Hi All, I have read all the shift shaft seal threads and cannot find an answer to my problem. Here goes but first a little history. Last year I decided to do my shift shaft seals. My old ones dripped just a little so I ordered new ones from Ferrari UK (as part of another order) and installed them with all the love I could muster. I buttoned everything up and re-filled the fluids. Next morning I find a little puddle (6 or 7 drops large) under my car where the shift shaft seals are. After suffering like a dog to put them in I decided that it will just have to wait until next year and let it leak if it wants to (I was pretty fed up by then) as it was now leaking much more than the 1 drop a day from before. Fast forward to this year. I am doing some other jobs and decided to do the seals again. This time I bought the Quattro seals and took everything apart today certain that I would find something wrong. As it turned out, the seals that came out showed no signs of wear. The old ones I took out had little flats worn on them but these ones were perfectly round and showed no signs of damage anywhere. I then compared these seals to my new ones and found them both to fit on the shift shaft with the same tolerance; which I think is LOOSE. I tried 10 different seals and they all are maybe 0.5 mm larger in id than the shift shaft's OD. Having found nothing wrong I don't want to fill my sump only to have it leak again. My question is: How tight should the seal be to the shaft before installation? I should add that I compared both the OEM seals and 10 different Quattro seals only to find their fit to be almost identical accross all 12 seals. I know that when you install the seal it compresses a little but these tolerances just seem too large. While it was out I also measured the shift shaft. It shows no wear and the surface on which the shaft seals operate is 0.788" +/- 0.0005" . In addition to this, the first time around, the seals were installed very carefully making sure that everything was well installed and lubricated. I do not think that there were any procedure errors during the install but would be more than willing to hear any input.
As I recall I used to cure the sloppy problem by adding another o ring, then peening the cover. It's a bit tight but with the leverage in the shift mechanism it isn't noticable at all. IIRC I added a slightly smaller seal as the second. This aided the install and helped close the shaft/seal gap.
From what I can see there is no room for another o-ring and I am not sure exactly what is meant by 'peening the cover'. What I do not understand is why the OEM supplied O rings in addition to the tried and tested Quattro rings do not fit my shift shaft.
That 211 size Quattro seal is actually an Imperial size (.796" ID x 1.074" OD nominal) for a 13/16" shaft and a 1.0625" groove so I think that you are counting on the OD being a little too big for the groove and for the seal ID to close down some when it's installed into the groove (and being a soft plastic part, the dimensional control isn't good to the thousandth -- so any seal, whether nominally Imperial or metric, will have some big tolerances). Of course that doesn't explain why the stock o-ring from FerrariUK didn't seem to work? Does it seem to have the same cross-section as the old o-ring that showed the compression flats? But just fitting the seal in the "free-state" onto the shaft won't give the whole picture (although I agree that it would be nice if it showed a little interference in that condition). Bottom line is that you need the free-state cross-section of the seal to be slightly greater than the (groove diameter - shaft diameter)/2 value.
