Thanks Harv. And thanks for saying they are ugly and out of place. I was trying to be nice and left that out previously. So now that the cats out of the bag, I'll say it. They look like shit.
I am not hung up on little things like that, I build my cars to drive and I want them to behave like any regular daily driver would. I will sacrifice a little form for function any day of the week. But to each his own. Don
I think original OP needs to post pictures. It is an 54 chevy with leaf springs and a straight axle high in the air. I think bump steer (uneven road surface) or change of steering geometry while driving and big tires on a 4x4 are helped with dampeners. Have you ever pushed a shopping buggy. If the wheel is bent in or out ( toe) its hard to push. If it is bent front to back it wobbles (caster)
I just took these pictures of my stabilizer. In the first pic, the link easily hides it. In the second pic, I moved forward to show as much of it as I could. From the front, you can't even see it. I painted mine black (So Cal only offered it in red or chrome). I have never had anyone notice it or question it.
Hey did the original poster ever get his problem cured?? To help explain this Death wobble issue understand this, it is caused by a dynamic generated by the tire as it is slightly misaligned during a bump obstruction. With an I beam axle this is magnified by the fact that the opposing spindle is connected directly via a tie rod. As the unbumped tire track is moved it tries to recenter pulling on the bumped tire steering arm. The bumped tire steering resists because it has already returned to its tracking, this sets up a deflection in the tire rubber contact patch as both excited tires fight to normalize. They can only normalize when they run out of energy or the speed is altered. Think of it basically as a tug o war between the tires. As the reacting tire treads fight each other usually the forces increase if the speed stays the same and wobble become more violent. This is where correct wheel alignment is important as you can have too much caster, too much toe +/-, unbalanced air pressure or just plain out of square axle to start with. It is important that you know the square of your cars axles as this is the start of most problems. Now to the instant fix tie rod shock absorber. Yes it can be installed but essentially is a band aid for some steering or alignment issue that is difficult to easily remedy. The friction with the steering system is usually the controlling resistance to prevent wheel shimmy. As the king pin bushings wear the resistance lessens so any worn parts also contribute to the ease that the shimmy can be initiated. A poorly adjusted or worn steering box can also promote shimmy as the drag link actually acts as a control rod and if it is worn there is a loss of linkage. Some modern vehicles such as VW, and Pickup trucks are now using the shock absorber as a damper on the steering because it takes up design errors under certain operating conditions, even changing the tire design or size can disrupt the steering tracking and produce a shimmy. The new vehicle MFG are using this as a band aid because it is cheaper than redesigning the entire system for one random operational situation. Does the guy need a steering snubber well technically NO, if its done correctly the vehicle should track correctly but if there have been modifications made to steering components or wacky wheel offsets this may be the only way to lessen the potential for a shimmy effect. But back to the beginning, the components must be free of slop and the axle squared correctly in the chassis, tire pressure even, slight caster and slight toe. If one of these is off there is a potential for an issue.
Worn components or "bad" geometry are probably the root of most problems, but ..... Kick one of Two spinning disks mounted on the ends of a common axle and there will be powerful gyroscopic effects that want to yank the whole assembly in a way that can feed on itself. Terms like "gyroscopic coupling" sometimes pop up. That is true even if the assembly is tight and stiff with no steering function at all, like the DeDion rear axle Jim Hall tried on his Chapparals briefly. Under some test conditions the rear suspension would suddenly go into such violent vibration that it would tear itself out of the composite chassis. The solution for that particular problem included putting a one directional pivoting joint in the stiff de dion tube to "de couple" the gyroscopic effects. Among the generic advantages mentioned for passenger car independent front suspension is reduced tendency to shimmy or tramp compared to beam axles. This results since with IFS hitting a one wheel bump does not force the "other" wheel to tip, and thus avoid initiating powerful interconnected (except by the steering)gyroscopic effects. Modern street motorcycles can exceed 150 mph. A Ninja 1000 has less than 25 degrees of "rake" (caster) where a few decades street bikes were built with something between to 30 to 34 degrees. Still, Even at legal speeds wobble could result under the right/wrong circumstances. Skip to 4:40 here - http://www.youtube.com/watch?v=fvsDIq3WwVA As mentioned by others, Land speed bikes (and cars) would use even more caster for straight line "stability" at the expense of turning ability. What changed? Well, for one thing Modern Chassis and forks have become MUCH stiffer. In that sense extra caster was a "bandaid" for those flimsy vintage chassis.
Double leafs add in a bunch of factors...more unsprung weight, some change in WB as springs act, torque effects of braking, and some extra places slop can be introduced by worn parts or soft rubber. Again, get it all tight... Then check out toe, camber (same problems as regular spring with radius rod) and caster (easier to adjust on this setup)...
New Kingpins new steerbox speedwayvega crosssteer with himes 165 70s radials the axle is set at 7 degrees 1/8 toe in. I will try to get some pics posted here soon I am back to the weekly grind but soon.
"Axle set at 7 degrees" needs to be clarified...this caster must be measured at the kingpins, not just by axle inclination. Camber must also be measured, and of course the axle may very well be bent a bit so measurements need to be done properly out where it matters.
1994 Jeep Grand Cherokee, bone stock. Death wobble on I-25 in Denver during construction. Everything looked good, everything was aligned. Pulled off stabilizer. Shaft pulled out of shock body, replaced stabilizer. No more death wobble and that was 11 years ago.
and how many Fords, chevys , dodges left the factory without them and not had problems??? many more than so -cal ever made Stablizers are a crutch . we do not use them on semis and when we do its because of the oversize steer tires like on a cement mixer or heavy hauler causing scrub from excessive tire width and toe in . and they do the death wobble sometimes and its nerve wracking because you have 30-50 tons of weight behind you
Wow..... how many Fords left the factory without them did I add under warranty to correct this problem??? Factory "bandaid". Something else that is often overlooked... the tires. Someone mentioned having a bent wheel that he found and was probably the culprit. Tires can and do cause DW.... when it does it is usually around 45 mph. (can't splain why, it just does)
These tires are useds but still has tits on the sides. I am going to buy set of 5.60 piecrust next pay and try that.
Everything on this front end is brand new except axle and spindles.Installed new bushings & kingpins but everything else is brandnew.Few friends of mine that has had axle cars & currently race axle cars say I built a very nice car correctly and safely done.Part of me says to chase the problem & part says put a stabilizer on it.
I work at a shop that also does truck (Pete, Mack, KW, etc) front end alignments on the same tools as small car front end alignments. We work on them and in between. One of the observations I've made of both subjects and in between is tire and wheel related problems, and it also relates some to my Model A hotrod. I see, every day, out of round tires, damaged wheels, incorrectly mounted tires, incorrectly balanced tire, incorrect front end alignments based on "calibrated" alignment tools, incorrect big truck rear alignments causing front tire destruction. My hotrod has a small dose of death wobble between 35 to 40 these days. It changed from between 30 to 35 mph after I put 1/4" wheel spacers behind my front wheels. I can make it relax some by steering left and right while staying in my lane of traffic if I want to. I blame it on the wheels primarily, and tires secondarily. Possibly wheel back spacing compared to what my combination needs, and tire width combined. Possibly toe setting, can't get time enough to get my car checked by the guys that work with me because of working on getting more work for them. Point? Put another pair of wheels and tires on the car, see if the condition changes. Experiment to see if the condition changes. You may accident into the cause of the problem. Also, have somebody help you observe for slack in steering components. I've worked with the stuff on a 13 mph farm tractor to a heavy haul road truck. There will be a reason why it happens.
i'm not sure everyone here knows what death wobble actually is, or what it feels like. seems like many are talking about wheel hop or random shimmies. death wobble gets that name from how destructive it can be. It's not just some imbalance condition. It is a violent self feeding convulsion, that can rip things up....even at single digit speeds
The Death wobble we are talking about is actually Shackle wobble , All the parts replacements and band-aids will only hide the issues. The biggest cause of shackle wobble is caused by Hot-Rodders re-inventing the wheel with their so called improvements. First problem is smaller diameter tyres which increase the scrub radius because the kingpin inclination is fixed. This causes excessive drag [toe-out] and the band-aid is too increase toe-in. Another issue is too much positive caster [ leaning back at the top ] which also counter-acts the wheels trying to toe-out because the weight of the vehicle wants to toe the wheels in. This all works fine until you get on an uneven surface and the scrub on one side and the caster on the opposite side work together in unison [ and the shackles swivel laterally trying to correct this ] Now another Hot-Rodder re-inventing the wheel problem is splitting the bones [ or A frame ] on early fords. The A-frame and front shackle angles are the only things that laterally locate the front end. When you split the bones the whole front end will try to parallelogram itself during a shackle wobble. If the front spring has been re-set to lower the front the spring will lengthen between the 2 spring eyes and the shackles will be more vertical and have less lateral control. Even if they appear to be on an angle, during a bump they will swivel vertical. Some reputable Hot-Rod front end builders claim they have fitted a stabilizer on all their front ends for the last 30 years, what they dont mention is they have actually engineered out one of the basic lateral control devices in the products they sell [ switching from A frame to 4 bar ] Their front ends need the stabilizer as a band-aid, They arent going to tell you to use an original A frame but bullshit about the merits of their Guru status 4 bars
Death wobble in car = Death rattle in human by time either symptom hits you, grasshopper, it too late...
Kerry makes a BUNCH of valid points. But this heap under discussion has parallel leafs, I believe, a situation in which springs and shackles maintain position but in a way that is not positive...there is no rigid swing arm like a wishbone and all loads will distort the springs in many different ways as they work. I've always suspected that the prevalence of parallel springs and/or primitive IFS with horrible dynamics in the 1920's and '30's were a very important reason that most early rods were Fords! I think best hope here is tight and perfect shackles to minimize the design problems, get the caster right, then measur the pin inclinations and probably fixxem. Scrub is also made worse by many aftermarket wheels with too much outside offset...you can really see the scrub radius on many gasser style setups.
Did stock original fords ever have death wobble? I owned a stock model A and drove it everywhere for a couple of months and never experienced any...and yes I got it up to 55 mph a few times.
Probably not as much, if any, because of the skinny, tall tires they ran. When we hot rodders started modifying the suspension we changed the geometry and balance a bit. Our tires are fatter and shorter, not to mention the caster we dial in and the split bones we like to run. We also put more weight on the front end with bigger engines, and that weight has to have some effect on things. A lot of very informative points brought out in this thread by some very knowledgeable people. Don
Stock old Fords...never ran into anything like that. Older rods often started with an actual Ford, added brakes from later version of the same thing, later Ford wheels, original axle dropped, original spindles...everything related by evolution and heritage. It all just naturally fit together and worked because it stayed within sight of the original concept. Now we are starting with junk frames that were hay wagons and buying, because of what we can find, streetrod parts that have taken funny design turns, modern brkes that push the also excessively offset wheels outboard, radius rod designs intended to make sales and assembly easy, etc. and we often do not realize that basics like scrub, axle control, and camber exist...it's all stuff the catalog says will go together. Often we are in trouble because we are in a design wilderness that requires theoretical knowledge and extreme skepticism to navigate... In the old days, we inherited good sound engineering from a used Henry and stayed out of trouble simply because the usual rod parts were closely related to the original concept. Now we bolt together apples and oranges and we have to learn to protect ourselves!
I no I no no pics yet but forgot to mention I set my axle forward 3 inches of stock center & moved my engine back as far as i could with out cutting firewall.So my axle sits center under the harmonicbalancer. So most of my weight is behind the axle.
lots of help here i thank everbody for options took to a front end aling shop and was told every every thing was good did add new tires thow asked about steering stabilizer and was told older Fords did not come stock with them but they also did not have heavy engine such as sbc over a 100 pound 4 popper with altered axle front wheelbase. So added steerstabilizer that was told was a bandaid well I geuss will see but so far was never able to put on the rug with out front end unloading and allHell breaknnnn threwww the the blacktop. She now drives and raisees kane with out a fuss.Thanks again for ideas.
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