Rear Leaf Spring Part Identification

[ossy21]

I had some knocking coming from the rear end of my 89 Comanche, so I started doing some investigating and found that my axle was rocking back and forth on the spring when torque is applied to the wheels. It seems like the inside u-bolts nuts were not tightened down properly and based on the wear on the bolts, there for sure has been movement. Once I got them unbolted, I found that the backing plate that was between the u-bolt nuts and the u-bolt bracket on the underside of the axle was also quite bent (picture attached). I can't find any sort of parts diagram for the Comanche spring-under axle. Does anyone know what this backing plate part would be called or where to get another one? Is it even a stock part?

 

I also found that the u-bolts that were on it seem to be a lot smaller diameter than stock Comanche bolts and now I'm not even sure that the leaf springs are actual jeep springs. Can anyone identify them from the picture below? They are some 4+1 configuration, so they could be the 1440lb springs, except that the truck has a 4.5" lift in the front and it sits level, so there must be some sort of lift in the rear beyond just the extended shackles.

 

The spring bushings are quite worn, so have been debating whether to replace the bushings or just get new springs, but I kind of want to figure out what I have before I can do either. Plan to get new u-bolts too. It is an 89 Comanche pioneer 4wd short bed with a Dana 44 rear.

[ghetdjc320]

Looks like you have an add-a-leaf in that leaf pack but hard to tell for sure in the pic. Not sure what the part is in that second pic. You should have a spring perch welded to the axle, u bolts that fit the axle diameter (approx 2.75) and a u bolt plate for 2.5” wide springs. The stock u bolt plates have the shock studs in them. Perhaps the wrong size u bolts where installed?? Take some more pics of the u bolts, perch, and springs. 

[Pete M]

definitely looks like an AAL in there where there are 2 leafs of the same length on top of each other. 

 

the part in the second image is the Ubolt support bit that goes underneath of everything and inside the shock mount bracket.  it was done away with in the later years when they simply thickened up the shock mount bracket.  it can be slightly warped and still do its job perfectly well.  

[ossy21]

Yeah, I suspected that the previous owner had put an add-a-leaf on, but hard to tell what it is. The spring perch is there and has the stock u-bolt plates (with the shock mounts), but my mystery piece was bolted on the underside of those u-bolt plates.

 

I think I might have figured it out though. That extra backing plate piece has smaller diameter holes, so I think they threw it in there to keep the smaller u-bolt and nuts from pulling though the stock 14mm bolt holes.

 

Based on that cobbling together of parts, it wouldn't be a surprise if these leafs are off some random vehicle with similar size springs.

[ossy21]

3 minutes ago, Pete M said:

definitely looks like an AAL in there where there are 2 leafs of the same length on top of each other. 

 

the part in the second image is the Ubolt support bit that goes underneath of everything and inside the shock mount bracket.  it was done away with in the later years when they simply thickened up the shock mount bracket.  it can be slightly warped and still do its job perfectly well.  

Awesome. Thanks!

[Pete M]

2 minutes ago, ossy21 said:

but my mystery piece was bolted on the underside of those u-bolt plates.

 

 

 

that is exactly where it goes.  

[AZJeff]

Associated story —- My MJ was fitted with about a 4” lift by some previous owner, and it had that same secondary plate installed as the OP showed in his photo.

 

All was well until I needed to replace the bushings on the springs and the shackles.  NOBODY on the inter-web seemed to have the right diameter bushings, so I finally took the springs to a local shop, and asked them to replace the bushings.

 

They told me that many aftermarket springs don’t use OEM sized bushings, and that’s why nothing I ordered would fir.  They were able to match up some stuff and install it.

 

I share this in case some other owner with other than OEM springs decides to do some repairs to his spring pack🤔