Front End Shake
 

Need some help. My 38 Ford has a stock front with drop axle. At above 45 closer to 50 mph to almost 60 it develops a front end shake. Replaced Front end parts all new, steering damper and the needle bearing king pins. Any ideas?

Re: Front End Shake
 

needle bearing kingpins move too easy??
has the caster and camber been measured after the modification

Re: Front End Shake
 

It was aligned but not sure if that was checked.

Re: Front End Shake
 

The only real alignment that can be preformed on a solid axle is toe-in without physically bending the axle. Unless it was a shop with that capability it is very unlikely they did anything beyond the toe-in. I would take it to a truck shop with the ability to actually check and correct any issues. But, before going down that route I would check the tires for balance and true round. It is best to check the tires, wheels, drums, etc as an assembly with equipment that can spin the tire/wheel assembly on the car. Next you need to be sure nothing in the whole front assembly has any play. One area that is easy to overlook is the ball at the end of the wishbone. The steering box can also be a source of shake. Lots of possibilities!

Re: Front End Shake
 

I just had my '46 Coupe into a Ford dealer that has truck equipment, but they put it on the car rack to check it first. They did a four wheel laser alignment, and the only adjustment needed was toe in. When I made the appointment, the Service Advisor said they would need the alignment specs. All went well until the Technician looked at the toe-in specs, which were in inches, where the alignment computer uses degrees. They figured out the conversion and only had to make a minor adjustment to the toe in. The car drives better now.

Re: Front End Shake
 

There is a grumpy old guy on here experiencing a front end shimmy too. He, like you, is running needle roller king pins. Others also run the same style kingpins with no worries. Disclaimer; I have no first hand experience with needle roller kingpins, but have read here, and elsewhere on the internet, of individuals running this same combo and experiencing the same dilemma. Including the late, great 'rumbleseat'.

Re: Front End Shake
 

I don't think the king pin needle bearings are strong enough to hold up under the abuse that they have to take. Lots of folks have had premature failure on these.

Now if a king pin steering joint it is good condition with little play experiences a wobble or high rate feedback (other wise know as the death wobble) then there are other factors that need to be checked. Caster is set around 6 degrees positive on these old straight axles. If the wish bone ball is loose, there can be problems with the caster angle. Ford put a lot of caster into the straight axles just for this reason. It makes them harder to steer but less prone to feedback wobble.

The tires can also get their fair share of the blame in many cases. A bad carcass can really give you a problem. If in doubt, take the suspect wheel/tire off the hub or axle and roll it on a flat surface. A ply or tread separation won't allow it to roll in a straight line. They will roll to a wobble and fall over. A good tire will roll well and straight for a long time.

There can be problems with cars that have a split wishbone arrangement too. This can cause roll feedback in a turn if there is not enough allowance for tilt of the axle. The wishbone allows for full roll capability in the range of the suspension travel. The split bone set ups generally only allow movement so far then they hits the stops and start loading up in spring tension. This is usually only a problem in turns but it can be a problem on extremely bumpy roads as well.

Re: Front End Shake
 

All the time or only when you hit a bump or dip in the road does it shake?

Re: Front End Shake
 

Try swapping tires/wheels front to rear.


Paul in CT What size/make/age of tires?? Stock wheels??

Re: Front End Shake
 

It is around that speed all the time. Tires are new Coker

Re: Front End Shake
 

I'm curious why needle bearing kingpins? Seems destine to be an issue or fail. Hardly seems necessary. Didn't know kingpins needed improvement. I don't know.


Lot's of variables.


I've bought all my tires from coker. Never had this issue.... ever

Just sharing info, you decide if they need a shave. Maybe an oddball issue?
https://www.jalopyjournal.com/forum/...#post-12712697

Re: Front End Shake
 

Not a bad idea if front/rears are the same.

Re: Front End Shake
 

I know it dont sound right but I had a car doing the same an oldtimer told me to check the rubber ball on end of wish bone it was bad replaced it no more shimmey might be something for you to check Cliff.

Re: Front End Shake
 

Good one. makes sense.

Re: Front End Shake
 

This Grumppyoldman is about to go nut's trying to figure this out. I have new Coker tire's , needle bearing king pins, had alignment reset now it shimmies worse than before. Trying to find a shop that will check wheel, tire and brake drum assembly. May have to try bubble balancer. Not giving up got to get-er-done. Al

Re: Front End Shake
 

I figured it out. I took my tires to a tire shop to have it Road Force Balanced. The maximum is 20 the New Coker was at 43 the other was 19. He said it will be better but not perfect. Put them on and road tested he was right. I put different tires on and was smooth as can be. Coker has and does warranty these but I'm done can't enjoy driving the car when I'm waiting for another set of potentially bad tires. I'm going to order Diamond Back Tires and drive it.

Re: Front End Shake
 

What is road force balancing, never heard of it. I had Hankook tires on my car when I bouught it they shimmied also, had them balanced and rotated, still no change. Bought new Coker wide whites still shimmied. Had front toe in set, shimmied worse. Just pulled tire, cleaned out grease in wheel bearings, put drum back on and it has a heavy spot on it. Will see if I can find a shop that balances tire wheel and drum on car, haven't seen one of those in years. I know of a shop that did it once upon a time. Going to call them tomorrow. The alignment shop that did the work had the tires towed out 1/4" I changed it to 1/8" toe in, does better but still has shimmy. Al

Re: Front End Shake
 

Someone didn't know what they were doing! :)

Re: Front End Shake
 

Bear alignment shops always used dynamic balance procedures back in the day. They were an old analog system that still used a strobe to get the cock angle of the imbalance. There aren't as many of these shops left now days. Modern dynamic balancers like the Hofmann SD10 Finish Balancers are out there and also Bee Line Smart Balancer equipment. The later ones are digital electronic so this is more likely what good alignment shops use to check the complete dynamic rotor of the wheel and hub assembly on the vehicle. This is the only way to check them on a problematic vehicle. Just checking the tire leaves a lot of unknown possible imbalance if the rotor, drum, or hub is out of balance. An alignment shop that doesn't have dynamic balance equipment may not be able to solve problems like ones that are mentioned here.

Re: Front End Shake
 

This brake drum does not have any balance weights on it. I'll check the other one when get back from the dentist today. Thank you guy's for listening to my problem, maybe we can get it fixed. Al