still got shimmy

flatmotor40

flatmotor40

Well-known member
Have had frt end align 2 times and still have shimmy until you move wheel a little to the left or right seems to go away.Everything in frt in is new includes roller brg for bushing in king pins Wide white radials.Some times it doesn't shake other times it does.About to drive me nuts.Thanks for help Flatmotor40
 
With the tire on the ground have someone move the steering wheel back and forth in the play are until it just bumps where it starts to turn the wheels. Look to see where play is. Wheel bearings, try rod ends, steering arm bushing, steering box mounted to frame, steering box adjustment, steering wheel bolted to shaft and where the perch bolts go through the axle. If the perch bolts are lose there is usually a ring of rust around the top of the axle and you see the axle rock as the wheels start to turrn. I bough a 40 coupe years ago and the steering wheel had over a half turn of play. It turned out to be most of what I mentioned juust a little loose. Tightened them and had perfect tight steering with no play and no new parts added. G.M.
 
Although I have no first hand knowledge, I have read on internet that this is a peculiarity of those needle bearing-ed kingpins!
 
GM gave you some things to look for, but I will add one more--toe-in. Modern alignment shops tend to eliminate toe-in. Ask the person who did the alignment and see what they set the toe-in to--should be set to 1/8 inch.
 
Wishbone ball needs to be shimmed? Do what GM said and watch for movement at the wishbone ball.
 
Thanks Plano, Theres so many places that can be loose I forgot that one. You can measure from inside the tire or rim front and rear of the front wheels from side to side and the rear should be 1/8 to 3/16" further apart. Once set and everything is OK they stay that way for years. I haven't touched my high milage 39 for 30 years and it still runs straight down the road at 65 if I take both hands of the wheel. Modern grease may have something to do with it also. G.M.
 
Thanks I"ll check the box seems to have a little play up and down. I"ll adjust it and see but everything else is brand new.New springs,shocks ,tie rods,king pins.wheel brgs just finished frame off restro on whole car.Had frt wheel balanced 2 times.Keep at it.I don't like these nes computer aligment shop but that is what they do nowThanks
 
In addition to the good advice received, you may want to double check your tire pressure. I have read that sometimes this can contribute to shimmy. Hope you are able to isolate the cause. Steve
 
When I finished my '40 pickup, it would sometimes shimmy and I set the toe in as already mentioned and it is A OK now.
 
I" go back and check toe in Seems to be a little hard when you turn left in a curve like it is pushing the frt tires but to the right not as bad
 
Sometimes you have to balance the whole wheel and drum at same time.
Did you have to machine to fit bearing check up and down camber.
 
I had a similar problem and by rotating the tire on the rim and rebalancing, the shimmy went away. I learned this from a Goodyear tire shop in Hawthorne, Nevada when my motorhome had a shimmy at speed. The shop boss told the guy in the shop to break down both front tires, remount them 180 degrees from where they were and use the tire mounting lube and reassemble and balance. Wow, what a differance. They ran smooth and straight. The shop fellow said that perhaps my tire bead was not all the way out against the rim, causing the problem. To me it didn't matter as what he did cured the problem.
 
Been there, done that.

If you have all new king pins, bushings, tight tie rod ends, tight drag link, no slack in steering box, no movement steering box-to-frame or wishbone ball-to-frame, balanced hubs, balanced wheels/tires, proper torque on spindle bearings, tires round and straight, it is probably something regarding tire construction.

Solution, buy new tires....... or do like they did "in the day". Read "How to Build Real Hot Rods" by Leroy Tex Smith and other old school books. When all else fails set tie rod for 3/8 to 1/2 inch TOE OUT. Sounds of the wall, but It will drive straight with no noticeable increase in tire wear.
 
Did you say your steering box had some play UP & Down? Was the steering box rebuilt? The bushings should have almost no play up and down.
 
Never, Never, set the toe out to 3/8" to 1/2" out!

Since you can remove some of the issue by turning slightly L or R it appears that you have a poorly adjusted or worn steering box. The use of the roller bearing king pins is just an wasted exercise of spending money, the bushing king pins are more practical as there must be some internal resistance in the steering to control speed shimmy.

Lets start here to make things simple.

First you must check everything for any loose connections or play including the wishbone bushing. Since you have just replaced everything with new parts you should look to the play in the used steering box and if there is anymore than about 1" rotation L/R of the steering wheel before you feel resistance, you should follow the recommendations in a service manual to adjust out the steering box play.

The next step is to make sure that you have the tires balanced and adjusted to air pressure to the range of 24-26 lbs evenly.

Step 3 is to check the square of the front end, disconnect the drag link at the spindle side and the tie rod and square the left spindle and tire to the axle to insure it points true straight ahead. Repeat the same steps with the right side spindle and tire. This insures that the tires are pointing straight. Now loosen the tie rod and adjust it to fit the spindle steering arm span with out moving the spindles to make the connection and both tires point straight ahead.

Step 4 is to adjust the toe of the tires, do this by taking a tape measure and with a partner, measure the inside span of the front tires at the mid sidewall point as close to the 9 o'clock and 3 o clock positions as you are able to get. The reading should be around 1/16"-1/8" greater on the rear measurement than the front measurement. Adjust the tie rod if necessary to get this measurement. Now center the steering box and wheel and reposition the drag link and adjust the length if necessary. It is important that you do not move either of the tires when you are doing these operations.

This should get you in the right direction to determine what further issues you might have. Do these steps first and then take you car for a test drive follow up for future diagnosis.
 
Thanks I did rebuild the box and it could be a little worn.It does seem like when to go around curve to the left it is a little hard to turn like tires are gripping then it get a little easier.Had this one ut say he does the aligment old school and it was way off so took it up to this new 4 wheel aligment shop by computer and no better.I have American whites and they are new
 
First off did you do the king pin change over.
Are the king pins tight and turn smootly.
Car on ground take a level up and down and see if wheels are straight.
Next check caster,axle could be bent,spindle bent.
If you take 2 2x4s , off ground say 2" for blug in tire, and 2 tape measurs and get 1/8/1/16 toe in.
You maybe better to put new pins and bushing like stock.
 
flatmotor40 said:
Have had frt end align 2 times and still have shimmy until you move wheel a little to the left or right seems to go away.Everything in frt in is new includes roller brg for bushing in king pins Wide white radials.Some times it doesn't shake other times it does.About to drive me nuts.Thanks for help Flatmotor40
Click to expand...
I cain't figure out what year auto your talking about. Is it a 1940 according to your name? Walt
 
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