Clearance Issues Have Me Stumped

Clearance Issues Have Me Stumped

Clearance Issues are Par for the Course…

I’m confident that everyone building a resto-mod will at some point abruptly smack into clearance issues.  That’s the nature of the beast.  Modifications are rarely bolt-in installations, and tolerance stack-up is a legitimate concern.  In other words, clearance issues multiply with each additional modification.  There’s no way to really anticipate how parts will get along with other aftermarket parts.  The market is huge, and it would be cost-prohibitive for every manufacturer to buy everyone else’s stuff to test-fit it all, particularly given the infinite number of combinations that could occur in the wild.  Fine.  I get that.

What baffles me, though, is when stock parts don’t fit with one another.  Or when a single modification that’s supposed to fit the stock configuration doesn’t fit.  I realize that manufacturing in 1966 was an “-ish” business and that even the workers on the line had to fiddle to get certain parts to fit.  That’s why many parts have slots, channels, and adjustment points.  But my frustration builds when there isn’t an adjustment, or worse, when something that fit when I took it apart no longer fits.

The Current Conundrum

My current focus is on the stock power steering linkage.  Ordering a warranty replacement power (slave) cylinder solved my installation problem with the ram itself, but that didn’t do anything to help the clearance problem with the center/drag link.  As I mentioned a few days ago, the drag link scrapes the oil pan.  And as much as I grumble about it, I’ve got to sort this out.  Grumbling, apparently, doesn’t help troubleshoot.

Troubleshooting is fun, heck, you get to play the car version of Sherlock Holmes.  To do it properly, you’ve got to understand how the system is supposed to work in theory.  Then you need to logically target and test the most likely culprit. Some parts aren’t worth the trouble of testing because they’re so cheap and easy to replace, and others can’t be tested or properly examined.  In certain cases that’s because specifications and measurements are unavailable, or the test method or apparatus isn’t in your toolbox.  When a part can’t be tested directly, I like to try swapping known-good parts for those I suspect are faulty.  And when I say “known-good,” I mean it in the literal sense that I know that the part is functional; new parts don’t qualify— they’re unknown-but-hopefully-good.

Troubleshooting Options

Here’s what I know:

  • The motor mount rubber isolators are new, made by Anchor (a name brand)
  • The metal motor mount brackets are factory Ford
  • The control valve/drag link assembly is an OEM piece rebuilt by Lares Corp, but it isn’t the exact unit that came with my car from the factory (core exchange)
  • The oil pan is a reproduction piece from Scott Drake (my original’s dented)
  • The drag link contacts the oil pan when I turn the wheel hard right
  • The cross-member under the oil pan is very close to the oil pan
  • The power cylinder contacts the left header

The components involved here are big pain-in-the-ass-to-change things, so quickly swapping one out for a functional comparison test isn’t an option.  Engineering measurements aren’t available.  And in most cases I don’t have a known-good part to compare them to.  My primary suspect is the motor mount isolators.  If the engine were 1/4″ higher it would eliminate the clearance issues I’m having with the drag link, the cross-member, and the power cylinder.

Eliminating Symptoms

For now, though, I’m going to drop the power cylinder to header interference as a symptom.  Most long-tube headers need a power cylinder lowering bracket for that exact reason.  I’ll temporarily ignore the fact that Doug Thorley Headers specifically states that these headers have been designed to “fit the vehicle as it came from the manufacturer,”  which “includes components like cylinder heads, chassis, steering, motor mounts, body mounts and bushings, etc.” (emphasis mine).

The cross-member is close but isn’t touching the pan.  If it’s actually correctly positioned, the maybe the drag link is bent?  Or if the motor mounts aren’t at fault, could it be the reproduction oil pan?  I’m at a loss.  Time to get out the straight edge and start measuring…

I need to call Lares again to discuss the fact that the control valve ball stud rubber boot is already deteriorating, so it’s possible I’ll end up swapping out the drag link anyway.

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