JH Moss Box striker felts

Attempting to eliminate the pool of oil that seems to permanently sit on the cross-member under the back of the gearbox, my first thought was to replace the rear oil seal. This was pretty straightforward, as I’m also in the process of fitting new floors (XK120 OTS) so everything is easily accessible. Blow me down if there wasn’t a fresh small pool of oil in the same place the next morning! Assuming the leak was coming from between the oil seal and the rear housing, I carefully removed it all again and used some high-temp silicone where the seal butts up against the lip on the inside of the housing as I drove it back in. I even checked that the mounting bolts went into blind threads (they do) in case oil was leaking along a bolt or two. Nothing appeared to be coming from the speedo drive area either.
Finally, it dawned on me! Oil is dropping down from the end of one (or more) of the striking rods directly above. I have seen that this subject has been raised on the forum some years ago.
New felt seals are on their way.

It looks like the easiest way to tackle replacing the felts is to take the gearbox top cover off, as well as the gear lever assembly. My question is: are there any tricks I should know about or snags I might encounter? Should the felts be pre-lubricated? Should the new top cover gasket be fitted dry or with some sort of sealant?

I will check that the breather is clear, and at least it will be a chance to have a peek into the box. It is otherwise functioning OK, though there is quite a bit of bearing noise, especially with the clutch pedal depressed.

an XK jaguar that doesn’t leak now that’s a new concept!

Don’t use the orig felt seals. They will always leak!
I bought modern rubber seals from SNG.
I trust that you mean the 3, round felt seals at the top where the shifters run

Is that the accepted mod these days?

I could only see felt seals on SNG Barrratt’s website. Tried fitting felt seals from Coventry Auto Components today, but they seem way too fat and too large in outside diameter. They certainly don’t go anywhere near fitting into the machined recesses for them. Ideas, anyone??

Coventry Auto Components explained to me that they expect buyers of the felt seals to trim them to depth (and presumably, to outside diameter). However, I’ve gone ahead and ordered from McMaster-Carr some quad profile square section O-rings, as recommended in a post on this subject here some years back. For those who may be interested, these are basically square section, but each side is concave, so in effect more of an X - section. This has the advantage of helping to retain lubricant, compared to a plain square or round section O-ring. They are size 207 (13/16" OD, 9/16" ID, 1/8" depth). McMaster-Carr number is 90025K377, for those who may be interested.

Hi Chris:

I experience the same leak on my XK and suspect it may very well be from the same area as yours. I would be interested in learning how the seals from McMaster-Carr work for you, also, any chance you can post photos of the fitment? Thanks.



McMaster-Carr have just turned down my order, as they say they can’t afford to comply with export regs! Sounds strange to me, as I get stuff sent from the US all the time. Gues I now have to try and source the O-rings here in the UK…

I paid an experienced xk mechanic to install round cross section O-rings on place of the felts. It still leaks but not quite as much. I’d love to know if there is a better solution.

Will report back when I’ve made more progress.

whilst I know that there are felt seals not seen them personally
what I would say is the from the early 60’s maybe synchro gearbox on instead of the small hole/breather in top of gearbox there was a pipe running from 1/4 inch hole up to the firewall with top hat on the jags.
This applies to diff early cars had pinhole in top of axle shafts early 60 jags on had 1/4 inch hole and little chimney in diff cover providing positive breathing.
The gearbox and diff in operation would generate pressure inside so some positive relief would help.
Later jaguars seem to leak less oil ??

Good point. Here is the breather on a JH box. Make sure it is clear to breathe.

McMaster Carr is only 7 miles from me. I really thought they would do international orders. Let me know if you can’t find those X rings in your country; I can get them here.

Breather is clear - at least, I can blow through it OK.
Yesterday, I trimmed the felts to half the original thickness and to something close to the outside diameter. So far, no sign of oil. Before, it would drip overnight, even if the engine had only run for less than a minute before putting it away. I’ll see how it goes.
It was only after reading an old thread about the selector (striker) rods that I discovered there was a roller in the 3rd/4th (middle) rod. Having already had this rod out the day before and re-installed, I was very apprehensive that the roller and/or interlock balls had dropped out somewhere… Fortunately, I discovered the roller on the ground where I had been working, and amazingly, when I took it apart again, the 2 balls were still in place either side of the bore for the rod! So, no harm done.
It pays to read up thoroughly before tackling these sorts of jobs!

Thanks for the kind offer, Rob. I may yet take you up on it!:smiley:

So much for the new felt seals! They are leaking slightly already and the car’s literally only done about 4 miles. I guess I’ll have to live with it - I’m certainly not taking it all apart again!