We borrowed a set of 335/30R18...
We borrowed a set of 335/30R18 Hoosiers from the CorteX Racing #45 American Iron Extreme car to ensure we had enough fenderwell to fit our tire of choice. Once we eliminate the fender lip, we should be in good shape and ready to get our custom Forgeline wheels.
Whether your pursuit of speed involves straight-line shots or curves that twist fore and aft, traction is the key to making the most out of your car's capabilities. As the old racer's saying goes, you can only be as fast as your tires will allow. One of the most basic tenants of improving traction is simply getting more rubber on the ground. Plus, you get the bonus that wide tires just make any car look tougher.
The trouble is that it's a balancing act squeezing modern wide wheels and tires under vintage quarter-panels. Most stock wheeltubs were designed when 235-series tires were considered really wide. With just the right offset most cars can take 9- or 10-inch-wide wheels with 275-305 series tires, but oftentimes in the pursuit of more width with stock wheelwells and lowered stance the question becomes how much tire rubbing you're willing to deal with over bumps and through corners. Our problem is that our plans call for much more section width than that; 312mm of magnificent meat to be precise.
To squeeze in that much rubber we've only got two options: flare the fenders, or mini-tub the wheelwells. For now, we're opting for the latter. Nowadays, there are a few companies that make high-quality prestamped mini-tubs that can cut dramatically down on the labor involved, like Detroit Speed and Engineering's Deep Tub kit available for Camaros and Novas. By all means, if you've got that option for your ride, save yourself some time and order the DSE kit. But what do you do if a set of deep tubs aren't available, or perhaps just aren't deep enough? You go back to the old ways of slicing and splicing.
That's our plan for Max Effort's rear wheelwells, and it works on the same principle as the premade mini tubs, i.e. we're just going to make the stock tub deeper by cutting away the inner floor and adding metal to the tub. Of course, there's more to consider than that, and with the help of Ryan Kertz at Kertz Fabrication we're going to show you some of the things to consider when mini-tubbing any car.
Here's the sketch of our basic...
Here's the sketch of our basic plan for creating Max Effort's deeper tubs from stock ones; we're going to cut just inside the pinch weld on the stock wheeltub and add in a strip of sheetmetal that overlaps the two sides slightly. Evenly spaced holes punched in the metal will allow us to make quick spot welds to hold everything together. This basic concept will work for any car.
Though not always a necessity,...
Though not always a necessity, we recommend removing the rearend and rear suspension before getting started to clear the way for easier access. That brings us to an important consideration that also needs to be addressed before you cut: What kind of rear suspension are you going to run and how much room does it need? In some cars the springs may be the deciding factor for how far you can cut if you're not ready to relocate them, which would have been the case for our Cougar. The CorteX Racing coilover suspension gives us much more freedom to tub.
In the case of Mustangs and...
In the case of Mustangs and Cougars, removing the factory bumpstop mount is also required to take the inner wheeltub all the way to the framerail.
Once the undercoating was...
Once the undercoating was stripped away, we exposed the recessed seam where the inner and outer wheelwells meet. We'll make our cut just inside of the seam to leave a nice flat lip to weld to.
Whatever your cutting method...
Whatever your cutting method of choice, the easy way to keep the cut consistent is to lay a strip of tape along your path.
Inside the trunk, Joe Chatterton...
Inside the trunk, Joe Chatterton just cuts along the line where the wheelwell meets the trunk floor. Try to cut as directly on the line as possible to keep proportions correct, especially if you plan to reuse the tub. Otherwise you'll reduce its height.
With the tub removed, note...
With the tub removed, note that the distance from the framerail to the cut isn't equal all the way around, but that we do gain 2 inches or more at all points. We could go further and notch the framerails (as is necessary on some cars to fit 335s, such as second-gen Camaros) but that will be enough inboard real estate for our goal.
Before moving forward, Kertz...
Before moving forward, Kertz uses a large C-clamp to press the now loose trunk floor to the framerail to weld them together and create a single, stronger point for the new tubs to mount.
His first pass consisted of...
His first pass consisted of tack welds spaced a couple inches apart to secure the trunk floor, but Kertz followed up with a solid bead to make the two pieces one.
To ensure a flush fit to the...
To ensure a flush fit to the framerails, the weld was ground smooth.
We're taking the easy way...
We're taking the easy way out with a set of stock '67 Mustang replacement inner wheelwell stampings from National Parts Depot, since we were in a time crunch and they're available cheap. The same results can be had by reusing your stock tubs if replacements aren't an option. Also, keep in mind that many specific application tubs can be made to work in other cars with a little trimming. Here, Kertz is trimming off the tab where the stock inner and outer would be spot-welded together.
Rather than a solid bead of...
Rather than a solid bead of weld, we're going to rosette weld the pieces together so holes are punched along the edges of the tub. This will be more than strong enough, and save time and welding wire.
Since Mustangs and Cougars...
Since Mustangs and Cougars are so similar, the tub fit quite nicely with little trimming and shaping. The passenger side required a little hammering to eliminate a bulge for the spare tire in Mustangs.
To create the splice that...
To create the splice that will connect our inner and outer tubs, Kertz presses a sheet of paper to the gap.
From the inside, Fillip Trojanek...
From the inside, Fillip Trojanek traces the cutline. The inside edge of our splice will lie along the recessed area where the inner and outer tubs used to meet.
Rather than attempt to make...
Rather than attempt to make a long and difficult-to-work-with single splice, Kertz opted to make two that will meet together at the top of the wheeltub.
Since he chose the rosette...
Since he chose the rosette route, Kertz was able to fully weld in the splice in short order. The leading edge where the tub meets the rocker was welded solid, however.
Since he chose the rosette...
Since he chose the rosette route, Kertz was able to fully weld in the splice in short order. The leading edge where the tub meets the rocker was welded solid, however.
From inside, the tubs will...
From inside, the tubs will have a stock-like shape and appearance once we lay a little seam sealer on the splice and paint everything a solid color-exactly the look we wanted. Wondering how we correctly reinstalled the trunk hinges for smooth operation? We're out of room here, but check out the web exclusive story on PopularHotRodding.com for the surprisingly simple answer!