I was able to spend some more time on the Fernley transmission. First had to fabricate a two more tools to use to support the output shaft while pulling off the transmission case and they worked!
As I said before, there is grounded up brass everywhere. Well, as soon as I got the case off it all become very clear! Take a close look at this picture:
Those two little blocks sitting inside the black square at the bottom of the page don’t belong there! First it explains everything at Fernley. During practice we got stuck in third gear. Couldn’t get it out of gear, but then Rye took it out on the track and at high revs suddenly it slides out of gear and we thought everything was good.
Well, what happened was those little blocks belong behind that smooth large ring at the top of the picture. They had shifted out of place and caused us to be stuck in third gear. But then at high revs those blocks, actually there are three of them, were spinning fast enough that they spit themselves right out of the gear cluster. And those little blocks have an important job! They keep the brass syncro ring aligned with the sliding collar. Without them everything for third and fourth gears are screwed. So every time we shifted between the two gears we had to grind on the brass syncro ring to get the shift collar to align. There are little dog house looking teeth on the brass syncro rings, you can just barely see them on the right side gear cluster. They have to align with the steel dog houses, again you can see them just above the brass ring on the right side. So without the three little blocks, every time we shifted the brass ring dog houses were grinding up against the steel dog houses. Guess who lost that battle! Yep, there are NO little dog houses left on the third gear syncro rings, totally gone!
Again, look at the black square at the bottom, all that gunk underneath those two blocks looks like gold, well it’s loads of ground up brass. It’s everywhere!
So now we know why the Fernley transmission “fixed itself” on the race track. And also why as the race wore on the grinding got worse and worse. Also explains why doing “Granny shifts” worked, it gave the gears time to match up without the benefit of the syncro ring.
I got the first shaft out of the case, here it is on the bench.
Sorry it’s a little out of focus, bit the brass ring on the right is the third gear syncro with all the “dog houses” gone, those steel “dog houses” just to the right of the brass ring eat them up! The brass syncro on the left is fourth gear, they are chewed up too, but not totally gone. And this has some logic too. Remember, this gearbox is not a close ratio box, so we were not needing 5th gear at all, too tall. So we where only getting into fourth gear. When you shift up your rpms fall, so things are spinning a little slower, easier to get the “dog houses” to line up, so less grinding. But down shifting to third, you need to have things spin faster and that is harder to do, therefore more grinding on those brass “dog houses” to get third gear up to speed. Here is where double clutching REALLY helps, gets those gears spinning faster before trying to shift into third.
As you can see, I am thoroughly enjoying my new skill, VW 020 transmission forensic engineer!
Next question that needs to be answered, other than the brass syncro rings, how much other work do we want to do on this tranny. I say do the minimum, reuse as many of the bearings as we can, so just replace syncros, oil seals and snap rings, put it back together. What could possibly go wrong!!?? Run it! Now, the other tranny, let’s call it by it’s designation, the FK tranny, is a close ratio transmission. Now that I want to get into and I think that is the one we want to use most. However, the Fernley transmission might be the best choice for tracks with a long straight like Thunderhill and Buttonwillow. So what will we have, just the opposite for Infineon, the taller geared Fernley tranny! Oh well.
And that’s your transmission lesson for the day!
Mr. Unruly
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