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So, when I last left this project (years ago) I was in the process of fitting convertible inner rockers into my 65 coupe. The reason for this was to stiffen up the chassis for some spirited driving / Autocross / some HPDE events. At least that was the plan. The inner rocker was purchased from Mustangs Unlimited back around 2010 or so. I removed the coupe inner rocker and was getting ready to weld in the convertible inner rocker. The issue I am having is that the convertible inner seems taller in the center, particularity where the door opening is. Now I am aware that reproduction parts may need trimming, but as you can see in the pictures, it may be significant trimming, and likely into the spot welded area.

I am hoping someone who has replaced the inner rockers on a convertible can weight in on this. Do the reproduction inners need trimming when being installed in an actual convertible?

Front DS , as you can see the inner and outer rockers are the same height. And the lower edges are lined up.
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Lower edge of rear rockers are lined up
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As you can see, in the door opening, the inner rocker is much taller, and in the next photo yo can see where the original PS inner rocker is slightly lower in the door opening
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Would it be possible for someone to measure the height of an original convertible inner rocker? I am thinking I can slice a little off the top and bottom welded areas, and then shape the top to be lower through the door opening. But before I do that I would like to know the height of an original inner rocker on a convertible.

Thanks!
 

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I know it's not much help but I recall being warned of this very issue if I was to install the vert inners on my 66 coupe. I could try to dig up the link that another member shared with me.
 

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In the area circled in red it certainly appears that the metal has been cut or ground down to match the door opening.
 

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The hem at the forward edge of the inner rocker is taller. Your aftermarket inner rocker is folded, rather than stamped, and will require trimming. This is normal.

This is a stamped reproduction center rocker, you can see the top edge follows the profile seen in your images.

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With aftermarket convertible inner rockers, they are not like factory pieces. Looking at a stock (or aftermarket) outer rocker, if you put a straight edge on the bottom of the rocker (along the door opening area), there is a rise in the pinch weld area 19"+/- aft of the torque box. Stock inner rockers are built with this "bend" in them to account for the fitment of the torque box and to match the outer rocker, which is 3/4" +/- at the torque box. A little modification to these parts is necessary so you don't have a bunch of fitment issues.

Taking a stock replacement part (69-70 are different on the inside are but the same mod applies) measure back from the bent flange 19". Remove this section of the stock backing plate by drilling out all the spot welds and cutting at your sharpie mark with a cutoff wheel. While your cutting, draw your same 19" reference mark on the inside of the rocker to basically cut it in half, but do not cut the bottom of the part (it will easily bend at this point, see below picture) and cut through the lower pinch weld area up to the bottom of the "box". This cut needs to be tapered from top to bottom, its only 3 degrees. A good gap at the top is right at 3/16" and tapered down to the width of your cutoff wheel (the thinner the better).

You will need 2ea pieces of 14ga CRS 20.5" x 7.625". This is the minimum size needed and will add the 7/8" lip for the lower A pillar attachment flange on top, which the replacement part does not have. I'll try to explain the measurements, but I should probably do a drawing. Measuring 19" from the left side of your new metal, draw a line all the way across at 90 degrees. This will be the tangent line of your bend once everything is laid out. Measure up 3/4" on this line from the bottom and at the edge of your sheet on the right side and connect your points. (90 degrees) From your 3/4" mark, draw a line from the bottom left corner to this intersection. From the bottom left corner (I'm laying this part out like the lower picture for reference) measure up 6 7/8" (or 3/4" down from the top on the left side) mark this measurement , then draw a line to the top of your 19" vertical line you started with. Cut the two triangles from your part, top and bottom and bend your tab (which I like a little larger for trimming once the torque box is in place) making sure that you have a left and right side part. I clamp the new parts all together on a flat table and tack weld everything in place. Once verified, solid weld all cut seams and rosette weld it back together. These parts had a billion spot welds that I filled back in. I also like to add a solid cap on the forward torque box end, to rosette weld to once these are installed.

760148
 
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Discussion Starter #8
With aftermarket convertible inner rockers, they are not like factory pieces. Looking at a stock (or aftermarket) outer rocker, if you put a straight edge on the bottom of the rocker (along the door opening area), there is a rise in the pinch weld area 19"+/- aft of the torque box. Stock inner rockers are built with this "bend" in them to account for the fitment of the torque box and to match the outer rocker, which is 3/4" +/- at the torque box. A little modification to these parts is necessary so you don't have a bunch of fitment issues.

Taking a stock replacement part (69-70 are different on the inside are but the same mod applies) measure back from the bent flange 19". Remove this section of the stock backing plate by drilling out all the spot welds and cutting at your sharpie mark with a cutoff wheel. While your cutting, draw your same 19" reference mark on the inside of the rocker to basically cut it in half, but do not cut the bottom of the part (it will easily bend at this point, see below picture) and cut through the lower pinch weld area up to the bottom of the "box". This cut needs to be tapered from top to bottom, its only 3 degrees. A good gap at the top is right at 3/16" and tapered down to the width of your cutoff wheel (the thinner the better).

You will need 2ea pieces of 14ga CRS 20.5" x 7.625". This is the minimum size needed and will add the 7/8" lip for the lower A pillar attachment flange on top, which the replacement part does not have. I'll try to explain the measurements, but I should probably do a drawing. Measuring 19" from the left side of your new metal, draw a line all the way across at 90 degrees. This will be the tangent line of your bend once everything is laid out. Measure up 3/4" on this line from the bottom and at the edge of your sheet on the right side and connect your points. (90 degrees) From your 3/4" mark, draw a line from the bottom left corner to this intersection. From the bottom left corner (I'm laying this part out like the lower picture for reference) measure up 6 7/8" (or 3/4" down from the top on the left side) mark this measurement , then draw a line to the top of your 19" vertical line you started with. Cut the two triangles from your part, top and bottom and bend your tab (which I like a little larger for trimming once the torque box is in place) making sure that you have a left and right side part. I clamp the new parts all together on a flat table and tack weld everything in place. Once verified, solid weld all cut seams and rosette weld it back together. These parts had a billion spot welds that I filled back in. I also like to add a solid cap on the forward torque box end, to rosette weld to once these are installed.

View attachment 760148
THANKS!!

Definitely saving this post!!

I did some measuring this afternoon. The distance from the bottom of the inner rocker seam to the top of the top seam is just about 5 1/2" near the front of the door opening. The height of the replacement inner rocker is just about 6". Did you wind up doing any additional shaping/trimming? I can trim about 1/4" +/- from both top and bottom spot weld seams to get that 1/2", then do the "bend mod" on the inner rocker.

If I am understanding your description of the new portion of the flat inner rocker, the bottom obviously follows the spot weld seam, but the top edge is parallel to the portion of the rocker that was not bent up? Sound right?


Thanks again!

Rusty
 
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