'75 Shelby Drop - Outer brace modification

Discussion in 'Technical' started by leeinphx, Feb 3, 2019.

  1. leeinphx

    leeinphx Member

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    This is a summary of the Shelby drop on my 1975 Maverick, LDO edition. I'm replacing all the suspension components in preparation for a Unisteer Power Rack conversion as well as any weight changes from the 5.0l EFI swap. Once all this work is done, will need an alignment anyway, so might as well get everything freshened up and get the drop done.

    The later mavericks have a brace on the outside of the frame to the shock tower located underneath the fender that is a reinforcement. This brace is welded in at an angle that matches the angle of the upper A-arm when it is in full down travel.

    With the Shelby drop of 1", the outside bottom of my new A-Arms would hit this support brace. If you look at the welds, they are on the sides, bottom and top, but there is a lot of material in the area of first contact (top corners) that is really not welded to anything, so I cut that out first. After the first cuts just removing some material the top corners, I just decided to cut off the sides all-together to ensure that the A-Arms would not make contact with the brace.

    The brace is still welded top and bottom, just lost the strength from the side welds. This is not a concern for me, as this car will be a cruiser, not a racer.

    The front of the shock tower provided good clearance at the new location. However, the back had to be massaged out with a BFH. I will have to do some more once the steering box is out of the way, as I hammered it until it made contact with the box, and still had to take the grease zerk out to get the A-Arm in without anything rubbing. I did not have the 90 degree zerk, just planned to drill grease holes in the shock tower once I get everything in. Will do that with the steering swap.

    The two center ribs on the brace were flattened out a little to ensure it cleared the A-Arm bar. Also did just a little grinding to clearance for the bar. The alignment shims do have to go in at an angle, but not a big deal, they seat completely down.

    The brace does make the thickness of the new bolt holes quite a bit more as the A-Arm bolts through this as well. When I drilled out to the final size using my step drill bit, it didn't cover the entire depth, so had to spend quite a bit of time with the Dremil tool finishing the hole size. Will get the proper bit when I drill out the passenger side. That will make this go a lot faster. Started with a small bit, and just worked up close to the right size.
     

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    Last edited: Feb 3, 2019
  2. BBMS18

    BBMS18 Member

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    Very nice write up. Ford did not install that brace for “racing” they felt the family car needed a little extra support on the bottom of the tower.
    IMHO If possible, I would have removed the complete brace, drilled the new holes in the tower then cut the bottom of the brace so it would fit using the original holes.
     
  3. dyent

    dyent Member

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    Thanks for the write up/pictures, I was thinking about doing the drop, but was concerned about the reinforcement brace too, your write up will help other members who decide to do the drop, having the brace!
    As you may know, this brace was added to help strengthen the shock tower to prevent them from flexing/ fracturing, which happened on many early Mustangs which had similar front suspension design. I believe that Mav/Comet (73 and up?) that came with this brace, had the additional wrap around bracing around the shock tower. Great for beefing up the shock tower, but sometimes interfered with headers, as it added another 1/4-3/8", so less clearance between header and shock tower........
    David
     
  4. leeinphx

    leeinphx Member

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    I like that idea of taking it out and shortening it, and re-welding it in better than what I did. Didn't think of that. It's pretty much just tack welded on, so it would come off pretty easily. Mine is still bolted through the brace. That would make lining up the new holes pretty straight forward for the drop as you could use that as the template. To shorten it, you would either have to put a new bend to flange it on the bottom, or just weld it to the top of the frame, instead of the outside edge.

    As an alternative, I guess you could cut it in the middle, and overlap it and weld it back together. This way, you wouldn't have to cut the frame weld, which is the only significant weld they did on this part. Just cut each side loose, cut it in half, slide top down past the bottom and hammer the bottom to the angle you need. Weld it all back in, and drill the new holes through the shock tower.

    Don't think it would affect this car doing it differently on each side, so I might actually give that a try when I get to the passenger side. Will post an update if I do it this way.
     
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  5. BBMS18

    BBMS18 Member

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    That sounds like a good plan, if the passenger side works out better you can post a ad in the “parts wanted” I bet another member would be willing to cut a brace out of a car they are scraping and send it to you at a reasonable price.
     
  6. 71Mavrk

    71Mavrk Member

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    I grafted these into my '71 when I did a TCP suspension with the "Shelby Drop" built in.
    http://mmb.maverick.to/threads/suspension-ideas.102301/page-3

    The side sections are important in tying into the inside bracing which wraps around the shock towers. The inner and outer bracing work together to reduce cracking in the tower and reduce flex. I would look to weld in some metal from the section you removed to return the structural design of the bracing.

    Micah
     
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  7. bmcdaniel

    bmcdaniel Senile Member

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    Maybe I missed something, why do you have alignment shims?
    Has anyone ever had their Maverick shock towers crack? My '70 didn't come with braces and I've had some pretty healthy engines in it and no cracks after 45 years of V8's. Probably 35 of those years I didn't even have a belly bar.
     
  8. 71Mavrk

    71Mavrk Member

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  9. leeinphx

    leeinphx Member

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    All I can tell you is that the shims were already in place when I removed the original upper control arm. Never gave it a second thought that these should not be there so they just went back in with the new Arms. Is this possible that an alignment shop didn't know how to make the lower adjustment and put these in?
     
  10. mojo

    mojo "Everett"- Senior Citizen Supporting Member

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    I have shims 1/8" in my UCA's to get the caster to 3+ to get caster where Borgsen recommends for there PS conversion kit. l could not get that amount w/ strut rod adjustments. It is the least expensive way I am aware of attaining my goal.
    I have had no issues w/ the shims in the 2+ years and few thousand miles in the arms.
     
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  11. groberts101

    groberts101 Member

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    As mojo eludes to above, they were likely added to achieve additional caster without needing to use up all the radius rods adjustment threads.

    Another old-school trick that can be done to these cars is moving the control arms mounting points rearweard by about 1/8 to 1/4" during the shelby drop. Basically the old 65/66 Mustang mod being applied to these cars again(doubled up) even though Ford already moved our cars factory mounting points to those "mod'd 65/66" mounting points. But as you well know, there's not much room in these cars shocktowers to begin with and it's tough to get carried away there without some additional clearance work. Another added tweak could be to offset the centershaft of each control arm rearwards as well. Usually gain another 1/16 to 1/8" these as well. Then you can adjust radius rods to maximize the caster settings without actually nipping on the fenders so quickly.. or at least keep the tire more centered after all is said and done.
     
  12. stumanchu

    stumanchu Stuart

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    I did a little of all 3.... turned the shaft 1/2 turn toward the front, 1/8 shim in front hole, and drilled holes 1/8" rearward of a plumb line dropped from center of original hole. I put a hole in the shock tower for greasing, and the braces got adjusted with a hammer for clearance (1974). I did loose some spot welds, but figured for my usage I could live with it. If you have a welder and skills to reweld, that is obviously better. I also used the lightest weight moog coil spring (8088?) uncut. I really liked the end result.
     
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  13. groberts101

    groberts101 Member

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    Smart man.. ^^^^.. took the cumulative approach.

    If there's one thing that I've learned through a lifetime of hearing people discrediting many of the little tricks and tweaks that can be done to cars and engines.. it's that all the little things being applied in cumulative fashion can and do add up to noticeable and measurable results. Proof's in the puddin'.

    @lee. Too bad the TCP rack and pinion setup isn't being made for our cars. That unit sits quite a bit tighter to the frame rails and has better geometry, especially for lowered cars. But the bracket mounting flange location near the gear on that unit would be tough to move to fit out cars narrower frame rails. Planning on revisiting the TCP unit later on to see if I can modify the bracket for the required additional offset to fit my car. Considering the differences between frame rail and suspension widths it seems odd that same part# fits 64 - 70 mustangs though.

    This one. https://www.youtube.com/watch?time_continue=30&v=V5dRyYHD_u0
     

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