Spring Shackles

[Merle Coggins]

Huston, we have a problem…

 

While tinkering with my truck recently I noticed that the back of the truck leaned to the left a bit. So this afternoon I crawled underneath to take a look. Not what I wanted to see… The left rear spring shackle was broken. It appears to have been broken for a while, based on the rust in the break. I just drove this truck 600+ miles to Back to the 50’s and back. I don’t recall when I last greased the shackles. I remember doing the fronts earlier this spring, but don’t recall if I greased the back. I certainly would have noticed this when I last greased them. 

 

Anyway, it looks like a shackle job in in my future. I may need to do some forum research regarding which bushings are LH thread, or maybe you all can remind me now and save me some digging. 

 

I see that Roberts, Bernbaum, and DCM all show shackle kits. Can anyone confirm the quality of any of these parts, from these vendors? Hopefullly they’re not all Chinesium junk. DCM has a slightly higher price, but I’m out opposed to paying more if the quality is better.  

 

 

 

Edited July 2 by Merle Coggins

[bkahler]

Merle, this is the info I have in my notes for the shackles on my 51 B3B.  Hopefully someone will be able to confirm.

 

Drivers side rear lower bushing is LH thread
Drivers side front lower bushing is LH thread
Passenger side rear lower bushing is RH thread
Passenger side front lower bushing is RH thread
All upper bushings are RH thread

[Young Ed]

I would guess all those suppliers get them from the same place. You can also get jeep shackles that work the same but will lower your truck a little. 

[John-T-53]

Check Rare Parts  - this is where I bought new shackles for the fronts on my truck. They were high quality, made in USA. My previous experience with suspension parts from Roberts (king pins) yielded Chineseum. 

 

https://www.rareparts.com/RP35420A-35420-SILENT-U-SHACKLE

 

The website indicates 1 on hand.

 

Edited July 3 by John-T-53

[JBNeal]

5 hours ago, Merle Coggins said:

...

...

looks like ya got a head start on IWOTDays '26 👈

[Merle Coggins]

7 hours ago, JBNeal said:

looks like ya got a head start on IWOTDays '26 👈

More like a late start on IWOYTD ‘25

[Young Ed]

Have you also inspected the frame mount? Seems like something else might be wrong for that shackle to break like that - assuming this stuff was replaced when you built the truck. 

[Merle Coggins]

1 hour ago, Young Ed said:

Have you also inspected the frame mount? Seems like something else might be wrong for that shackle to break like that - assuming this stuff was replaced when you built the truck. 

 

I never reworked the shackles when I built the truck. I left the frame as a rolling chassis. I only replaced the grease zerks and made sure everything took grease. A couple of them were a bit stiff, but after I started driving it, and regreasing, they all freed up and worked fine. 

 

I have ordered a set from DCM Classics, along with one hanger bracket. I'll work on getting it all apart this weekend and await the arrival of the new parts. Hopefully they'll be serviceable. Will they last another 75 years? Who knows. I likely won't be around long enough to find out. 

Edited July 3 by Merle Coggins

[John-T-53]

Have fun with those dadgum rivets, that's all I can say.... 😬

[BobK]

After grinding the rivet head off, center drill a hole in the rivet and hit it with a center punch. Should pop right out.

[Young Ed]

47 minutes ago, John-T-53 said:

Have fun with those dadgum rivets, that's all I can say.... 😬

I can't imagine trying it with the bed on....

[Merle Coggins]

I got it all disassembled and cleaned up today. It should be ready for reassemble once the shackles from DCM arrive, hopefully Monday. I was able to rattle out the spring eye bushing, on the broken shackle, with my impact gun. Then I had to do some digging to get at the upper bushing. There was a lot of caked up dirt and grime packed in the pocket that I had to chisel out with a long screwdriver. I could finally get a socket on it, but my impact wouldn’t budge it. I had to use my long breaker bar and my foot to get it broke loose. Then a about 30 degrees at a time I repeated the process until It started loosening up enough to rattle it out the rest of the way with the gun. I expected a struggle, but all-in-all it wasn’t too bad.

 

I wanted to run a brush through the holes to clean them up. I was wondering what I would use for that when I came across my injector cup brushes in my tool box. I one for the old 2 stroke Detroits, and one for Cummins engines. The Detroit one was a perfect size. I cut the handle off so I could chuck it up in my drill. Spinning the brush through the holes with a lot of PB Blaster cleaned them up well.

 

Then on to the passenger side. I figure if I’m going to do this I may as well update both sides. I suppose I should inspect the fronts well too, but that’s for another day. The spring eye bushing needed the long breaker bar and foot method, but at least I could get a little more rotation with each bite. Surprisingly the upper wasn’t packed full of dirt like the left side was. However, I soon found out that the head was rusted so that much of the hex was gone. I couldn’t get a socket to grab it. So out came the cut off wheel to remove the rivet heads. My 90 degree die grinder with a cutoff wheel came in clutch here. This allowed me to remove the hanger bracket and get it into the vice so I could weld a nut to it. I first gave it a good dose of heat to burn off the grime and rust so that my weld would stick. You can see what’s left of the hex here. Welded a big nut to it and let it cool for a couple minutes. It spun right out with the gun. I cleaned everything up, then headed to Fleet Farm for some grade 8 hardware. The hanger bracket is now reinstalled and everything is ready for the new parts to arrive. I ordered a new hanger bracket, just in case, but I don’t believe I’ll need it… Spare parts for later…

 

Still smokin’…

 

  

 

On 7/2/2025 at 4:30 PM, bkahler said:

Merle, this is the info I have in my notes for the shackles on my 51 B3B.  Hopefully someone will be able to confirm.

 

Drivers side rear lower bushing is LH thread
Drivers side front lower bushing is LH thread
Passenger side rear lower bushing is RH thread
Passenger side front lower bushing is RH thread
All upper bushings are RH thread

 

I discovered that it’s the Right (passenger) side lower (spring eye) bushing that is LH thread. All of the others are RH thread. At least that’s how it was on my truck today. 

Edited July 7 by Merle Coggins

[bkahler]

2 hours ago, Merle Coggins said:

I discovered that it’s the Right (passenger) side lower (spring eye) bushing that is LH thread. All of the others are RH thread. At least that’s how it was on my truck today. 

 

I guess I'm not surprised they were different than mine.  I replaced my front springs with springs from a junk yard and it's entirely possible I put them on wrong.  I'm glad you were able to sort yours out.  

[Merle Coggins]

2 hours ago, bkahler said:

 

I guess I'm not surprised they were different than mine.  I replaced my front springs with springs from a junk yard and it's entirely possible I put them on wrong.  I'm glad you were able to sort yours out.  

I’m not saying mine is correct. Just reporting how it was. My manual doesn’t mention anything about it, that I’ve found so far. I’ll have to do more research. 

[Merle Coggins]

I still am not finding anything about LH and RH threaded bushings in the service manual. But I did find something interesting in the parts manual. It seems that some of the 3/4 ton trucks were fitted with 1 ton spring shackles. My S/N doesn’t fall into that group. I also find it interesting that they have separate listings for the B models, series 1,3,& 4 of the C models, and the 2-C models get their own listing. However, they are all the same P/N’s, L & R. Maybe they weren’t originally, but then they superseded to share the same parts?

 

[Merle Coggins]

We’ll… just after I posted that last message my step son was leaving for work and found a package on the front step. My parts have arrived. When I checked the tracking yesterday it showed a Monday delivery. A quick check of the parts confirms that the one marked LH has the LH thread on one of the bushings. Apparently someone has done some spring shackle work on my truck at one time in it’s life and switched the shackles. Or it was a mistake from the factory. 

I did find another thread on the forum that referenced LH thread on the left side lower bushing. I guess I put it back together that way. Possibly tomorrow now. 

[Merle Coggins]

I got the new shackles installed yesterday afternoon. It went together quick and easy. A few things to note on these DCM replacement shackles. I'm sure they are Chineseium, but they seem to be decent, so far. The old ones have a 7/8" hex, except for the LH thread one which was 15/16". I had to dig out a 23mm socket for the new ones. This tells me that they are made with metric sizes. The new ones have grease fittings in the end of both bushings, whereas the old ones only grease the upper bushing through the side of the hanger bracket. That seems that it would only grease the outer threads, and not the inner ones. The new ones will certainly grease the shackle to bushing area, which I believe is better. 

Edited July 7 by Merle Coggins

[Plymouthy Adams]

Mess up at the factory,   could it be?  We had a batch of cars delivered to the dealership one time back in mid 70s  The assembly line got out of sync when assembling.  Fender emblems on one side were for one model whereas the emblem on the other side was for the sister model.  The fix...remove the emblem that offends the dealership and replace.