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I am working on my 1929 133 springs. I am interested to hear members thoughts on the engineering FLAW that Pierce did (sacrilidge I hear you cry!!!) using ball races for the shakel pin bearings. Engineering wise ball bearings are designed for full rotary motion. Using them for shakle pins is in my opinion a bad engineering decision. The bearings Brunell (dimple indentation) due to the balls taking VERY HEAVY POINT LOADS. The movement of the springs even thru full up & down travel wouldn’t be more than 1.5mm. TOTALLY against ball bearing design criteria. As I am newbie to the cause I notice that what seems under the tyranny of “originality” the flaw is perpetrated. For those cars that are only driven a few thousand miles a year is probably doesn’t matter. But the high milage drivers must be affected. It was common in the old days to use ball race thrust bearings on stub axle kingpins, in the interests of reducing friction. The same problem happened ie. Brunelling. The affect on the steering was much more noticeable than the springs. We only notice the adverse affects on the shackle pins when we do a dismantle. Mine are original and absolutely jiggered!
But why perpetrate the original design flaw? Enjoy the spring weather! Jak Guyomar
There is no doubt that ball bearings were not the best bearing for the spring shackles.
There are several aftermarket sources for ROLLER bearing spring shackle conversions.
The conversions use bearing caps from driveshaft U-Joints for bearings,
They work very well.
A judge has to look very close to see the conversion parts in the spring shackles, so I’d
not be concerned about authenticity. Drive-abliity is more important.
Greg L
Well, I’m not sure it’s fair to criticize the engineers with such force.
We are quick to assume faulty engineering, when something doesn’t make obvious sense, or newer things have been developed that seem to be better than the original.
Fafnir designed roller bearings specifically for spring shackles, and they were used on both Pierce and Studebaker cars, and available to convert other makes to the system. Literature of the time states that the bearings were good for at least 20,000 miles, which was a lot of driving in the 30’s. Viewed from out “100,000 miles on a spark plug” mentality, it would seem that’s a flaw in engineering, but I’d disagree. It was an engineering decision based on design and calculation of the time in which it was produced, and used as a selling point for many a car….
Pierce used Ball Bearings not roller bearing. Mr.Guyomar’s critique is correct. In the past I made new pins with bronze bushings in the cups both drilled for grease fittings, worked well.
Pardon me, I mis-typed, and meant ball bearings. I also stand by my statements, what we see as “failure” is on cars that have many more than 20,000 miles on them, and the parts have never been replaced, thus the damage. Period literature states the design is for 20,000 mile life on a car.
I agree that modern pin/bushing arrangements are more durable, but the original design is not at fault if used within stated limits.
Thank you Greg, David &Leo, Yes I WAS being provocative! I find it makes for an more interesting discussion. David is right that back then distances driven were less than modern times. Plus we all try to make the best conclusions with the info we had at the time. Pierce engineers being no different. Hindsight could win us all the lottery! As for authenticity—here in the Land of Oz we tend to follow the English pattern of the hobby with authenticity not being a primary criteria. “Judging” here is more often than taken fairly lightly. Relative minor modifications being NOT frowned upon, especially in the area of safety closely followed by usability. It is not unusual for vintage drivers here to drive their cars 5-8000 miles a year. At the moment we have one of our “mob” doing the South American jaunt. 14600 kms in 24 days in a 1923 Vauxhall along with similar English entrants. So some modification of minor “design flaws” are not frowned upon. Just different cultural views. Good fun with our old cars in our own way is what it is about!! Cheers
Jak, perfect reply by you, and I agree that driving them is the goal…although will admit I have too few miles behind me in an old car during the past few years…but retired now, and doing trim work as a hobby, so hopefully will view over the bonnet much more often in the coming years!!
Thank you David for your kind remarks. Yes! age eventually catches up to all of us! At 74 I have slowed somewhat—But driving our machines is one the great pleasures of life. Also when you have 3 or 4 driving cars of various types & eras that you drive regularly plus maintenance it tends to fill the time space. Keep up the good work!—-Cheers Jak.
I must take issue with the discussion thus far. The criticism of the engineering of the ball bearing shackles is unwarranted. Suggestions of Brinelling failure in this application are incorrect. Brinell failure is associated with impact loading which is impossible at the end of a leaf spring. The failures I have seen have been due to failure of the felt seals after many years exposure to the elements, and failure to re-grease the bearings at the prescribed interval (every 20k miles).
This design subjected balls to an acceptable stress level of about 125 lbs/ball (7000 lb car on eight 7-ball bearings) which were deep groove, so loading was a line, not a point, load.
The only valid criticism is one related to the company decision to not install zerks for periodic lubrication, vice requiring dis-assembly at 20k mile intervals. This was a management decision, vice design engineering decision. The plan was to require dealer service instead or user, or local garage, maintenance. There were, undoubtedly, no Pierce-Arrow owners who would opt for personal periodic maintenance of spring shackles; it would be beneath the dignity of any who could afford the purchase price of a Pierce. I suspect that few cars were lubricated at the prescribed interval.
Thank you Bob for your comment. Adds interest the the discussion!
I totally agree with you about the lubrication problem. Owners of Pierce Arrows when they were new were NOT grease monkeys. It probably was left to the hired help. At the recommended interval of 25,000 miles between servicing I suspect that the majority of cars NEVER received any more shackle servicing once the car left the factory. Most owners memories were not that long & as Bob says the local garage would take one look at it and seeing no Zerks, quickly move on!! BUT I still subscribe to the design criteria of a ball bearing of any application was that it was loaded during at least a large rotation. Shackles are, even if travelling thru full spring movement (Maybe 1% of their lifetime)of say 6″ at a radius of around 16″”—the movement of the balls under load (ONLY the top 3 or 4) would move not much more than 1/32″” back and forwards And then only on the 3 balls taking the load of the car. ie. 7000lbs on 36 balls (12 pin sets) = nearer 600 lbs per ball as an almost point load rocking back & forwards incessantly. Or does the race rotate around under a minute rocking load? I suspect that any rotation would eventually cease after a minute amount of wear srarted. All food for thought. This discussion was NOT meant to insult the GREAT Pierce Arrow!! Even Rolls Royce had design shortcomings in hindsight! Our Automobile Heros all had feet of clay sometimes.
All your answers good fun & much appreciated. Enjoy the Spring weather!!! Jak.”
Sorry Jak, I cannot agree with your math. These bearings are deep groove and are designed for zero end-play. They are to be adjusted via the Shackle bolt length with shims at every lubrication interval. This keeps all seven balls in each cage under load, thus about 125 lbs on a line contact – not a point load! I suspect, as you said that very few cars were properly serviced over their lifetime.
Happy motoring, Bob
I agree that most regular garages would not service ball bearing spring shackles, but I bet the Pierce dealerships did…..from a business standpoint a service manager was probably telling his mechanics “look at the odometer, 20K 40K 60K let’s work on those shackles and generate income!!……and I agree with Bob, who has taken a sound engineering approach to the discussion, as did the original engineers……..
Hello all, good discussion.
Bob Koch, would you describe what you mean by a ‘deep groove’ ball bearing, or post a link to a drawing of this??
I have to say, that regardless of what a deep groove ball bearing is, that it has far less surface contact than a roller bearing of similar size, and FAR less than the U-Joint conversions have..
I’ve taken apart a few of my shackle on my 836, and they are not rusted or corroded, but here are noticeable wear dimples or contact points on the races. and I have a coffee can full of rejected balls and races that came with the car..
Even with excellent OCD type lubrication, there is a lot ‘wanting’ in the use of ball bearings for this purpose.
Spring shackles take a ferocious beating, in the S80 cars, the brass bushings and steel pins get a lot of wear, and they had zerk fittings.
In later years, the use of rubber molded pivots for spring eyes and shackles solved most of the problems..
Greg L
Didn’t the Studebaker President also use the same ball bearing spring
shackles as Pierce? I have several beasts that use this system and
none so far are crying for attention;nary a squeak.If we didn’t have
this conversation,who would know from their car’s operation,that the
bearings in their shackles need replacing? If I replace them,will I
have a smoother ride?
All this talk about spring shackles makes me want to tear into mine to see how they look.
Is there a Service Bulletin that I can reference so I can tear mine down and make any needed correction?
Yes, Studebaker used the same ball bearing system, and it was promoted in their advertising. If you Google the topic you can find an article that discusses the testing that the Studebaker engineers did on the system.
I don’t know what other cars other than Pierce and Studebaker used these shackles, but Fafnir advertised at the time that kits were available to convert any make to the system.
One point made in this discussion was that there is very little travel for the balls themselves, thus a dimple in the race may just be the travel range, not a “failure” of the system. I would bet that, over the 80 years since they’ve been in place, more bearings have “failed” due to corrosion and non-lubrication than due to wear or breakage.
Whether it was a design flaw or not, the bearing cups I have examined have deep dimples on only one side. In the case of the shackles and front mounts I have just disassembled, I KNOW that the 1930 car was taken out of service in 1942. I would argue that Pierce (or Fafnir) should have designed for longer service.
Greg Long said that the replacement roller bearings are almost undetectible. I would say they are totally undetectible. No reason whatever not to use them. I’ve put them in the front mount of the front springs, too.
G’day all
I have used the roller solution just to be cus-sed! ( and practical)
Fafnir must have had damn good salesmen!!
Happy & a safe Easter