Day 2: Prepping for Mini Tubs

Today we have an update on Project Grandma as Mike Ryan gets our ’78 Malibu ready for our Chassis Engineering Mini-tubs, and then the 25.5 Roll Cage. We’re starting with a Chassis Engineering chrome moly cage kit and then adding the bars necessary for the SFI 25.5 spec.

With the Malibu being a full frame car, with a perimeter outer frame, we’re going to be adding inner frame rails for the 25.5 spec, and tying up the control arms structure into the roll cage for more rigidity. The Malibu actually has a nice suspension design from the aspect that it’s easy to add support to both the upper and lower control arm locations.

We’re going to walk you through all of the steps we go through so you can do this to your own G-body. Of course we’re using TRZ Suspension and QA1 front and rear shocks in the build, as mentioned, so when we get to that stage we’ll give them props there! The Mini tubs will allow us to use our Mickey Thompson 295/65 drag radials and tuck the body nicely without it looking like a stink bug.

Check out the photo sequence and captions below.

Sadly, the stock bench seat had to go. We’ve got a fresh new Kirkey seat to go in here instead. I really wanted to keep the bench seat, but nightmare’s of crashing at 160 mph erased that quickly as I imagined myself tearing through the stock 30+ year old fabric and springs.

We already had used some aircraft stripping agent to remove the coating from the trunk area, plus 30 years of grime. Looks nice huh.

The Cornwell Plasma cutter is our friend today. We’ll use a combination of the plasma cutter, cut-off wheel, and a sawzall to remove the wheel wells.

Before we starting cutting out the stock tubs, Mike Ryan started by cutting out the connected sheetmetal between the rear trunk hangers and the wheel tubs. They are tack-welded here. We’ll be getting rid of the trunk hangers and go with a pin-on trunk since the hangers are huge and gangly, and they are where our Chassis Engineeing Mini Tubs are going.

Here you can see the rough cuts that Mike is making with the Plasma cutter from the inside of the well.

The wheel tub is really made of two pieces in most cars, and the G-body is no different. You can see the seam line here, as we used the plasma to cut out the inner well.

The way the wheel well looks after the rough plasma cut.

Mike wants a nice crisp line for doing the mini tubs. Here you can see he used masking tape (not finished yet) to start a line that he is going to use a cut off wheel to follow to make a nice crisp cut on the inner sheetmetal for the wheel tub.

Finished after trimming nicely.

A cut off wheel is used to remove the outer wheel well. A plasma cutter will burn through your sheetmetal so it’s a no go.

Nobody said chassis fabricators had it easy.

All finished and ready for final trimming!

About the author

James Lawrence

James started working on a Nostalgia Top Fuel drag racing team in 1992, and the rest has been history. A life-long automotive enthusiast, James is in fierce competition to see whether he can collect more cars or cats. Right now, the cars are winning. James co-founded the NMRA and NMCA Drag Racing Series in 1998 and continues to be an avid and passionate fan on everything 1320. He also thinks he can drive. Thinks, is the key word.
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