The Stovebolt Site Forums The Shop Area The HiPo Shop Another Mustang II issue

I've installed a Speedway bolt-in MII in my '50 3100. I followed the template instructions, measured numerous times before drilling, however, after all bolts were tightened, one side is a 1/4" forward/rearward than the other side. Just wondering if I should just loosen all bolts and see if I can get close to square,(or square), by re-tightening the bolts one at a time if I can get it to move enough. Thoughts and suggestions?

When you say one side is 1/4" forward of the other one, what is your frame of reference?

As I recall, all the measurements the instructions have you make are relative to frame features on their own side.

If there is enough slack in the bolt holes to rejockey that setup, then your holes were drilled too big. If you are able to line it up evenly with oversized holes in the frame, then going over a deep pothole would likely push it right back out of alignment.
You might be better off to carefully line it up perfectly and weld it on.

I need to check template and distance measurement for EACH side. A good point! As far as hole sizes, I purchased the size of drill bit per the instructions. I doubt that I had the template off that much when the holes were established. The instructions did state to measure from the center of the original spring perch bolt hole which I thought was a little sketchy. As I recall another option was to measure back so many inches from the front of the frame rails, (I don't have the options for each measurements in front of me while writing this memo, they're in my shop). As I recall, they were in the 18 to 20 inch distance back to the center of the crossmember.

What are you measuring from to say one side is 1/4 farther forward than the other?

If you measured each side against the spring mount, your frame could be out of square. That could cause what you are seeing, depending on the reference measurement point.

I would recommend picking a point that is unmodified on your frame (such as the rear spring hanger location) and measure from there to the opposite side on the rear.

So as an example, measure from the front-left spring hanger to the rear-right. Then measure the front-right to the rear-left and compare those numbers.

Is it this kit?

Speedway Kit

you will be hard pressed to notice 1/4” or even 1/2” difference, but need to be sure what you are referencing from…. checking true squareness of a chassis is cheap but no small task, it’s about (old school way) setting up string control lines, one down the center of the truck, then to create a “square” string box around the truck, then measure from there…
I took one my vintage race cars to a body shop so they could check squareness, LF was 3/4” back……………tough to fix…..

Chuck

Fibonachu...yes, that's the kit. Hanks custodian...never gave it a thought when installing the IFS that the frame would be out of square. Hindsight, should have checked that prior to installation...live and learn. There was never any appearance that the truck was hit, however, it's probably a testament to Chevy that after 73 years it would only be a quarter inch off! So, with all that stated, as the preferable option, i.e., leave as is, will the quarter inch create any driving issues? Alignment issues? (I wonder how exact the alignment was originally, plus the flex of the frame over the years)?

Some of my competitors would build a dirt track car 1/2" out of square on purpose- - - -they claimed the shorter track on the driver's side made it turn left better. I never really bought into that idea!
Jerry

Once again: What are you measuring against to say that it is 1/4" off?

Depending on where/what you are measuring, it could be nothing, or it could be indicative of a different/larger problem.

Fibonachu...the center of the crossmember. Per the instructions from Speedway, you had two options. One was measuring from the center of the front spring perch bolt hole and the other was so many inches back from the front of the frame rails. That is how I'm now finding I'm off by the quarter of inch. (measuring each distance to the center of the crossmember). I suspect that when I used the template on each side I had it correct, however the frame is that much out of square.

How far along are you on your project? Better stop and get the frame to a shop with a frame straightener.

You can double check whether the template was right or not by measuring from those points to the center line you should have scribed on the frame (assuming you were following the directions).

The instructions have you test fit the crossmember to the measured/scribed points and clamp it in place to ensure the holes are in the correct locations relative to that line.

Before jumping to any conclusions, I would take the crossmember back out, remeasure that scribed line, measure from it to the bolt holes you drilled on both sides, and measure diagonals on the frame to identify the actual source of the issue.

You will never notice a 1/4” difference while driving, setting alignment will not be an issue…..
You will be chasing your tail for no reason IF it is out a bit.
I would hazard a guess most frames are out a bit, on a beam front axel even a slight deviation from straight would cause 1/4….
Chuck

Hanks custodian...I will do some more measurements, however, if I still determine that I'm no further than a quarter inch off, I'll probably go with your recommendation. I'm 70 years old and this truck is NOT going to be a show truck...somewhere between ratrod and streetrod...just a daily driver pretty much locally. (I realize correct is what you want, however, I wonder how many other builds out there aren't exact here and there).

Scant few is my bet.
You have your holes drilled. Run it as is.

I would agree that 1/4" is small enough to be unlikely to cause any problems that can't be addressed with a good alignment.

My concern is that if an offset appeared in the process of setting it up, that offset could be indicative of a different and/or larger problem.

If it were my truck, I would want to understand where that offset came from before dismissing it.

Fibonachu...such as, i.e., examples of your concerns? (I've got a new box, floor and rear fenders for the truck that I can remove and will do to weld the perches to the 10 bolt. I have it sitting on the truck so I can determine new wheel offset. By the way, the mounting bolt holes in the floor lined up perfectly with the frame. When its removed, it will be easy to at least square the rear measure of the back half of the truck). As a sidebar, I installed new Posie 3 inch dropped leaf springs on the rear...they fit like a glove! I hung the rear shackles and used a floor jack for a little pressure on the front mounts to get them in place. Very surprised as to how smooth for once a modification went!

1/4" is a fair distance for a template to slip. The various pieces (such as the upper control arm mount) need to be aligned together. Having the upper mount off 1/4" from the lower *is* a big issue.

If the centerline was not scribed properly vertical, the template could have been aligned at one height, but not at another. Again the concern would be that the suspension/steering parts are in the correct orientation relative to one another.

It probably isn't a big problem, but now will be the easiest time to correct anything that you find.