alright i have greatly appreciated all the tech advice ive recieved here. so heres another search for tech help. my coupe is on a model A frame with a 37' ford ford end. i removed many leaves from the spring to soften it up. new kingpins and bushings were installed, along with new tie rod ends and wheel bearings. it is cross steering, 56' chevy box. front tires are motorcycle radials. ive tried different toe settings but a twisting shake is still spured by bumps. slowing down is all that stops the shake. has anyone had similar problems or have an idea? thanks billy
Shocks on this thing? What's the caster set at? I run 9 degrees on the Beater and it runs straight and wobble free. Made my own friction shocks outta connecting rods. Just gotta keep 'em tight enuff to actually work.
Kind of like a shopping cart front wheel? My model A has done the same thing a couple times. Only going about 15 mph though. I slowed down and it stopped too. New bushings, king pins, etc. I need to check my caster I think. I didn't pay as much attention to getting to 8-9 degrees.
How come whenever guys ask about their shimmy or "death wobble" they don't post pics and never mention their shocks and caster settings?
We get a post like this every other day. "I threw together some junk,and it's trying to kill me." What have you got for caster ? Toe ? Shocks ? Why are you running bike tires, when they are not designed for the weight ?
One more possibility is the steering box itself. I have seen them cause the exact problem you describe on a live axle vehicle. And this was with no other outward signs or symptoms of trouble with the unit.
The umpteenth time those posts that complain about front end shimmy the posters fail to leave out specifics of their chassis. Here T/a coupe is having a problem and has kind of put all the parts in perspective but has failed to indicate if there are any shock absorbers on this creation. The key part that says that there have been a bunch of leaves removed therefore implies not to be running shocks. This design would contribute to a problem of uncontrolled spring oscillation when the wheels hit a bump. With out controlling the spring rebound after hitting a bump( no shocks or weak ones) the spring dribbles like a basket ball until all the energy is dissipated. This continued spring effect creates a shimmy that can only be controlled when the vehicle slows down. Excessive caster change also causes a tracking problem but with out knowing the caster initial setting it is hard to place that as the culprit. So I'm voting with flatheadpete, problem due to lack of or inadequate shocks. Repost what your settings and parts are for a reevaluation of the problem.
can you accelerate out of it? If so it's the dreaded death wobble. Two of the biggest problems are incorrect toe or caster. Caster should be between 5-7deg and toe should be 1/8 to 1/4" I've also had a problem with this caused by a weak or bent tie rod. Do you have any bends kinks? Is it a DOM tube or an original ford item? If it is an aftermarket link what material and diameter? Can we get some pics?
I suspect that these specs aren't posted because they don't know them OR don't understand the importance of these settings. If they knew how these specs affect steering and handling, they'd know what they are and what they should be.
it is an orginal ford frontend, it has new gas shocks, toe is out an 1/8"(that seemed to work the best), caster was set at 5 degrees, but could have changed when much taller rear tires were added. i ditching the cycle rubbers before i try anyting else. by the way thanks for some of the smart ass posts, it is good feed back to recieve on a forum with as good a reputation as the hamb. the helpful posts are much appreciated thanks again.
I think I would try a little more caster and I am not sure that "1/8" toe-out" is what you would want. I believe that would give you some really lively steering. Toe-in is more of a normal setup
The toe-in in my 32' was way off but the car handled find. Didn't know my tie rod was too wide until I went to an alignment shop that specialized in rods. My caster is at 7 degrees and the car handles fine. I've had it upto 120, no problems. The one thing that did cause a vibration in the front end was when a front shock broke. Didn't see it until I was wiping down the front end at a cruise. The rod had snapped by the mount but the shock stayed upright, so you couldn't see it unless you got down and looked. Also, tires out of round could cause the problem. Good Luck
Ok well this is better info. Now lets start to address the problem. Nobody is being a smart ass, it is just that this problem is on every week and it is like nobody pays attention to the posts or uses the search topic section. This is one area where some half ass attempt at a cool suspension can be turned into an engineering deathtrap and most responders are trying to be helpful.. 1. Has your front end been squared to the rear end of the car? 2. Have the tires been balanced? If not get them. 3. Even air pressure both tires. Usually 24-28 lbs 4. Jack up front end and spin the tires by hand, look to determine if they run true without wobble side to side and are spinning in a circle without being lumpy. Check for loose wheel bearings or excessive play in the hub. Check for loose king pins. Check for loose tie rod or tie rod that may be hitting wishbone or radius rods during cornering. 5. Set car back on ground. Measure toe in and reset to 1/8" IN. Excessive toe out creates a condition where the tires attempt to find a neutral position and the more caster the more the wander problem. With a carpenters protractor you can check caster setting using the flat spot on the king pin washer front to rear. Should be 6-8 degrees. 6. Now check the steering box alignment, drag link should be close to parallel with tie rod. Now check box for wear or play by having someone turn the steering wheel until you can feel the pitman arm move. Steering wheel should move no more than 1-11/2" from center before you see movement. More than that box needs to be replaced or adjusted. 7. The next to address is the position of the steering arms, they must point rearward to function correctly. In addition you must check to see if the arms are not shortened, lengthened or bent and an imaginary line drawn thru the king pin center and the tie rod end center should converge on the center of the rear end. This checks the ackerman. After you have done all this take it for a test drive and let us know the results.
check for kingpin wobble. If this is the case you either need to put new busings or check ot make sure the hole has not been egged. If the axle king pin hole needs to be drilled and sleeved
Not to highjack but, Thanks for the advice. This subject does show up from time to time but, doesn't just about every subject on here. How about more talk about boobs With pics 1.I checked my caster and it's at 7 degrees. 2.My Acherman is spot on. 3.I am running old Model A shocks that seem like they could have more resistance. I'll see if I can compare them to ones that somebody knows are good. 4.Wheel/ tires spin true. 5.Steering box is tight. 6. The link from the sreering arm to steering box does go down hill from front to back slightly. Cowl steering. There is about a 1/16" or less of movement(flex) at the box when you turn the steering wheel with the car stationary. It does have a bit of bump steer. If you jump on the front of the frame you can see the steering wheel turn. Tire balance is the next thing on the list for me. Hope this info. helps, Gary I'll try to post a pic or two later.
Hey "corn boy" if you are going to hijack a thread for help, answer the questions in order, no skipping around.. Ok, to address your situation you forgot to answer #1 and #3 and they are important. Your Model A shocks have to be checked, should be stiff on rebound. Next issue is the steering wheel turning when you compress the suspension, this initiates a bump steer especially if the drag link is at an angle opposite the radius rod angle, potential for a problem. Drag link should be close to parallel of center line between axles. Panard rod installed? I also think you got this a little backwards, your request should be for more picture posts of "Boobies", answering dumb questions is talk about boobs.
Dick S, The shocks are definately stiffer on rebound. My drag link line would cross paths with the axle line at some point back behind the car. I know it is an issue. # 1 will be a little tricky to sort out. I'll see what I can figure out. #3 is good. Bias plys by the way. I wasn't really trying to hijack. I was adding some input to the thread that would maybe help anybody, especially t/a coupe who started it. Thanks for the input. Seems like sound advice. It'll keep me busy this weekend. Sorry no boobie pics
Do a search on the subject. There is one thing that keeps coming up over and over that seems to help this situation and no one has mentiond it yet. It's always stated as masking the real problem but millions of VW's had the mask right from the factory. Search is your friend. Frank
Back again. Answer to Corn boy, Squaring your chassis is pretty important. This procedure allows you to determine which way your axles and tires point. It is very easy and can be done with a carpenter square, chalk line and a tape measure. The was a post on the HAMB by a Brian Angus that detailed the procedure. If you search you can read it. From the pictures you posted appeared that there was a bit of feather edging of the left front tire, Out side to inside. With out seeing a better picture this would indicate there is an excessive toe in setting or the steering arm Ackerman is off and the outside tire on the turn is over rotating and scuffing is induced. This condition also causes the steering to wiggle as the tire tries to find a neutral track. You might want to check there. Fab 32, wasn't a truce was called on the discussion of the merits of dumb ass shock dampeners?
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