Questions regarding rear leaf spring U-Bolt top-plate on a 91 Chevy K1500 Pickup

Hi everyone,
I'm hoping I can get some feedback regarding the rear leaf spring U- Bolt top-plate on a 1991 Chevy K1500 pickup.
I have attached two gif drawings for reference. Here is the download
link for the drawings, only 201.19 KB...
http://ifile.it/fg3beao/U-Bolt%20Drawings.zip
Referring to the drawings, my questions are regarding part # 5 (spacer) of drawing A, or what is called the "top plate" in drawing B. I purchased the top-plate from the GM dealer and I know it's the right part because I used the Vin # to order it and I verified the part number at two different dealers.
When I installed the top-plate, the nut on top of the leaf spring center-bolt would not go all the way through the hole in the top- plate. If anything, the hole in the new top-plate looked a little bigger than the hole in the old top-plate. I went ahead and torqued the U-bolts to factory specs of 81 foot-pounds and followed the correct tightening sequence, thinking this would force the nut through the hole in the U Bolt top-plate (it seemed close enough).
The ends of the top-plate are now clamped tight against the top of the leaf springs. However, the center of the top-plate is not touching the top of the leaf springs. The nut on top of the leaf spring center-bolt was not pushed all the way through the hole in the top-plate. I can only guess that its' designed this way for some reason but I wanted to check to make sure. I replaced the drivers side today and I'm replacing the passenger side tomorrow. I cannot just look at the old one that is still on the passenger side because there is so much rust present, I cannot tell if there used to be a space there or not. According to the factory service manuals I have, there does not appear to be any other spacer or anything that would "take up" the space.
I did not install the plate upside down, it's installed just as shown in drawing A and that's how the plate was originally installed as well.
I would really appreciate any feedback anyone might have on this.
Thanks John
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Some people said they had trouble downloading the two gif drawings. Here are download instructions that will help.
File download instructions:
You don't need to register or sign-in with the site to download the file, just click on the link http://ifile.it/fg3beao/U-Bolt%20Drawings.zip and after the page loads click "request download ticket" then it will say "download" where it had said "request download ticket" before. Then you just click "download" and save the file. The two gif files are in a zip file that you can open with winzip, winrar, 7-zip, or similar programs.
Thanks again, John
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Here are some links that will allow you to see the drawings without downloading or unzipping anything.
Just click on the links below and the drawings will show up in your browser. You have to use Internet Explorer or Firefox, for some reason the images did not show up in my Opera browser.
http://www.shareimages.com/image.php?32835-pZSel5mjk6Kpk6SZ-drawing_a.gif
http://www.shareimages.com/image.php?32836-pZSel5mjk6Kpk6SZ-drawing_b.gif
John
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When I took the old U-bolts off, there was quite a bit of rust between the bottom of the top-plate and the top of the leaf spring stack. All I can think of is that there may have been some rust in there around the center-bolt nut that made it larger than it was originally. I took a chisel an hammer to the top surface of the leaf spring stack, and then wire brushed it, and sprayed on some wax based rust inhibitor and wax based under coating. It looked pretty clean, but perhaps there was something there. The wax based undercoating is soft, so that's not a problem.
If the passenger side goes better tomorrow, I just wonder if I should take the drivers side back apart and try to re-do it ? I thought I read once that you should not torque U-bolts and then loosen them and re-use them, but I'm not sure what it would really hurt ? I would hate to have to buy another set of U-bolts and nuts if I don't really have to.
John
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When I took the old U-bolts off, there was quite a bit of rust between the bottom of the top-plate and the top of the leaf spring stack. All I can think of is that there may have been some rust in there around the center-bolt nut that made it larger than it was originally. I took a chisel an hammer to the top surface of the leaf spring stack, and then wire brushed it, and sprayed on some wax based rust inhibitor and wax based under coating. It looked pretty clean, but perhaps there was something there. The wax based undercoating is soft, so that's not a problem.
If the passenger side goes better tomorrow, I just wonder if I should take the drivers side back apart and try to re-do it ? I thought I read once that you should not torque U-bolts and then loosen them and re-use them, but I'm not sure what it would really hurt ? I would hate to have to buy another set of U-bolts and nuts if I don't really have to.
John
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On Sun, 4 Oct 2009 22:50:05 -0700 (PDT), John2005

Personally, I'd remove and reinstall, being careful about locating the plate, and making sure that things are right. I don't know about problems reusing the U bolts, maybe someone else can chime in, AFAIK, they are reusable.
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Hi Peter,
Doing the passenger side, I found out a little more about what is going on.
I took the U-bolts off the passenger side and removed the old top- plate. I cleaned all the rust from around the center-bolt nut very well and I installed the new top-plate over the nut. What I found is that even with the ends of the top-plate sitting on the top of the leaf spring stack, there is still a very small (about 1/6") of space at the center of the top plate between the top plate and the top of the leaf spring stack.
I think this is simply because the leaf springs have a very small arc at the center of the springs (I also checked it with the straight thin edge of the top plate, and there is a space there). It's not much of an arc at the center of the spring stack but it appears to be enough to create a very small space there. It's probably not noticeable on most vehicles because as soon as you drive down the road you get dust, debris, and rust in there. You have to clean everything well to see the space.
On the drivers side, I had about a 1/8" space. I shined a bright light in the space and found a thin piece of rust in there. I would like to just loosen the U-bolts back up, take a chisel to the piece of rust, and then torque everything back down on the drivers side. I had heard you should not loosen and re-torque U-bolts but I have not even driven on the U-bolts and I don't really see what it would hurt. It's probably OK just like it is with the 1/8" space but I like to do things right.
I looked at an 09 Chevy and found the design is a little different than on my truck. On the 09, the center-bolt nut is sitting on top of the top-plate, but on my truck, you cannot even see the center-bolt nut unless you remove the top plate, all you see are threads sticking up before the top-plate is removed.
Another thing I noticed when I took a closer look at my original (old) top-plates is that the hole is hexed shaped. It seems at least originally, the top plate hole was very close in size to the nut and it was pressed over the nut a little.
John
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