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Drive line vibration and u joint angles 59 Caddy

Started by TomJudd, May 29, 2020, 10:04:21 AM

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TomJudd

Hello all, I am a new member today. Please offer any constructive criticism or helpful hints where due!!I have been reviewing your forums for several years as visitor through Google topic search. I want to share some information on eliminating that unacceptable vibration 55-60 MPH only. I have read the many blogs etc, what worked and what didn't to correct vibration. Over a period of 6 months and multiple drive shaft removals for various steps in correcting vibration I FINALLY NAILED IT. Granted every Caddy is a individual stack up of components, worn items, crashes etc,  I will only relay what steps I took and what corrected My CADDY !! 1) shaft out 3 new joints . Front 2 were acceptable rearmost  disintegrated.Did Not replace carrier or balance. No shim under carrier. Shim was found loose in tunnel and did not install. NO CHNGE IN VIBES. 2) pull shafts,add new carrier brg and professionally balance. Install carrier shim. NO CHANGE IN VIBES. 3) Look seriously at driveline pinion and powertrain geometry(angles)4) Replace trans rear rubber mount. no change. THE AHA MOMENT!!! Trans tail was near 12 degrees down, leaving a unacceptable angle at front joint.  Shimmed between trans mt and crossmember 1/2 inch. Net angle at front joint now less than 1 degree. front shaft 1/2 inch to top of shaft tunnel. 5) pinion angle was angled down slightly so removed 1/4 shims at front of lower rear control arms. DONE. NO MORE BAD VIBES!!!Basically u want trans centerline parallel with pinion angle.  Little or no angle at front joint. Now the rear shaft act like a one piece shaft (equal and less than 3 degrees at middle and rear loint. Sorry wordy, but just the facts jack, rid'n SMOOOOOTH NOW

Roger Zimmermann

Thanks for the explanation! Obviously, the theory of driveshaft's angles is still valid.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Cadman-iac

First off,  welcome to the club. You obviously already know what is available here.
And secondly, congratulations on correcting the vibration in your car. Lots of repeat steps,  but well worth it in the end.
If you can share some pictures of your car, we would love to see it.
Stay safe,

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

TomJudd

Appreciate the welcome. Help with a couple things. How do I add photos? I tried to copy and paste in this mssg box.  When u responded to my entry, does that not show up as a message? Is it proper to leave my phone # for any one to discuss particular issue directly?

TomJudd

pics

5390john

#5
Tom:
Thx for the detailed posting, very timely for me as my car was in the shop in the last few weeks for this issue.
I have a '55 CDV that has had eerily similar problems; vibration at freeway speeds. This car was subject to a complete disassembly/frame off restoration and reassembly, taking me about 7 years.
Efforts to diagnose and eliminate the vibration include balancing wheels/tires several times, truing the wheel/tires, new driveshaft that was perfectly balanced, and the shop told me they adjusted the angles you discussed.
Question - where can I find a specification for the driveline angles? I would like to go over this with the shop.
FYI, most of the vibration has been eliminated, but there is still a little "thrumming" at speed. Much improved, but not "smooooooth" as you describe.
Ideas?
John Adams

BTW, Nice '59!
 
1955 CDV "Marilyn"

"Panic Accordingly"

Daryl Chesterman

John, when they balanced your wheel/tire assemblies, did they use a hub-centric balancer or a lug-centric balancer.  On the older cars that use the lug nuts to center the wheel on the hub, it is important to have the wheel/tire assembly balanced on a lug-centric machine.  There are few tire stores that can do this now as almost all cars on the road (excepting our older classic cars) today use a hub-centric wheel and therefore hub-centric balancing.

Daryl Chesterman

35-709

With all the custom wheels being marketed today and very few (if any) having the same hub size as the car they are going on, tire stores with lug centric balancers shouldn't be hard to find.  My local Tire Kingdom has a lug centric balancer and used it on the new wire wheels I just got for my Speedster.  The wheel maker had large stickers on each wheel saying they required lug centric balancing.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

5390john

The Wheelsmith wire wheels on my car had specific instructions with them to use lug centric type wheel balancing. I am extremely sure that lug centric adapters were used, NOT hub centric.
Also had the tires trued because the Goodyear wide whites I got from Kelsey were slightly out of round. New drive shaft too!
Problem mostly cured, but still room to make it SMOOOOOOOOOTH.
Any info on tranny to diff angles? That's the last thing I can think of to verify.
John Adams
1955 CDV "Marilyn"

"Panic Accordingly"

TomJudd

Steak on grill gotta it short! Car loaded w all wheels on ground, pinion shaft must be parallel w transmission output angle. Want less than 1 degree joint angle at trans.. Inherently rear shaft is now essentially a one piece shaft with equal angles at middle and rear joint. less than 3 degrees each. Feel free to call 585 350 8011 Tom

5390john

Tom:
THAT'S the kind of info I need!
Appreciate that it's OK to call, what time zone are you in? When is it OK/not OK to call?
John Adams
1955 CDV "Marilyn"

"Panic Accordingly"

TomJudd

In Rochester NY, 4.30 PM here. Call now or 9AM -midnight EST

TomJudd

https://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml  Try this site. driveshaft 101 201 and301 !!!Extremely well written, illustrated and ACCURATE!!

foxsnout

just a few thoughts: i have a 1959 Cadillac Fleetwood Sixty Special. Complete engine rebuild....trans rebuild...a lot of effort went into my Cadillac. Everything runs smooth....BUT at 40 to 50 mph there was a vibration. Tires balanced, new driveshaft support+ bearing, correct wheel alignment. Everything double checked. I recognized the vibration also in "park" and "neutral"...so i could exclude this components anyway. It drove me nuts. Worst case scenarios came to mind: an unbalanced crankshaft????  But the solution was so easy: i removed the four nuts from the flyywheel-to-drive-plate screws and turned the flywheel 180 degrees.! No more vibrations! My Cadillac runs smooth as silk...i can´t stop driving it. I love it.
Marco
1959 Cadillac Fleetwood Sixty Special
1973 Cadillac Eldorado convertible
1952 Buick Super
1952 Fabulous Hudson Hornet Race Car #92
1973 Chrysler New Yorker