Re: 1928 Front End Shimmy
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DP, they steering assembly appears to be very similar and your comments/suggestions are right on.
One of the local old-time car restorers in my area (relatively speaking), agrees that the steering gear, bearing, washers might need adjustment and would be a good 1st step. He also suggested that I look at the king-pin assembly as a second area to check as the trouble appeared to go away for a while. He is thinking that most likely the issue is with both areas now. He thought was that the king pins needed to be adjusted (worn shim/washer) and the severe shimmy caused the steering gear misalignment, which is causing more dramatic shimmy. Is there any documentation on the removal/adjustment of king pins? Thanks again Gar
Posted on: 2022/7/17 15:35
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Re: 1928 Front End Shimmy
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Gar;
In the ’29 service manual page 221, there is a ‘cut-away’ of the front suspension and steering knuckle. That graphic suggests the Packard ‘Steering Knuckle Pin’ features ball bearings that require some type of shimming. The adjustment procedure is on page 222, procedure S119. The material call-out mentions shims of 0.005” or 0.025” thickness. All of this suggests either a minimum vertical motion or bearing pre-load is being set. I’m significantly out of my league with that design . . . I’m strictly from reamed Bushingville, with a simple thrust bearing to support the weight of the car. The note in S119, step #5 suggests a check should be made to ensure the bearings have not been pinched with excessive preload, therefore if you use the procedure to check the bushing design a near zero ‘looseness’ would be expected. The contents of Technical Letter 1840 (referenced in S119) may contain the missing pieces, but I’ve been unsuccessful finding that document. Assuming this site has a copy, I think I need HH56’s site navigation skills. Update: I finally found TL 1840. I'll look it over for some insight on the adjustment "do's and don'ts". Seems the bearings were being ‘pinched’ in the field by not shimming correctly (still no insight on the correct procedure). The fix was a different plug, and two Belleville washers to replace the stack of shims. Seems the new plug could be made locally by machining the original design. All of that detail tells me the bearings were designed for a preload (zero slop), but the field exceeded the desired pre-load while maintaining the cars. Gar, download a copy of Technical Letter 1840 and measure your cap against the 13/32 dimension called-out in the letter. If it’s 3/16 longer, then you have the original design. Still no idea of the Belleville geometry. dp
Posted on: 2022/7/17 20:08
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Re: 1928 Front End Shimmy
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David, can you tell me where(how) you found TL1840? I am not finding that letter.
Thanks, Gar
Posted on: 2022/8/17 10:52
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Re: 1928 Front End Shimmy
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Gar
Advanced Search with "Technical Letters" as Keywords, and only the technical/service sections checked. A list will appear . . . at the bottom is "Show All Results" . . . click that choice At the bottom of the next list is "Technical Letters" . . . click that choice A listing of TLs will be displayed . . . scroll until 1840 . . . click that choice This link might work: packardinfo.com/xoops/html/downloads/TechLetters/TechLetter-1840.pdf dp
Posted on: 2022/8/17 14:42
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Re: 1928 Front End Shimmy
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Thanks for giving me the link to the doc.
I did check the steering gear and connections and they are all consistently tight but still movable. What I did find was a service letter vol-2 no-17 that discusses a front spring trunnion and bracket. There are four heavy coil springs inside the trunnion.I did notice that the springs have some play in them and are not snug on the top of the trunnion. Should these springs be tight on the top and the bottom of the trunnion? Please see attached picture... I may try to place some wood shimms inside the trunnion to close gap and see if that reduces the shimmy. Gar
Posted on: 2022/8/20 9:08
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Re: 1928 Front End Shimmy
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I wanted to close the loop on this thread.
After performing all of the suggestions above and a couple of Hail Marys, I switched out the TRUNION springs (set of four) and all of the steering shimmy issues went away. The car steers firmer and has a much better road feel even it 45MPH (max speed that I drive it at). The old springs were between 1/16" to 1/8" more compressed(shorter) than the new springs. Car now steers better. Thanks for all of the suggestions! GAR
Posted on: 2023/8/24 13:08
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Re: 1928 Front End Shimmy
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I am still becoming a "car guy" and am an authority on absolutely nothing, but I have been told by a guy that has restored more of these cars than all of us put together that the first issue to address (beyond the obvious worn out parts), is to make sure it has 2 degrees of caster. My car is still a rolling frame, so I don't know if it will shimmy or not, but I tend to believe my "guru".
Posted on: 2023/8/24 13:58
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