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PSC Ram Assist Rebuild

Posted in How To: Transmission Drivetrain on November 19, 2018
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On a great day out on a challenging rock trail we bumped our rig on some big boulders. During our quick, post-trail inspection of suspension and drivetrain, we noted some new scars underneath but nothing obviously damaged. However, when we hit pavement for the drive home, something felt odd in the steering action, as if something was binding. A closer inspection of our PSC hydraulic-assist ram revealed no fluid leakage, but its rod was bent from hard contact of the cylinder body with rock.

Our temporary fix for the drive home was to remove the assist cylinder and hoses from the vehicle, and the now-open ports at the power steering box were closed with a couple of -6 AN caps. (If you don’t carry caps you can loop one of the lines and attach both ends to the steering box.) This left us with standard power steering capability and eliminated the binding assist cylinder from our axle.

Later examination of the cylinder showed that the body was scarred but otherwise straight and undamaged. Only the rod was bent. We ordered a replacement rod and seal kit from PSC Motorsports, and we were able to rebuild the ram in about an hour with a few basic mechanic tools.

We transferred one rod end to the new rod, installed new seal components onto the piston and head, and reassembled the cleaned ram with some hydraulic fluid to ease sliding the seals into the bore. Overall, it was an easy project and we were able to restore our hydraulic assist without a lot of fuss or expense.

Before we removed the hydraulic hoses we zip-tied the two together and marked the fittings as to where each connected on the cylinder. This was to save us time guessing how the hoses needed to be mounted upon reconnection.
We held the ram in a vise by clamping onto the square portion on the end of the cylinder. We unscrewed the head cap from the cylinder using an adjustable pin spanner wrench.
Here is what the disassembled assist cylinder looks like with the piston and rod assembly removed. Our cylinder body was externally scarred but otherwise undamaged. The internal bore looked to be in good condition.
The piston hex nut was removed from the end of the rod. The piston assembly is also threaded onto the rod, so we used a set of pointed snap-ring pliers to loosen it, and then spun it off by hand.
There are internal and external seals, which need to be removed from the piston assembly.
Internal and external seals also need to be removed from the head cap. Note the orientation of the internal wiper and seal as you remove them.
Here are the parts we purchased to do the cylinder rebuild. We checked the length of the new rod against our damaged one to ensure that they matched, then transferred the rod end and jam nut over to the new rod.
We used a set of flat-bill retaining ring pliers to easily expand the split seal onto the piston. The rest of the piston and head seals were installed after being wetted with some hydraulic fluid.
With the rod assembly all put back together, it was slipped back into the cylinder bore. Use caution when stretching the Teflon seal onto the piston and later when pushing it into the cylinder bore to make sure it is not twisted or nicked. Threading the head cap back into the body completed the rebuild.
We regularly carry a handful of plumbing fittings in our rig to allow us to repair, plug, or bypass our ram-assist steering hoses. Having a couple of caps to close off our power steering box connections made a temporary patch job easy.


PSC Motorsports
Azle, TX 76020

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