going to turn that much more and that could be dangerous. At the very least it is going to be miserable to drive since the car will be wandering all over the road even if you held the wheel straight. If you hit a mild bump and it deflects one side, that will cause it to steer more and at high speed it will be really dangerous.

Now let's talk about the axle location and the roll center. The axle is located laterally by the springs (as is commonly done with a leaf spring setup). The roll center is the place in space where the sprung mass (the body) rolls around and is based on the geometry of the suspension. For a leaf spring setup like yours, the roll center height is the intersection of a line between the spring eyes, and the contact patch location (center of the wheel). Your roll center is up off the ground a good bit, because your mounting points of the spring are pretty high up in the air. Not sure where your rear roll center is, but you really want to keep the roll axis level or a bit pointed down in the front. If you do a google search on 5 link rear axle roll center you can calculate where it is and make sure your don't have the rear roll center below the front since that makes for a weird feeling car. With independent suspension you typically want the roll center a couple of inches off the ground. You can't get that low with a beam axle but generally lower is better.

If your roll center is too high the car will jack, and that is dangerous. What happens in that case is that as the car rolls the car lifts as well as rolls. Old VW's had a rear suspension that was prone to jacking and we all know they were unstable if they got to the point where they were jacking. Modern tires are so much better, so the forces that can cause jacking are higher and consequently you need to design with lower roll centers than in the past.

You would really like the front spring to be mounted as low on the chassis as is possible to get the roll center as low as you can.

I would rethink the whole thing and use a proper dropped axle and get the springs as low as you can on the chassis.

As it is designed now you most surely will have a problem with roll steer so that needs to be fixed before you drive it.

[88workcar]

I did speak to two fellas today that explained this too. Thanks, I will make some changes.