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So I decided to try the Shelby drop using a template I bought from daze cars. Once I got all the suspension removed and installed the template, I started with a*17/32-inch bit and drilled the initial hole (but thinking back on it now I guess my mistake was removing removing the template which I did thinking in I would have the same size template holes for the other side.) After drilling the 1/2" holes, i found out that they are not aligned correctly. They are just a tiny bit too apart from each other. I'm just curious what I can do to correct this without making a bigger mess? Should I drill one of the holes out to be 9/16"? Or should I just go with control arms like Specialty Products Company Adjustable Control Arms which give the Shelby drop from the factory holes?*

https://www.cjponyparts.com/specialt...-1973/p/UCA61/
 

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You mentioned 2 things.: Not aligned correctly and also they are a bit too apart.

How much is a bit? 1/16", 1/8", 1/4"?

If they are only a bit too far apart (1/16") but aligned correctly, you could ream out the insides (using the original template to ensure accuracy and you do not take too much off)
 

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You start with an 1/8” bit, then 1/4”, 3/8”, 17/32”.
 

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When I did mine, I had one hole off by about 1/16”.
This was when I was stepping up as mentioned above, so I was not at final size.

One of the smaller steps, I went in with a little carbide bit and opened up only one side of one hole.

Then when I stepped up to the next bit, it recentered and worked perfectly.
Getting that pilot hole spot on is CRUCIAL.



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I just did my holes though the car isn't back on the ground yet. I used the the template from Day as well as the DIY roller perch kit. I started with an 1/8" pilot, removed the template then stepped it up to just below 1/2" where I finished off with the 17/32".

This thread can serve as a reminder that it's best to step up (by either multiple drills or step bit) to just under the finished size then finish it with the desired size. Guys that aren't used to drilling metal with larger holes may not know the ins and outs of getting the hole to the right size.

 

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I just did my holes though the car isn't back on the ground yet. I used the the template from Day as well as the DIY roller perch kit. I started with an 1/8" pilot, removed the template then stepped it up to just below 1/2" where I finished off with the 17/32".

This thread can serve as a reminder that it's best to step up (by either multiple drills or step bit) to just under the finished size then finish it with the desired size. Guys that aren't used to drilling metal with larger holes may not know the ins and outs of getting the hole to the right size.

Sliced bread takes a back seat to a quality step drill bit! A quality step bit is not cheap!. An electrical supply house is the place to buy.
 

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Thanks guys. :yoho: The wells and underside were mostly covered in old oil, grease and kack. I'm pleased with original condition. I only wanted to clean that much because I want to drive it. A good soak with purple Zep degreaser, some Simple Green, elbow grease, the Krug Thug, Scotch Brite and it came out well. I finished that well with Krylon 1613 until I tackle refinishing the entire front under hood.

The stepper bit was surprisingly Harbor Freight. I've had it a while and this was the last two holes it did. Not bad. I'm looking at Amazon right now for the Greenlee set and yikes it's about $100 for the three piece. Quality costs.

If anything our posts can help convince/guide someone through doing the drop. It's nearly free and I'd say easily the most cost effective mod for the front end even if you don't change anything else.

 

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I usually use a good sharp 1/8" bit to start a hole as easier to get the centers right, but then the step bit does the rest of the work. As others have mentioned, step bits are one of those tools that once you use it, you wonder where it has been all your life. Especially effective on thinner sheet metal where regular bits make a twisted mess on larger holes.
 

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I took a 3/16" thick steel plate and drilled 2 1/2" holes and 2 17/32" in it holes on the drill press. I bolted the plate to the factory holes with the 1/2" plate holes and drilled new 17/32" holes in the shock towers using the bottom holes in the plate. Checked them with short digital calipers. Elperfecto !
 

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WHen I did mine, I dropped them straight down on my 66. I couldn't get any caster for years until I figured out my mistake. The next time I had my motor out I rat-tail filed the holes to the correct location then welded the other side, ground the welds flat and used the rat-tail to complete the holes. While I was at it, I welded up the old holes. Soooo, I pity the guy that gets my car in the estate sale, cause he is gonna think the Shelby drop was never done adn create a monster of a mess...
 

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Just put me in your will...

WHen I did mine, I dropped them straight down on my 66. I couldn't get any caster for years until I figured out my mistake. The next time I had my motor out I rat-tail filed the holes to the correct location then welded the other side, ground the welds flat and used the rat-tail to complete the holes. While I was at it, I welded up the old holes. Soooo, I pity the guy that gets my car in the estate sale, cause he is gonna think the Shelby drop was never done adn create a monster of a mess...
we can save that whole "estate sale heartache" thing. I'm here to help.....
 

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The stepper bit was surprisingly Harbor Freight. I've had it a while and this was the last two holes it did. Not bad. I'm looking at Amazon right now for the Greenlee set and yikes it's about $100 for the three piece. Quality costs.
the HF step bits are surprisingly good bits, I have quite a few.


I used the Daze template on mine also, it's been a while, but iirc the instructions even say to start with a pilot and step up from there.
 

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Just be careful, double check along the way. The template and starting at 1/8” isn’t fool proof.
I thought I was being careful and mine got off a little bit.
I fixed it to perfection, but just pay close attention.




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