Part 118: Monroe Sensa-Trac Rear Shocks

In 1955, automobile manufacturers placed much more value in leaf springs and coil springs when it came to suspension and overall handling of the vehicle. Even the trucks back then had "I beam" front suspension with leaf springs. Not too much research and technology went into shocks. Back then, shocks were used to control the rebound rate or to dampen the ride. These days, most vehicles have struts up front (mostly a shock and spring combination) and coil springs and shocks in the rear. Additionally, most mechanics choose the gas-charged option over hydraulic.

Technically, there was nothing wrong with the shocks I installed several years ago.

A number of years ago, I had installed Monroe Matic 31125 shocks in the rear. These worked fine, but after watching the GoPro camera footage of shock action I decided it was time for an upgrade. I am sure the shocks were dampening the leaf spring action like Ford had wanted them to back in 1955. However, while the videos showed the dramatic improvement a new set of leaf springs made to the car, I believed that there had to be a better performing shock with the double-stud mount.

Enter RockAuto.com. On a wholesaler closeout, I purchased a set of 58539 Sensa Trac shocks that included a heavy duty coil. The overall length of this shock is 17.88" and the compressed height is 10.63". I paid roughly $60 when tax and shipping were included. For the way these shocks performed (the video is below) I received a very, very good deal.

So what is the difference in length between the 31125 and the 58539 from Monroe? About 2"

I had initial concern over the difference in length for the new shocks.

Removing and installing shocks are pretty much standard fare, and I would think that all of the readers of this blog could handle such an otherwise easy assignment.

I did have to use a shop jack to bring the leaf spring shock mount closer to the stud.

Once the shocks were installed, I removed the shop jack and just allowed the rear end to hang, similar to positioning things in order to change a tire. I was surprised at how much room I had left over, and from all appearances there was plenty of room to clear the drum and the lip of the wheel well as you can see.

Plenty of room after installing the new shocks!

Feeling pretty confident, I attached my homemade GoPro camera mount to the rear bumper bracket and fired up the Ford for a test drive. The footage is included in the video below, but suffice to say, I am very happy with the results. The new shocks really help the rear tires stay glued to the road, but the ride is not as "harsh" as you think it would be. I am very impressed and think my money was well spent. Enjoy the video.

New Rear Shocks for the Fairlane

The Hot Rod Reverend

aka Daniel Jessup