DMC Racing Mini Tub Installation - Chop, Drop, And Roll

DMC Racing chopped, dropped, and almost got the '90 Mustang LX rolling when we visited the shop's Halifax, Massachusetts, digs.

Traction Is critical during rapid acceleration. Without it, our Mustang's drive tires won't stay glued to the pavement. Instead, the tires will spin, and the car won't accelerate quickly.

Over the years, MM&FF has covered many different suspension upgrades to help your Mustangs and other fast Fords work better at the track and on the street. Nevertheless, there comes a time when you need a tire with more width and overall diameter to get the required traction.

Mustang owners are restricted in tire options due to the rather smallish wheel tubs on most late-models. The Fox-bodies are worse off than the SN-95 models, while the S197 Stangs seem to have plenty of room in the back. In addition to improving traction, many Mustang owners love the look of a lowered ride, and that's another tough thing to accomplish with a stock suspension in your Fox Ford. The answer, as we see it, is to add mini tubs that will allow larger tires as well as a lower ride height.

We mocked up a variety of wheels to show how they look under the fenders. Here's a Weld Racing Aluma-Star with optional bead-lock ring. This rim measures 15x12 and has a 5-inch backspacing. The wheel is shod in Mickey Thompson 28x10.5-inch racing slick. This is the typical wheel-and-tire combo on a NMRA Super Street Outlaw car. And yes, we went a little crazy with the guido grease (aka tire shine) on the tires.

The wheel tubs are capable of handling some large meats. The only requirement for 29.5x10.5W slicks and 315/60x15 drag radials is that the body must be trimmed a bit on the lower portion of it in front and behind the wheel. These are BFGoodrich Comp T/A Drag Radials that check in at 315/60-15.

If the 315/60 tires are too large for your liking, try a set of 275/60x15 drag radials. These are from Mickey Thompson, and they can fit under a stock wheel tub. The mini tubs and narrowed rearend allow us to move the tire further under the body and lower the car some more. It gives the Mustang a more aggressive and cleaner look.

Replacing the stock wheel tubs with mini tubs isn't just for hard-core drag racers anymore. We've noticed a trend, with more and more street enthusiasts utilizing this modification, as well as road-racing car owners. Adding larger tires and lowering the ride height gives a better stance and aggressive appearance, even if you aren't competing for a heads-up championship. The larger wheel tubs allow taller and wider rear tires along with the ability to lower the vehicle substantially. The best part about this modification is that you can do it at home, or just pay a shop to handle the chore.

We chose the latter and showed up at DMC Racing (Halifax, Massachusetts) to modify the long-lost Project X-Rated, our own Fox flyer. DMC routinely performs this modification for street and race cars and, in addition, offers a do-it-yourself mini-tub kit specifically designed for Mustangs, which sells for a reasonable $130, plus shipping.

Mini tubs are designed for use in stock framerail cars and can take up a weekend for installation, depending on how elaborate and fancy the finished product needs to be. If you're going to tackle it yourself, be sure to have some heavy-duty equipment, including a welder and a variety of hard-core cutters.

The puny stock wheel tubs are exposed when you remove the interior trim panel.	This is the OEM rear shock tower. It's molded to the floor, and we're cutting it out. We won't need it in this application since this car is getting a set of coilover shocks, which will be attached to a custom mount in between the framerails and incorporated into the rear portion of the rollcage.	Cut away the support bracket on top of the stock tub.
DMC's DAN Rondeau cut out the wheel tub and removed it easily.	Cut Out the shock tower as well. For those who want to retain their stock shock mounting location, DMC builds custom brackets for that application.	The framerails are exposed, and there's more work to be done. In order to fit the wider and taller tires, the frame must be notched for tire clearance.

It's necessary to remove the entire rear suspension for this conversion. Dan MacPherson of DMC Racing says, "We normally add rear coilover shocks when we do the mini tubs. If the customer wants to keep the stock shocks and springs, then we build a custom upper mount for the shocks to bolt to." The reason for the rear shock conversion is that the upper mount is removed when the tub is cut out and the framerail sectioned for tire width.

We were amazed how quickly the wheel tubs were removed once the interior panels were out of the car. DMC's Dan Rondeau and Michael Guthier quickly tore into our '90 Mustang LX. Before we even had our camera gear setup, one tub was cut out, and they were waiting on us to start on the other. The Stang featured in this story is scheduled to receive rear coilover shocks, which were coming at a later date. The mounts are being built into the rollcage, so we would be unable to get the Mustang back on the ground at the conclusion of this story.

Due to the Stang's future status as drag-race superstar, the 8.8-inch rearend was dumped, and DMC sized up a custom 9-inch combination. The 9-inch housing specs come in at 49 inches, end-to-end, and it's the narrowest we could have gone while still retaining the stock-style rear-suspension setup. Strange Engineering built the rear and added a back brace to help stiffen it up for brutal and torturous action. Strange also added a set of lightweight brakes, 40-spline axles, 3.55 gears, a spool, and an Ultra Case centersection. It represents the ultimate rearend setup found in True 10.5-inch and Drag Radial racing categories.

Rondeau used a straight edge and applied tape...	...to properly mark the rest of the floor and framerail that was to be removed. He measured both sides, ensuring he cut them the same way.	Trim the floor straight in...
...and right up along the framerail.	Once the floor was trimmed back, Rondeau cut a notch into the rear framerail.	It's easiest to drill out the spot welds and remove various mounting points on the face of the framerail before cutting through it completely.