Mythbusting Shelby drop?

Discussion in 'Technical' started by flynbrd, Mar 16, 2011.

  1. flynbrd

    flynbrd Member

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    After reading several posts on the shelby drop I've gathered the loose theory that doing this mod actually will not lower the vehicle.(despite what some people claim) Assuming the statement is true about mid 70s mavericks coming with the shelby drop from factory and the fact all maverick springs are the same length the shelby drop should not effect ride height. If the drop affected ride height the mid 70s suspension springs should be longer to account for the drop right? Hope this makes sense because I'm about to sleep Zzzzz.
     
  2. injectedmav

    injectedmav Member

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    with no other changes, I lowered the mounting holes for the UCA pivot 1.75" and the ride height "dropped" by approximately 3/8". Mine is a Pro-Motorsports engineering kit and their literature specifically states that it will lower ride height. I have found no concrete information that the UCA geometry was changed for the Maverick vs any other Ford with that suspension since it is essentially a carryover from the Falcon line.
     
  3. PaulS

    PaulS Member extrordiare

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    The Shelby drop lowers the MOUNTING POINT of the upper control arm to modify the front end geometry. Any lowering of the car is incidental.
    The front end of the Maverick is based off the Mustang - 68 - 73 (??) I was told by the Ford instructor (Ford program at CC) that the 73 Mavericks that I gave him to perform the drop on did not need it becaust Ford had corrected the geometry by incorporating the drop into the Mustang and cars that used that suspension. He said if I used the alignment specs for the Shelby (1967) then it would perform as it should. He was right! After the alignment to the new specs it was an entirely new car.
     
  4. injectedmav

    injectedmav Member

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    I am just passing on the info I received from the company I bought the parts from and relaying the experience I had when performing the mod. Is it necessary? I don't know for sure but my understanding is that it corrects the fact that the camber goes positive before negative through suspension travel from ride height. I verified this effect on the alignment machine before the mod and after. It went positive(almost .7 deg) for the first 1.5" of travel before it crossed to zero and finally on the stops at 2.2 deg neg. After lowering the control arm, It starts at .5 deg neg and the sweep maintains .5 deg for the first 1" and then to around 2.5 deg neg. It never goes positive. I have changed this set up of late by cutting the springs to achieve the desired ride height and I am about to change it again as I have bought new control arms and I think the 1.75" is too much. The custom designed suspensions suggest in most cases to lower the UCA pivot point with their arms and I just figured they designed it so they know where it should be. It might be interesting to get more insight from a few of the engineers on this matter, so I will try to contact the designer of the UCA that I bought sometime this week. As a side note, I had good results after installing the components I mentioned at the beginning so I did notice some improvement. This is just my experience, not a rule, so I'm open to all experiences and I am not to proud to say I may have been misinformed or flat out wrong either so please don't take this info as argumentative. Just trying to learn as much as I can. I figure with all of the people on this site and others, we're bound to find what works best.:tiphat:
     
  5. dtb147

    dtb147 Member

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    The point that most people try to make is that the ride height change is not equal to the mounting point change which is what some people assume. For the average 1" drop the ride height change is minimal. With the 1.75" drop mentioned, you would see a larger change in ride height as observed by injectedmav. With the standard 1" drop the ride height change could be 0" - 1/4" depending on how accurately it is measured. Not many people do a comparison as detailed as injectedmav. There is also the consideration that many people modify or change their springs when the perform this mod.
     
  6. flynbrd

    flynbrd Member

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    ride height

    I'm trying to make sure my car is going to be level. I have used 4 leaf in the back off a 76 maverick with 1" lower blocks. I'm going to buy 1" drop springs for the 67 stang with the shelby drop being done. Just hoping everything will be level.
     
  7. injectedmav

    injectedmav Member

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    Mine took some fine tuning. A few years after doing the initial drop, I replaced the strut rod bushings and lower control arms and I decided to lower the car. I bought 67 Mustang big block springs and cut 1.5 coils off to start with and it sat up in the air like it didn't have an engine. In the end, I cut more like 2.75 coils total. I still run 1" lowering blocks in the back with 4 leaf springs and I have a slight rake of 1/2". Point is, while I hope the best of luck to you getting it right the 1st time, it may require pulling them back out after the initial install to fine tune it where you want it.

    btw: if it's only slightly high with new springs, leave it alone for a while to see if they will settle in. New springs tend to relax on average about a 1/4" over time. :D
     
  8. injectedmav

    injectedmav Member

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    Just an update on the questions presented. I did a little more digging and I have found a thread that discusses the same issues with the Shelby or Arning drop but from the perspective of bumpsteer. I had forgotten what led me to this to begin with when I did the upgrade, and bumpsteer with the wide tires I was using and excessive tire wear when cornering hard was my major concerns at the time. My original purchase of this kit was in 1998 and all the info I had at the time was from sources that were touting the advantages of the drop. I am really on the fence on this upgrade now after more years and more research and there are a lot more options that are available to get the same effect. I personally believe that for the money and what you get, the 1" drop is more than sufficient. The 1.75" drop is excessive for anything other than autocross and if not used in conjunction with their (ProMotorsports) bumpsteer correction kit, will give you what I believe is excessive bumpsteer. Most manufacturers that build custom suspension systems know what is necessary when engineering the parts and they all have their preferences on the specific settings and/or mounting locations. It seems to me that systems that are designed as packages are the better choices as they have most of the design flaws worked out. One thing to keep in mind is we are meddling with things that were designed to do much less than what we are asking of them now. We are running much wider, stickier tires, lowering the suspensions and driving much more aggressively than was the norm when our "economy car" was built. Quite honestly, I had never heard that the drop was incorporated into later cars as Paul S has said a few times, but it certainly peaks my interest in regards to when specifically this was incorporated and what would need to be done to compensate when we modify these cars. Sorry for my long-winded babbling, so I'll wrap it up. I am installing the Street or Track UCA's which is going to require that I weld up the holes that I made for the 1.75" drop because their template indicates about a 1.25" drop. I also ordered roller perches and the hiem-joint type adjustable strut rods, and the Baer Tracker bumpsteer correction kit with adjusting sleeves. I will post with pictures as I get things done and we'll see how good I can get this old suspension design to hang a curve for the least amount of money. If anyone has anything to add or suggestions, feel free, I would love to hear them. I like to find out the good, the bad, and the ugly before I throw my hard earned greenbacks at anything.

    Sorry if this is hijacking, just trying to open up the discussion. :16suspect

    Btw: for those interested, the link to the info on the bumpsteer I referenced is: http://www.corner-carvers.com/forums/showthread.php?t=26792

    Note that he had no positive camber gain as I experienced. I imagine that all of these cars, while from the same design, have substantial differences due to manufacturing, fatigue, parts sourcing, susp setup, wear and tear, modifications and just being out of adjustment. Suspension height when measurements are taken plays a huge role on camber gain as well and I was lowered at least 1.5" if not 2" by my recollection. :tiphat:
     
  9. mjm0395

    mjm0395 Member

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    I was thinking about doing this and was wondering...In the branda cobra catalog it has a template to follow for the new hole locations. Do we actually need this for our cars? I thought it was to correct understeer? I am not interested in lowering my car, so what are the advatages vs dissadvatages? (sorry about spelling)
     
  10. Hottrod1991

    Hottrod1991 Member

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    I dont know why it'd be a myth, the aftermartket control arm combo from total control "TCP" has the drop built in..so you dont have to drill new holes in the car..

    now if someone is doing the shelby drop with the TCP contol arm or coil over setup then I can see a problem.. double negative making bumpsteer worse then stock
     
    Last edited: Mar 26, 2011
  11. Speedy

    Speedy Member

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    I've bought all new moog parts and have the front end stripped. Roller perches and roller Idler, also. Im really pumped up with the build. However, I was going to do the Shelby drop and the spring perch move, even considering the mavman spring cut thing w the mustang springs.
    The perch move would help the spring cut from my understanding anyway...,

    Anyway, I started this week-end and found ther's not enough room to lower my UCA's more than 1/2". And that will require some persuation with the sledge or press...
    Has anyone had any experience with the shelby drop?
     

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  12. 71Mavrk

    71Mavrk Member

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    I'm curious about the drop being integrated into later cars. I have never heard this before. When did this supposedly take place? I say this because I grafted the reinforcement plate from a '74 into my '71 and the mounting holes were in the same place.

    Also, the TCP suspension is amazing on these cars.

    Micah

    [​IMG]



    [​IMG]
     
  13. Speedy

    Speedy Member

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    That looks awesome by the way
     
  14. stumanchu

    stumanchu Stuart

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    My car had cut springs, worn out upper control arm bushings, and was sitting 1/2 inch from the stop. It is a 74. I removed all the suspension, and am going to use all moog replacement stuff (8088 springs). I did a 1" UCA drop by scribing a line parallel with the bottom of the frame and lowered my holes 1"( perpendicular to that line) and 1/16" to the rear. I installed a 1/8 shim on the front UCA bolt, installed lower control arms and Granada brake spindle. I had to flatten out the support below the UCA original holes with a hammer, and hog out enough material on the sides of that support bracket to make room for the control arm and bushing. (the pic Micah posted above is what you need to do. I used a die grinder with a burr bit) I put a 90 degree zerk in the front bushing and drilled a 9/16 hole through the shock tower to access the rear zerk. The towers do not require a ton of effort to adjust with the hammer......I was surprised.

    So....I am now experimenting with camber settings. The car is raised, and the front frame where the strut rods bolt is level. with the suspension fully down (No springs yet) I adjusted the camber to zero (level placed on rotor shows it to be perpendicular). when raised to the full up position, the level when placed against the rotor (8 inches long) is 1/4 inch away from the rotor at the top. According to the right triangle calculator I found, this is 1.8 degrees negative. This is as far as I have gotten for now.
     
  15. jasonwthompson

    jasonwthompson Member

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    I used control arms that had the 1 inch drop incorporated into the mounting shaft. The front height dropped about 3/8 of an inch. No Mavericks ever had the Arning drop from the factory, no matter what anyone may tell you.
     

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