Projects Question about axle wiggle

My own track roadster has cross steer, split bones with heim joints, a monoleaf, no panhard bar, a 38 ford box in it, handles like a slot car and has zero input as far as bump steer goes. I live on a gravel road, tire pressure is a big deal to early ford front ends, I also run 7 degrees caster and its toed in to 1/8.

 

Well as mentioned it doesn’t do any of that.. the steering wheel doesn’t move in my hands,nor does the car steer itself in anyway.

I’ve also mentioned I have had many,many ppl follow and no. Have said they noticed anything. I usually have a trail car,I’m rarely out in it by myself due to the fact I’m usually driving it to a show or cruise night and others go with me.

I mentioned I’m going to try 6* since it seems to be a medium. It does straighten up the bones relative to the frame and looks much better that way. Still need to figure out the tie rod on the end of the drag link. I have pretty big rubber rake also.

My steering arm is also a taper,so it can’t be flipped since I’ve bent it. Will have to get a new one and change the drag link to accept a small tie rod end

 

Well, you have my sympathy, I chased a steering wheel shake for years in my 36, after many wheel balances, tire changes, front end checks, turned out to be a bent driveshaft, which was custom made and had never been off since it was made. I had no reason to check the driveshaft, it was made in a machine shop, supposed to have been balanced and trued, but in the end it was ever so slightly out of round exactly in the center, and produced a weird shake that took years to find. Sounds stupid, but have you checked the driveshaft for round?

 

Are all grease points properly lubed? My model A felt like a new car after I put fresh grease in all the joints.

 

Might just be the pic, but it looks like your shackles are down from 45*. Did you swap leafs to lower it and have you tried pushing teh frame sideways at the axle to see how much lateral movement there is in the shackles?

 

I have also been working on a "shake" issue so I feel your pain, you think you could take a video of the problem and post it?

 

So have we isolated "death wobble"??

A split bone/hairpin car with no lateral axle control which can be compounded be a greater degree of caster in which would explain why some cars hit a "sweet" spot of wobble.. Obviously each car is effected differently by the steering used..

Solutions

Side Steer? I think not because "death wobble" usually effects steering/spindle arms which would still be transmitted to the steering box.. not for the op because it's not a spindle/steering arm effected shimmy I'm assuming because of the steering dampener?? Then the side steer takes car of the rest?

Lateral axle control? Yes imo.. but just theory at this point.. I've never heard of a factory ford with the death??.. I'm assuming because the wishbone was triangulated??..

Reduce caster? and this issue may be compounded by running wishbones.. so a four link may effect? Hit the right bump in a corner with this set up lots of caster and split bones which can effect the caster more and you have?? Yes imo.. up to you to test..

Sounds to me we are back to a panhard, ideal caster.. if you run a panhard I don't think you need a four link per say??

All questions.. I hold no liability for these statements..

 

I'm not sure we're understanding the op's question. I have 2 Model A's a roadster and a truck. They both have custom built frames which are very well made and both cars drive like a dream. 70 miles an hour both hands off the wheel. When I'm on a bumpy road in either of them, the "front ends" will shake, the radiator wobbles and twists and I can see the radiator support bars moving around. There is no front end structure on these cars which will stop this flexing.

 

I have not read the whole thread so someone else may have brought it up but are you certain the spring U-bolts and plate are actually tightening against the spring and is the spring the proper width to fit snugly in the crossmember? Does the head of the spring centerbolt fit snugly in the crossmember hole? Just a shot in the dark....

 

I don’t know anymore.. I’m going to put the bones up to 6* cause that seems to be common and it takes some of the twist off the spring.
I guess get a new steering arm and figure out how the hell to get a tie rod for it that will work with the male instead of female threads, and maybe a panhard.

But I’ve ricked it sideways and the shackles don’t budge at all from side to side. I’m starting to think it’s just the car is so light there’s not much that can be done.

I’m not going to even respond to any comments mentioning the driveshaft again or things I’ve went over already.

 

Another shot in the dark..you say you feel it in the body. Do you have the body mounted solid to the frame or on rubber mounts by chance?

 

I guess I will give up if you won't get the 4 wheel alignment checked. Good luck, Gary

 

It’s the whole front of the car moving. Engine/frame everything.

It’s mounted on very thin rubber.

 

What rear suspension setup are you running , I was chasing a similar shake on a 30 roadster and it ended up being in the rear end and not front . Everything led to the front of the car , radiator shaking motor and headlights shaking . This was a fully boxed frame split bones . The rear was 36 bones 40 Ford spring .


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I’ve already mentioned that the FRONT is the only thing that hasn’t been changed. I think I mentioned but not 100% sure that I have truck arm suspension. Literally has nothing to do with the rear. I’ve had 3 different rear suspension setups in this car. All with same front end results.



I’ll state again also that the drive shaft has been done for the 3rd time and this time it’s 100% brand new from a very reputable shop. If it was the drive shaft it would vibrate at speeds and not go away. This accurs only on bumps like small potholes. Gradually undeveloped spots do not do it. Only bumps.

 

So fellas, I did find that my passenger front tire was a little bit forward of the rest of the car. I’ll be redrilling my wishbone mounts to fix this and give it 6 degrees of caster.

Can I get a definitive answer on, what the toe should be? I’ve heard both 1/8 in and 1/8 out.

And a definite answer on, is it worth the time and money to change the steering arm and drag link to mount it under the arm as opposed to on top

 

Toe-in will track straight and Not be drawn by ridges in pavement.
Toe-out? Used on some FWD cars.

 

That’s what I think also, but I’ve heard some folks doing toe out on these things at times. I just can’t understand why since the wheels would be forced out at the front when driving.

 

I'll disagree with you on the driveshaft making vibration at all speeds, my 36 only had a shake at exactly 60 miles per hour, that's why it took me so many years to find it. Mine was bent hardly enough to even see it, but enough to shake the truck at a certain speed. Not suggesting yours is a problem, just relating how difficult it can be to find these things, good luck.

 

straight axle on the street is 1/8 toe in. circle track, 1/8 or more toe out. toe out works kinda like ackerman. when you enter a turn the inner tire pulls you into the turn harder. toe in does the opposite and wants to push you back straight.

 

I didn’t say at all speeds. And I’ll say it yet again. It’s not my drive shaft. I said ‘at speeds’ I’ll except last n this yet again, it can happen at most highway speeds but mostly in the lower speed limit. And does not happen continually but only at bumps....

But yeah,tracking it down is a nightmare.

This is so frustrating

 

This reminds me of my buddys shoebox. It was making a funny noise we couldnt isolate. I kept saying lets check the rearend up on stands with the engine going. He kept saying the rear end is a new currie, not the problem. It was a wheel bearing that finally let go. Fixed it quick but ruined our roadtrip 30 miles out of town.

I had a bunch of issues, some youve addressed. I had triangulated ladder bars, but with the quick change i was getting rear wiggle and needed a panhard. But it does have a locker and model a's have a short wheelbase. Just food for thought.

Your front shocks, what are they? My car had a front end wiggle as i said. My tires had to much psi and my shocks sucked. I had the socal or P&J chrome aircraft style. they are cheap and one went bad in a year. Bought the nice hot rod bilsteins and that helped a lot.

Does your spring have room before it hits the frame? My spring hit the frame and I had to address it.

 

My opinion...you have a car that steers and handles fine to you. It just wiggles a bit.
Now you have started to change all the related geometry (you know...that stuff that determines how it handles and steers.) in an attempt to fix the wiggle.
That COULD end up biting you on the ass.

Why don't you just leave it all alone and add a simple panhard bar to see if that doesn't fix any side to side rocking in the shackles before doing something that really screws things up? It's easy, it won't change anything you have now except remove any shackle rock, and even if it doesn't fix the issue you have, you can simply leave it in place because it does no harm.

 

As I e mentioned it’s had more than one rear end in it. Has nothing to do with the rear end.

The front shocks I don’t know,just some chrome shorties. And I mentioned before the car does it with or without shocks.

Yes the axle has room,my frame has a notch in the front for the spring to go in. It’s boxed,and a reinforcement plate on the outsides as well. A panhard won’t have much room though, I’d need to figure out some drop brackets. My stabilizer is now pretty close to hitting after I changed the caster so I’ll have to move it also

 

Haha I know right, well my caster was a bit much. It put my spring in a bit of a bind and my bones was pretty angled. I’ve got it drilled to 6* now.the front end looks like it’s at a better angle. Pete and Jakes book says 5. It handled good at 8 so I figured 6 would be good. Most I hear run it at 6 anyway

Yeah I do plan on a panhard,and I think if it doesn’t fix the wiggle,it will still help in corners. I took a trip in the mountain be a while back and I could feel when the front unloaded (a dip while turning)that the car would act a little funny in the front. Nothing huge but I think in big dips while turning the shackles move a bit.

I think I should fix the drag link angle too anyway cause I know it should be straighter.

 

I read in a magazine article years ago that everything needs to be parallel to the ground--bones, tie rod, drag link, and if running one, panhard bar. That being said, my 47 Linc came factory cross steer, and the rod from the pitman arm is level, then slopes gently down to level again at the spindle arm. The panhard bar is made the same way.

 

Ok here ya go, looking at the photo provided, it appears like your steering damper is off. It also needs to be parallel to the axle. Also, if my old eyes aren't giving me headaches, it appears that the right side is off, axle to crossmember. so- - -straighten out the damper, square up the axle to frame and check the tightness of the front perch bolts. Another thing, I also noticed that you have the very old drag link with the spring inside behind a cup that fits over the stud ball. That old system is what gave the old fords and other makes such lousy steering. I'd replace it. Speedway makes tubing at different lengths that would work. Actually, tie rod ends are tighter that the old ball stud and cup tie rod.

I had a really bad case of "Torque Steer" a while back and it all went away after installing a panhard rod. So give it some thought. This is just some old advise, measure- - - - measure- - - and write everything down. A build book can solve questions down the road. Good luck and I'm going to stay with your problem to see what remedies you came up with. Jon

 

Look here >> https://www.jalopyjournal.com/forum/threads/rear-suspension-ideas-please.1072176/

That short panhard bar with triangulated 4 bars is your current set up?
That short pan hard bar will yank the chasssis and body and you to one side every time it goes over a bump.
If so, take the panhard bar off and go around the block over some bumps and try it.
That thing is way too short, and you do not need it with a triangulated 4 link .
The pan hard bar is fighting the 4 link at every bump.

 

The Pan hard bar should be as long as possible.
This one could be about 8" longer and be better.
Again hooligan, that set up from your earlier thread does not need one but If you have to have it, A pan hard bar should look like this one and even longer

 

31vicky... I said it has truck arm rear suspension. That stuff in that picture is long gone.only the axle itself was reused.