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Car Guy Diary – 9/225/2013 – Shock Absorber Swap

Old and new oil shocks
Old and new oil shocks
Bart R. Orlans

Some parts wear out slowly enough that you’d be heard pressed to tell when it’s time to change them. Shock absorbers are like that. Sure, if they break, they’ll rattle around under your car and you’ll know something’s up. But if they just slowly wear out, the change in ride quality is hard to notice…especially when you drive the car every day.

A generally accepted rule of thumb is that shocks should be replaced at around 25,000 mile intervals. Some shocks, particularly your ultra-premium brands like Koni, will last longer than that, but that doesn’t mean they don’t need minding. The parts under your car not only wear out from just doing what they are supposed to do, but the inhospitable environment under your car take their toll too. Rain, sleet, snow, gravel and other road hazards throw a beating into undercar parts like your shocks so it’s a good idea to take a look and see if they are damaged or leaking.

If they are undamaged physically, the old bumper push test can tell you if your shocks have had enough. If, after pushing down on the bumper it takes more than one or two cycles for the shocks to settle the body movements down, it’s time for new shocks.

The front shocks on my Marlin were damaged beyond repair as I highlighted in a previous installment. The rear shocks looked like they had been under the car since the ‘80s and the body took three or more cycles to settle down after the bumper test. They weren’t leaking and appeared undamaged externally, but after getting them out of the car their condition could be better diagnosed. The passenger’s side shock was tired, but still damping suspension oscillations. The driver’s side could be compressed and extended by hand with little effort proving that it had completely had it.

A new set of Monroe gas shocks were ordered from Rock Auto.com and somehow the installation went off without a hitch. Seriously, replacing shocks is not a particularly difficult task and doing them yourself can save you some cash. The hardest part of the installation for me was climbing into the trunk of the Marlin. The car’s fastback roofline forced a rather small trunk lid to be used on a car with an otherwise spacious trunk. Loading my banged up, 50-year old body through that small portal was my biggest challenge. A younger, more flexible person may not have struggled so much.

Check out the photos and see how I did it…maybe you can do it too?

Old and new oil shocks
Old and new oil shocks Bart R. Orlans

Old and new oil shocks

The old shock looks like it's been working hard for decades. This is the driver's side unit and was completely worn out and offered up virtually no damping at all. The new Monroe on the bottom looks good and is ready for years of service under the Marlin.

Starting with a spray
Starting with a spray Bart R. Orlans

Starting with a spray

Before I broke the tools out, I sprayed all of the hardware with WD-40 Specialist Rust Penetrating oil. The nuts and bolts weren't particularly rusty, but I didn't want to take any chances.

Gunning the hardware
Gunning the hardware Bart R. Orlans

Gunning the hardware

The penetrating oil had a few minutes to work while I got the tools out, and work it did. With just a middling amount of effort from the impact gun, the nut that holds the lower end of the shock to the rear axle came off undamaged. I could have used regular hand tools, but when you have the air tools you might as well use them.

Top hardware
Top hardware Bart R. Orlans

Top hardware

I gathered up my tools and crawled into the trunk through the Marlin's small opening...not easy with a load of arthritis, but once I got in, there was plenty of room to work. I used a Kobalt universal socket and ratchet that's hollow and allows the shock stud to protrude though it to remove the top hardware. Because the top hardware was in the trunk, it was protected from the elements and came apart easily.

Installation ready
Installation ready Bart R. Orlans

Installation ready

With all the hardware undone, I pried the bottom of the shock off the stud and it came right out from under the car. I looked up at where the upper shock stud goes into the body and none of the rubber bushings were stuck to the car which sometimes happens when they've been in there a while. We were ready to install the new shocks.

Top in first
Top in first Bart R. Orlans

Top in first

With one washer and rubber bushing in place, I snaked the new shock through the hole in the body, compressed the shock and pressed the lower eye of the shock onto the lower stud on the axle.

Bottom hardware
Bottom hardware Bart R. Orlans

Bottom hardware

I pushed the lower eye of the shock onto the lower stud and replaced the washer and nut that attach it to the axle. with the nut spun on a few threads, I used the impact gun to tighten it the rest of the way. Again, regular hand tools can be used but air tools speed up the process.

Top hardware again
Top hardware again Bart R. Orlans

Top hardware again

With the bottom all buttoned up, it was back into the trunk to tighten up the top hardware. Again, the Kobalt Universal hollow socket and ratchet were used to great effect. Done and done.