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Thanks for the responses – interesting. Some of the background of my question. Springs are very highly stressed when just at rest, and can be very highly stressed when overloaded, hitting bumps, and also under heavy braking. They are theoretically very sensitive to surface corrosion that can cause pre-mature breakage from fatigue, however the original designers would have set a fairly conservative stress level to avoid failures. They wouldn’t have anticipated us still driving these things 70 years later after they sat around corroding. The main leaf for our solid front axle cars serves both to be a spring and to keep the axle in position. The secondary leaves pretty much just contribute to the spring action , but keep the overall stress level down on the whole assembly. In the extreme alarmist scenario, bouncing over Tioga pass with no guard rails, a main leaf breaking between the axle and fixed fwd bearing (on P-A)could cause the axle to shift back to the limit of the rear shackle, and cause a sudden turn. As indicated above, the friction of the clamps or spring covers might keep it from being sudden and catastrophic, but a bit of an unknown and variable. If the secondary leaves fail, they should mainly just cause the car to sag and have a cascading failure over time as the spring stress levels go up and cause successive leaves to fail. If the main leaf is in good shape, it could end up on the rubber snubber between the spring and frame. Years ago my ’36 Packard had bad corrosion and broken leaves, replacing the complete springs wasn’t optional. The elegant thickness tapers of Packard and P-A leaves wasn’t practical so I ended up with new springs that were 10% stiffer and left the car riding too high. Eaton Spring in Detroit does indicate they can taper the thickness, I don’t know to what extent. I have elected to replace the main leaves for peace of mind, and keep the original secondaries.

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Yes, getting that better upper pin out (I mislabeled as a lower)was a bear, took most of the day to cobble together a one-off puller to get it out, and when it finally started it did so with a bang! Now I get to try to put it back in without damaging. I considered replacing with needles or Timken rollers, but after reviewing the PASB methods to get the original Fafnir cups out by grinding and chiseling – that looked like more potential for damage than gain, and would have had less load capacity. The brass fittings use the original cup without trying to force them out. Also, having spent entirely too much time thinking about it, my theory for why the aft lowers failed way before the rest is that they are the ones subjected to the most water/salt/dirt kicked up by the wheel. I was surprised that there could be so much rust inside the bearing with no evidence of it below on the outside of the shackle. I think the rubberized washers on the sides managed to let water creep in while the car was bouncing around in the winter, then kept it trapped in the bearing. The PTFE lubed composite bushings can get wet and still work without damage. If I were to do it again, I might substitute stainless shafts for chrome plate to avoid corrosion on the pin ends, but of course all of this is gilding the lily given how little the car will be driven. However, I did end up driving my 36 Packard 300 miles through the rain to a meet this summer, but that car has an automatic Bijur constantly pushing a little oil through them. I think the main thing to get it to handle properly should be installing with near zero clearance axial and radial. The difference in resistance to shackle turning due to the somewhat higher friction of the composite bushing compared to a ball bearing I calculate is well less than 1%. The variability of the spring interleaf slippage is probably greater than that. That’s my theory anyway, and I am sticking to it!

At any rate, I will still have 5 out of 7 on the original balls.

Thanks,

Jim

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Correction, and sorry for spewing some mis-information. I just re-checked the fit-up of the same spring shackle bearings while measuring for my new shackle pins and now I can torque the bolt to 40 ft-lbs and the shackle rotates freely with barely detectible endplay. i.e. no apparent axial pre-load. It isn’t totally repeatable, but may have had the felt washers installed the first time throwing me off. My apologies to Fafnir.

Jim

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Too impatient – found a good match for the spring in an online catalog and ordered. Minimum order of 10, so if anyone needs one of these, I ‘ll have them.

Jim

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Dave indicates he no longer supplies the shackle rebuild kits. At any rate, the spring shackles must take significant side load when the car turns. A needle bearing is great for vertical loads but does not react side loads, therefore I assume the old rebuild kit had provision for simple thrust washers. I have considered refitting with Timken rollers (which could fit), but coming up with a suitable preload method might be complicated. I will be working on a rebuild design to take side loading into account. I’m looking at chrome or nitrided pins with some very high load capacity permanently lubricated bushings.

There is some wear and brinneling on the ends of the Fafnir pins on the good bearings, indicating possibly the Fafnirs were designed to bottom out before overloading the balls, however fitting up the rear shackle assembly with its lower pin but balls removed showed the pins do not bottom out before the balls on the upper bearing take a significant preload. On my original units as I found them, tightening the assembly finger tight is enough to take out all end play, a mere 5 ft lbs – 1/8 turn – starts to measurably create drag on rotation, 25 ft lbs stiffens rotation up considerably indicating significant preload on the balls. Bottom line, I have no doubt the original assembly can easily preload the bearings. 5-10 ft-lbs torque is probably the limit – at least on this one example, the cotter pin a vital part of the assembly. The article reproduced in PASB 92-6 indicates no shims, – but also ‘impossible” to over tighten. I don’t believe that part.

The lubricant recommendations say “because of the necessity of adjusting the shackle bearings after lubricating….” Would like to know what that procedure was.

Thanks for responding, Jim

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Thanks for the offer. I was able to remove the metal covers without ruining them and I think I can re-install them – after I deal with the toasted Fafnir ball bearing shackles.

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I’ll get them apart and see where I’m at from there. Thanks for the responses. I think of the metal covers as “crab legs””. Jim”

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Thanks Ed, I am not concerned about cosmetics here. Years ago I restored a ’36 Packard and found bad corrosion and broken leaves under the spring covers. A broken main leaf could be very dangerous. I ended up having all new springs made – hopefully not necessary in this case. Back then (1980’s) there was a guy who reproduced the metal covers. Sounds like I can get the originals off and back on again.

Thanks, Jim

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Thanks for every ones response, actually over-restoration and worrying about judging points wasn’t a concern – just curiosity about whether anyone has noticed cost-cutting shortcuts as production levels plummeted through the ’30’s.

This is going to be a tour car, not a museum piece. I’m afraid I have a less rigorous view of restoration. I have been looking for a rear view mirror for twenty years. If I still don’t have one when the car is ready to drive I will find a substitute rather than hide it because it has a non-authentic part. I think that still puts me somewhere above the 95 percentile in authenticity when the term “restoration” now seems to include attaching a 350 Chevy with automatic, independent front suspension, and power steering column to a bare frame and body shell that came from what once had been a Packard or Pierce.

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Thanks Greg, I’ll take some photos but will be a while, meanwhile I am cogitating on how I will build the filter. The tank is already out and the bellows is worrisome, it doesn’t appear to be cracked, however if it is I will use miraculous Pro-Seal high temp aircraft fuel tank sealer if I can still get it. The stuff is a latter day replacement for MIL-8802 high adhesion/high temp fuel tank sealer and has the advantage over the epoxy you buy at the auto parts store of curing flexible and rubbery. 30 years ago I used it to seal the cast aluminum oil pan and glue the trunk lid to its new wooden frame on my ’36 Packard! Also has the advantage of making the garage smell like an aircraft factory.

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Ed, thank for the response. The tiny size of the percolator riser tubes of the King-Seeley sender unit suggest I will never be able to clean the tank sufficient to prevent plugging those tubes. Internal rust does not appear to be an issue, just a coating of varnish and some sand on the bottom. I think plan B is to build a cylindrical mesh screen attached to the sending unit/pick-up tube with a mesh size just smaller than the riser tubes ID, and flush the inside of the tank as best as practical. Drain the tank after it gets on the road and back-flush the mesh if it gets gunked up. I will be able to access the mesh from the trunk by pulling the sending unit assembly if necessary. Fortunately the tank has a drain plug, unfortunately the head is sheared off so I’ll have to drill it out. the POR 15 system for cleaning and sealing sounds impressive, but worry it would cause more problems than good if a tank doesn’t really need it.

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Thanks Ed, I’ll give that a try. Getting everything setup properly is important!

Jim

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“Back in the day’ I have read engineering papers indicating that in the ’30’s engines were re-rung without re-boring and the head “de-carbonized” at 15000 miles. Valves were also ground. Wear from airborn dirt with simple cast iron rings was the biggest contributor, so a city car driving exclusively on pavement would last longer than a car driven on country dirt roads. Tnis doesn’t mean they couldn’t go much longer than that and run okay. Loose, worn rings loose compression and leak more blow-by, make it harder to start, but have less friction at speed, and can still have good power. Full flow oil fltration helped some, but my reading has indicated the biggest improvement to ring/cylinder life was the chrome face top rings after WWII and the paper pleated airfilter in the late ’50’s. Chrome top rings were developed to give WWII tank engines better life in the desert. The dry pleated air filter was possible by the ’50’s because most of the roads were paved and the dust was reduced enough to allow a paper filter to have realistic life before getting plugged.

I find modern airfilters to reversibly retrofit to ’30’s cars to keep the wear down. I’m not into authentic wear.

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Dave, does this mean these are 40 durometer rather than the (very hard) 80 durometer I bought from someone years ago? (my original doughnuts I believe were marked 40 and were definitely softer).

thanks

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Bob Koch has requested by seperate email copies or references of the engineering documents I use to support my assertions regarding valve materials, stating "You adhere to several positions that are at variance with textbook and repair manual literature that I have." The report I refer to cracking valve seats being caused by knock does not address valve temperature directly but is an interesting insight into engines of the 1930’s. It is "Problems in the Development of a High-Speed Engine" by Sparrow in the SAE Journal volume 36, No. 2, 1935. It is available for a copying charge from SAE.

I didn’t intend to make this into a large technical dissertation, I just wanted to highlight the danger of knock being a cause of seat cracking and that the lower conductivity of modern aftermarket valves may contribute to the problem since hot exhaust valves promote knock. However, since questions remain I have written up a response that is too large to post on the forum, so anyone interested in my response as well as the original 1930’s engineering paper on valve seat recession can email me and I will fwd. My email is listed in the roster on this site.

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what part of the country are they located in?

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Curtiss, sorry I haven’t been on the forum for awhile. I haven’t actually tried this myself yet, but a while back I found a company that has convex glass lens’ in graduated sizes intended for clock repair from 2" to 15". The website is timesavers.com.

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