7 or 8 years ago I replaced the old wallowed out rusty slightly bent leaf spring shackles along with bushings, etc, front and back. In the years since I've had both rear shackle retaining bolts break and on three occasions I've had to remove and straighten the shackle brackets. I'm planning to replace everything again, but wonder if there isn't a better non-stock set-up or a higher grade stock replacement.
The shackle pins are tapered and fit in tapered holes in the side plates. Yours shown with the bolt drawing it up so tight the side plates bend might not be helping the fit at the tapered ends.
The shackles for larger trucks have nuts on the ends of the shackle pins and don't need the carriage bolt in the middle. One through two ton trucks use 2" wide front leaf springs and the smaller trucks use 1-3/4" wide springs (front and rear), so the shackles/pins and bushings aren't exactly interchangeable from the larger trucks.
Perhaps there is still a 1-3/4" wide shackle kit with the nuts on the ends of the pins, I don't know.
Picture shows both types, but these are all for 2" wide springs. Not sure why the different length side plates or which application gets which ones.
I don't tighten the center bold enough to bend the side plates. I only tighten that enough to take the play out of the shackle assembly. After a year or 2 of normal driving those side plates get bent way out of shape and I have to take everything apart and straighten those back out. I'm looking at replacing everything, but I'd like something that doesn't need rebuilt every 2 years.
Bending and straightening metal eventually weakens the metal. Time to get new side plates. If NOS can not be found and after market is junk maybe a spring shop or a machinist can make you new side plates with stronger metal. Jeffrey
Dang! How many times did your truck roll over down the side of that hill? I didn't know there was any hills in Iowa. Are those side plates and bolts aftermarket? They may not be up to specs for stiffness. I try to reuse the original side plates and bolts when I change the pins because I have had problems similar to what you have. Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
No joke, these look like they've been through a roll over. The old ones I pulled off were a bit bent but they were so rusty they weren't worth saving. This set shows signs of bending after a few months use. When they get bad enough I just pop then off, tap then straight with a hammer, and reinstall. Way too soft.
All good comments for sure....but what is the "root cause" of the problem?? Could the rear housing be shifting at times putting the spring in a bind against the shackles? Something is making those shackles twist....... maybe I'm all wet? Just a thought.
Back when I replaced the rear shackles I also replaced the spring eye bolt and bushings. Everything fit nice and tight and I've kept everything well lubed, but I've noticed that the spring eye end of the spring is getting sloppy. It seems to me the entire kit is failing. I wish I could remember where I got it.
The first thing I thought when I saw the disfigured shackle brackets is that the rear end must be dancing side to side quite a bit to cause that kind of damage.
Any chance one spring pack is flipped around end for end, and thus rear axle is out of alignment? Something just doesn't seem right. If the same shackles hold up OK on the front axle even of a 2 ton truck I'd think they'd be fine on the rear of a 1/2 ton truck, if everything is in good order.
I'm with Alvin and Grigg...something else is going on.
Are the U-bolts tight? Is the frame twisted? Are the spring pack clamps still in place and in good shape? Are the spring front eye's and pins still in good shape?
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
Spring front eye's and pins were replaced the same time the shackles were and are beginning to show a little slop. Spring packs are correctly oriented. U-bolts are tight. Frame's straight. Spring pack clamps are still in place though a little worse for wear. I've got the original rear end but it's been converted to open drive and the perches are welded solid.
The thing that gets me is the OLD shackle side plates I pulled off and threw away were badly rusted and the holes were wallowed out bad, but they were relatively straight. The retaining bolts were rusted to half their original diameter but were almost impossible to bust, which is how I had to remove them. The NEW side plates bend out of shape too easy and can be straightened out with a couple taps with a hammer and the retaining bolts bust with very little torque applied. I wish I could remember where I got them so I don't make that mistake again.
If I've got a problem other than grossly inferior parts I'd like to know, but while I'm at it I'd like to find a better shackle arrangement (if possible and practical).
Start with some NOS shackles and see how they last.
If the rubber in the old axle mounts was worn out and then welded fast the alignment may be off. May be off even if the rubber was OK at time of welding. Probably worth actually checking rear axle alignment. Instructions in the shop manual or have an alignment shop check it.
" If the rubber in the old axle mounts was worn out and then welded fast the alignment may be off. May be off even if the rubber was OK at time of welding." (Grigg)
Twotone, did you use the old axle mounts with/without the rubber removed?
The rubber was removed and the perches were welded up while the axle was on a welding table. The perches were double checked for angle and triple checked to make sure they matched each other. I had a professional mechanic do the welding for me because he's meticulous.
I would think that the OEM shackles would be way more sturdy than what you have. Short of heating them or using a lot of leverage I have never seen a bent set. Something is wrong in the geometry of your axle set up.ðŸ›
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
Once again, the old set of shackle brackets I took off looked like they'd been there since the beginning of time, but were pretty straight. When i put the new set on I changed nothing else. I still had the torque tube. The geometry of the rear end was not changed. yet the new shackle brackets started bending within three years. I've since changed to open rear but the bracket bending hasn't gotten any worse.
Originally Posted by Justhorsenround
Short of heating them or using a lot of leverage I have never seen a bent set.
But that's my point. I can knock a shackle bracket off onto the floor, smack it with a hammer a couple times to straighten it out, and put it back on. So, what I didn't know is that these brackets should only bend under extreme cercumstanses. Not with a couple light blows of a hammer.
So I need to find a QUALITY set of shackles and spring eye pins. And when I install them I'll recheck rear end geometry (though I don't think that's the issue).
twotone, Obsolete Chevy is no longer in business so this may be a mute point....however, the last two sets I had ordered, one from Obsolete and one set from another vendor, and both sets were made in Canada and were dang good steel in every way. Maybe when you purchase another set ask where made before paying up......or find a local fab shop with a water jet and let them cut you a set out of real steel.....or even a regular machine shop...... just excercising my brain!
Are those side plates and bolts aftermarket? They may not be up to specs for stiffness. I try to reuse the original side plates and bolts when I change the pins because I have had problems similar to what you have.
