I'm changing the clutch on a '06 R52 S (R53) with 208K. The rear main crank shaft seal has never been replaced and is not leaking. I'm trying to decide whether to change it out while I'm in there. Let sleeping dogs lie or preemptive attack? I'd hate to change it out and then have it fail for some reason - my screw up or poor quality seal.

The part is already en route in anticipation of changing it out.

 

I recently was confronted by the same decision, and opt not to touch it as the car has only 42k. I know of a case in which a well known local Mini specialist shop installed an LSD and clutch for a client. They also changed the rear main seal. They botched the job and had to pull out the transmission and clutch to do the seal right the second time. The shop has been servicing and modifying Minis since early Gen 1.

If it were my car with 90k or more I would change the seal though. I bought a Felco but didn't use it.

 

With 208k on the ticker and full access, you can bet your bottom dollar that I'd replace it...

Familiarize yourself with the process via reading up on the topic, asking questions here and if possible, watch some videos. Just take your time and you'll rest easy that you did it.

And make sure you don't cheap-out on the seal itself.
I'd only go OE on this part.

 

I agree

 

I wasn't even questioning whether to replace it. It's right there with the flywheel off so why not. But then I started reading that people have had problems with replaced seals. Hence my post.

To help get it installed properly I've been thinking I would 3d Print an install tool to give me something to tap on while pushing it into place. I've watched Mod Mini install one on YouTube when he was changing out a clutch and he talked about using a soft hammer. A ring that is about 1/2" thick and the exact size of the seal could help spread the force when tapping it in. Perhaps I'm over thinking or over worrying about installing this component.

Attached is an image of what I was thinking of making. This is a random tool I found while searching, not an existing Mini tool.

 

Appears to be a very good idea.