I think I figured out my handling problem

[Jimal]

I've been chasing a weird handling problem for about as long as I've had the truck on the road, and although I've replaced some really crust old parts (cab mounts, transfer case mounts), the problem has never really gone away. I've been getting some driveline wrap when I first take off from a stop (the rear of the truck feels like it is lifting) and I get a weird seat of the pants wiggle on decel.

I went to look at something else under the back of the truck and stumbled into this.





Note the gap between the leaf spring and that big girder looking perch. I might soak these things in deep creep and see if I can tighten them down, but I'm sure they're not going to take that well. I'm looking at the parts schematic on LMC and that piece doesn't appear and the u-bolts they show are much shorter.

Thoughts?

[jonzcustomshop]

I just go to a local trailer/spring shop and have them bend me new U bolts, I don't have to wait on shipping, and the cost is about the same...although the cost is expensive... the bolts for my sub with the 4 inch lift were about $70

make sure you bring an old one with you to compare to the new one they bend for you (so they can visualize what you want.)

** my stock 63 k20 has that same lift block, I am sure it is stock.

[Jimal]

Originally Posted by jonzcustomshop

I just go to a local trailer/spring shop and have them bend me new U bolts, I don't have to wait on shipping, and the cost is about the same...although the cost is expensive... the bolts for my sub with the 4 inch lift were about $70

make sure you bring an old one with you to compare to the new one they bend for you (so they can visualize what you want.)

** my stock 63 k20 has that same lift block, I am sure it is stock.

We actually have one of those near by. And since I'm not finding anyone yet online who has an application for a '65 K10, my options might be limited.

[padresag]

that is the way to go. just get them made. the old ones can more than likely get stretched a little and a little wear in the spring leafs over 50 years can do it. it may be simpler just to cut them off instead of struggling to take the nuts off. your not going to use them again. check the centre bolts in the springs while you are there
http://www.lmctruck.com/icatalog/cbe/full.aspx?Page=37
ron

[bhc41051]

My 62 has a shim between the lift block and the springs, I assume it has something to do with the drive-line angle. It looks to be OEM

[evan396]

Jimal, you should run down to Danbury springs and get a new set, when we removed ours the thread's were shot. You should also remove the block's as padresag suggested, we had some rust built up under the block and on top of the block between the Axel pad and leaf springs. Evan

[Jimal]

Originally Posted by evan396

Jimal, you should run down to Danbury springs and get a new set, when we removed ours the thread's were shot. You should also remove the block's as padresag suggested, we had some rust built up under the block and on top of the block between the Axel pad and leaf springs. Evan

I might try tightening them first to see what happens. I can always cut them off if they won't turn.

[66Gilbert]

Originally Posted by Jimal

I might try tightening them first to see what happens. I can always cut them off if they won't turn.

I doubt you will be able to tighten them up any with all the dirt and rust that is trapped by the bottom bracket all those years. Even here in Arizona I had to remove the U-bolts and chase the threads with a die in order to get them to tighten up. Being from the area you are from and the way the pictures look I agree with the others on replacing the U-bolts and cleaning the lift blocks and springs.

[1971 GMC SHORTY]

Originally Posted by Jimal

I've been chasing a weird handling problem for about as long as I've had the truck on the road, and although I've replaced some really crust old parts (cab mounts, transfer case mounts), the problem has never really gone away. I've been getting some driveline wrap when I first take off from a stop (the rear of the truck feels like it is lifting) and I get a weird seat of the pants wiggle on decel.

I went to look at something else under the back of the truck and stumbled into this.





Note the gap between the leaf spring and that big girder looking perch. I might soak these things in deep creep and see if I can tighten them down, but I'm sure they're not going to take that well. I'm looking at the parts schematic on LMC and that piece doesn't appear and the u-bolts they show are much shorter.

Thoughts?

I have That Same Gap on mine

[BigDan3131]

I've been looking into new U Bolts and from what I have read it says to never reuse them because they are torqued on and stretch like rod bolts do.

[luvbowties]

Originally Posted by bhc41051

My 62 has a shim between the lift block and the springs, I assume it has something to do with the drive-line angle. It looks to be OEM

Look how close each of bhc41051's spring leaf hugs its adjacent one(s).
Sam

[evan396]

Almost forgot jimal, look closely at the blocks. We had at least three cracks in the rear one's. Dad brought them to work to get the welder to grind out the cracks and weld them back up.Evan

[Jimal]

Originally Posted by evan396

Almost forgot jimal, look closely at the blocks. We had at least three cracks in the rear one's. Dad brought them to work to get the welder to grind out the cracks and weld them back up.Evan

Will do. This will be one of those "check everything while you have it apart" opportunities.

[Jimal]

Originally Posted by 1971 GMC SHORTY

I have That Same Gap on mine

Between the leafs or between the bottom leaf and the block? because I don't think either one is ideal.

[Jimal]

https://youtu.be/mo6RBeKChuQ

This is what I found when I went to check the u-bolts. I'm seriously lucky nothing bad happened and more than a bit surprised things got this loose. Everything was nice and tight when I checked it last summer while I was working on the rear brakes and shocks. New u-bolts have been made and I'll pick them up in the morning.

[earl84]

Holy crap!! Glad it didn't all fall apart on you.

[Jimal]

Originally Posted by earl84

Holy crap!! Glad it didn't all fall apart on you.

That makes two of us. It definitely wasn't like this when I started.

[PGSigns]

One of the things we have found working on the old cars and truck around here is there can be lot of rust between the springs in the stacks and that causes them to not work as they should. I would pull the spring out and pull it apart and clean and paint the leafs and rebuild the stack when you do the ubolts. Also look for cracks in the center where the bolt goes through.
Jimmy

[mattbert56]

These are the blocks that came on my k20 frame. The U bolts had to be snuggled up on mine a little after 50 years.