What The Hell’s That Sound?
I’ve always struggled with tire clearance issues. While many guys sidestep the issue entirely by tubbing their Mopars and packing ‘em full of clown car rubber, I’ve always fought to fit the maximum amount of tire under my cars without cutting metal. It’s like the metal is precious. It goes back to my upbringing in the rust belt state of Massachusetts. Growing up, just about every older car had massive amounts of quarter panel rust that was often hastily patched with pieces of sheet steel, pop rivets and a liberal application of plastic body filler. So commonplace were these “bondo buckets” at local car shows that I lost sight of what original, unmolested quarter panels looked like, having seen so few.
But when I arrived in California in 1991, I discovered a constant state of bliss brought on by all the rust free cars at my disposal. Out here, guys say a car “has rust” if the paint is oxidized. They know nothing of flapping fenders and inch-thick quarter panel mud. So when I scored a clean 1967 Dart 170 two-door Sedan, I marveled at its pristine quarter panels and vowed to keep them intact. An original E-code 273 Four Barrel car (Galen says it is one of 29 built), I packed it full of 520 cubes worth of Stage V Engineering Hemi Conversion power back in 1997.
With a chassis-dyno proven 440 rear wheel horsepower, I pride myself that I’m able to get it to hook with a set of “tiny” M&H 27-10-15 drag slicks. Sure, I had to move the leaf springs inboard using the Mopar Performance 1968 Hemi A-Body kit. This trick setup is a mostly bolt in deal that uses offset shackles and hangars to gain about an inch of sidewall-to-leaf spring clearance. Coupled with a set of 15x7 steel wheels (4.25-inch back spacing) the sticky M&H’s fit and best of all, there was no cutting of my precious quarter panels involved.
I remember the first time I took the car to the strip for shakedown runs in August of ‘97. This is back when the fabled Pomona quarter mile was still operational for monthly “street legal” racing – not just the big NHRA national events it’s been restricted to for the past several years. I remember being in awe that my Hemi Dart and I were sitting on the same starting line that had played host to Don Garlits, Dick Landy, Ronnie Sox, Gene Snow and countless other Mopar legends.
I did my burnout and pulled to the line. At the last amber I flat punched the pedal and the Hemi slammed the car forward so hard the glove box door popped open (spring loaded on these old A-Bodies) and dumped papers all over the floor. I clicked the B&M shifter into the next gear at 6500 rpm and the car kept charging. At the top end I zinged through the traps but the MSD rev-limiter (set at 7,000 rpm) was dulling spark about 200-feet before the finish line as the inefficient bargain basement “blue” torque converter turned black from excess heat. Despite the lousy torque coupling at the top end, the succession of time slips I generated that day read in the 11.4’s at 118 mph. Not too bad, though I’d later whittle it down to a 10.99 at 127 at Carlsbad after switching to a better converter.
But getting back to that late summer day at Pomona, after the final run on the 27-10-15 slicks, I decided to bolt on a set of soft compound M&H 275-60-15 D.O.T. tires to see if they were as good. It was late in the day and as I drove around the water box on these treaded “street” tires, I wondered how much their added half inch of diameter would affect the final drive ratio. I staged and was surprised by how they gripped the strip with only minimal slippage. No, the glove box door didn’t slap open, but the 1.8-second 60-foot times were only 2-tenths slower than the 1.6’s generated earlier by the slicks.
Then there was that sound. As I passed the finish line and let off the gas I heard a distinct buzzing noise coming from the back of the car. I goosed the throttle a few times and ruled out any drive line trouble. As the car slowed, the noise went away. So when I rolled up to the time slip shack and the attendant said “If you want to make a final pass, get right back up to the line,” I hustled right back up there without giving the mystery sound second thought.
The second pass on the D.O.T. tires generated another 11.9 at 116-mph and damn, that buzzing sound was there again as I let off the gas! By now the staging lanes were closed so I drove straight to my pit area to wrap things up for the day. I rolled up to my space and clicked off the Hemi, ready to swap tires for the drive home. As I walked to the back of the Dart I heard a distinct “hisssss” as air escaped from the left rear D.O.T. slick! I noticed a deep slice running around the entire circumference of the tread that was in perfect alignment with the chrome wheel lip trim. Let me tell you, my blood ran cold at the thought I was traveling at over 116-mph just a few moments earlier on this very tire! I thanked my lucky stars this was a slow leak…and not a fast one.
Closer examination revealed nearly a full inch of clearance between the chrome and the sliced tire tread. But when I noticed a black rubber smear on the chrome I knew there had been contact. As it turned out, the bottom screw that holds the chrome trim to the wheel lip was missing and as the tire diameter grew at the top end, the rubber grabbed the trim, turned it sideways and created just the neatest little knife you could imagine. The tire was ruined, but I learned an important lesson about tire growth that day. I also learned that sometimes you just have to buckle under and do a little trimming for tire clearance. If you don’t, the car might do it for you!