Hi All,

I read through some previous threads (Oct 2016) on the subject of replacing PTFE seals in a K bike and having gone through a botched attempt recently, I am about to attempt it again. But I dread the installation process and the finicky nature of the seals lip. Therefore, can anyone give me advise on the best "dry" procedures for installation and how to seat the seal - without risk of damage, into the engine recess (what tools /procedures are recommended to get the seal safely into place) should it be seated half a mill out from the edge for example? Should I heat the "lip" before inserting the clutch carrier?

Any help/advise would be most welcome.

Trapper

Alyn

First thing is the seal itself. Not sure if its same as the 8v but in my case [8v] there were two seal types and it was genuine BMW one that was used. From what I have read first check which seal you are using.

Mine came with instructions to soak it in oil for an hour or two before installing it. Same instruction was with the gearbox and gearbox output seals.

If you use the Teflon lip seal put it in using a small hammer and a block of soft wood against the seal. Make sure the surface of the shaft is good by feeling it with your finger nail for wear. If there is no wear then you can put the seal in level but no further. If the shaft is worn then turn it into a frizzbee.
To get the seal to expand oil the lip and run your finger round and round which will slowly expand and warm the lip a bit then put the shaft in and let it sit for about an hour so the seal slowly comes back to tension and size on the shaft. Usually this time is not a factor to consider as it takes at least that long to finish the gearbox and final drive installation.

Many thanks for the advise.

My seal is very slightly proud and done 4,500 miles since it went in.

Interesting tips - many thanks, I distinctly remember tapping the seal all the way home in the recess with a timber dowel and soft mallet. However, I did not soak in oil beforehand, nor wet the clutch housing shaft or heat the malleable seal. Seems that's where the fault may be. I may also have read too much into following the PTFE manufacturers recommendations of performing a "dry" install.

There's merit in the saying "Those who say it cannot be done - should not get in the way of those that are actually doing it!!!

G'day All, after having replaced a couple of seals on a K75 and a K100, I found that a genuine BMW seal is the way to go. I  have had pattern seals fail soon after installation. My 2c worth. Good luck Tom

My one was a genuine BMW seal too and my friend warned me off others, I suspect for the same reason. Clutch cables are another that he insists should be BMW.

Its really annoying having to go in again and the only plus point is you know it will come apart.

I have replaced quite a few over the years and have used the pattern seals but if I use them they must be[size=16] [size=13]VITON and not nitrile material because the nitrile will fail due to too much heat. The manufacturers of the seals and the many "experts" will tell you that the viton is not needed and the nitrile will do the job. I just reply that it is a well known issue and wont argue.[/size][/size]

So, in short - should I avoid the PTFE brand of seal?

The Teflon seals are fine there is no question of that but what I was saying is that the Nitrile seals that are sold as a suitable replacement are not going to go the distance and that soon you will have to renew it. I would say that the Nitrile was what Olaf was warned of. The Viton seals are available here in OZ where I need to order the Teflon ones from Motobins so they are a better bet for me.

Got into the main seal again this evening and this is what greeted me! Seems like the lip got squashed and then separated on the shaft!! The seal was ALL the way "home" in the recess - perhaps not giving the lip much of a chance to wrap around the flywheel? Comments welcome.

As was rightly mentioned I was probably warned off the non BMW seal for the reasons above. Anyway the man who warned me off it I respected and went with his advice and used the BMW seal and it wasn't 'home' all the way. He didn't go into Nitrile and Teflon arguments just insisted on the BMW one as there are quite a few types out there that will fit but are not up to the job and won't last. I guess sometimes we need to have the right label on the box.

Hope all goes ok Alyn.

Thanks Olaf, The original BMW seal lasted for 27 years and I'd be very happy with a repeat of that time period again.  Not convinced the new PTFE seals are up to the mark???

Jimmy Ellis in Cork spent many years on BMWs at Kearys [local motorrad] and also on his own to the point where he can do them blindfold. He won't spend money unnecessarily but won't spoil a job to save a few cents. I don't have the timescale to do that job myself so we did it in his place.

Just an update on the refitting of the main output shaft seal - I damaged (slightly) another seal in the repair process, so I thought, there must be a better way. I made up a 2mm aluminum disk 81mm wide and drilled a hole in the center. This allowed me to slowly compress the seal into the engine (without tapping it) using the old 30mm nut. I checked the progress several times and to my surprise it was a perfectly even fit. I soaked the seal in warm oil for 1 1/2 hours in sunshine and now I'll give the seal 4 hours to settle before I top up the engine with oil and then leave it over-night to check for leaks. Hopefully tomorrow I can then start the rebuild with the clutch plates and fit the gearbox.