Project: Shelf Butt. Mini tubbing a 1968 Camaro By: Eric
One of the most ubiquitous of pro-touring style mods that can be done to a first gen Camaro is the minitub. It’s not only extremely menacing to look at but it also provides the ability for much needed grip. It allows the builder/owner the shove massively wide wheels and tires under the car while keep the rubber between the fenders. The great feature about this project is that the project is relatively inexpensive if you already own the tools, but on the flip side is quite labor intensive.
With a good minitub, we’ve seen tires as big as 345mm wide get shoved up under the fenders without any clearance problems or need to roll the fenders. Now, it must be said that the tolerances for building a car back in the ‘60’s isn’t quite what it is today, so expect a fair amount of variation side to side and fore to aft. This is the main reason we cannot give concrete numbers for how far to cut and where to weld, there’s just too much variation from car to car. We’ve seen cars with ½-inch of difference between the frame rails as well as from bumper to bumper in total length; it’s a total crap shoot at times.
Our test vehicle is a 1968 Camaro with an already standing very clean paint job. The good news is that you’ll only be cutting the inner fenders and not the outers, so the paint is safe assuming we don’t get too wild with our cutting or welding implements. At the end we were able to stuff a set of BFGoodrich KDW’s measuring at 335/30R18 with plenty of clearance all around on each side. As a rule of thumb, it’s good to have a minimum of ½-inch of clearance all the way around the tire to allow for side to side travel and rear-end articulation such as clearing a curb.
The question we often get is; can I do this in my garage? The answer is yes, of course it can be done, however we must caution that this will take some ingenuity and a lot of tools. Now, we recommend that you have sufficient room to move around the car so you don’t catch anything on fire and good ventilation as cutting and welding fumes can be dangerous. On a scale of 1 to 10 for difficulty, this one certainly ranks up there as a solid 8.
Prepare yourself for a minimum of 40 hours of work. Remember these are cars that are close to 45 years old at this point and a lot of them have rust, shotty old repair work and just aren’t what they used to be. So, be prepared to replace rusty metal and fix someone else’s quick fix. Again, go slow and always do it right the first time.
The tools and materials you’ll need are as follows:
– Welder with welding mask and shielding gas with the ability to weld 22-gauge sheetmetal and a minimum of 1/8th-inch plate for the frame rails.
– Various cutting implements such as a (but not limited to) plasma cutter, oxyacetylene torch, sawzall or reciprocating saw, cut-off wheels, hack saw, chop saw and a chisel and hammer.
– Air Hammer, air chisel and nibbler.
– Body hammer and dolly kit.
– C-Clamps and various sheet metal clamps.
– Seam sealer and paint.
– 1/8th-inch or thicker plate metal for frame rails.
– 18-20 gauge plate metal for patches.
– Eye, ear and hand protection.
– Drill with metal wire brush and various drill bits.
– Inner tubs.
You may not need to use all of these tools, but we’ve found them extremely handy over time and make the job much easier.
Measuring for a new rear-end
As with everything in life, it must follow a logic order. You must start from the end point and work your way backwards. Picture in your head what you want your build to look like in the end. Got it? Now, picture what you want your wheels to look like. You might be wondering what this has to do with your rear-end, but in fact it has everything to do with it. Depending on how much lip you want on your rear-wheels, this will determine your rear-end width. If you’re wheel lip is very shallow, you’ll most likely have a very wide rear-end. Conversely, if you like a very deep wheel lip, you’ll have a very narrow rear differential. So, until you determine your wheel offset, you shouldn’t purchase a rear-end unit. Ironically, the minitub has just as much to do with rear-end width as your wheel purchase. And you won’t be able to fully complete your minitub project without having the exact sized wheels and tires ready to mount up.
This is because of section width which we discussed in the wheel and tire section. This factor will greatly affect how wide your minitub needs to be. So, hopefully you’ve fully read this section and quickly figured out that you will need to purchase the wheels and tires you want first before diving into any other project in the rear of the car.
Once you’ve completed the minitub you can start mocking up the rear wheels. It’s important to get them at ride height and exactly in the right position in the wheel wells before measuring.
A word of warning before you begin: This modification is not for the faint of heart. This will require a fair amount of welding and metal working skill. You will be required to cut and reinforce the frame. While you can complete this project without hurting your paint if it’s already good to go, it would be worth a car cover and safety precautions to protect your paint. You will also be required to do a lot of measuring and mathematics, so take your time, go slowly and be purposeful before you start hacking away.