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Thread: Another Nomad project... :)

  1. #111
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    There are two areas I'd be concerned about if 1/4" of shims was used everywhere. One, the bumpers will be low. Two, if you have a steering box, you're going to have column to steering box misalignment.

    I don't know why you wouldn't want to use the square shims that are sold to be used with the replacement body mounts.

    If it was my car, I'd just drop the body on without shims, then inspect for obvious gaps at every mount, and add shims where there were gaps. If you started with shims, intending on removing shims either side of where you saw a gap, I just think you'd be chasing around and doing more fiddling with shims than the other way for no advantage. Once you have the gaps that you eyeballed shimmed up, you can start torquing the bolts, obverving whether some locations tighten more quickly or less quickly than others, and watching the door gaps. You may have to do some addition adding or removing shims at that point.

  2. #112
    Registered Member BamaNomad's Avatar
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    Quote Originally Posted by chevynut View Post


    Or the body mounts on the frame aren't properly located. It wouldn't be hard to measure them to find out.


    Yes, I plan to do that. Richard has an 'empty frame' at his shop so I will measure it next time I'm there. I've measured the high and low mounts on the Corvette corrections frame... I had sold the original frame before I noticed the issue...


    Quote Originally Posted by chevynut View Post
    Shimming shouldn't cause any problems. If it was me I'd make some custom shims or use large washers like the ones on the body mounts. GM used some large square shims at the body mount locations. But you really need to shim to make sure your door gaps are good, and/or adjust them afterward. I'd consider cranking down at least some of the body mounts first with the doors open and see where things end up.
    Richard and I made some 1/4" thick square shims with center holes for the shimming, but I can't decide whether to reduce the height of the tall ones, add to the short ones, OR just start cinching down as you and Rick suggests and see what happens. It's a "new" problem for me and I don't want to be hasty in my decision...

  3. #113
    Registered Member BamaNomad's Avatar
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    Quote Originally Posted by Rick_L View Post
    There are two areas I'd be concerned about if 1/4" of shims was used everywhere. One, the bumpers will be low. Two, if you have a steering box, you're going to have column to steering box misalignment.

    I don't know why you wouldn't want to use the square shims that are sold to be used with the replacement body mounts.
    I'm not planning on using them *everywhere*, only where I have 1/4" or more space to make up. I am using the thin shims where appropriate. I like to have all the mounts shimmed to no/little gap before I tighten down any mount; that generates the least body distortion. I have a R*P steering, so that's not an issue, but the possibly 1/4 bumper situation bothers me a little, as I'm not sure that the bumpers have that much adjustment (been a long while since I've adjusted a trifive bumper!)..

    Quote Originally Posted by Rick_L View Post
    If it was my car, I'd just drop the body on without shims, then inspect for obvious gaps at every mount, and add shims where there were gaps. If you started with shims, intending on removing shims either side of where you saw a gap, I just think you'd be chasing around and doing more fiddling with shims than the other way for no advantage. Once you have the gaps that you eyeballed shimmed up, you can start torquing the bolts, obverving whether some locations tighten more quickly or less quickly than others, and watching the door gaps. You may have to do some addition adding or removing shims at that point.
    That's what I've done and I've experimented with thinner rubber spacers where the body hits first, but unsure which will work better (shimming up) or reducing the taller mount shims~ I probably won't be CERTAIN which way I should have accomplished it until the bumpers are on and adjusted... so I'm fretting about it.

  4. #114
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    I had to go back and read your post where you described the gaps. I must have not read that in detail previously. I don't know how I missed that.

    Do you have the body sitting on the cowl mounts and rear frame crossmember mounts without shims? And several others have 1/4" or more gap? That's the way I read it now.

    Given that, I would make up some 1/4" square spacers to use in the big gaps. Same size as the regular shims. Round ones would do too. Just depends on what you have available for material, and what would get built with the least effort with the tools you have available. You might also want to make up some 1/8" thick ones too. I wouldn't use rubber, I'd use steel or better yet aluminum. Then just start filling the gaps. Again, once you get to tightening the bolts, watch for any that seem to be reluctant to tighten up, which would indicate you're pulling on the body and more shim might be required.

    If you don't have a big shim stack under the cowl and rear crossmember mounts your bumpers should be OK, or at least as OK as they would be if this problem didn't exist.

    Does that guy in TX build an entire new frame or modify a stock one like Cnut does? If it's a new frame, I wonder how he jigs up the body mount brackets and does he plan on using extra shims?

    Hope that floor pan screwup doesn't cause other problems. I would also try to check and see if each side turns out similarly. You wouldn't want the body to be tilted side to side. It's all probably ok though if the rear crossmember and cowl mounts are close at all.

  5. #115
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    One more thought. You said the floor was replaced. Was the cargo area floor replaced too? Just wondering if the tail pan brace is in the right place. You might be able to tell by looking. If the tail pan brace is too high that would screw up a bunch of things.

  6. #116
    Registered Member BamaNomad's Avatar
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    Yes, the cargo floor was also replaced. I began by placing the reproduction pads (1/2" rubber with a steel washer integrated into them) on each mount (by specification). When I lowered the body until it hit, it hit the four central mounts first, and left a 1/8" or 1/4" gap at several other locations (including 1/4" gaps at the rear most mounts).

    Billy Dawson (Corvette Corrections) builds the entire frame using a JIG, so all his frames should be very close to the same as another, but I am going to compare the mounts to a stock frame. I really think the issues are due to how the floor was installed in the body (I'm thinking the builder did them on a rotisserie rather than on a frame)... but I don't know for sure.

  7. #117
    Registered Member chevynut's Avatar
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    Quote Originally Posted by BamaNomad View Post
    Yes, I plan to do that. Richard has an 'empty frame' at his shop so I will measure it next time I'm there. I've measured the high and low mounts on the Corvette corrections frame... I had sold the original frame before I noticed the issue...


    I'd just use the dimensions in the frame drawing to check the mount locations relative to each other. Then shim the ones that are off.

    You can build a frame in a jig, but that doesn't mean things won't move around when the frame gets welded up. Typically you can't do all the welding in a jig. A jig can LOCATE parts, but it can't necessarily KEEP the parts in the right location. I can easily see the rear of the frame drooping after welding. We've used a torch to heat and correct rear frame sag on a stock frame before.

    Last edited by chevynut; 08-16-2018 at 05:40 PM.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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    2019 GMC Sierra Denali Duramax

  8. #118
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    Well that sounds more complicated than I had envisioned. Are you actually going to lower the body onto the spare frame with mounts in place? That's probably the only practical way to evaluate that. Good luck. I don't see trying to measure the height of each body mount bracket on 2 frames and getting accurate results.

  9. #119
    Registered Member BamaNomad's Avatar
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    No, I'm only going to measure the relative height of the four central mounts as compared to the peripheral mounting points. My body comes down on the four central mounts solid, with the gaps (shims required) around the peripheral mounts ranging from 'zero' to 1/4". I just checked this again tonight, and maybe I'm making a mountain out of a molehill, but I'm still going to Richard's tomorrow and check the mount heights on his frame. PS. I am doing this with a long straight edge across the central mounts and measure the gap at the peripheral mounts.

    This issue, in my mind, is caused by using a new custom frame, AND a body with a new floor, that I had nothing to do with either prior to purchase, and the results are significantly different than what I'm used to with stock body/floor and stock frame.

  10. #120
    Registered Member chevynut's Avatar
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    I'm betting the rear of your frame is lower than it should be based on what you're describing. That gives the appearance of the middle of the frame being too high but it's easier to get the middle ones right because they're on the same piece of steel. I think I recall that the rear of the frame was welded on and is not part of the main rails, so it's most likely to not be in the correct location.

    The assembly manual has all the dimensions for every body mount height off the datum. You could put some sort of straightedge or string line on the front mounts at the appropriate height and measure the heights to the rest of the mounts relative to the string to check the frame. Or you could just shim it and forget it.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

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