Quote:
To lube or not to lube
So the only remaining question is - do I use permanently sealed u-joints or re lubable u-joints (assuming there is a choice in the size/series you are using)
This is not so simple to answer, and has long been the topic of many fierce debates. It may well come down to personal preference, but there are some points to consider.
Most importantly - relubable u-joints MUST BE re lubed. It sounds obvious, but the one thing you do not want to do, is to kid yourself that you will do regular routine maintenance on your driveshaft and u-joints, and the not. And yet, this is exactly what a HUGE number of people do. Avoid it. Be honest with yourself. If you aren;t going to re lube them - use the "permanently" sealed kind, if not, you will experience premature failure.
So, we have to be brutally honest with ourselves, fine. But what if we are the kind that actually would re lube the joints EACH and EVERY time they require it, properly, completely (see Part 3), and without fail (am I making a point here? There aren;t many people who fit into this category). Is there then any reason to prefer on kind over the other? You have to decide for yourself, but some advantages and disadvantages to consider are:
Re-lubable
* (-) They have to be religiously re-lubed, a PITA
* (-) They generally are not as strong, due to the grease channels in the cross
* (-) If you lose or break a grease zerk (not uncommon) the joint is useless (you could just replace it, but it it's been out for a while, way more contaminant will have ingressed into the joint than can even be flushed out by proper lubrication
* (-) Slightly more of a pin to install, as you have to get the grease zerks in the right place and all lined up
* (+) They are generally cheaper
* (+) Depending on environment, they may last longer (if conditions are wet and muddy, the ability to purge the joint and relubricate it, may well extend the life of the joint beyond that of a joint that cannot be relubricated. However, in dry condition, this will likely be much less of a factor.
Sealed
* (-) Depending on environment, may have a reduced service life than a relubable, since nothing is ever really 100% sealed, so that if contaminants do get in, there is no way to flush them out
* (-) More expensive
* (-) A bit more of a PITA to install, as you have to make sure you have sufficient lubricant in the caps before you install the joint, since you cannot add any afterwards.
* (+) Stronger, due to absence of through-cross grease channels
* (+) Less to worry about - don't require any maintenance.
http://www.pirate4x4.com/tech/billavista/PR-shaft/index4.html