While many of today’s modern musclecars have plenty of room between the quarter panel and inner wheelhouse for larger, wider tires, it’s not the case for most classic musclecars. Even back in the day when we were installing M50s under the ass end of the car, we had to stinkbug the back end to get those fat tires to fit without rubbing.
However, like bell-bottoms and leisure suits, what was cool in the ’70s is not quite as cool today, and the 1970’s street freak look typically gets more laughs than admiration now. These days, people seem to like the more aerodynamic look of a tire tucked up under the quarter panel with the car sitting somewhat level, but that limits our choices for tire width on a classic musclecar.
The jacked up rear of this Fury from the movie Thunderbolt and Lightfoot depicts a common sight from the 1970s musclecar era. Air shocks and extended shackles helped raise the rear of the car so the fat tires wouldn’t rub.
Though we may be somewhat limited in our choice for wider tires on 15-inch wheels, the desire to make older cars more drivable with big brake upgrades almost always requires a larger diameter wheel. With that upgrade comes the opportunity to go back to having a much wider wheel and tire combination in the rear – if you’re willing to make some changes.
You’re not going to get a set of steamrollers under the car unless you make some room in the wheelhouse for it. Since it’s unusual (and sometimes just gaudy as hell) to put flares on a classic musclecar, the only other option is to expand the inner limitations and mini tub the car.
A car sitting more level with the tires tucked up under the wheelhouse is how it’s done lately, and it keeps the tail end of the car down lower.
These days, 17-, and even 18-inch wheels just look good on classic musclecars. The days of the ‘big wheel’ look have transitioned into these sizes being more acceptable, and now the 20-inch and up diameter wheels are the wheels that people scoff at.
For Project Track Attack, we opted for a set of 10.5-inch Weld Racing wheels to mount our 315/30R18 Falken Azenis tires. Of course, these nearly 12-inch wide fatties weren’t going to fit within the confines of our stock wheelhouse, so we reached out to our friends at US Car Tool for a mini tub kit.
The US Car Tool mini tub kit includes the extensions for the wheelhouse and the hinge support for our kit.
Stretching The Wheelhouse
There are some cars that just don’t lend themselves to making modifications to the wheelhouse because the rear frame might be in the way. That typically calls for back-halving the car with a new, narrow subframe to provide some needed room.
But for many other cars, the wheelhouse is sometimes the first obstruction, and that can be moved inwards as much as three or more inches. If you have leaf springs, they might need to be relocated inward if your plan is to install mini tubs.
Top: Along with the US Car Tool kit is a set of templates that can be cut out and laid down to mark where to cut. Bottom: We were also replacing the rear floor pan with a Classic Industries panel, so removing that first made access for the wheelhouses much easier.
Spring relocation kits are available from a few different manufacturers, including US Car Tool. But for this project, we’re not only moving our wheelhouses inward, but we’re converting to a coilover setup and four-link rear from Control Freak Suspensions, so we already knew that suspension-wise, we had a few extra inches.
Our limitation was the wheelhouse, and the US Car Tool mini tub kit provides the sheetmetal components we need to move our inner wheelhouse. US Car Tool continues to expand its coverage and products for classic musclecars, and can even perform a complete body-in-white restoration of your car.
Top: We began our cuts on the lines for the inner cut, then ran a straight cut to separate the inner and outer wheelhouses from each other. Bottom: Once we removed one of the inner wheelhouses, we decided that there was a little bit of rust in the way, so we ordered a new set of wheelhouses from Auto Metal Direct (AMD).
The mini tub kits are very affordable, and if you’ve ever had to cut a two inch strip to weld between the inner and outer wheelhouse, you might find that it’s not always a straight line from point A to point B. Our kit not only included the strip of metal to weld between wheelhouse halves, but that strip included the flange to weld to the outer wheelhouse. And since we had to dissect our trunk hinge supports, the additional bracket the guys at US Car Tool fabbed up was a great fit and allowed us to reattach the hinge support to the inner wheelhouse.
AMD saved us from dealing with rusty wheelhouses, and had our new panels in stock, ready to ship the same day. As you can see, the quality is spot on, and the fit was perfect.
With the inner wheelhouses out, we knew that it was better to replace them than to weld them back in with the US Car Tool kit. Auto Metal Direct (AMD) stocks replacement sheetmetal and other components for classic cars and had them on a truck to us the same day we ordered them. We decided to put a little fire under it with express shipping to keep our down time short, and it was worth it.
You can find replacement outer and inner sheetmetal, as well as various interior and exterior trim pieces for classic musclecars from both GM and Mopar, and with so many products in stock, we were able to get our project back in gear within two days.
Before tacking anything into place, we did some test fitting, and installed the assembly with Cleko fasteners to make sure everything lined up, then went to town on the final welding.
With the inner wheelhouse removed, we attached the strip from US Car Tool to the new AMD wheelhouse, and lined everything up in the car. With very little tweaking (it is a 50+ year old car) we were able to get the new wheelhouse tacked into place and ready for final welding.
The trunk hinge supports from US Car Tool allow some finessing to attach them to the new panels. These cars weren’t all built with the type of robotic precision like with today’s cars, so we found that the brackets allowed us to easily manipulate them for each side to fit over the stock support and spot weld into place.
After attaching the hinge support brackets, the rest of the assembly was ready to weld into place. Just look at all that room for some fat meats in the back!
With the new tubs in place and all the finish welding completed, we added enough room to swap out a 275/40R18 tire for the new 315/30R18 Falken Azenis tires, with 10.5-inch wide Weld Racing wheels on a narrowed Moser Engineering M9 rearend. We added well over four inches in total width within the wheelhouses, part of the grand scheme of things for the new Control Freak coilover suspension system.
Our planning worked out perfectly, and the new wheels and tires fit within the outer wheelhouses with the exact same track width that we had with our prior setup. We did some measuring, and some planning things out with regards to the new Weld Racing wheels and the narrowed Moser rearend. Both companies worked closely with us to get this project under way, and with companies like AMD, Classic Industries, and US Car Tool on call for the sheetmetal work, we’ve now got plenty of room for a couple of fatties under the rear of the car.
Success! The measurements were all correct, and Project Track Attack is ready for the next step: mounting the Control Freak rear coilover suspension.