The photo below shows a UJ from a Wrangler TJ front half shaft, which was only fitted 9 months ago! The corrosion is not due to lack of maintenance, as this particular UJ is classed as maintenance free or more commonly known as sealed for life ( in this case not a very long life). On a road going vehicle that does not see any real off-road use this type of UJ could last years, I know one guy with a Cherokee XJ that has never change the UJ’s and it is 16 years old and they are still in good condition!
The reason for the premature wear & corrosion is basically the ingress of water into the cups. How does this happen so quickly? You can see the seals look in good condition! When driving to the shops or work the UJ’s heat up expanding the grease and pushing any air trapped in the cups out. This is not normally a problem, as when you park up at your destination the UJ’s cool, the grease contracts and it pulls air back into the cups. When you arrive at the off-road site you drop into low box and trundle off hitting mud holes water splashes and such like. The UJ’s are cooled down by the water hitting them and the grease inside the cups cools and contracts pulling in whatever surrounds the UJ’s. Water, a water-sand mix, water-mud mix. So starts the rapid detrition of the UJ’s, and as these are sealed unless you strip the UJ out, which is not an easy job, there is no way in which to grease the UJ and push the dirt/grit out.
There were some UJ’s that were cross drilled with a grease nipple (red arrow) but this caused an inherent weakness and they often broke across the middle (in off-road use). There are a few heavy duty UJ’s available such as CTM, but these are not designed for long road use at high speed. So what is a good alterative to the stock Spicer UJ? Alloy-USA make a UJ that fits the bill, serviceable flush grease nipples at each cap allows you to flush grime and fill with grease. Made of cold forged steel composition made of chromium, molybdenum and nickel alloy, with a hardened case for excellent wear resistance. These UJ’s are not a lot more expensive than the stock Spicer units, but if maintained will last and give years of trouble free miles.
So the next time you are stripping down the front axle to pull the half shafts to change out the UJ’s why not upgrade to a serviceable unit. Its is a lot easier to pump a bit of grease into a UJ then replace it!
For more information and prices contact Steve at
FTE 4x4 Specialists Ltd. on 01268 730131/07973 198483 or email
steve@fte.co.uk
Technorati Tags:
Jeep,
Wrangler,
Cherokee,
Axle,
Off-Road,
UJ's,
Dana 30,
Dana 44,
TJ,
XJ,
ZJ,
JK
Posts
