Im hoping there are some suspension gurus here that can help me out on a front end vibration ive been chasing for a very looooong time.

Ever since we got our 56 sunliner it had a bad vibration.  At 52 mph, the front end starts to shimmy.  In fact, you can see the right front headlight/fender top going up & down.

Well, i had figured doing a frame off resto would have cured it.  With new floors in, al new suspension bushings, tie rods, shocks, springs, spring seats, sway bar bushings, ball joints, tires, rims and brake drums ..... and it is still there!  It isnt nearly as bad, but still somewhat there.

So last weekend i decided to try to chase it down.  I just replaced all 4 rims with new ones (welded vs. rivited), and had all 4 balanced.  I measured the lateral runout at the mounting face of the brake drum and it was 45 thousandths(!).  I re-indexed the brake drum (roatated it about 180 deg relative to the hub), and got it down to about 8 thousandths.  Thats weird too since I had the new drums cut with the spindle, and had kept them indexed as they were cut... but anyways.

Today i pulled it apart and repacked the wheel bearings, and tapped the inner races to ensure they were fully seated.  Put it all back together and got the lateral runout to 6 thousandths.  HOWEVER, the fore/aft runout (not sure of the term) is at 95 thousandths (although im not sure if that is a precise dimension, and i havent figured out how to measure if the lugs are that far out of whack, if that makes sense)

So the vibration is still there, although much less.  I did notice that when i spin the wheel it feels like it drags or tightens up at one point in the rotation, even after I adjusted the brakes out a bit to ensure they werent dragging.

Im relatively certain that at some point in its life the car was hit in the right front corner.  Im wondering if the front hub got knocked out of whack somehow?  Im not sure what else to look at/adjust/measure, etc.  I dont want to just go swapping parts, but what else to do?

One other thing that may offer a clue is that sometimes its worse than others.  As example, in a long high speed left hand sweeper, sometimes the front will start to shake after not doing it for a while.  Also, how tight is too tight on the front wheel retaining castle nut?  Ive read the shop manual, but everyone has a different interpretation of touch stuff (just start to feel drag...).

Anybody have any thoughts?  What did I miss or screw up?  Any thoughts are REALLY appreciated at this point, since im at my wits end!  Thanks!

Here is some more info based on some more poking around today. 

Fore/aft runout on the edge of the front hub is 48 thousandths.  This was measured on the center section of an old but true rim i have.

If I bolt the rim up to the hub without the brake drum, I get 68 thousandths measured at the lip ot the rim. 

Also when i was tightening the castle nut i noticed something unusual.  If i kept a constant pressure on the socket while spinning the wheel, the ratchet would advance further/move easier at the same point every revolution.  Does that make sense?

Ive rebuilt/repacked both front wheel bearings.  there is no movement if i grab eitehr tire from at the top/bottom.  If i grab on the sides, there is a tiny bit of play, although im not sure if that is loose tie rods (having been beaten by the vibration) or play in the steering box, PS control valve, etc?

My current thought now is to find a replacement hub, and at that point probably having to replace the tie rods.  But I also have a bad habit of interpreting information to "tell" me what I want/think the answer is, so im looking for a sanity check as to other stuff im missing?  any thoughts; anyone???????  HELP!

Thanks!

    No, not to me! Try putting the left hub on that side and see if the same thing happens.

yes, had an alignment done.  I replaced the tie rods when we did the body off resto, about 8 years ago.  All new bushings, etc too at the same time.  I also replaced the wheel bearings at that time, and I assume they were the right ones.

The weird thing is that this problem, in varying levels of severity, has been with this car since we bought it.....before the resto and after....

As for the idea of switching sides with it, what would that tell me?  Would i just be looking to see if i have the same issue on tightening the castle nut?

Thanks for all the replies!!!

      If the hub form the left side does not exhibit the tight / loose condition, you at least know the right hub is the problem. If it acts the same, then the issue is probably with the spindle. You could do your runout checks with the left brake hub (on the right side) as well.

I looked at my nos upper shaft, it is not symetrical.  If installed backwards, it moves the upper A arm forward or back from its intended position.  The distance from the bolt hole to the shoulder for the bushing is different by 3/8", so installing it backwards moves the arm 3/4".  Unfortunately nothing on the shaft indicates which way is "front".  If you need to know, maybe I can measure it on one of my Birds, they have the same front suspension as passenger cars. 

WOW... that never occurred to me.  If someone would be kind enough to check some dimensions I could measure/check, I would be REALLY appreciative!  That might be a logical explanaition as to why it is intermittent, wouldnt it?

Also, per franks earlier comments, I had always thought that a bent spindle wouldnt matter... that since it didnt rotate that any bend, etc. would be consistent at any wheel angle, so would not be an issue.... Am i wrong?  Im having a hard time visualizing how a bent spindle would cause these types of issues?

Also, the car now has radials, but had the problem with bias ply as well

Thanks!!!!!!

I guess it would depend on where it's bent, but I really suspect the hub more than the spindle. Not really sure how much run out is acceptable, as a guess I'd say .030 should be OK.

It might be that the bearing bore centerline does not agree with the centerline diameter of the exterior shoulder that locates the wheel and bolt circle of the 5 studs.  Locate a dial indicator in such a way that it can touch each stud as the hub is rotated and see if they all describe the same dia circle.  Even better measure the runout of the shoulder.  My guess is that the hub machining should quite precise, say within .002 or .003 thou especially the shoulder to the bearing bore runout.     

Looked at my '56 Bird, the long end of the shaft is toward the rear of the car, as is yours.  On the Bird, it it was reversed, the A arm wouldn't clear the inner fender, so it has to be correct.

The discussion has mentioned hub runout, but what is the runout at the tire tread.  Maximum allowable is pretty small, maybe 1/8" or less.  Of course, none is best.  If you have .030 runout at the hub, it should be a lot more at the tire tread.  Has the drum been removed from the hub?  If so, the swaged part of the wheel stud may be preventing the drum from seating flat on the hub.  That would give you that tight/loose feel when you turn the wheel because the brake shoes would hit on the lowest point of the drum as it rotated.  Did that make sense?  Sometimes the things I see in my mind don't come out of my fingers to the keyboard in an understandable form.

Ill let you all know what i find out this weekend.  THANKS!!!

Stamped production wheels are not round.  Neither are molded tires.  You established everything is tight and within alignment specs.  I assume your universal joints are good and your rear axles run true. Vibration occurs as a result of imbalance (static or dynamic) and/or out-of-round (radial or lateral) conditions. 

My tire guy pulled the tire off the wheel and measured wheel runout.  Finding it within specs, he remounted the same tire turned 180* and measured runout again.  Runout improved and my vibration problem went away.  Runout stacks up between components.

You can use a 'turned' aluminum wheel on your hub to detect eccentricity if it is suspect.  You can also mark your stamped wheel for 'high' runout, advance it two studs, and measure it again to detect any difference.  That will show an off-center hub.

Assuming your car is mechanically sound and axles run true, the only thing left is drum and wheel balance.  The farther out from the pivot (radius) the more a small imbalance will show (we go by gram/centimeters).  Some tires are manufactured with a heavy spot on the crown.  If it is excessive the tire must be replaced.

If unequal weight is on both sides of the tire/wheel assembly’s circumferential centerline, the tire/wheel assembly has a side-to-side wobble or wheel shimmy.  A good tire company will do everything they can to make sure your wheels don't vibrate.

  - Dave

Anyway, he told me they actually spin each completed painted and baked steel wheel to find the "heavy" side - and all of the tires come marked with a belt "lap" position. I would guess these points are assembled 180° apart ....again I dunno....but apparently there is a balance (and probably a reduced balance weight cost) reason to doing this sort of matching operation.

Would there be an advantage to checking the spin balance of replacement (steel) rims - before you go to the trouble of putting tires on them? Might sort out some problems.

Spin the wheel for balance?  Any cost-saving and weight-reduction methods are a plus.  The real imbalance happens at the crown of a tall tire.  14 grams (1/2-oz) of crown-imbalance at 300mm (11.8") radius on a 175/70R14 tire is VERY different than the same weight on a larger diameter tire crown.  The imbalance may be from a heavy OR light spot.

I replaced the hub this weekend.  Got the lateral runout to .003, which is spectacular; better than the other side actually.  Also the weirdness when tightening the spindle nut is gone.

The fore/aft runout of the wheel studs was over .018, now about .005.  So i think this confirms that the hub was bad, and im assuming it shows the spindle is good.

However, the problem still isnt totally solved;  It is MUCH better though.  At first drive, it was probably 50% better.  I then switched the tires on that side from front to rear.  It is now 90% better than before.  My assumption is that the tire wasout fo round due to the pounding from a bad hub.

However, it still isnt gone.  And it still happens at 52 mph (indicated).  IM really at a loss as to what to look at next?  What else can i check?  Im out of ideas.

If there arent any other ideas, i may have to relent and take it to a pro.  Of course, as you all know, finding a really good suspension guy who works on old cars and doesnt just replace parts is REALLY hard to find!  Im assuming that they could check tire roundness, etc as well

Thanks again for all of the ideas/help!  I continue to be amazed by the experience, helpfulness, and knowledge here!

So moving the tires around changes the vibration?  Maybe you're on to something.  Simplyconnected gave us information on tire dynamics which was very enlightening.  Anyway, do you have a car with wheels that fit your car and do not vibrate?  If you have access to a set, put them on and try it.  Are you using repro wide whites or the newly available wide white radials?  I have read on other sites where there were problems with such tires, some are not made within our shores.  Tread wear is excessive on some of the offshore tires also.

I think that will be the next step, probably even before i keep moving tires around, etc.

As for the idler arm, etc. im still trying to figure that out.  If i put the car in the air, the pass side wheel wiggles the smallest bit if I do the tie rod wear test (hands at 9 & 3 and push/pull to check for wear).... BUT the movement is not in the tie rod ends... the whole linkage moves (again, just the tiniest bit), and i cant really see where the slop is.  The same test on the other side shows no wiggle/slop, so i need to spend some time on that too.  Again, the slop is miniscule, but its something.

One other thing; I can see the vibration at speed in the tip of the fender.  From the drivers seat looking at the tip of the stainless on top of the headlight bucket, I can see it oscillating up & down on the pass side but the drivers side is rock solid.  Thats whats making me think it is not likely to be a tie rod, but more like something out of round, etc.  Do you guys agree, or am i all wet?

Oh, and unfortunately I dont have another set of wheels/tires to try.  And the tires on there are Coker WW radials, about 5 years old.

Thanks again; Ill keep you posted once we get the road force balance done next week.

I didn't mention any names earlier, and I don't endorse or condemn any dealers, but that brand is one that has been mentioned among the T-Bird club members as having balance and concentricity problems, and have problems getting them warrantied.  Sorry, Mr. Coker, I'm sure not all your tires cause problems, I only repeated what I've heard.  I have no personal experience with this company's tires.

Ron, what's your spare tire like?  Since you feel the problem is in the right front, put the spare there and try it.  Of course if you're chasinig more than one bad tire, switching only one tire at a time will only drive you crazy.

As for the spare, it is a coker, and has a few k miles on it.  I rotated it out a while ago when I thought the issue was a bent rim; I used that rim as the spare, and havent given it another thought.  I have no idea if that rim is really bent, the tire is messed up, or if all is fine?

I may hold off on any other changes until i get the results from roadforce balancing.

Thanks!

Bottom line is that they said all FOUR tires failed, AND TWO of my four new rims failed!  What that means is that those items are so far out of whack they cant get them balanced/pulled together!  The tires Im not that surprised (although all 4 is a bit disappointing), but the fact that 2 of my 4 new rims are out really is upsetting.  All stuff bought from Coker, by the way.  To be fair, the tires have a few thousand miles on them, but car has had several alignments; not sure why they should be trashed already......

So I know Coker has a lifetime warranty; Im now trying to figure out if i should get 4 new coker tires under the warranty (they woudl be prorated) or invest in 4 new ones from Diamondback or similar.....  I really dont want to do business with coker after all of this, BUT 4 new tires isnt in the budget for this summer....Id like to think that if i get 4 new cokers and get them road force balanced they would be ok, and stay ok, at least for several years (we put about 3k-4k miles/year on this car)?  Thoughts?

Also, the balancing shop said to just get 4 new tires now, and let them see if they can get them to work with the 2 "bad" rims.  (we didnt get a printout that showed how bad they were....).  Im wondering if i should just get 2 new rims anyways to get it all done at the same time?  Problem is I dont know if coker will warranty the rims, and even if they do, there is time/expense in painting the bloody things.  Does it make sense that they can use the existing rims, or am I/he dreaming? 

Thanks again for everyones help!  I REALLY appreciate it, and look forward to opinions/thoughts!

Yes, I was going to do diamondbacks until i found out about the coker warranty.  Now we will see if they stand by the tires when they get them or if they try to discredit the claim with something like "they werent really bad" or similar.....
Also, the shop said that they didnt recommend replacing the 2 rims now because they couldnt be 100% sure that the rims were bad... the tires were that far out of whack.  Im hoping that the rims are ok.  we will see!

Road force balancing is a method used (on a special piece of equipment made by Hunter) that tries to even out high & low spots, lateral runout, and weight offset between the rim & tire.  Think about it as putting the high spot on the tire opposite the high spot on the rim.  Others here have explained it better; you can google "road force balancing" and go to hunters website for more info...

When I was showing my '57 Bird, I had a set of NOS Atlas tires that were 16 years old when I bought them, still in the wrappers, at '61 price.  They ran OK for a little while, then started to lose air and vibrate a little.  So I got another set of wheels, put modern local tire store radials on them, and used them as my drivers.  When I wanted to show it, I changed wheels with the "correct" tires in place.  You could do something similar if you are so inclined.  I, too, am skeptical that new tires from the same place would be any better than the old ones.

You can go to hunters web site and they have a lookup to find local dealers by zip code.

My first car, a 54 Custom would go into a terrifying wobble at 50mph if a bump was hit just right. Although I'm certain that there were other problems balancing the tires stopped the problem.

Sometimes the upper A frame arms bend toward each other, front to back and are no onger a tight fit on the bushings. With all the work that was done to the car it sounds doubtful that this was overlooked.

Talked to coker; they said to send in old tires and they will check to see if they will warranty them.  They said that they probably would after i described all we had been through.  I said i cant be without tires while they get them and try to figure out, and after discussing with them, I ordered 4 new "radial classics" from them.  Interesting side note, the cust serv rep indicated that these tires are much lighter than the Coker Classics that i had.  Reading between the lines of some of his comments, it would appear that they had many, many issues with people getting the coker branded tires to balance out, so IM optimistic that these will work out better.

So had the 4 tires road force balanced, and it turns out all 4 rims were fine.  So far, all seems to be fine.  If i look closely, i feel like i can still see a slight fender oscillation on the pass side, but i cant tell if that is what i had before or just cowl shake due to road variations, etc.  It doesnt seem to be rhythmic, which it was before, so fingers crossed.  Car finally feels smooth at highway speeds (for the first time ever).  Im just keeping my fingers crossed that this is really fixed, and not just masked temporarily by the new tires,e tc.... we will see.

So bottom line, I replaced:

Pass front hub

Both front wheel bearings (inner & outer, with races)

4 rims

4 new tires.

Hoping the root cause of all of this was the bent/tweaked front hub.  Bummer is I replaced 4 rims that were probably fine; probably better because they were the FoMoCo rivited center sections, and the replacements are welded.  Supposedly better for radials,e tc. 

I do want to say a HUGE THANK YOU to everyone who weighed in and offered suggestions & help!  You all have no idea how much I appreciated all of the help!  THANK YOU!!!!!!!

PS - look for the OE rims on ebay or let me know if you are interested.

I can tell you absolutely NOT true.  In fact, we ahve taken our daily drivers back to the place that did the tires on the ford and noticed an improvement even on what were well balanced tires.  I saw the machine and how they used it; regular balancing equip cant compare.

Having said all that, I think it does depend on what price you can find it at locally vs. the problem you are chasing.  Every other local shop around here charges $50+ PER WHEEL to do RF balancing.  At that price, I would be reluctant to jsut do it every time vs. conventional balancing.  If however, you had a vibration or nibble you were trying to fix, it would be worth the $.  But honestly, at $15/wheel that i found from this one shop, there is no reason NOT to do it.  Im only worried they will figure out how much cheaper they are and raise there rates!!

Pete