[mrennie]

Hi,

I'm working on alignment of my panels before I disassemble for final bodywork and paint, and need some advice on shimming the core support.

I've seen drawings that show there were shims that could be added, but I am not familiar with how you would determine when they are needed. I currently do not have any shims between the core support and frame, and the hood latch and bumpers have not been installed yet.

I am using new reproduction hood, fenders and core support, and have everything except the inner fenders and front valance on so far. I am getting about as close as I think I can get with these parts, but one thing I am seeing that needs addressing is the front driver's side of the hood sticks up higher than the passenger side at the nosecone.

What I mean, is that when I close the hood, the passenger side is flush with the nosecone and fender but the drivers side sits about 3/8" high. I can push it down with my thumb and then it aligns OK along the length of the fender, but it is seems like the hood is either twisted or the front of the DS fender is a bit low compared to the PS fender.

I am thinking that adding a few shims to the DS of the core support would raise the DS fender and improve the fit of the hood, but then I don't understand why shims would only be needed on one side of the core support and not the other.

Any advice?


Thanks!

[400 4spd.]

There is a lot of info I could throw at you about panel alignment, but let me ask a couple of questions.
Are the fender bottoms hitting the rocker panel ends?
If you lay a straight edge along the rocker and lower fender, are there gaps indicating the bottom of the fender is twisted?
Is the hood latched installed?
If so, does the opposite hood corner raise when you push down on the driver's side?

[mrennie]

Originally Posted by 400 4spd.

There is a lot of info I could throw at you about panel alignment, but let me ask a couple of questions.


Are the fender bottoms hitting the rocker panel ends? The DS fender seems tight and I need to push it away from the rocker slightly to get it to slide into place. The gap on the DS door to fender is also slightly tapered at the bottom while the section above the body line is good. The PS fender touches the rocker without any extra effort. This, along with hood issue, makes me think front of DS fender is too low...



If you lay a straight edge along the rocker and lower fender, are there gaps indicating the bottom of the fender is twisted? Yes, on both sides if I hold the rear of the fender flush with the rocker, the the front edges twist inwards a bit. To get them straight with the rocker I have to tighten the rear bolt, then pull the front into alignment and then tighten the front bolt. I am using shims at the bottom of the fenders as required to stretch fender and pull body line into place.


Is the hood latched installed? No, no latch or bumpers installed yet.


If so, does the opposite hood corner raise when you push down on the driver's side?

See my answers above, and your help is appreciated.


Thanks!

[mrennie]

I'm thinking about this some more...the rad support is mounted below the frame so I think adding shims would pull it down, would it not?

[Chief of the 60's]

Dozens of variables can be had here. The obvious was already touched upon and that is how the bottom of the fenders fit. If the front edge of the bottom of the fender kicks out that could be an indication that the core support needs to be shimmed up, but not always a telltale sign. Somethings shims were added to the upper front mounting point of the fender to correct the same issue. However, if you need to add a 1/4" of shims to the upper front of the fender (which will look hideous), that IMO calls for more shims at the base of the core support.

[HWYSTR455]

You're using an aftermarket core support? Which brand?

My core support required a lot of work to fit right, which is why I'm curious.


.

[mrennie]

Originally Posted by HWYSTR455

You're using an aftermarket core support? Which brand?

My core support required a lot of work to fit right, which is why I'm curious.


.

Generic Taiwan brand. Came from a Canadian auto body panel supplier, equivalent to whatever Sherman or Keystone would sell in the US. It didn't come in a box, it was shipped loose to the Napa store on their truck so I can't say for sure which brand it was.

I know the bottom rail was not welded correctly and I spent many hours fixing that, so entirely possible the thing is not square or has a dimension that is wrong.

[R68GTO]

Originally Posted by mrennie

I'm thinking about this some more...the rad support is mounted below the frame so I think adding shims would pull it down, would it not?

That is correct. If you add a shim between the core support and the frame horn the front of the fender will go down. The other question I would ask is how tight is the core support to frame bolt on each side? Put a wrench on it, tighten/loosen it and watch how far your fender moves in relation to your nose. It is surprising how much it moves.

[mrennie]

Originally Posted by R68GTO

That is correct. If you add a shim between the core support and the frame horn the front of the fender will go down. The other question I would ask is how tight is the core support to frame bolt on each side? Put a wrench on it, tighten/loosen it and watch how far your fender moves in relation to your nose. It is surprising how much it moves.

Thanks, I will check that. I haven't torqued them to spec but thought they were pretty tight.


I will also try to get some measurements to see if the height from the bottom of the the frame to the top surface of the support are the same on both sides. If not, then either support is off of perhaps on of the bushings has an issue.

[mrennie]

I checked the bolt for the bushings and they were tight. I measured distance from the bottom rail of the rad support to the top rail and the DS is 3/16" shorter, so this is making sense...except it means the support is out of whack.

For a quick test, I put a 1/8" shim under the front of the DS fender and after tightening everything back up, now the hood is evenly raised 1/8" above the nose rather than flush on PS and 3/8" high on DS.

So I don't want to use shims on the top of the support, so I guess I'm going to have to shorten the sleeve in the bushing to move the rad support up?

Repop parts are such a PITA at times.

[mrennie]

I cut a piece of tubing 1/8" shorter than the original bushing and used that to test, and after tightening everything up, hood fits great....except now my gaps are off so I have to go over them again.

At least I found something that makes sense and is fixable.

If after I've got everything aligned and gapped this seems like the right fix, I will turn the original bushing down by 1/8" and will probably have to shorten the harder rubber insert on the bottom of the rail by a similar amount to keep the rubber "squish" to what it was. Right now the top side rubber is squeezed more than normal since the bushing is shorter.

[mrennie]

Wanted to provide a few follow up pics in case someone else is looking for help with a similar issue later on.

Also wanted to mention that my previous thought about trimming the bottom rubber insulator to match the shorter bushing would have been a mistake.

The bottom insulator is a harder rubber than the top one, and it is this piece (along with the steel bushing or sleeve) that sets the height of the rad support. If I had shortened the steel bushing but trimmed the rubber insulator, the net result would be no change in location of the rad support as the effects would have cancelled each other.

So I am going to leave the rubber pieces as is, a bit extra "squish" in the top insulator doesn't seem to hurt anything.

[scott70]

That looks alot better....good info. Im sure I will be going through some of this myself this winter. Funny to watch some original GTO commercials and seeing how far off some of the alignments were.