If someone tells you that you can bend that axle to correct camber, they are wrong, its cast iron. Snap! You really need to read up on Ackerman angles for your steering. The genius who built your car evidently didn't, and you will always have tire scrubbing on turns until it is fixed. Not saying that your death wobble is caused by the incorrect steering arm angles, but I bet they don't help. Now, I'll give my guess at what has caused the death wobble. I think it's probably caused by the sheet steel steering arms bolted to your spindles, and the heim joints on the tie rod. I've seen plenty of used heim joints with slop in them. I don't think heim joints belong on hot rod steering systems. The fluctuating in the system that is causing your problems is probably caused by weak parts or loose parts. Throw in some misalignment and you have a perfect storm.
We still haven't determined why the spring perch sheared. Just note, in a spring over axle rod, the axle wants to move left to right when the car is turning. Usually a panhard bar keeps it from moving left to right. I don't see a panhard bar. I suspect the builder felt the friction shocks would serve a similar purpose. If there is any flex and the axle actually does move left to right, the perch would be absorbing this movement and would eventually fracture. Any other theories on why the perch broke?
With all respect to you, I must defend the builder/designer from some things you have stated unfairly. You casually said that the toe out masks other problems so the car could be driven “somewhat” comfortably. You also stated the cowl steering geometry is incorrect creating bump steer…and that the heim joints add to loose steering. None of that is true. Maybe as a rule of thumb, but in my particular situation none of that was ever stated. The car is very comfortable to drive with respect to tracking and steering response. I have never experienced bump steer, and never did I mention loose steering. This car, as I stated, drives great…for what it is. Definitely isn’t Cadillac style, but then again what style does Cadillac have anyway!?! I do have to thank you for potentially shedding light on the cause for the perch bolt shearing. As I read your post, you stated that spring over axle creates a shearing motion to the axle which could lead to my problem. I remembered while reading that, I had to replace a shackle bushing that was severely worn. I would imagine that the slop created by the worn bushing could have put undue stress on the perch bolt resulting in the shear. I will keep and eye on the new bushing for wear. Also, as far as Ackermann goes, my short and incomplete research on the subject revealed that appropriate Ackermann can never be reached when steering arms are projected forward as in suicide set ups like mine. So I don’t think it was overlooked but instead was slightly sacrificed for a little bit of a “cool look” factor…move the steering rod forward, drop the car down low look, while sacrificing a little scrub on tight turns. I also read that severe caster angle(10*), and toe out helps with Ackermann(?)…maybe there is a little method to the builders madness?? Thank you again for helping me figure the potential cause for sheared perch bolt.
As I read through the thread I was betting that if pictures were shared we'd see a lot of scrub radius; sure enough... The added scrub radius increases input forces from the wheels into the steering linkage, probably setting off the cycle that results in the death wobble. There is so much wrong with that entire set up, I'm surprised nobody has mentioned the r-rod word yet. Personally, I'd start all over with that entire front end design, but I doubt that will happen here. No insults intended toward the OP, in the spirit of the holiday I wish you well, stick around this place and do some reading, there's a lot of valuable information to be had.
Much appreciated. The reason I am here is to find out if there is something dangerous about the set up. So far, what I am gathering is that toe out and poor Ackermann angle results in severe tire wear. I understand there are gives and takes with cars like this but I want to be as safe as possible. I don’t mind replacing worn bushings every so often or buying new tires every 10,000 or so, but a catastrophic failure I would like to avoid. Can you share with me what is unsafe about “scrub radius”? Poor Ackermann? Toe out? Thank you
If you are willing to replace parts periodically, try replacing the heims now and see if that does anything. Also change out the front wheels for something that will center the tread over the kingpin pivot point. Imagine a line drawn straight through the kingpin, and where it hits the ground should be the center of the tire tread. Maybe just a touch inside the center. But not clear inside the whole tread. Looks like right now you have two large rubber balls each pulling the steering system to their side as they oscillate. And, I still think the oscillating is allowed by the flimsy steering arms and the heims (even if they don't show any looseness to the naked eye).
Just as I said above, the excessive scrub radius results in increased feedback from the wheels to the steering linkage, it's all about leverage. Any rolling resistance experienced by the wheels is amplified by the increased scrub radius; as @alchemy put it above "Looks like right now you have two large rubber balls each pulling the steering system to their side as they oscillate." This is not an uncommon situation with hot rods, we see it a lot with disc brake'd cars; but I think it tends to be even worse with the average finned Buick drum brake'd cars. It doesn't have to be, larger diameter wheels that will fit over the calipers/drums and center the tire tread over the kingpin inclination angle.
Thank you. Let me reiterate that there is no current problem with the drivability of the car. It drives great. The problem occurred when I changed the toe. I toed in, and created a death wobble. I toed out where it was originally and now the car once again drives great. The reason for my post was because the online consensus is that toe out is wrong. I was wondering why? What catastrophic problem could toe out be masking?
Toe out masks worn parts. It may mask them until they are ready to fail, or it may mask them until they do fail. You stated that your steering box has a slight "flex" at its mounting point. A mounting point steering box mount by itself can cause your death wobble. If the steering box can move while you turn the wheels, the wheels can turn when the steering wheel doesn't move because the box can move. If the box moves, its in the process of breaking a chunk out of the frame where it is attached. If you move metal back and forth enough times, it will break. Your car looks pretty light, if the steering box mounting point is flexing with a light weight car, it could be close to failing that mounting point already, at minimum its in danger of failing the box mounting point at some time. Your toe out masks the steering box flex, you won't be able to tell it is getting worse until it fails, at which point the steering goes away. Pull the steering box off the frame and look for signs of the mounting point flex and reinforce the area. Heim joints were installed into race cars to reduce weight. Their intended life cycle was maybe 1 to 2 racing seasons on a car (or truck) that runs maybe 20 nights a season, for usually a lot less then 20 miles a night. That means they were intended to be replaced about every 400 miles. Everything thing about them wears. How are your heim joints doing in regards to the 400 mile life expectancy? Toe out masks worn parts. Maybe it drives great because the toe out is masking the worn parts? What I find most interesting is that you come here explaining you don't have a lot of knowledge concerning suspension (nothing wrong with wanting to learn, not many here came here knowing everything) and you have heard the people here are very knowledgeable (they are), but when they offer advice, you want to argue with them. Why is that?
*Except that all cowl steering setups where the drag link pivot is not exactly over the leading link pivot have inherent bump steer (and those still do when turning). The farther the drag link pivot is from that point, and the more that the drag link differs from the length of the leading link, the worse the bump steer will be. The only model where cowl steering has no bump steer (except when turning, where they all do), is a parallel 4-link, with a drag link is equal in length to the suspension links, and exactly parallel to them
Awesome!! And that is what I need. I have learned so far that suicide set up’s create lateral movements on axles that put stress on perch bolts…and now what you just explained. Thank you
Joe, here is a thread on the much debated cowl steering issue started by Pete Eastwood. Long but a good read, informational to say the least fwiw. Hot Rods - Cowl Steering . . . just stop ! | The H.A.M.B. (jalopyjournal.com)
Except his car has cowl steering, so its pretty hard to say just how the box is mounted or what kind of bracing is added to the cowl. Still, the issue with flexing remains and yeah, if it's flexing at the mount it's a matter of cycles until something gives. Heim joints have come a long ways, the off-road crowd use them extensively, and the steels used, the design and construction are much improved. You can purchase very high quality joints that will withstand the rigors on the road for a long time. Not that the typical cheap joints from Speedway will, but you can get high quality heim joints from a lot of places. And ball joints fail too, Ever have one come apart on you on the road? It can ruin your whole day.
Toe out, or toe in, prevent death wobble. Neutral is the wobble zone, as it doesn’t load up the slack in one direction!
Nobody has asked one of the most important questions..............what is your tire pressure? too much will make the Deth Wobbel tm even worse. Most folks run wayyy to much pressure in their tires on these early cars. If there is any loosness in the system the high pressure turns the fronts into super balls
To the OP , please , before you accept any information here as fact , do a lot of research from other sources , make sure you form a consensus before making final decisions . In case you haven't figured it out. there's a tremendous amount of dis information everywhere ,there's a lot of " I heard or I read or I saw " being repeated as fact . Another is the willingness to accept less than perfect (?) Nothing is ! . Each of our hotrods is different , no one idea works on all of them , some ideas don't work on any of them . Again , please take the time to do lots of research from lots of sources !
Hey Joe, Read (or re-read) this entire thread. You will see that some of us guys run a little toe-out without any issues. Technical - Need help/suggestions - '34 Ford front end trouble | The H.A.M.B. (jalopyjournal.com) And let me reiterate, adding a panhard bar and a steering damper on the tie-rod or the drag link can solve some seemingly unsolvable issues.
I have a genuine question about this. Toe in would put the tie rod in a state of tension if it is mounted behind the axle.... correct??? So if we move the tie rod out in front do we still want it in tension? If we do, we would need to run toe out to achieve this. Anyone have the correct answer to this? It is something I have not thought about before. To the OP, asking a question and then correcting everyone's answers because they don't suit is a sure-fire way to create silence...............
Yep, I know that's what happens. I was wondering if the tie rod should be in tension when forward mounted. Should a forward mounted tie rod actually be set up to run with toe out to achieve the tension state???
I would say yes, they are not very big and are way stronger in tension. The GM diesel guys found out the weak link while pulling. The torque and toe in would fold the front end up like an accordian.
That makes perfect sense. A lot less chance of deflection and deformation (bowing and bending) if the tie rod is in a state of tension. This would mean that with a tie rod mounted forward of the axle, toe out would actually be preferred. But.... how does this affect the rest of the steering mechanism and setup???? If you were to run toe in with a forward mounted tie rod, could the compression state cause flexing, and therefore be a contributing factor of the wobble? (By the way, I am not trying to justify running the tie rod out in front...)
The way I learned it was: front steer = toe out, rear steer = toe in. I may be the only guy here who doesn't think it's a big deal to run a little toe out though.
It sounds like the OP should be running toe out with his front steer setup. Seems like "problem solved" to me............
Thank you…but there is something you said that I need to correct…HA!…kidding, just kidding!! Seriously though…going back and reading my responses I think there was only one thing I refuted. The only thing I feel I know better than anyone here is the driving characteristics of my car. And when I am asking for help troubleshooting problems, searching for causes and effects, I felt that adding symptoms needed to be addressed. Thank you for chiming in and making the best argument for toe out yet!!
Don't take my word as gospel on the subject. I am learning as I go too. There are some very astute guys on here that will know....... @Kerrynzl
Another important part is where the steering is located in front of the front wheels or behind. Next time your pushing your two wheel recycle bin up the driveway try pushing it then try pulling it. Notice the difference its the same thing with steering linkage.
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