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Cyclic intensity front end shimmy

  • Terry Cockerell
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20 Sep 2017 10:13 #33589 by Terry Cockerell
Replied by Terry Cockerell on topic Cyclic intensity front end shimmy
Stan Gilliland wrote a detailed article on how to stop the shimmy in one of his parts catalogues. As I had previously stated rear springs sag with time and people tend to prefer cars that are lowered at the back. This is wrong for a Cord there was about a 2" gap between the tyres and the rear fender arch when they were new. Check the attached picture which was taken in 1936 with the original owner of my Cord. Allowing for the slight slope where the car was parked at the time. The rear end must be sitting up.

T cockerell
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  • scurtis623
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19 Sep 2017 19:44 #33580 by scurtis623
Replied by scurtis623 on topic Cyclic intensity front end shimmy
I thought this was my problem but after reading it, mine is different. Where do I find info for what is transverse leaf spring or axle tramp? HELP

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  • Frank L
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17 May 2017 07:33 #32979 by Frank L
Replied by Frank L on topic Cyclic intensity front end shimmy
Found it .
Tech talk in newsletter no 4 1992

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  • Frank L
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17 May 2017 06:21 #32978 by Frank L
Replied by Frank L on topic Cyclic intensity front end shimmy
There was a article about shimmy in one of the older newsletters.
Couple of things I remember are to check front wings for loose nuts and bolts fit of the doors.

Frank

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  • ilikescars
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17 May 2017 01:17 #32975 by ilikescars
Replied by ilikescars on topic Cyclic intensity front end shimmy
Terry's idea of a lower rear end is pretty important. According to Stan, the rear on a car must be a bit higher than the front to stop shimmy.
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  • Stevedavis
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16 May 2017 23:48 #32973 by Stevedavis
Replied by Stevedavis on topic Cyclic intensity front end shimmy
Thank you to all who responded. Definitely some very good ideas of things I will check out. The fact the shimmy comes and goes at such perfectly consistent intervals really has me perplexed. And based on the replies, I've come around to the realization that it could be something as 'simple' as wheel and drum balance. Thanks again.

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  • johnmereness
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13 May 2017 17:09 #32943 by johnmereness
Replied by johnmereness on topic Cyclic intensity front end shimmy
You may just want to jack the car up and see how true the tires run via hand spinning - I have seen some really oval and square tires out there (and often right out of the wrapper).

We are very fortunate in Cincinnati to have a race guy who does not mind working on 30's cars and has a mind for getting geometry right. Surprisingly, he had a program for a 1935 Auburn via Hunter and we just drove it onto the rack, hooked up all the gauges, and adjusted the car - fabulous on the road, but only as good as the quality of its tires (which leave something to be desired).

JMM

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  • Tom_Parkinson
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13 May 2017 01:28 - 13 May 2017 21:01 #32937 by Tom_Parkinson
Replied by Tom_Parkinson on topic Cyclic intensity front end shimmy
The double ball bearing from the steering W bellcrank shows up on EBay occasionally. Goes for about $80 when it's there. It was also used in GM applications.

It was also available from OLCAR Bearing Co, Southern Pines, NC, a few years ago; might still be. It is new Departure 900916.

--Tom

With brakes, two cylinders are better than one.

Editor-in-Chief Emeritus, The Hardtop News Magazine, the Journal of the Michiana Dunes Region, Lambda Car Club International

See pix of 1509A here: mbcurl.me/YCSE
Last edit: 13 May 2017 21:01 by Tom_Parkinson. Reason: Added info.

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  • mikespeed35
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12 May 2017 15:47 #32929 by mikespeed35
Replied by mikespeed35 on topic Cyclic intensity front end shimmy
I had a shimmy on my Marmon 16 above 60MPH and it turned out to be bad front shocks. Just a thought.
CORDiallyMike

Mike Huffman

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  • Terry Cockerell
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12 May 2017 06:46 #32922 by Terry Cockerell
Replied by Terry Cockerell on topic Cyclic intensity front end shimmy
After checking everything for correct adjustment and removing any wear or slop from things like the centre steering arm pivot the next thing to do is balance the brake drums and wheels separately. I wrote an article on balancing my brake drums in the Cord Forum. Separately is best as you will move wheels around from time to time. A front end alignment using the Factory Specs must be done. Then after all the above has been done you need to look at the rear springs as they usually sag which lowers the rear end too much and this changes the front end geometry.
The rear springs are often overlooked.

T cockerell
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  • 1748 S
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12 May 2017 04:26 #32920 by 1748 S
Replied by 1748 S on topic Cyclic intensity front end shimmy
tHERE ARE MANY REASONS FOR WHAT YOU DESCRIBE. lOOSE STEERING LINKAGES ON BOTH SIDES CAN CAUSE ALL KINDS OF SHIMMY.sO CAN THE CENTER BOLT THAT HOLDS THE STEERING "y" IN FRONT OF THE CAR. a SET OF BAD WHEEL BEARINGS CAN ALSO BE THE CAUSE. sADLY THOSE ARE NO LONGER MADE SO i CAN'T SUGGEST A REPLACEMENT FOR THEM. oTHERS MAY HAVE THE REPLACEMENT BEARING SIZE. i HAVE EVEN HEARD LOOSE TRANS MOUNTS OR ENGINE MOUNTS CAN CAUSE SHIMMY. sO YOU HAVE PLENTY OF PLACES TO LOOK FOR LOOSE PARTS. Sorry I was not yelling.I do not watch the screen when typing but watch the keyboard for the next letter. Then fat fingers hit just the edge of the caps and letter A key.

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  • Stevedavis
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12 May 2017 03:10 #32919 by Stevedavis
Cyclic intensity front end shimmy was created by Stevedavis
I recently bought an 812 Custom Beverly and am looking for ideas why the car has what I can best describe as a cyclic intensity shimmy. Going down the road at 45 mph (3rd or 4th gear doesn't matter) and after about 1/4 mile the front end starts a slight shimmy, but over the next 2/10 mile the shimmy gradually increases to its maximum intensity (fairly severe). Then over another 2/10 mile it gradually and completely goes away. Then after another 1/4 mile the cycle starts again. The first time I encountered the issue was my first time driving the car while not in town, and it happened as I was approaching 55 mph. At that speed the maximum intensity of the shimmy was so bad that the entire car was shaking almost violently. Since the shimmy doesn't occur all of the time I believe I can discount wheel imbalance. Since the problem exists in both 3rd and 4th gears I believe I can discount transmission gearing. Can anyone clue me in as to what is causing this issue and what I might be able to do to remedy it?

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