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Front End Alignment.


James_Douglas

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All of the alignment shops around here (San Francisco) have moved to the new versions of the computerized alignment systems.

 

For those of us with cars that have the rear fenders hang down over the wheels, this presents a problem. The new systems do not feature a software override to tell the computer to do a two wheel alignment only.

 

Without the "read heads" hung on the rear tires the systems will not work.

 

A friend found one shop that does a lot of big trucks that has figured out a way to get around the problem. He did his Chrysler Town & Country and it cost him about $450.

 

I don't mind spending money, but I have two cars to do. That comes in at $1000!

 

I decided to go buy the equipment. I purchased a set of wheel plates, a set of rim clamps, a Castor, Camber, King Ping angle gauge and an new old school toe trammel with the spring loaded tire marker.

 

This will require that I take a level and find the drop, due to the garage floor slope, on my rack in the garage (Winters not in SF) so that I can make up some blocks to level up the rear of the car before I start.

 

I will swing back in a week or so and let people know how the new tools worked and if the car feels like it is driving correctly. Time and tire inspection will tell me if in addition to the driving feel if the tires like the specifications.

 

Over time, the tools should pay for themselves.  If I get both cars aligned, I break even and in the future it will be free.

 

In the past 10 years I have had alignments where they set the specification and yet the equal distance tire rods (on my 1949) were between 3/8 inch and 1/2 inch difference. I have had the tie rod clamps such that if you hit a bump and were turning at the same time, you would cut a hole in the oil pan (Clamp bolts are supposed to be on the bottom parallel to the ground). I have had tie rod boots go missing.

 

It looks like, in Northern California, that is you want a high quality front end alignment job the only way to get it is to do it yourself. At least I will check the tires, cycle the springs, check the spring ride height and the like.  I noted that even though my friend spent $450 on an alignment job, the shop did not do a toe out on turns test or a King Pin Inclination test to look for bent parts.  I was going though an old book for kids learning the alignment trade and the author cautioned that even though the camber and caster can come in on specification it could be a fluke of "opposing errors canceling each other out". The problem this that the specifications can be correct and the car will still not drive right. At least if I do it myself, I can check everything before I start.

 

Best 4th to all, James.

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I like to have my own stuff for this also....I grabbed a caster camber gauge, nice set of Hunter turn tables, built my own toe-gauge...I also for the newer cars have the hang on heads adapted for use with the caster cable gauge for more modern cars....my 4 post lift is dead level front to rear and left to right...and I have rear drive on levelers to compensate for use of the turn table in the front....but 450.00 for an alignment.....ridiculous no matter where you live...

Edited by Plymouthy Adams
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16 minutes ago, YukonJack said:

There are several videos on YouTube showing how to do an alignment at home.  

 

and one or two may be half way on track......if you 'you tube' browse.....just be sure you view a few applicable videos to weed out the idiots and get a overall good understanding of the involvement...only takes a minute to separate the wheat from the chaff....

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I dropped of the tools at my place out of town yesterday.  The only problem I have is that my rack does have a drop to the rear.

 

Since I have a "by the book building inspector" we had to make a positive slope as per the code on the 44 foot long garage floor.  That means that front to rear I have a fairly good drop for a rack with the posts 18 feet apart. (Although on the planes it said a 1/4 inch a foot...we ran it closer to 1/8 or less and he did not notice or look at it.) 

 

I jacked the front of the '49 up yesterday and put the turning plates under it. I then took a laser level and pointed it to the rear resting on the top of the plates and next to the tire.  I then places a steel rule to the side of the rear tire and measured the drop. 2-1/2 inches.

 

So today back in SF, I will make a set of raiser blocks 2-1/2 inches thick. The drivers side was about 1/16 or a little more lower than the left. I feel that anything under 1/8 inch is ok as the tire deflection, weight loading, and springs will no doubt not be the same side to side even if one is careful.

 

I did find in a MOPAR Service book that once can compensate for castor readings by using some x inches equals some y degrees. Interesting thought.

 

The one thing I did not buy with the rack was the trolley lift. I think I will order that as even though I purchased the rolling lifting plates that go across the center, using bottle jacks on the front end is a PITA as a standard bottle jack with a about 15 inch lift is just not quite enough to get the tires off the deck. I have to do it side by side and that is what is a PITA.

 

On Sunday AM we are heading up to see how the tools work. I will swing back and let folks know.

 

I have a book from a JC or trade school I purchased at a swap meet in the 1970's. It is a suspension and brake book. It is perfect for telling people how to do a front end alignment and is just old enough to deal with king pin cars with eccentric cams that adjust both camber and castor...which is a lot of the MOPARS before they came out with ball joint and torsion bar cars.

 

Best, James.

 

Edited by James_Douglas
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The rolling jack for the lift is a big big cost...I at the time could not justify it and have looked a couple times since but still way costly...often raising the car on the lift is a bit of a challenge for sure but have found a means to do so.  The blocks to level the car when on your lift will pay off in spades for aligning purposes.  

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I am not sure what you'all are talking about. Goodyear in Concord N.C. put my 1948 Chrysler Royal on their rack and aligned my front end in 20 minutes.

It rides like a new Cadillac (I know, I know, what T.H. kind of foreign car is that)? L.O.L.

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On ‎7‎/‎6‎/‎2019 at 1:55 PM, Tom Skinner said:

I am not sure what you'all are talking about. Goodyear in Concord N.C. put my 1948 Chrysler Royal on their rack and aligned my front end in 20 minutes.

It rides like a new Cadillac (I know, I know, what T.H. kind of foreign car is that)? L.O.L.

 

Tom,  it depends on how old their machine is. The computers used up to about 10 to 15 years ago would allow you to tell the system to ignore the computer. Newer ones, you cannot.

 

Also, I have found out that Hunter, and the others, do make some wheel clamps for the heads that can be used with old cars with low fender skirts, but, 99% of the shops do not purchase them as they hardly have the need. The shop that did my friends 1946 Chrysler T&C, at $450, does have the arms as they do a number of trucks and Hot Rods for Roy Brizio Hot Rods.

 

Since I have a couple of cars to do, it is more cost effective in the long run to buy the tools.

 

It all depends on where you live and the shops in the area.

 

James. 

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On Sunday, I did a front end alignment on the 1949 Desoto using the new tools I purchased. All in all it went fine.  But, the end result is not what I wanted.

 

The tendency to feel twitchy and wander is still there. Better, but still there. 

 

All the specifications are within the range. My thinking is that the king pins are to tight. I think it is the thrust washers. The car also does not caster back to straight ahead even though the castor and king pin inclination are all within spec.

 

James.

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You know...I have head the comments about radials needing more positive castor for years when running radials.  However, I cannot find anything in writing on the subject. A lot of stuff on car forums on the internet, but nothing from the tire or car companies. I know that when power steering came along, they went to more positive castor as the power steering removed the need to go to zero or negative to make the steering easy.

 

I would love to read something scientific on the subject if anyone has a reference.

 

If one is to use more positive castor in a car designed with negative castor, I assume one heads toward zero and not the other way. In a positive castor design it is obvious, but there was actually a discussion at lunch the other day as to if you want more "castor effect" on a car designed with negative castor as to what direction you go.

 

In 1949 Chrysler-Desoto went with -1 to -3 negative castor with -2 preferred. If one wants more castor effect on a 1949 does one go to -1 or to -3 ?

 

I found my MOPAR instruction sheet that came with the NOS king pin kit I put in the car. It says to "...use shims to remove all up and down movement..." when installing the thrust bearing and shims.   I found a note in one of my period "Motors" manuals that said to make sure you have 0.08 inch of free play in the thrust bearing or you will have wander and return issues in the steering.

 

I am sure I did what the insert sheet stated and the problem fits both the Motors comment and the "Tech" booklet on the subject. I suspect that my steering not returning on its own and the wander at highway speed is a combination of the king pins binding and the car needing more castor. The king pins will be checked next week. Then the only question is do I go from the -2 preferred castor to -1 or -3 for more castor effect?

 

James 

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I put radials on my p15 in 2004.  205 75r15.  In 2007 in advance of a long road trip ,I pulled the rears and swapped the 205's for a pair of 225 75r15.  I replaced the fronts this year as the were nearly down to the wear bars.  Without going through the paperwork the were installed at 72 or 75k miles. The change over was done with 111000 0n the odo. Never touched the front end except for new shocks, and tightening the adjustment on the steering box.  Now my steering is still pretty loose but the car tracks well and holds an arc on exit ramps and through curves.  Tires were worn evenly on both sides.  Kept the inflation at 34 psi cold.front, 32 rear.  Rears still look brand new and are just above half tread after 30k miles.  Yes I put the 14 year old 205's that were on the rear on the front to replace the worn ones, and will run the 12 year old rears till the fail or wear out. And in the spirit of frugal full disclosure the 205's were Uniroyals from Wally World and the 225's are Cornell's from Pep Boys.  I believe the fronts were 40.00 each, and the rears around 50.00. So in neither case we're these premium tires.  Nothing scientific here just personal experience.

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I have posted this before, the bias ply tire will by rolling effect transfers it contact patch rearward at speed.....the radial will not...thus the need for positive caster.

 

IN PART:   Non-radial tires had a tendency to distort at highway speed so that the contact patch moved back past the centerline of the tire (Picture a cartoon car speeding along, the tires are generally drawn as eggshaped). The contact patch generally moves behind the caster line causing, in effect, a positive caster. This is why, when you put radial tires on this type of car, the car wanders from side to side and no longer tracks straight. To correct this condition, re-adjust the caster to positive and the car should steer like a new car.

 

the complete white paper:  http://www.valleyofhastings.com/WheelAlignment2.pdf

 

I do not think the average tire guy in the business today truly has seen bias ply tires and know the rolling characteristics compared to radial..radials have been with us since the late 40's but truly only came into being in the US in great number on new cars until the 70's  most were all onboard by 1980.  so with that in mind the average years of radials in America is some 39 years.  I was fortunate to have known a real great front end alignment man who in just a couple minutes explain the difference and correct my driving issues in 1975 on my car when I went to radial and poor handling.  His tuning my suspension the very catch phase of X car advertising of radial tuning was simply a change in  caster to that of positive over neutral or negative caster. Tire company employees are not on the average up to speed on alignment issues.

Edited by Plymouthy Adams
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The information on the contact patch moving to the rear with bias and not radial is very interesting.  Thanks for the link. However, if one searches for the text on that link, it shows up a lot of places and it has no reference or anything to show where it came from. I am not saying it is not correct, but I am looking form something a little more comprehensive and well documented.

 

One thing is that my 1947 is using the same tire as the 1949 and it tracks straight as an arrow with the castor at positive one (the spec is -1 to +1). Although the 140 inch wheelbase may have a little to do with that. The 1949 has a range of -1 to -3 and mine is at -2 on the right and -1.5 on the left and wanders like a snake. It will be interesting to see if the king pins are causing the issue as the "Tech" booklet states and the later Motors manual implies with the note to make sure one has .08 inch clearance in the thrust direction on the spindle.  I really suspect my is too tight as I am sure I followed the insert which said t remove all thrust clearance.

 

I have a request in to the man who brought the radial tire to the USA when he worked at Ford in the 1960's. He is still alive, although getting up there. He runs a tire engineering consulting group. I may have to pay for his service.  What I sent him was a request for what his recommendations would be for classic car people using radials on pre-radial suspensions. In some of his writings he talks about several things they did to "tune" suspensions to utilize the positive aspects of radial tires. It was much more complicated than it looks at first blush and they did a number of things to accommodate the radials.

 

I figured that since he IS the "horse's mouth" on this subject, perhaps I can get some definitive guidance form him, even if I have to pay for it. That is if he will give me the time of day on this...

 

James.

 

Edited by James_Douglas
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I don't know whether its me or the tyres but I've been running radial tyres on my 1940 Dodge with the original tho' upgraded front suspension albeit with a rack & pinion steering since 1973..............when I bought the 1941 Plymouth Coupe it came with crossply tyres and wandered all over the road, I had the wheel alignment done before getting it registered by a qualified mechanic and even after it whilst improved its road manners was still a PITA as far as wandering..........when I went to the Coker Radials on 15" tyres the overall steering and handling was much better, no wandering or tramlining or following rutted areas on the road..........yeh, I know that crossplies may "look" more original but for me as a driver who drives my cars I'll stick to radials every time...........my 1.5 Oz cents worth.............Andy Douglas 

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Not to be blunt but that seems like a lot of effort for something that is well known. You need positive caster for stability no matter what kind of car it is. I would add as much positive caster as the front end will allow and retest. It will probably only allow a couple of degrees but anything positive will help the wander. 

I don’t have the OE specs in front of me but I remember 0-1 degrees positive. I would never set up negative caster on a street driven vehicle no matter what the “book” says, it will always cause a wander. I think I got 2-3 degrees positive out of my 49, it’s adjustment is maxed. 

A simple angle finder can be used to add the caster you need. 4-6 degrees would be ideal but expect 1-3 with the old front end. 

Maybe they ask for negative caster on your heavy car to reduce steering effort but trading stability. 

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5 hours ago, Adam H P15 D30 said:

Maybe they ask for negative caster on your heavy car to reduce steering effort but trading stability. 

That's why the push for power steering in the early 50's to counteract the upcoming even heaver cars later that decade.  

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"Not to be blunt but that seems like a lot of effort for something that is well known. You need positive caster for stability no matter what kind of car it is."

 

Then why did the Engineers at Chrysler have the cars in 1949 go with negative one to negative three degrees of castor?

 

My issue is that there is a lot of common mythology running around and too little data on the subject of radial tires on cars that were not designed for them. That is why I am trying to run down facts, data and not repeated "well know" suggestions.

 

James.

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20 minutes ago, James_Douglas said:

"Not to be blunt but that seems like a lot of effort for something that is well known. You need positive caster for stability no matter what kind of car it is."

 

Then why did the Engineers at Chrysler have the cars in 1949 go with negative one to negative three degrees of castor?

 

My issue is that there is a lot of common mythology running around and too little data on the subject of radial tires on cars that were not designed for them. That is why I am trying to run down facts, data and not repeated "well know" suggestions.

 

James.

James,

I can think of a few reasons why the engineers built negative caster into their specs:

    1. The engineers made a mistake - Yes it does happen, a lot!

    2. The engineers were counting on the rolling resistance of bias ply tires to stabilize.

    3. The engineers were trying to minimize steering effort with the heavy car.

    4. People in 1949 weren't rolling down the freeway at 70mph with slicker radial tires.

Positive caster for stability at speed is a FACT not a suggestion.  Radial tire's less rolling resistance may make it more noticeable.  For less than the time you have invested in your research, you could have rolled the upright back (add pos caster) and been done with it.  It does take a little creativity with the front end to adjust the "non-adjustable" caster but it can be done.

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  • 2 weeks later...

Finally had some time to get the car apart today. I got the passenger side down to the spindle and measured it with a dial indicator and the spindle end plat was about .002 to .003. That 1954 Motors Motor Manual book had an entry that said to make sure you have .008 or tightness and wandering car happen. That is what is going on.

 

In addition to that, the upper outer side of the king pin has some fairly good galling. You can see it in the photo. This is with 3K miles on it. I suspect that the line honing of the bushings in the Sunnen honing machine with oil provided too good of a fit. The pin fit like a high tolerance bearing. Spun perfect no movement. I suspect that the clearance was so good that no grease could get in there to create a film and hence the galling.

 

I took out my new period reamer and ran the bushings. I did get some material. The pin now spins just the same but there must be more space given that material that was taken off.  I also took out one shim and now have .0085 end play.

 

The spindle definitely is more free than it was. It was free before, just a little more now.

 

It will be interesting to see if the drivers side has the same issues.  Once it is all done, over the next 3 to 5 days, it will be interesting to see if the steering is any different with all other things not being touched.

 

James.

 

1949_desoto_passenger_king_pin_small.jpg

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