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Hello,
We have a 1930 series A 7 passenger sedan. The front end was supposedly rebuilt. We just put new proper tie rod ends and had a four wheel alignment. The tires are ballanced well. The right front wheel has a shimmy feeling. When you get to about 30 miles an hour it litterally through us into the other lane of on coming traffic and we almost put it in the ditch. This has happend now everytime you get close to 30mph. Even at lower speeds it feels a small shimmy.
Could it be a bad front shock???? We are new to Pierce’s so any advice would be greatly appreciated. Thanks!!
Steering box issues? In 1930 Gemmer boxes had lots of problems. Does a 30 have a kick shackle? Most shimmy issues are at higher speeds than 30 mph. How much free play is in the wheel? How about the pitman arm? Ed
Jack up the front end of the car, and slowly spin each front wheel/tire.
Tires can be BALANCED, but be out of round, or have a left-right run-out. Either one can cause a violent shimmy that is downright frightening at times.
A tire that is out of round, can be the wheel, or the tire. Same for left-right run-out. Put a marker or indicator on the floor next to each tire/wheel. A simple pencil taped to a chunk of wood will work. Set the indicator/pointer on the floor next to the tire/wheel. Slowly rotate the wheel, if you have ANY runout, or out of round, you will have a very hard time getting rid of the shimmy.
The 1930 Pierces had at least 4 different types of wheels available. Depending on the TYPE of wheel on your ’30 car, you might be able to use a rear tire/rim that has less run-out or out of round on the front end of the car. The rear axle is not going to care much, if any, if it has an out of round tire/wheel on it.
What brand of tires do you have ?? Some brands are notorious for having an out of round tread. There are tire-trueing machines that ‘shave’ or grind the outer surface of the tread to make it concentric with the axle.
Post a photo of the wheel and tire assembly if you can.
Hope this helps.
Greg Long.
John, I forgot to comment: make sure your king pins do not have a lot of wear, do this by pushing/pulling at the top/bottom of each front wheel. If you feel any play in the wheel, next check the wheel bearings for play..
The easy way to do this is to put your finger on the outer edge of the brake drum, such that your finger is on the drum and the backing plate. Then have someone rock the wheel top/bottom. If you have play in the wheel bearings, you will feel it with your finger tip.
Next, with both front wheels off the ground, grab the driver’s side wheel tire at 9 and 3 o’clock, and rock the wheel back and forth. If you have play in the drag-link, which connects the pitman arm on the steering gear box to the left wheel steering arm you will feel and see it by watching the drag link ends. On most Pierce arrow cars, these ball-joints in the drag link are adjustable to take up wear.
If you have no visible play in the drag link ends, but still feel a lot of play, take a look at the steering gearbox where the pitman shaft comes through the frame rail. If you see the shaft and the arm move when the wheel is rocked left/right, then the steering gearbox bushings are worn. It is important that there is minimal play in a steering box, so that it can dampen any movement transmitted to the box from the wheels.
The other item that could be allowing a shimmy to set up, is excess play or wear in the front spring shackle pivot bearings. Look at the front of the spring, where it is has the front bearing in the very end of the frame rail. have someone turn the steering wheel left and right. Look to see if the spring is moving fore and aft with the steering inputs.
The steering gear box’s pitman arm pushes fore/aft on the drag link. If the front spring pivot bearings are loose or worn, then the entire spring/front axle/wheel assembly will move fore and aft, This play will allow the impact of a road imperfection, or an out of round tire to set up a shimmy. Without the steering system to be near zero-play, the shimmy will amplify and get violent.
Hope this makes sense and helps.
Feel free to look in the roster for my phone number if you wish to talk..
Greg Long
Years ago our Pierce had a real bad shimmy when a bump was hit at around 35-40mph.
Front end was tight with proper alignment.
Had new tires put on all the way around and had the front shocks rebuilt as they would leak out their fluid in a few weeks.
I don’t know which one solved the shimmy but the car has never done it again after those things were done.
At such a slow speed I would suspect a loose front end component. If the car is un drivable at 30 mph I don’t think it could be a tire issue. Ed
Thank you all. We really appreciate all your input. You are kind to help. HappyThanksgiving.
One other thing to check: (This is from my experience with a member’s 1930 Model A, which got into the Death Wobble at about 35-38 mph, requiring a full stop to terminate the shaking).
Jacking up one front wheel at a time, I found looseness in the right front. It seemed like the wheel bearings were loose, i.e., the spindle nut wasn’t tight enough. I could not get it adjusted properly, so pulled the wheel, tire, and drum as a unit.
As everyone knows, the inner wheel bearing seals are not available. Some previous owner had a metal seal for a smaller hub installed in a soft red plastic “carrier” which extends to the Pierce hub. HOWEVER, the lip of the carrier, which fits into the recess in the hub, was too deep–or the recess was not deep enough. The result was that when one pushes the hub home on the spindle, the hub would bounce back (out) slightly.
The cure, of course, is to find a plastic carrier with a shorter lip OR to machine a slightly deeper recess in the hub. I offered to explore those options, but the owner decided to send the car to the facility which had done other work on it.
For what it may be worth….
If a tire’s tread moves left and right when rotating, like a potato chip, or a warped LP record, the car can have a bad shimmy even at 20mph.
If a tire is out of round, it takes higher speeds to have it back feed the vibration back through the steering.
My 836 has very old Lester tires, and they are not rally roadworthy anymore. If I jack up the front axle, and check the tires and wheels, both front tire treads have at least a 3/8″ left and right ‘snake’ in the tread. Surprisingly, they are not out of round more than a 16 th. The car gets a front end shimmy if, over speeds of 25 mph. Especially If I hit a bump with the right front wheel.
Greg Long
All interesting observations. The hardest things to find are often a combination of issues. With no loose front end parts being detected, I would start by rotating tires. It’s the fastest and easiest way to begin elimination of issues. My 36 1602 had a high speed wobble after hitting a bump. Everything was known to be correct after the total restoration. (Remember most people don’t dig deep into the chassis when restoring a car due to money or time issues.) we had brought every part back to new factory condition. We ended up being able to install a steering dampener where you can’t see it. In 25 years of judging no one has ever deducted for it at PAS or CCCA. I didn’t want to use it, but it solved the problem. The joy of old cars is spending all your free time on weekends trying to solve issues that make you want to pull all of your hair out. Some cars can be a big challenge. I am working on a car right now that every nut and bolt is kicking my AXX! Sometimes a new set of eyes will make things go easier. It will be interesting to see what the final problem/s are. In the past when we have a wheel shake at the shop and there is another Pierce there, we just swap all the wheels from a car with no issues. Thus eliminating any tire or rim problems. Makes fast work of the repairs, but most often people don’t have access to another car. Good luck, Ed.
Hi John, what was the toe-in setting used when the front end was alligned after the tie-rod ends were replaced ?
No toe-in, or toe-out can let shimmy start much easier than proper toe-in.
Greg Long
Hi Gregory,
The toe was set at 16. The death defying shimmy was prior to the alignment and after as well. How scary to be thrown all of a sudden into the on coming lane. I think the man driving towards us must have had a heart attack. All the wheels and tires were balanced at time of alignment last Friday. They were just a tad out of balance, but kind of standard for 8 ply Bedford Famous Coach 7.50×18 inch tires.
I wonder to if this might be a brake issue…?????
I really appreciate all of your ideas. Sincerely, John
Hi John, is that 1/16″ toe in? I don’t think that is enough. I need to look up the specification, but I think 1/8″ to 1/4″ is more in line of what I have used in the past.
Have you had a chance to jack up the front of the car and check any of the items that have been suggested?
The Bedford Famous Coach tires are very high quality tires from my experiences. But they and the wheel’s run-out still need to be checked. What type of wheels do you have on your ’30 Sedan ?
If you can get someone to assist you, just to work the steering wheel back and forth, while you look under the car to see where there is any free movement of steering and spring or suspension components. You should find something with excess play.
My ’29 roadster had about 1/4″ fore and aft movement of the driver’s side spring when I first drove it. The car would not shimmy, but would ride up the slight worn traffic depressions on the road, then dart over to the other side of the lane, to climb up the other side of the worn depressions in a road. It was a ‘bit exciting’ to say the least. When I tightened up the Fafnir ball bearing spring pivot in the front of the spring, 90% of that wandering from one side of the road to the other went away.
Hope you sort it out soon. , Oh, no I do not think it is brakes, but, do you have the car ‘dive’ left or right when you step on the brakes? If so, it could be the same play or wear in your suspension.
Greg Long
More information is always helpful, and I agree with Greg it is not the brakes. Having the same issue before the alignment and new tires points to other issues. 1/16 toe in is probably in the low side of the correct range, if memory serves me. I have done hundreds of alignments in my modern repair shop, and if no listed toe was available, I would put it at 1/4 inch. Tire wear is not a concern for 99 percent of old cars so you could even try more and drive it to see if it helps out. I expect you will find king pin or some other issue. You stated the front end was rebuilt, bot who ever did it may have a different defination of what that means compared to the rest of us. Have the shackle pins and bearings been replaced? What is the condition of the kick shackle? 30 Pierce Gemmer steering boxes had pot metal races in them, they are unsafe and should be changed out no mater what the condition of the steering box. It probably would make sense to go through the box if you have the skills. Often this is one of those problems that can be a real test of both skills and patience , don’t give up. It can be a long hard grind getting the death wobble to go away. Keep us posted with what you find, Ed.
Hello,
We took a look at the Piece today. As mentioned above by one of the members there is lots of slop in the steering wheel. The shop we had it at did mention that the steering gear box would have to be rebuilt. They had tightened it as best they could before we had to use it for my sons wedding. At this point there wasn’t much steering wheel slop, but it was almost impossible to turn to the right. It still had the FRONT END DEATH SHIMMY. After the wedding I tried to adjust it and made it easier to turn, but there is still slop in the steering wheel. We are going to have the steering box gone through, but I believe there has to be something wrong still. The front brakes were gone through two months ago by our Pierce Arrow friends. They now are locking up the front wheels and are making it hard to turn the front tires when jacked up.
The steering box is out of adjustment. It’s a complicated box and people not familiar with them should not adjust or service them. With the box binding to only one side it is way out of adjustment. You can gall and damage the worm, a very expensive problem. I recommend only a quailified tech service it. There are virtually no parts available over the counter. Seems with brake and box issues, you are fighting multiple issues as I stated earlier. It’s best to go through EVERYTHING or else you are just running in circles. Ed.
John, I do not know if this will help, but it might. And if nothing else you might understand your steering gearbox better.
The steering gear box has a non-symetrical radius cut into the worm gear, The worm gear is the spiral gear on the steering shaft. The grove in the worm gear pushes and pulls on a round rolling ‘tooth’ on the pitman shaft. Pushing or pulling on the rolling tooth makes the pitman shaft rotate in the gearbox housing. Since the worm gear is pushing and pulling on the rolling tooth, and the pitman has a lot of resistance to movement when it is trying to steer the front wheels, the worm gear has thrust bearings on each end of the gear to provide very low friction and to take up any up and down movement of the worm gear and steering shaft. These thrust bearings have rollers in a potmetal bearing race. When the potmetal breaks, the rollers can bind up and lock the steering box. This is what Ed Minnie was referring to.
What I mean by ‘non-symetrical’ when describing the worm gear is that the grove in the worm gear at the very center of the worm gear travel is closer to the rolling tooth than the worm gear groove just 30* rotation of the worm, either way. At the end of the worm travel, either left or right there is quite a bit of clearance between the worm and the rolling tooth. This reduces friction within the gearbox.
When you described that your gearbox locked up when turned one way but not the other, that means to me that the pitman arm is on the pitman shaft at the wrong spot. The car’s wheels are pointing straight, aiming the car down the road, but the steering gearbox is NOT in the center location with the worm gear at the minimum clearance central location in relation to the rolling tooth and pitman shaft.
This can be proven by jacking up the front axle, with the wheels pointing straight ahead. Put a piece of masking tape at the top of the steering wheel. Turn the steering wheel fully one direction, and count the number of turns and partial turns the steering wheel makes. Then turn the wheel back to the center, and then turn the wheel fully the other direction, again counting the number of turns and partial turns. I believe you will find that the mid point of the steering gearbox is not the same as the straight-ahead location of the steering wheel.
NOTE; the wheels have travel stops to prevent the wheel from being turned too far and running the tire into the frame. The front wheels can hit their travel stops before the steering gearbox reaches it’s full travel. This can confuse the job of finding the central point in the steering worm gear.
The way to correct this is to reposition the pitman arm on the pitman shaft. This often is not an easy thing to accomplish. The shaft has a tapered spline, and can take a very good puller to remove the arm. Do not hammer on the shaft!! The impacts can damage internal parts in the gearbox.
Once the pitman arm is removed, turn the steering wheel fully one way, note the wheel’s position, then turn fully in the opposite direction as far as it will turn, count the number of turns the wheel has made. Return the steering wheel to exactly half way between the the extreme travel the steering box will turn..
If for example, if there are 4 full turns of the steering wheel from full right to full left, then the exact center would be when the steering wheel can turn 2 turns each way.
With the steering wheel in the exact center point, and the cars front wheels pointing straight ahead, put the pitman arm back on the pitman shaft. The straight ahead position of the front wheels will now be with the steering gearbox at the minimum worm gear clearance location.
Adjust the gearbox to bring the rolling tooth to zero clearance, but do not tighten any more, you do not want to have extra force on the tooth or worm gear. You should be able to get a no free-play adjustment and the gearbox should not get tighter as you turn either way off center, it should become easier to turn.
When doing ANY work on a steering system, make sure all the fasteners are tight, and all cotter pins, locking plates, etc are installed.
If the gear box has a ‘notchy’ feel when you turn the steering wheel from lock to lock, then your thrust washers are probably ready to break or are broken, and cause the gearbox to lockup. Don’t drive the car with the gearbox in this condition.
I hope this makes sense and allows you to get your car back on the road, with no play in the steering, which will allow you to control the tendency of your wheels to shimmy..
You still need to check the front wheels and tires for out of round and left-right runout [potato-chip wobble].
And make sure the toe-in is at least 1/8″, 1/4″ is better.
Hope this helps.
Greg Long
Greg’s post is correct. I would only add that the best way to adjust the box is out of the car, on a bench. At the point you are at the box should be taken apart and cleaned. Most often the old grease in the box is so dried out it will interfere with adjusting it correctly. Also, you can inspect all the bearings and worm. To be honest, I think getting the box correctly set up is beyond most people’s ability. There is a learning curve of what is ok and will work and be safe, and what will damage the box. The box design causes the high or tight spot to be in the center with the cars wheel in the straight ahead position, thus if the wheel is tight or binds to the left or right your roller wheel is not centered. Driving the car this way WILL damage the box. When the box is on the bench and cleaned up, it is much easier to understand how it works and adjustments are made. Also when adjusting the box, I like to have the wheel off the shaft. You can feel the binding and high spot much easier if you only turn the shaft directly with your fingers, with no wheel on it. Also, many boxes have been run dry over the years when the lubricant leaked out and people were not aware of it. The Gemmer box can be quite a challenge to service, even if you have done them in the past. Member John Cislak has done more than 25 of them in the past few years, and has made parts for them also. Watching him in the shop repairing one I see him spend hours getting them just right. Hope all this makes sense. Good luck, Ed Minnie.
Ed’s message is ‘right on the mark’ regarding the setup of a steering box. It is much easier to do a thorough inspection and adjustment when the box is on a work bench. However, finding the tight clearance location, or tight center is still required when installing a rebuilt box. Hopefully my ‘novel’ will help explain the process.
But, many car owners do not want to take their car out of service for months to correct what appears to be an adjustment. It is quite a job to remove a steering box and steering column from our cars.
It is for those car owners who wish to try to do their own adjustments that I wrote the above ‘novel’. As Ed mentioned, damage can be done if anything is forced, any binding ignored, or through lack of lubrication. Do NOT use grease to lubricate the steering box. Use a correct gear lubricant. Grease does NOT flow into bearings, or into gears. The lubricant must be some form of liquid in order for it to flow where lubrication is needed inside the gear box.
Regarding my ‘novel’ I posted above. My spelling ‘auto-correct’ changed ‘groove’ into ‘grove’ without my noticing it. There is no ‘grove’ of trees on the worm gear in the steering box. However there IS a ‘groove’ machined into the worm gear.
This bears repeating: whenever you are working on steering systems, braking systems, or fuel systems on any car or truck, SAFETY is the first concern. Please do not drive your vehicle without all fasteners tight, cotter pins and lock plates installed, and fuel leaks repaired and dry. Driving out cars in modern traffic can be enough of a challenge without having problems controlling the car, or having it catch fire !!
Greg Long
The real message is, get it fixed before you drive it again…look at what happened to this Auburn with the same problem…