I don't understand the heavy caster guys (6-9) degrees, why would you have to go that far? Henry didn't have that much caster in stock form.
I know this subject has been discussed a million times, but you can see from the varying opinions that there is more than one way to attack the problem. The fact is, you could build two cars side by side and one may develop the problem and it's twin might not. Every car is unique and might take different adjustments to cure it. Yes, some cars DO need TOE OUT. As strange as that sounds, it is true. I had to do that myself years ago, after I read about it in some hot rod magazine, and it cleared it right up. Caster............"generally" 49-54 Chevy spindle front ends like 4-6 degrees and early Fords like 7-9 degrees. But those are just starting points, your car could like less or more. I shoot for 7 to start and go from there. I had a friend with a motorhome that was all over the road, wouldn't track straight. An old time truck repair guy put wedges in both sides to give it more caster and it was a totally different RV. Wheels and tires are a big factor. Even new rims can be slightly out and might not be noticed on a IFS car, but put it on a straight axle car and the problem is magnified. IFS cars will mask a lot of problems that a straight axle car won't. A steering damper is the best $ 40 you will spend on your car. Call em a "bandaid" if you like, but even on a car with no problems they make it a better car, and if your car has the tendency to have some twitch in the front end at speed it will take it away. Death wobble is one of those things that once it happens you never want it to happen again, especially if you are going 60 mph or faster. It will stick in your mind and you will be watching the front tires from that point on, wondering when it will hit again. Don
You describe my current problem almost exactly! I also have a vega box.. the box is new... When i put the pickup on the rack yesterday to inspect the front end, I had another guy turn the wheels back and forth hard and noticed some movement of the box. I will check this out. Thanks
the dodge truck guys battle death whoble when they lift their trucks, even 3" lift, and try to align it to factory spec. there is no toe adjustment since these are solid front axle 4x4's. the culprit has been caster. bad ball joints, tires etc will set off a death whoble episode but it always comes back to caster angle.
Ch***is Design, Principles and ****ysis (Maurice Olley's papers ***embled by Milliken pere and fils), pp 322: "Of the various forms of oscillation, only two are indefinitely self-sustaining on a smooth road. These are shimmy and caster wobble." ... Shimmy: "This happened only at high speed, generally over 60 mph. It could shake the driver's hands off the steering wheel, or break the steering spindle or Pitman arm. It could also blow a tire, or tear a tire off its rim. If the driver slowed down by applying brakes the immediate effect was to slow the frequency and increase the amplitude of the shimmy. The car became completely out of control." "As early as 1925, by work on smooth ch***is rolls with shimmy excited by wheel unbalance, Rolls-Royce [Olley worked at Rolls before GM grabbed him] established the fundamental characteristics of the shimmy-cycle: 1. The energy comes from tire contact. Wetting the rolls stopped the shimmy cycle instantly. Lifting front of car stopped the shimmy. 2. One wheel alone cannot sustain shimmy. Wetting ONE drum stopped the cycle. (In this it differs completely from caster wobble.) 3. Unless the wheels turn about the kingpins together the shimmy cannot occur. Dropping (removing) the steering tie rod stopped the cycle. (Again this differs from caster wobble.) 4. Each wheel meets the ground toed-in, and is swerved outward by tire contact. 5. Increasing the toe-in setting of the wheels increases shimmy excitation. It has further been shown that increasing the aligning torque by reducing tire inflation also increases the violence of shimmy." ... "...on p***enger cars, a relative freedom from shimmy was frequently found when the wheel offset d [kingpin inclination/scrub radius] was INCREASED. Apparently this was due to increased damping action at the tire, due to changes in wheel speed." There's a bunch more, none of it directly related to troubleshooting a car as-built but interesting background, the lag between wheel motion and the maximum force applied through the tire at the contact patch appears to be a significant factor. He notes some of the things that help with shimmy, like tire pressure changes (based on '20s-'30s tire construction), tend to hurt with caster wobble (low-speed oscillation). It's not clear exactly what they tried regarding scrub radius, camber, etc...he does show a bunch of spring-decoupled steering linkages he says did NOT work, but by this time Olley was already working on IFS designs at GM. There must be a body of literature out there in the truck world on this, since they're still running the things...
All these front end set ups and car's conditions are unique. Plus we are using terms that may have different meanings in different parts of the country or world. I understood "death wobble" to be the front wheels turning slightly back and forth or left to right very quickly causing the steering wheel to oscillate slightly (but usually violently) back and forth. This is commonly seen the the Jeep 4WD set up and seems to be cured by a proper damper. "Axle tramp" is the front wheels moving up and down rapidly like a see-saw. Search "deth wobble"(that is "deth") for comprehensive information. Back to death wobble. I had a bad death wobble on my buggy sprung cross steer model A. I could change it somewhat by messing with the toe-in. After hours of trial and error and measuring with 2X4s and a tape, I got off my wallet and got it checked at a good alignment shop. The toe in was way out of whack. A professional toe in alignment fixed it completely.
I did cure my death wobble as it turns out the rod ends had just enough wear to cause the problem, I replaced the panhard bar rod ends 2, the drag link rod ends 2, and the rear rod ends on the radius rods 2, no other changes, PRESTO problem solved Each rod end had just a tiny bit of loosness but altogether they caused the death wobble. Sorry for late reply
seems if you type Death Wobble instead, you'll get a lot more hits - but then who knows with this bunch.
yeah my 29 only has 700 miles on it when i bought it, went for a cruise and hit a hole and good lord it sounded like the car was coming apart, check spindles, 4 link fronts and tie rods and adjusted the Vega steering box a bit, still had it found the steering u-joints loose on the steering column and on both ends of the DD short shaft to the steering box, the damn set screws weren't tight, tightened it up and seemed to be better although it was fall and car got put away already for winter so will check in spring. modern alignment shops are equipped to handle early straight axle cars?
I think a place like Pep Boys Auto Center would have no idea how to align and early car, but if you found a small, old time shop you might have better success. You probably would have to work hand in hand with the technician, telling him what specs you wanted it to end up at, because his computer or books won't help him on a custom built hot rod. What I would probably do is first have them check the existing camber, toe in ,and caster, and tell you what it is. That would give you a good starting point. If, for example, he said you have 3/8 toe in, you would know that was not in the ballpark and could have them set it to a more reasonable 1/16 to 3/16. I generally use 1/8 inch but read recentlly (I think in a Pete and Jakes catalog) where they like 3/16 for bias plies. That seems excessive to me, but they do build a lot of cars, so who knows ? I think the alignment shop could also tell you the squareness of the front to rear axles in comparison to the frame. Isn't that what 4 wheel alignment does ? I'm getting a funny wear pattern on both front tires on my 27. I have run the same 5.60 x 15 US Royals for years and never had an issue. When I was cleaning my car for Turkey Run I noticed the individual treads are wearing different from each other........one tread is worn more than the one next to it. When I get home I am going to replace the tires and check everything over. P***enger side tire: Drivers side tire: Don
we have a hot rod shop here in town that would most likely know how to go about doing an alighment i would guess, id have to stop over and chat with freddy the owner first but they build some good stuff, i also have one of my best friends that works at a small repair shop and could get what the cars at now, thanks don i have some ideas now.
My truck didn't have "death wobble" but was stiff and had a lot of "grille shake" when I hit bumps. Superbell "4 dropped axle and Speedway reversed eye spring. I've removed the top leaf and the 2nd leaf up from the main and it is much better. I put spacers on top of the spring to make up the lost spring thickness so my ride height didn't change. Blue
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