hi all, i have a 1934 ford pickup, stock lowered front spring, radius rod back to the outside of the chasiss,original type oil shock anyway this has happened to me about 3 or 4 times now. while driving along i hit a bump in the road and the axle started to hop violently, shaking the crap out of the truck until i come to a stop each time i was doing about 30-40 mph. ive jacked up the truck, put the chasiss on jack stands and checked out every thing nothing seams lose or out of place. the truck drives fine and there is no sign of out of wheel balance lose springs worn joint etc, what could be causing this as its a bit concerning. could it just be the original style shocks need oiling up?? what could cause this to be hapening
Check your caster? original front crossmembers dont have enough degrees in them and if your radius rods are set to straighten your king pins up this problem will occur! Wayne
Are the radius rods attached to the frame at the same height as the original ball? If they are higher, you have lost some caster, and that may cause "tramp" in the front end. So can a bad tire, or looseness in any steering component. I doesn't take much!
I really doubt the axle is "hopping" which is a term that, in my mind, suggests up and down movement. I think what you are describing is more commonly called "shimmy", which is a rapid side to side wheel movement and could be mistaken for hopping. That is what caster and/or loose components cause. Up and down movement is more a function of tire issues...such as wheel balance or out of round conditions. Ray
I have had the same problem in my 37 for years. Seems to have gotten worse lately. Tried brand new radials and still hopped at at anything over 45-50mph. Just built a new tie rod because I found my old stock chromed one to be bent. Haven't put it on yet, I'm really hoping this helps. Also going to check my wheelbase from side to side and I hope to find a local shop that can balance my tires while bolted to my truck. <img src="https://sphotos-b.xx.fbcdn.net/hphotos-prn1/11824_578025275553183_1612480218_n.jpg"> <img src="https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-ash4/307024_261579403864440_1092041_n.jpg">
My roadster does it, and it is DEFINITELY a hop. It is a hamonic bouncing, left up, right down, etc, in a violent dribbling action. I keep it to a minimum by only running about 15 lbs of air in the front. I think it has to do with soft springs and poor shocks. Rich
When I first fired up my 28 PU I took it for a trial spin on the highway. When I went over some bumps I had the same thing happen. I thought I was gonna go into the ditch. I didn't have any fornt shocks on it at all. After putting shocks on it, I never had it happen again. I'd bet you need different front shocks.
Lets start this way, do a search of threads posted on the HAMB under the title Death Wobble, there are a number of issues you have to address and reading these posts will give you a quick education. Now there are two basic types of front wheel agitation, Wheel Tramp which is an up and down motion and then Wheel Shimmy which is a side to side motion. So you will have to determine which action is occurring. The first thing to look for is that every item of your suspension is tight and there is no steering box play. Second is that if you have split your wishbone that the axle has been installed back in the vehicle and is square to the centerline of the vehicle. If these two criteria have been met its time to play Sherlock Holmes, so the problem could be any or all mentioned. Here is a starter. First is to check the balance of the tires on a spin balancer, this will determine if the tires and or wheels are running true and if the tire is in good condition and balanced. You should also do a static check of your brake drums, with the tire off spin the brake drum and note where it stops a couple times , if it stops in the same spot always there is a potential brake drum balance issue. Even swapping the tires side to side is a good way to determine the tire casing condtion. If the aggitation swaps sides then you know its the tire or wheel. Next is to air both the tires to between 24-26lbs, this prevents the tire from distorting as it hits a bump or pot hole. Too soft or low tire pressure will cause wheel tramp as the tire circumference is distorted when a small bump or pot hole is hit. At this time you should check the toe dimension of the vehicles front tires , that should not be out and toe inward no more than 1/16-1/8". The Caster adjustment will have NO bearing on Wheel tramp. Excessive Caster adjustment will create a Wheel Shimmy issue if there is to much in an I beam axle application and with todays tires over 5* positive should be avoided as it produces hard steer at slow speed issues. After checking the previous items you should look at the shock absorber condition to insure that there is sufficient resitance in both rebound and compression. None or too soft a shock cannot control spring occilation effectively and will lead to a front axle harmonic. Too often vehicles are assembled without sqaureing the spindles to the axles and this leads to harmonic issues when one tire fights the other to maintain a true running alignment. It is important that you make sure each spindle is sqaure to the axle before the tie rod is adjusted. The spindles should be squared with one side of the tie rod disconected and then the tie rod re adjusted and installed to the proper length after the sqaureing procedure has been completed . After squareing the spindles it will be necessary to reset the toe dimension. After doing this the vehicle should be given a short test run to see if the problem has been addressed. Post back what you found out.
I just installed my new tie rod and found that the front axle was a little out of square to the chassis. Adjusted that and Im going to find out in a min if things have improved. I know there are a lot of threads on here dealing with things like the death wobble. I've never heard what Im dealing with called Wheel Tramp... Good to know.
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