I recently built a wild custom and am now experiencing death wobble on occasion. I have a model A 4” drop axle with traditional steering. I have noticed my axle isn’t straight up and down would this cause the issue ? Do I need a pan hard bar in the front?
how straight up and down the axle is, is related to how much caster you have...you want the top leaned back, perhaps 7 degrees. Steering linkage looseness is one factor that can cause shimmy, but there are many others. Like he said, pictures will tell us a lot, and help us help you figure it out.
I agree but it depends on what it's in. He hasn't told us what kind of vehicle he built. Could be a T-Bucket then it's probably okay.
To much wheel offset as Squirrel pointed out will add to it every time. That also put's a big load on the Tie rod and the faster you try to go the more the load grows. Add in the position your front shocks are mounted and you might as well leave them off. Yep, you have a shaker.
Nice done body,I like it,though I may of done grill shell n windsheild in another way may self [ our art eye maybe close!!] . High five on that custom design work. Your front shocks are too close together at the bottom of axle, there mounts as is,not enough movement ether up n down. A panhard bar* would help a lot on front axle to frame/if you don't have one now?. The front tires are a bit heavy,being as wide as they are. About 1 or 2in. less tread/wide gets better to control. I can't tell with those photos,but there maybe too much front scub?{ if rim n hub,is mounting tire too far outside of kingpin? If all the other things;like balance,round n true, and castor n camber/tow are right,with no sloopy gaps have been address.
I have raised the front up more since the picture was taken thinking it was wheel hop but that wasn’t it.
I bet his axle should have about the same amount of caster as his radiator? If the axle doesn't mimic the angle of that shell, is it not enough.
First 120 miles no problems . Thankfully it’s only been at lower speeds . The car drives great at 60.
Also, inspect for any evidence that the shackles are hitting the frame on compression. They look awfully close. Notch the frame as necessary.
Nope. On a stock Model A crossmember, the pads for the radiator mounts are flat level. The spring cross member is not. The spring crossmember is tilted back to match the arc created by the front wishbone, so torsional twist to the main leaf is kept to a minimum on cycling. It does not, and should not match the caster angle. Those two angles have nothing to do with each other. One is the kingpin angle, when observed from the side, in relation to level ground. The other is relational to the length of the wishbone, when observed from the side, offset to the point of shackle attachment, and taken as an average over expected normal suspension cycling. If it happens to compute to the same angle as caster, it is pure coincidence, and bears not relationship to the radiator angle.
Caster, per Ford, is to be set at 7º, with the vehicle loaded. That radiator shell is over 15º. On an a Model A, it would be vertical.
Might be an illusion, but pictures look like both front tires are leaning out pretty significantly? Too much negative camber? If so that could easily cause the death wobble. Have you measured side to side at 6 o'clock and 12 o'clock to make sure the axle isn't bent and causing the tires to be out at the top? Other things to check are: Toe in, need about 1/8"-1/4" max. Worn parts, like kingpins, tie rod ends, etc. Steering drag link ends. Wishbone ends. And of course the previously mentioned @ 7 degrees kingpin angle.
I think what's being referred to here is the vertical line of the tread grove here to the edge of the photo. If this is a true line from true vertical to the world you have a real problem. It may well just be camara angle. If this is an issue that truly exists only an alignment shop can correct it, but not all shops can. Google what is camber angle and watch a video. Easiest way to explain it.
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