Manly Rear Tires on the Falcon

Okay, so there are those who are committed to purity, and those who are just too lame to figure out how to fit shit into place without making the outside appearance really suck.  The latter point here means when some geek cuts out the actual outer fenders, after installing huge shackles or doing a spring/axle flip, just to fit some ridiculous big back tires–this is much of what was bad about 70s hotrod styling.  My direction with this car is to make it handle, without making it look stupid (or modified to an untrained eye); in this case, my objective was to go from a 15×7 rim with 4-inch backspacing to a 15×8 inch rim with 4.75 inch backspacing (on all four wheels–on the front, I had already rolled the fender lips previously; for this change, I also had to grind down the upper control arm edges to very near the ball joint edge).

Even with the Panhard bar, it was difficult to eliminate rubbing of the old 215/60/15s on the inner fenders; I never had any contact with the inner wheelhouse on the snubber/spring side, as 4-inch backspacing was just not all that much for the rim size.  With the new 15x8s, I have just about 1/2 of an inch of clearance between the tire and the spring.  On the outside, I actually have more clearance, but one picture I’ll provide here will show the insurance I provided.  The new tire size is 225/50/15; I have no intention of ever using a tire larger than this, as there is really no point, and I have no pro-touring fashion goals to meet.  This new tire size is close to what was stock on the Fox-body Mustang that my engine and transmission came from, with a bit less height.

To accommodate the greater rim and tire width, I did a few things.  From a crash when the rain started at the end of fall, I had some bent leaf spring shackles; these were stock-style, and quite wimpy.  (I also bent a couple of my rims, hence the excuse to go to a new size–note that I’m only using Cragar Soft 8s, not douchebag pro-touring stuff that costs as much as my house.)  I replaced them with some beefy Mustang units that included very thick steel plates and poly bushings, along with sleeve reinforcement (see Sacramento Mustang).  Since the Falcon only has a 2-inch spring, and Mustangs have 2.5-inch springs, I had to cut half an inch of off all lateral hardware with the shackles.  Secondarily, or primarily, depending on which offends or turns you on (or off) more, I cut the hell out of the inner fender with my new (non-Harbor Freight) angle grinder that cost three times as much as my old one (worth it, so far, although the Harbor Freight one was excellent, given the mileage and cost).  Get good eye protection…  (Note that the fourth picture is what you do to re-set the Panhard bar when you don’t have a 155-pound dummy.)

The overall result of the changes made here is awesome; the rear is much more planted (resisting lateral flex much more effectively), and I have no tire rubbing issues anymore.  The Panhard is worked a bit less, too, although my welds are surviving quite nicely…

DSCF0037 DSCF0051 DSCF0052 DSCF0050 (2)

3 Comments

Filed under Jibber Jabber

3 responses to “Manly Rear Tires on the Falcon

  1. Okay, you lost me. You installed Mustangs 2.5 inch wide leaf springs after cutting .5 inches off the lateral hardware with the shackles? Being a neophyte I can’t figure out what you cut from where to get a 2.5 inch spring into the front stock 2 inch leaf spring mount.
    Heard of folks cutting the front leaf spring mounts out of a donor mustang and replacing the stock falcon with the mustang. I guess one would have to deal with the rear shackle configuration.
    Clarification, suggestions or thoughts on this appreciated.

    Thanks

    • gashp

      Hey Dennis,

      I still have two-inch leaf springs. The idea was that nothing really good is in that size, so I had to buy heavy duty shackles/poly bushings for 2.5-inch springs (same internal diameter), then cut them down (metal sleeves + bushings) to the correct length. The two-inch springs are very weak in every direction, but I’ve made them work pretty well with the locating devices (and Koni shocks); without the additional hardware around the rear axle, these springs are horrible (even with five leaves). One day, I will go to some kind of coil configuration (probably more stock car than pro-touring), if only to have better choices of spring rates, but it won’t be for years, due to time (and sanity) constraints. Cheers.

      • Okay, now I understand. Looking at the forward leaf spring mounting/torque box and measuring the inside dimension it is 3.5 inches wide the same as a 64 Mustang. My theory is the 2.5 springs would fit the forward box and modification to the rear frame at the shackle mount point might allow for a simple conversion to the 2.5 springs.

        Any thoughts on this one?

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