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  1. #1
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    Default Factory Build Quality

    Well, I have finally gotten back on the 84 Turbo GT build. Installed the MM K member. I have been having trouble getting the diagonal alignment right. Front to rear is dead on, but have the K member all the way to the right and the left rear to right front is 1/4 " less than the right rear to left front.

    My first thought was that there was some front end damage that I had not seen. I started looking for any kinks or ripples in the engine compartment. I have the motor out and this being a rust free California car, I can see all the welds, and all are factory. I started doing measurements and first found that on the passenger side the distance from the fender bolt hole nearest the firewall to the fender bolt closest to the front of the car was 1/2" less than the driver side. It looks like the front core was welded in crooked at the factory. Other measurements were just as bad.

    I suspect the build tolerances allowed are probably the issue with the K member alignment issue. Since the front to back is dead on, does anyone have any thoughts on the 1/4" out of square will have any effect on handling or tire wear? The MM spec is 1/8".

  2. #2
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    82GTforME's Avatar
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    Not sure I can answer the operational issues with the 1/4" difference. I would honestly think it would even be noticeable if the wheels are aligned properly but I could be way off. With mine below I have no noticeable drivability issues.

    For discussion, here are the measurements I took using four plumb bobs and putting a factory K member back in. I had three measurements for fore and aft and two for diagonal. The fore and aft measurement is 1/8" out and I could not get it closer. Note that I did NOT have really much movement but ended up pretty close.

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    When you do the alignment, I used string lines to do toe settings. you could try to confirm the 1/4" side to side difference if it still matters.

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  3. #3
    FEP Super Member xctasy's Avatar
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    Final check is on where the wheels sit after the k memeber is adjusted to suit. 82GTforME has it.

    1/8" is typical and fine. Jag XJ-6's, XJ-12's and XJ-S's were potentially 155 mph cars with modified engine, and they were 1/8 inch longer on one side than the other because of how the jigs were welded. Often much more.



    When you do the alignment, I used string lines to do toe settings. you could try to confirm the 1/4" side to side difference if it still matters.
    In the end, try to adjust the front k member to suit the correct postion of the the wheels. Even the later Fox 4's shifted the K member almost 1 inch further forward on the frame to improve crash protection. You can change the frame mounts, add a 17 mm spacer to the gearbox, do all sorts of stuff to make one side longer or even shorter. A unibody is never sqaure, its a giant mechanno set with spot welds instead of bolts.

  4. #4
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    Thanks for the input guys. I did use 4 plumb positioned per MMs instructions. on the rear, they were hung off the threads against the nut on the lower control arm mounting bolts, seemed a little sketchy to me, and on the front, they were hung from holes in the K member specifically designated for alignment.

    I am going to give this another try. If I cant get any improvement, I will probably see if there seems to be any handling or wear issues after I get the car back together.

    Tomorrow, I'll give MM a call to see what their take is on this problem.

    Maybe the person who assembled the front of this car was having a bad day.

  5. #5

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    If you look at the factory k-member, one of the upper bolt holes is barely larger than bolt. The other three holes are all different diameters. The further the hole is from the small hole, the larger diameter it is. I believe that Ford's design intent with this is to allow the k-member to be pivoted around the small bolt hole when installed. This will allow the front and rear axles to be made exactly parallel to each other, but it does not guarantee that the front axle isn't offset laterally from the rear axle. Ford has massive creepage and clearance requirements for the gap between the front tires and fenders. 0.25" to the left or right, is probably designed in as part of the tolerance on the k-member position.

    Having the front and rear axles parallel to each other has by far the greatest affect on handling and tire wear. If the front axle is offset laterally from the rear axle, there will be some asymmetries to the handling, but these will be much smaller.

    When measuring with the rear plumb bobs, everything must be done correctly. The RLCAs must be installed. The nuts must be on the outside of the frame rails. The nuts must be the same models, so that they have the same overall thickness. The strings must both be wrapped around the bolts so that they are both behind the bolts or in front of the bolts. The torque box sheetmetal must not be in the way of the string.
    Jack Hidley
    Maximum Motorsports Tech Support

  6. #6
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    What you describe as far as the plumb bob placement on the rear is exactly what I have done. The front to back is dead on on both sides. Just the diagonal is off by a quarter of an inch, the spec being 1/8 of an inch. I was hoping to get this much closer.

    I know on top, the the the issue is that the diagonal is going to be off. The radiator support is factory welded in nearly 1/2" inch closer to the firewall than the driver side. This is visually obvious as well as measurably. What I am most concerned about is front frame rail alignment.

    Maybe I am being too OCD on this, but dealing with this now will be easier than after the car is finished.

    I am going to do additional measurement underneath to try to see if there us something that is not obvious. I have ordered a trammel gauge to assist in this.

    Just to clarify, this is a 84 1/2 Turbo GT Convertible. Closer to an 85 GT from suspension and some body standpoints than an 84.

    This is my dream build.

    Again, thanks for all the valuable input.

    BTW, I am hooked on the 2.3 turbo. I also have an 84 SVO. Keeping it close to stock.
    Last edited by Tordaan; 09-17-2019 at 12:55 AM.

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