The repair manual for my 2000 VDP calls for Loctite 270 on the rear axle splines. My mechanic cautions against this and suggested just grease if the hub is ever to be removed again. I wonder what is the prevailing wisdom for using Loctite and what do the majority of people use?

thanks,

 

Jaguar in their infinite wisdom employ masterful engineers to write up the JTIS proceedures and if a situation calls for Loctite to be used.....use it.
It was obviously done for a reason and not for the benefit of some grease monkey who can't be bothered doing the correct procedure!

 

Then why do the Wise Jaguar engineers not practice what they preach. I pulled the hub carrier apart and the splines were greased. As these are originally installed hubs what gives?

 

First, there are plenty of things that make it in to documentation that were meant to be amended and never were. We're not likely to see JTIS materials for the X308 series ever be updated again.

Second, on principle I hate Loctite and its kin. Fasteners should have no problem holding together if the necessary torque is attained (and, preferably, no more than that - more is not better). I personally prefer anti-seize lubricant wherever it's reasonable to use it because correct torque will hold the fasteners in place but it prevents corrosion and galling and allows them to be removed if necessary in the distant future with far less likelihood of problems.

I went through a similar discussion on those beloved of lock washers, which all engineering studies indicate are not effective (at locking, anyway, distributing force across a larger surface area is a different issue).

Splines are meant to transfer rotational energy from one object to another by interlocking. They are not meant as a fastener and there are obviously other fasteners that hold the parts together. If those fasteners are properly torqued then the splines will be just fine without Loctite or similar.

God knows that the next mechanic who has to take this apart will thank you.

My guess, and it is only that, is that the Loctite was recommended as a way of keeping oxygen and moisture out of this connection, which grease can do equally well. In the end, it's probably more a matter of which substance you think will be better at performing that function and whether you anticipate disassembly in the foreseeable future.

 

Hi Brian.

In the end, I decided to go with greasing the splines. The way the rear end uses the axle as an upper control arm, I figured there had to be some movement in/out required as the suspension moves up/down. Also, when I pulled it apart and saw grease not Loctite, I didn't want to alter what was done at the factory. The rear axle on these cars are hard on the bearings and after doing both sides, there is always the possibility that I would someday have to do another bearing job. Loctite would make removing the hub assembly problematic. I have searched in other forums BMW, Audi and the like and saw where their manuals also call for Loctite on the splines. However, the factory certified mechanics in these forums also questioned the validity of this procedure. In fact, they cautioned against it due to the extreme amount of force it takes to remove the hubs with Loctite applied. I did apply a small amount to the threads as this sounded prudent in that this one nut is the only thing holding the hub assembly together and could result in catastrophic damage if it loosened. This may be why this particular nut costs $38 - you wouldn't want to crash because of a .38 cent piece failing...lol.

 

Michael,

When faced with a dichotomy between what's in the documentation and what is found when a known OEM assembly is taken apart I, like you, will go with what was actually in there (provided there hasn't been some major technological improvement of some sort - I wouldn't use single-viscosity non-detergent motor oil under any circumstances, as an example).

Loctite on threads certainly won't hurt anything, but it probably doesn't help anything either if the fastener is properly torqued. Loctite can help to prevent corrosion, but so can other things that don't lock a fastener more tightly in place. When you consider that Loctite started its commercial life in the early 1950s, and that there was significantly "less robust" metallurgy at the time that led to a greater fear of tightening fasteners to the point of failure, thread lockers made a great deal of sense. They were a work-around for low torque values being used by necessity and the increased likelihood of fasteners backing off from vibration later. Things really have changed a lot since then, and you almost never hear of a fastener "coming loose" if the specified torque has been applied.

My guess is that the nut costs $38 because the Jaguar name is associated with it. It's rare that anything beyond Grade 8 (or its metric designation rough equivalent) is ever used in automotive applications (see here and here for Grade 8 references). You can find Grade 8 nuts, bolts, etc., in virtually any half-decent hardware vendor. The cachet of a given name often results in parallel cash-et in prices for dirt common parts.