Rubber Room

Installing Detroit Speed & Engineering's Camaro "Deep Tubs"

One of cool things about a g-machine is a fat footprint. But squeezing 9-, 10-, or 11-inch-wide rims and the requisite rubber beneath stock-appearing fenders of '60s- or '70s-era sheetmetal isn't very easy.

For First-Generation Camaros, Detroit Speed & Engineering's (DSE) solution is to replace the stock rear wheel houses with wider, "deep tub" versions. These tubs provide room for rear tires up to 335mm wide but, when installed properly, give an almost factory appearance that casual observers would have a hard time discerning.

DSE's first mini-tub setup was developed when DSE's Kyle and Stacy Tucker built their famous Twister '69 Camaro. The DIY kit was launched in 2003 and to date nearly 300 sets have been sold.

We recently followed the installation of one of DSE's mini-tub kits on a yellow, supercharged '69 Camaro--a car that looks very similar to the Tuckers' Twister. The ProCharger-equipped big-block car makes about 900 hp to the tires, so the planned 335-series rear meats would not only give the car a cutting-edge g-machine stance but the enlarged contact patch will give the powerful F-car some much needed grip, both in the corners and when launching the supercharged Rat.

Detroit Speed's tubs look like the Camaro's inner wheel houses, only wider--2.75 inches wider. They are made from 18-gauge steel and, unlike so many other manufacturing jobs these days, the tubs are stamped in good ol' US of A.

In addition to the First-Gen F-car tubs, DSE also makes tubs for '68-74 Novas that, too, are nearly 3 inches wider than stock. The company also offers subframe connectors for Camaros and Novas--parts sorely needed in any powerful street machine.

Although the tubs can be purchased as a pair, we elected to follow the installation of DSE's more complete kit, which includes a new rear upper shock crossmember. The kit, which lists for about $1,300 (vs. $400 for the tubs alone) also comes with offset shackles needed to relocate the leaf springs, but as that is more or less a straightforward swap of the shackles and springs, we're focusing just on the tubs in this story.

To keep those super-wide rear skins in the newly enlarged fenders our Camaro project car also required a narrowed axle, so its 9-inch rearend was removed and trimmed about 2 inches on either side.

This is not a project for the faint of heart or someone who questions his welding ability; the DSE tubs are sized correctly, but 35 years of chassis flex on the somewhat flimsy First-Gen F-car unibody invariably means some tweaking and fine-detail metal finishing is required. Also, the rear framerails must be notched and re-boxed to accommodate the tubs and tires--a procedure that, while relatively straightforward, nonetheless demands experienced welding and metal-finishing skills.

Cutting into the stock rails also reveals the early F-cars' built-in weakness.

"The truth is the steel in those rails isn't very thick--it's more like boxed tin," says Tucker. "But while it made the F-cars prone to chassis flex, it is pretty easy to cut out. modify and strengthen."

Once in place, the new deep tubs absolutely look factory installed, particularly when viewed from inside the trunk. DSE made sure their contours match the originals, only wider. The tubs do require some minor modifications to the rear seat--a nip and tuck at the corners that still allows the stock seat cover to be used.

This isn't an instruction guide, however, as we simply don't have the space to show every intricate detail. It should, though, give you an idea of the labor involved in the project. DSE's kit comes with detailed instructions, including a video CD, so someone who is competent with a torch, cutting tool and MIG-welder can accomplish the project at home. Tucker tells us a 110-volt welder will handle the job, but a 220-volt unit is recommended.

DSE also says most enthusiasts who order the tubs tackle the job as an at-home project, while the others opt for professional help. Either way, the DSE kit takes the guesswork out of fabricating the parts and that has made entry in to the g-machine Touring ranks much more accessible to many would-be pilots.

But whether you attempt the job yourself or farm it out, use this story as the "20,000-foot" view of the installation--it provides an excellent look at the tasks involved, but we simply don't have the room to show every weld stitched.

"The best thing you can do to ensure a successful outcome is take the time to measure everything before cutting or welding," says Tucker.

That's sage advice, because once that cut-off wheel hits the tin, you're committed.

Tucker also tells us to plan on about 40-50 hours of labor for the job--figures that certainly will be skewed by the experience of the installer.

Patience and attention to detail, however, should pay off with stunning results.

Novas, Too
DSE has a deep tub kit specific for '68-74 Novas, but the installation procedures outlined in this story apply just about exactly.

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Stock Camaro trunk prior to the deep tub installation. It is imperative that the car is square and level before starting the procedure.

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The first real step in the procedure is stripping the interior of the seats, upholstery, side panels, and carpet. Paint and seam sealer should be removed, too. Of course, the rear suspension must be removed, along with the driveshaft, shocks, leaf springs, and fuel tank. The undercoating must be scraped off, as well.

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Next, detailed measurements are taken at all areas surrounding the stock inner fenders. Close attention to detail with the measurements is necessary, especially when marking the centerline points of the stock upper shocks; it's an important reference for the new upper shock crossmember.

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Measurements also are taken from the outside. Numerous points regarding the depth of the framerails, the depth of the original inner fenders, the depth of corners and more also are taken. DSE records the measurements on pieces of masking tape and affixes the tape to the outside fender to serve as a constant reference.

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Before the stock tubs can be removed, the trunk hinge support mounts must be removed. They'll be used again, so care must be taken when removing them from the wheel houses. (Drilling out the spot welds usually does the trick for loosening them.) Care also must be taken when working around the trunk springs, as they're under tension.

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DSE uses a cut-off wheel to slice around the stock inner wheel houses, but a die grinder or plasma cutter will work, too. The outer wheel houses (closest to the fender) are used with the new DSE tubs, so care should be taken not to damage or warp them while removing the inner houses.

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With the stock tubs out of the way, more measurements are taken on the framerails. They must be cut to clear the new tubs and make room for the wide rubber to be housed there. Measurements also are taken from the framerail inward (2.75 inches) to determine the placement of the new tubs and, correspondingly, the amount of trunk floor material to be cut away to make room for them.

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DSE's deep tub kit includes templates to guide the size and shape of the required steel inserts. DSE suggests 1/8-inch steel stock for the inserts. Note the vertical lines on the far right template; it indicates a piece that must be radiused to fit.

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Here is one of the new inserts for the framerail being checked for placement. It will be tacked-welded in place, at first, then finish-welded and ground smooth. Because the rails are pretty thin to begin with, DSE recommends 1/8-inch steel.

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This shot shows the completed metalwork on one of the Camaro's framerails.

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With the framerails modified, the tubs themselves can be inserted. If the measurements and corresponding cutouts were performed accurately, the new tubs should simply snap into place.

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Like the framerail inserts, the tubs are first tacked into place. This prevents warping and, if required, allows easier adjustment if the previous measurements weren't accurate.

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On the inside, the new tub and the corresponding outer wheel house are joined. Again, because the metal involvement is thin, a series of tack welds spaced every few inches is the best way to ensure a warp-free finish.

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With the new tubs in place, the trunk hinge support mounts are reinserted. Some tweaks to the flange are needed to ensure a perfect fit with the contours of the new wheel tubs.

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A look through the fender shows the new tub installed with the metalwork more or less completed.

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Another part of DSE complete kit is a new shock absorber crossmember, which is recommended to ensure optimal suspension travel, the right stance and uncompromised handling. Here, a section of the trunk floor is removed to make room for the new crossover section. Camaros with staggered shocks, like the '69 used in this story, will have an angled mounting of the crossmember.

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The shock crossmember is inserted from the top of the trunk, but the installer must get under the vehicle (shown here) to trim the crossmember's edges to fit the profile of the floor pan.

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Finish-welding for the crossover is completed inside the trunk.

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A new bracket must be fitted between the tubs and the rear seat frame. DSE supplies the templates for the brackets, which are constructed from .18-guage steel. Pre-made pieces are not included with the kit, because production variances between cars and deep tub kits makes it difficult to offer a one-size-fits-all bracket.

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Here's what one of the new seat brackets looks like after it's been installed.

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Our '69 Camaro project car had the rare fold-down rear seat option, which required additional surgery. DSE took the stock seat back and sectioned it to fit. This step is not required if the standard rear seat is used.

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The back corners of the rear seat must be modified to clear the new tubs, but only slightly. Basically, the seats and a couple of springs are notched on each side. The modification is subtle but necessary. Luckily, the stock seat cover will fit over the slightly modified seat.

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Although the stock fuel tank will work with the DSE tubs alone, it will not fit with the DSE complete kit that includes offset leaf spring shackles. That means the stock tank must be modified or an entirely new tank must be sourced. DSE offers a custom, stainless tank for F-cars and that's exactly what was used here. It bolts to the stock locations.

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A slightly narrower rearend also is recommended (unless you want to roll on rims with a really odd-looking offset). In the case of our project car, which already had a beefy 9-inch underneath it when we started, approximately 2 inches on both sides will be chopped off; DSE recommends all-new rearends for cars that started with one of GM's weaker axles.

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Insisting that form and function are equal, DSE determines the width of the narrowed axle by first placing the new rolling stock in the fenders to judge the look. This way, the wheels and tires are positioned just right for the g-machine look.

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DSE's Kyle Tucker says the deep tubs in a First-Gen Camaro will accept 315- or 335-series rubber. He likes wheels, then, that offer about 5.5-inches of backspacing, such as the wheel mocked in position in this photo. With the wheels and tires mocked in place, measurements are taken to determine the necessary width of the rearend.

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Here's the finished deep tub installation. Compare it to the "before" photo at the beginning of the story and its hard to tell this shot from one of a stock Camaro. DSE's craftsmanship is top notch, but thanks to a well-designed kit, the results can be replicated by a qualified shop or experienced at-home enthusiast.

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There's still quite a bit of work involved in the completion of this Camaro's transformation. In addition to fitting the narrowed rearend, the rear suspension must by modified to accommodate the narrower confines. Yes, DSE has that covered with a kit containing offset shackles and new lowering leaf springs, too.

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