Props to Isleblue65 for raising this topic.

I had been wrestling with this issue since 2014 off and on, and had basically just been living with a dodgy 4th gear. I'd loose interest in chasing the fix, then build momentum again, but nothing I tried seem to get it done.

Just as I was about to give in and move forward with a gear box swap, I stumbled across this thread. I immediately ordered a new oil seal kit as back up, and started playing with the dust boot already on my car. Sure enough, the boot appeared too long, as the shift rod appeared to rebound back. With little to loose, I cut one rib off the boot (shift rod still fully protected in 2nd and 4th gear, minimal gap in 1st and 3rd) and went for a test drive.

RESULT: Drove fro 20 min - no issue. Parked it for dinner - ran another 20 min no issues. Drove it again this AM for 40 min no issues.

I'll be holding my breath for a few days, but it looks very promising. Will keep a log on this for a few weeks to keep everyone posted. If it solves it, I'll end up using something with a little larger opening to fit over the coupling right at the roll pin, so I still get dust protection, but avoid the springing/bounce back.

Fingers crossed~!!

Old seal came out fine and new aluminum o-ringed sleeve and new seal installed.  The soft bellows solved the shifter issue, so I'm going with inconsistency batch to batch.  

Oh, so you're one of those people!!   I always wonder if its just because it's easier than pulling the old seal out!  Sure it probably works the same as one good seal, but the kit has the nice aluminum sleeve that supports the stub shaft far better than a stack of seals could!

Ditch the oil leak kit, push the old seal further in and put a new seal behind it. Works a treat. My two bob.

 

Jemal, motor mounts are firm, and I have two Lower engine steadies and upper dogbone steady, all with poly bushings. 

I found this dust boot locally, which will stretch up over the 1" od of the coupler, and is made of very soft rubber that compresses easily with a finger.   This rubber bellow will not have any negative affects on shifter linkage movement. 

 

 

Don't overlook sloppy motor mounts for rod-change cars that like to jump out of gear!  If the engine moves back and forth under accel/decel, you bet the stub shaft out of the diff will feel it!  In my view, ANY 1275 or bigger rod-change NEEDS an extra engine stabilizer or two if driven in a spirited way. Mine has FOUR, and the engine still tries to jump out of the car!  But it doesn't jump out of gear!

This is even more likely if the car jumps out of 2nd or 4th on DECEL.  When you let off the throttle of a classic Mini, the engine lurches backwards at the top, so FORWARDS at the stub shaft.... quite easily clicking out of gear.  Try it by undoing your dog bone, put the car in second (car NOT running for you lawyers!),  then shove the valve cover back towards the firewall.

McMaster-Carr has a good selection of bellow style dust boots.  I will order a low profile boot today that fits over the coupler and butts against the seal lightly in 1st gear, ensuring that the compression of the boot does not work against the engagement of 2nd, 4th or reverse.  This would have been a better design in the first place.

I think the issue is that there is little consistency in the boots from batch to batch. I do have a couple of spares on hand and there is great variation. Some of the boots are so thick that they barely compress at all. I have not seen a really thick one recently and have three relatively new engine builds in the cars.

Certainly some wear and tear on the gearbox components would contribute to the problem.

Terry

Anyone buying a mini with a "rod change shifter" should buy an oil leak kit fixer right upfront and keep it in stock, not expensive, $25.00 or so but you will need a new one sooner than later

Big AL

The accordian makes it very difficult to push the shifter all the way into 2nd, 4th or reverse, and more likely (in my case) I did not get 2nd fully engaged.  It would not 'pop' out of gear if I intentionally jammed it in with force, but that is not how it should work.  

I noted that the accorian is already in compression with the ridges touching eachother in first and 3rd gear.  

I also verified the same travel distance of the rod going into the gearbox with no shift linkage attached (pushed in by hand and marked at the seal) as it had with the linkage attached and no boot.

So in this case, it is not internal gearbox problems, mounts or incorrect rods. The issue is a boot that is either improperly spec'd, older rubber that has stiffened on the shelf, or I am not patient enough to wait for it to soften and break in. 

I've heard that story before and all I can say is if that accordian boot has enough pressure to kick the gearbox out of gear (it squishes in 2nd, 4th and reverse) then one has a gearbox with internal problems, or one is using the wrong "rods," or one is using the wrong mounts for the rear end of the shift rods, or a combination of the above.

If it makes you feel better, trim as little as possible off the boot, but never run without it...unless you like changing the seal more often than it usually needs to be.

I installed the anti oil leak kit MSSK050 with my rod change gearbox, and found that it would not always engage second gear, or would come out of second gear as soon as I decelerated.  I thought my 2nd gear sycro was bad, or I had a linkage problem until I read that others have had this issue.

The rubber boot that comes with the above kit is too thick to compress, and acts as a rubber stop preventing full motion of the rod.  Once I cut off the boot, all was well.

If you plan to install one of these kits, I would not recommend installing the dust boot, or at the minimum you will want to cut off 25% to 50% of it before installing.

I made a short before and after comparison video:

https://youtu.be/LooJcx-xmzc