Now that there’s snow on the ground here in the Midwest, have you been looking at your bike sitting there in the garage and can’t wait to get busy fixing things? If so, have you considered tackling those leaking fork seals?
Here in the great state of Missouri, we have yearly Motorcycle Vehicle Inspections that must be completed in order to renew our state issued sticker. Many riders dread inspections, and quite frankly, I think it is quite a hassle for the shop staff and the customer. This is also the time when we, as customers, have to open our wallets and have a shop perform repairs, or attempt it ourselves. Either way, we will most likely need to buy some parts.

The problem with leaking fork seals is that after time, this will eventually happen to all motorcycles. When they start leaking, your braking can be greatly reduced due to contamination, and the suspension travel will bottom out more easily, giving you a mushy feeling that increases over a short period of time.

Repairing your fork seals can be tricky and very messy if you attempt this without the proper tools and a service manual. If you do not have a service manual for your bike, I suggest purchasing one. There is so much valuable information in these manuals, and you may just become a pro after reading it over your morning coffee.

Before we get started, I want to point out that this article is for conventional forks only. Cartridge forks, like you find on most late model dirt bikes and sport bikes require special fork seal drivers and fluid, which we will be covered at a later time.

Piston rods - a suitable case for hardening
A Parker Hannifin product story  Edited by the Engineeringtalk editorial team Mar 14, 2000Why Parker Hannifin European industrial tie rod cylinder piston rods are manufactured from precision ground, high tensile carbon alloy steel, hard chrome plated and polished to 0.2um max.

The integrity of piston rods, bearings and seals is paramount to ensure the leak-free operation of hydraulic cylinders demanded for today's major industrial manufacturing and process lines.

The piston rod is most vulnerable part of the hydraulic cylinder, with damaged piston rods being, by far, the most common cause of rod seal failure.

Piston rods are at risk of damage from tools such as spanners and wrenches used in installation, falling objects, and even operators using cylinders as steps to gain access to machines! If the piston rod receives only a slight knock, denting can occur which can lead to fluid leakage even if the seal itself is not damaged: the size and shape of the denting may allow the hydraulic fluid to bypass the seal.

Severe damage can lead to tearing of the seal and a more obvious source of leakage.

Obviously, if oil can get out, then dirt can get in ã leading to even more damage.

Induction case hardening is recognised as the most appropriate treatment for piston rods.

As standard, all Parker Hannifin European industrial tie rod cylinder piston rods are manufactured from precision ground, high tensile carbon alloy steel, hard chrome plated and polished to 0.2um max.

Piston rods are induction case hardened to Rockwell C54 minimum before chrome plating, resulting in a dent-resistant surface.

"Other manufacturers often use non-induction hardened steel as standard", says Parker Cylinder Applications Engineer, Andy Lindgren, "and may only offer induction case hardened piston rods as an option - at extra cost! Piston rods manufactured from non-hardened steel ã even if they are chrome plated ã are prone to denting, which leads to early failure of bearings and seals." "Additionally", says Andy, "the process of induction case hardening is simple to undertake during piston rod manufacturing, and has very little effect on the final cost of the cylinder.

OEMs and end-users should bear in mind that a new piston rod is a made-to-order part and replacement requires a complete stripdown and rebuild of the cylinder.".

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