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One more snag --- the "new" rear u-bolts that I ordered don't fit the springs properly. The '46 had a forged, flat top that made full contact across the top surface of the spring but all of the new replacements I have found are "bent" with a big [censored] radius that only contacts the edges of the springs. They call'em flat, but they are not. And so far, no one I can find has anything even close to a proper fit.

Has anyone else run into this issue? Found a solution?

There are comparison pix in my Flickr Album...
Album https://www.flickr.com/photos/tango88/with/15618469700/

I had a blacksmith friend forge the tops flat and basically copy the originals for me. I started with u-bolts like you show, bent at a local shop while I waited.
Not the best picture but you can see them.
https://picasaweb.google.com/lh/photo/rWrnxUcHA5wPyk9snDe_O9MTjNZETYmyPJy0liipFm0?feat=directlink

After I had those made I recall seeing just what I needed on a P-30 or Chevy 3500HD chassis, and thought it'd be worth going to the GM dealer and see what the availability and cost of u-bolts is. I never checked.

Another option is look for or make some blocks that fit the u-bolts like GMC used.
again not the best picture but these cast or forged blocks have curved tops and seats for the u-bolts to nestle into. You may need different yet u-bolts but this slightly curved shape should be easier to get bent for you.
https://picasaweb.google.com/lh/photo/O4Ywa09vkE6UBw3tGMhrYdMTjNZETYmyPJy0liipFm0?feat=directlink

I have also seen similar saddles on the front springs on P-30 chassis, and I have a few loose I can measure. They may not be spaced far enough apart though to use on the rear axle (4" OD tube).

In any case your options are to have yours forged, find the proper ones, or find some blocks to work with/fit easily available u-bolts.

Hy Tango, I have seen many "spreader plates" on the top of spring packs, some to adapt round "U" bolts to the flat spring surface, some just flat plates with notches on the edges for the "U" bolts to sit in. I suggest you make up some flat plates that contact as much of the flat section of the "U" bolt as possible and install them between the spring pack and "U" bolt. The only alternative I can think of would be to take one of your old "U" bolts to a shop which supplies/fabricates "U" bolts and see if they are willing/able to do the forging to duplicate them, hope that helps.

As a Toolmaker I would agree with this approach.The added plates would fill the gap and spread the load across the top of the spring.
I would be hesitant to heat those U-bolts as you do not know the steel type or heat treat they were subjected to.Heating and reforging them flat could affect the strength.
Why take that chance?

I agree with that.
It seemed like the best idea at the time when I did it now 11 or 12 ago, and has given no trouble. Still I'd look for other solutions as given above before having u-bolts forged again.

I would think that most big truck spring shops could make you u-bolts to fit your application. I have a local shop that I have had many different types made over the years.

Too bad no one is still making the OEM style. May have found a better fit from Eaton. It has what looks like a much tighter radius at the corners. We'll see in a few days but the top pad is still a possibility.

Thanks to all.

Have you tried looking for them at the GM dealership?

Our local farm/home center has a selection of flat top U-bolts.
Not sure of the spread/length/diameter that's required for the big bolt, but they have several to choose from in 1/2" 5/8" range.

Thats were i get my ubolts they can make you what ever you need and they are cheaper,

I have had them made locally as well, around here and I expect most places, they can not/do not forge them or bend them with as crisp and square corners as the originals. Not quite good enough to use with just that sheet metal spacer.
What they can bend works with various blocks shaped to fit the as bent U-bolts.

I buy a lot of suspension stuff from these guys. They call them square bend U-Bolts.

http://www.stengelbros.net/Square-Bend-U-bolts_c_566.html

Sadly, GM is a joke these days. Without a VIN number they can't find their arse. And I would love to find a shop that could make what I need but no luck here so far. If someone has a shop name, I will be happy to pay for custom work.

Seen these also, today: Ebay

What size are you looking for? I would think that with all the sizes Stengel Bros list that something should fit. If they are too long, just cut them off. GM probably listed close to 100 part numbers for U-Bolts in their master catalog of the period. Dealers never stocked many. Everyone that I have known either ordered them from the aftermarket like Stengel Bros. or had them made. I think buying from Stengel Bros. is a lot cheaper these days than having them made.

Trailers used to use square bend U-Bolts. Probably 40 years ago the round bend U-bolts became more popular because they stretch a lot less than the square-bend U-Bolts. Back when I started trucking over 50 years ago, we were constantly tightening U-Bolts, replacing broken leaves as well as broken U-Bolts. I'm glad those days are long gone. I have 9 dry fans on spring ride that all use the round bend U-Bolts and they are maintenance free. Everything else is on air ride, and air bags do blow out.

Tango,

I second that Stengel Bros should be able to make what you need at a very good price. They are a great company.

Paul

Edit: Could these work for you?

http://www.ebay.com/itm/1941-1942-1...ries&hash=item3a9bf9e5e8&vxp=mtr

Thanks Paul --- ya, I saw those too and got excited. That is the style but those are for the front and way too short.

And the ones from Stengel look like the replacements that Eaton is now sending. Still not the forged, flat surface like the originals, but will hopefully lay flat on top of the springs. Should know in a couple of days.

Many thanks to all for getting back. Is this a great forum or what!?

Given the further discussion I think your best option at this point is to make or find used something like the blocks with curved tops as shown on the GMC in one of my earlier post. Given that you'll have a lot of more or less square U-bolts already on hand making something to fit is probably cheapest.

I made these for my front axle to mount air helper springs.
Think I started with 1/4" plate and milled the appropriate radius grooves in them at the proper spacing. Then filed the edges for clearance on the bend radius of the u-bolts.
You may want to start with 3/8 or even as much as 5/8" plate. I kept them thin because I needed the clearance.
https://picasaweb.google.com/lh/photo/XhpxTSOlop6_8t-sRPk_rNMTjNZETYmyPJy0liipFm0?feat=directlink

I had mine made at a local truck alignment shop. Gave them the
dimensions I needed and they made them in minutes. www.mercerspringcorp.com/ They may be able to send them or know of spring shop in your area

EDIT: I see now you issue with the radius. Could you machine that radius on a thicker plate on top?

These guys in San Antonio can build almost anything you want.

http://www.acespringservice.com/u-bolt.html

Years ago I did a lot of business with them, but I find it cheaper to buy off the shelf stuff now.

Thank All --- waiting to get the replacement tight radius u-bolts from Eaton to see what I have to deal with on them. I'm guessing they too will require some kind of homemade top pad to fit correctly.