Pre-war (up to 1942) 1930 353 limo front end shimmy problem

[clinton1080]

On my 1930 Cad limo, the front end shimmies from 35mph to 40mph. All wheels have been balanced twice, with the same result. The tires are new Coker Firestone Balloon Whitewall Tires. The car rides smooth below 35, and above 40, even on newly paved surface. Play in steering wheel is negligible. I checked for loose suspension parts, and found nothing excessive. All four shocks have been rebuilt by a professional shock rebuilder. The caster has been checked, and I believe it to be correct. The toe is set at 3/8 inch toe in. Driving on the road, the car tracks perfect. All that being said, I welcome any suggestions. Thanks in advance, Dave

[The Tassie Devil(le)]

3/8" toe-in seems to be a bit excessive to me.

I would be starting at 1/8" to 3/16".

Looking back to my "older" books, 1/8" is about the norm.

Bruce.

[TonyZappone #2624]

Had the same problem with my 1931 other make large convertible coupe.  Take the car to a trucking repair shop that does alignments.  They are familiar with these primitive type front ends, and will adjust it to perfection.  Those shimmies are dangerous and a nuisance

[James Landi]

Urge you to inspect for BENT wheels. Years ago, I threw a lot of money at the same kind of problem, and only after I  drove next to the car while it was driving down the road did I see just how bent one of the wheels  was.  The alignment and dynamic balancing "technicians" either didn't see the problem or ignored it.   Hope this helps James

[Warren Rauch #4286]

   Shimmy must have been a problem when new. There were several mentions in the Service Man.

 Service Man 1929 #17 page 3
 Service man 1929 #22 page 4
 Service Man 1930 #5 page 7
 Service Man 1930 #20 page 3
 Service Man 1931 page 40
  A new Steering Modulator for model 353.This is the funny looking front spring shackle of the left front spring. There are 4 coil springs in it. Any broken? The nuts should be drawn up with the end of the bolts, not more or less.
 To check operation. Jack up front end,with wheels straight ahead.  Wiggle wheel in and out (not up and down). The modulator should be moving ,but the steering gear arm should not. Little or no movement -Nuts may be too tight. Or it may need to be freed up and greased. Or need new springs.

 They also warn about tires. If not aired flat on ground ,they may not stay   balanced.

King pin angle was changed to 10 1/4 for 1930.And To 8 1/2for 1931. Be sure you have the right parts.

Caster 1 1/2 degrees
Camber 2 Degrees ( start of production)
              2 1/2 degrees ( Shop manual)
 toe in  1/8 to 1/4

Warren