Chevy Chassis Swap - Super Chevy Magazine

Chevy Chassis Swap Tri Five Chassis Shop

Chevy Chassis Swap Removing Body Bolts For Old Chassis

The first order of business was removing the body bolts. We presoaked all of them with PB Blaster (any good penetrating oil will do) to help the removal process. While in the air, we got a chance to survey the underside of the body and found places like this rocker panel where new metal will be needed later.

The first order of business was removing the body bolts. We presoaked all of them with PB

If you're swapping an aftermarket frame/chassis underneath your Bow Tie, there are some things you should know that'll help make the job go easier. If you're having a shop do the install, there are still some things to know so you can understand what the shop's doing (and why) to install your chassis.

In our September '10 issue, Fatman Fabrications built a brand new chassis for our '55 hardtop project. Now the time's come for us to install the new rolling skeleton underneath our shoebox's body. Even though the chassis is specifically designed to fit underneath any '55-57 Chevy (each frame has the specific body mounts to match the body application), there are still a few things that have to be tweaked for everything to fit correctly.

Chevy Chassis Swap Under The Old Chassis

Our '55's original frame has seen a rough life and more than one custom driveway modification, like this mounting tab for a transmission crossmember, and a front end collision that left the front frame horn bent up.

Our '55's original frame has seen a rough life and more than one custom driveway modificat

While working on our XS Chevelle convertible project, the crew at Classic Automotive Restoration Specialists (CARS) was nice enough to volunteer some time and lend a hand with installing our Fatman chassis. After several ups and downs with the body on a two-post lift, everything was fitting like a glove and the way was made clear for doing some much needed metal repair work to bring our hardtop's body back to rust-free condition.

The central part of the floor was found to be in really good shape despite years of sitting outside exposed to the elements. We'll be covering some specific floor brace and floorpan patching in later articles.
The central part of the floor was found to be in really good shape despite years of sittin
This particular mount had a new bottom bushing installed at some point over the years. Notice the difference in thickness compared to the upper bushing which is factory original.
This particular mount had a new bottom bushing installed at some point over the years. Not
Tri-Five Chevys are notorious for shock mounting issues. From the factory the shocks are mounted directly to the body, with the stress of driving over the years eventually tearing the sheetmetal out (circled). The piece of box steel welded to the frame is from someone making a homemade shock mount because of what happened to the original.
Tri-Five Chevys are notorious for shock mounting issues. From the factory the shocks are m

For removing the body bolts, if you've got an impact gun, use it! Don't strain your arms breaking loose and removing old, rusty bolts.
For removing the body bolts, if you've got an impact gun, use it! Don't strain your arms b
Some of the body mounts used a bolt through the top with a nut and washer underneath. A couple of the nuts were rusted enough that they rounded off when hit with the impact gun, so Tommy Barber of CARS had to break out the plasma cutter and make some sparks.
Some of the body mounts used a bolt through the top with a nut and washer underneath. A co
With all the bolts removed and some other miscellaneous hang-ups taken care of (including a long-forgotten battery cable leading to the trunk), the two-post lift was used to pull the body off the frame. First time since the car was built in St. Louis that they have been apart.
With all the bolts removed and some other miscellaneous hang-ups taken care of (including

Here are the original frame and the new Fatman chassis sitting side-by-side.
Just by looking at them together, you can see how much stronger and more rigid the Fatman roller is. This car is gonna be fun on the track once everything's back together.
Just by looking at them together, you can see how much stronger and more rigid the Fatman
At the factory, shims were used to get the fit right on all the body mounts. When you take your car apart, note which mounts had shims, and how many/how thick they were. This will be handy to know when you put the car back together, with either an original or aftermarket frame.
At the factory, shims were used to get the fit right on all the body mounts. When you take

With the body off the frame, we got a good look at the cancer-ridden rocker panels on both sides-never a pleasant sight. The good news is these parts are easily fixed thanks to the aftermarket. We'll show you how to do it in a future story.
With the body off the frame, we got a good look at the cancer-ridden rocker panels on both
One of the more interesting modifications on our original frame was this homemade trailer hitch. Whichever previous owner in the car's life installed this masterpiece of DIY engineering didn't want it to fail, using plenty of heavy gauge steel for the hitch.
One of the more interesting modifications on our original frame was this homemade trailer
Mounting the body to the new chassis, we're using PST polygraphite bushings, and Totally Stainless bolts, washers, and nuts. The polygraphite bushings mean squeak-free and long-life cushioning between the body and frame, and the Totally Stainless fasteners take care of rusted bolt worries. Both are offered in full kits specific to a variety of applications, taking the guesswork out of getting the right parts.
Mounting the body to the new chassis, we're using PST polygraphite bushings, and Totally S

One of the great things about Totally Stainless' bolt kits is they come prepackaged and labeled to the individual parts of the car they're used on. This means no guessing about which bolts go where, and it's easy to organize all your fasteners and keep them from getting lost. If you don't need certain bolts, just leave them in their labeled bag.
One of the great things about Totally Stainless' bolt kits is they come prepackaged and la
With all the new bushings and washers in place, the body was lowered down onto the Fatman chassis. Even though we noted where the body had shims before, we still needed to do some additional shimming to get everything set.
With all the new bushings and washers in place, the body was lowered down onto the Fatman
During our fit check, we noticed the factory pinion snubber was hanging things up. A few minutes work with the plasma cutter and the snubber and its mount were gone. Danchuk offers this part brand new, so we weren't worried about saving this piece for future use or swap-meet value.
During our fit check, we noticed the factory pinion snubber was hanging things up. A few m

The instructions with our new Fatman chassis noted that a notch needed to be cut out in the trunk floor on the driver side to clear the left rear coilover shock. This is one of the things you have to be prepared for with a new chassis, some minor cutting on the body to get everything to clear properly, no matter if you're doing this at home or having a shop perform the installation.
The instructions with our new Fatman chassis noted that a notch needed to be cut out in th
After some quick work with the cutoff wheel, the notch was ready. Because we've got other body work to do on the car, we're going to let this sit as is in case further mods, for any reason, are necessary. In the end we'll box this part out cleanly to match the other side of the trunk floor.
After some quick work with the cutoff wheel, the notch was ready. Because we've got other
The Fatman chassis features oblong holes in the body mounts to allow for adjustment and varying factory tolerances in the construction of the various bodies, along with their natural tendencies to shift a little over time from driving and chassis flex. On an almost 60-year-old car that's seen a hard life, some things are bound to have moved.
The Fatman chassis features oblong holes in the body mounts to allow for adjustment and va

During fitment, we found the rear sway bar mounts were hitting the rear of the backseat floor. With any new chassis/old car combo, you're going to run into these issues. Chassis companies like Fatman take into account every possible variable, and do lots of measurements with various cars to ensure their products are correct. But, there's no way to account for the various production tolerances and variances that happen with 12 different plants producing Tri-Five bodies.
During fitment, we found the rear sway bar mounts were hitting the rear of the backseat fl
The cutoff wheel was called to duty once again, and the necessary notches cut out of the rear floor area to clear the sway bar mounts. Once all of our floor repairs are done, we'll fix these holes and make them look pretty. The great thing is they're both right under the rear seat, so no one will even know we had to do this.
The cutoff wheel was called to duty once again, and the necessary notches cut out of the r
You can see (arrows) that we had to do some shimming with stainless steel washers (why use regular ones that'll rust?) for this particular body mount. We've also got an issue with the mount on the rocker side, where cancer from the rocker panel has infected the mount. No worries though, this is easily fixed thanks to a plentiful market of Tri-Five repair parts.
You can see (arrows) that we had to do some shimming with stainless steel washers (why use

SOURCES
Performance Suspension Technology PO Box 396 Montville NJ 07045 877-226-4101 www.p-s-t.com	Totally Stainless 717-677-8811 www.totallystainless.com
Fatman Fabrications 8621-C Fairview Road, Highway 218 Charlotte NC 28227 704-545-0369 www.fatmanfab.com	Classic Automotive Restoration Specialists Inc. 8235 Nautical Point Drive Belews Creek NC 27009 336-595-3900 www.classicautomotiverestoration .com