Making more tire contact with the pavement is the name of the game. We build all of our chassis to your specifications so you can have a larger tire/wheel combination under the fender. We design the amount of the rear chassis rail width based on your desired tire and wheel width and back spacing. We'll tub the chassis specifically for the rear wheels and tires you want to use. This is how we build all of our tubbed chassis' so it will be right for you. The best scenario is to call us with your wheel-and-tire information and discuss what you want to do and we can tell you how much tub is really necessary for your application. We really want to help you build it your way.
All of our direct-replacement chassis (and that includes the tubbed chassis too) feature all stock body mounts, stock core-support mounts and bumper-bracket mounts all in their stock locations. The standard chassis package (and tubbed chassis) feature 2X4X.120-inch wall box tube mandrel-bent chassis rails. For a lower stance, our chassis have an additional 1-inch step over the front suspension and a 1 ½-inch step over the rear suspension. To accommodate the lower chassis, the engine mounts have been raised for increased ground clearance for headers and oil pan. Either big block or small block engines can be used with a stock rear sump oil pan. The engine mounts have also been moved forward slightly to install the larger GM HEI ignition without cutting into the stock firewall.
Whenever we “pinch” (or tub) the rear chassis rails for bigger wheels and tires sizes, you will need a new gas tank to fit the new frame width at the rear. The stock tank is almost as wide as the stock rails and usually can't be used. You will also need to tub the body fender-wells at the top and into the floor with any pinched rear frame. This customer wanted to use a 15-inch wheel, 14-inches deep, with a 6-inch back spacing. After we calculated his numbers, he needed a 5.5-inch pinch on each frame rail to keep the tires under the body. The tires to be used were 29-inches tall X18.5-inches wide. We also build the correct width 9-inch rear end with Dutchman alloy axles.
The first thing to do before ordering a tubbed chassis is to purchase or determine the tire/wheel diameter and backing spacing you would like to see under your ride, then we build your new chassis around those dimensions (for front, rear, or both). Our (stock) 115-inch wheel base G-4 tri-five chassis tubbed or stock has a very beefy 2X4-inch box tube X-member that connects directly to the rear 4-link bars on the rear end housing. If you're looking for more traction, this really puts the strength in our chassis for big block power or stroker mouse motors, and it will put the power to the ground.
At the end of the rails, we bring it back out to the stock width to accommodate the original bumpers and brackets. Notice, we also include the stock rear body mount at the end of the rails. This is where you'll need to determine what size gas tank will fit between the pinched rails.
Looking down the side of the rail, you can see only the small antisway bar link sticks-out passed the frame rail. The 1 3/4-inch diameter X .120-inch wall tube thru-frame crossmember hides the 3/4-inch diameter antisway bar inside. For superior strength, the tubular crossmember is tig-welded on the inside of the rail and on the outside of the rail.
Since the rails are 5.5-inches to the inside, the body mount that is normally just in front of the housing is eliminated. All other body mounts are in their stock locations. The mandrel-bent rear frame rails have an additional 1 ½-inch higher step over the suspension and a 1-inch rise over the front suspension for a lower stance. In this view you can see the antisway bar arm on the outside of the rails. Every part of our chassis' are tig-welded.
We offer two styles of rear coilover shock or ShockWave air bag mounts. The one left is the multi-position drag racing style lower rear mount. We also add support tubes between the center housing and the multi-hole bracket. Notice, to the left of the two mounting bolts is the end of the tube welded through the bracket from the housing. The second style shown on the right is our street rod version with a three-hole bracket for either a coilover shock or a ShockWave air bag. We also offer 3-4-inches of stance adjustment for the front suspension. We are the only chassis manufacturer that offers an adjustable stance chassis as a standard feature. Get the stance you like best!
Looking at the forward right end of the tubbed section, you can see the 2X4 torque arm of the main X-member connecting directly to the forward 4-link crossmember (bars are missing). This design really helps to distribute the torque to the chassis and not just the forward 4-link crossmember. The missing 4-link bars are 1-inch diameter, adjustable and urethane bushed for silent operation. Notice the body mount in the corner just in front of the pinched rail.
Looking inboard at the left forward end of the tubbed section, the curved mandrel-bend on the right is stepped in 5.5-inches from the outer rails. This is where we tub all the tri-five chassis no matter how wide a wheel and tire you want to use. The body mount conveniently fits on the frame just in front of the tubbed area. We also plumb the brake lines to all four corners at an extra charge. This is a great option since we weld tabs on the frame at each wheel and use -4 AN lines (1/4-inch) and -4 AN fittings and bend all the lines so all you have to do is install the stainless braided lines to each caliper.
Read more about all our Chassis Options by following the links below