Intermediate shaft counterbalanced?!

tylernt · Post by **tylernt** » Sat May 26, 2007 12:21 am

I'm tearing apart my first engine, a Mk1 1.6TD in preparation for an overbore and crank regrind before I put it into a Mk2 Jetta. I pulled out the intermediate shaft (only minor flaking of the bearing, BTW) and to my great surprise, I found an eccentric weight cast into it!

Now, I know that many engines have counterbalances to reduce the 2nd harmonic forces from the pistons, but I didn't know VWs had one... but maybe that's not even what this is for? I mean, the intermediate shaft pulley is smooth so there's no way the belt can keep it in time. If it's never going to be perfectly in time, wouldn't this eccentric weight *cause* vibration? Why is it there? For the torque pulses from the diaphragm vacuum pump? If so, that's still no good as the vacuum pump isn't timed to the int shaft.

I don't get it.

jackfrost1031 · Post by **jackfrost1031** » Sat May 26, 2007 12:30 am

it's a relic from carbureted rabbits that run a mechanical fuel pump off of it, afaik.

tylernt · Post by **tylernt** » Sat May 26, 2007 12:35 am

jackfrost1031 wrote:it's a relic from carbureted rabbits that run a mechanical fuel pump off of it, afaik.

Ah, come to think of it, it is approximately where the blockoff plate is. I presume that's where the mechanical fuel pump mounted?

Would there be any benefit to removing it? I know these things vibrate a lot already so maybe you'd not even notice the difference.

jackfrost1031 · Post by **jackfrost1031** » Sat May 26, 2007 12:42 am

people who go for performance builds cut em off and polish up the shaft. It would definelty move the axis of rotation closer to the centroid of the shaft, and thus make it easier to rotate. I don't know how much real world gain it would be, but if I had access to something to do it I would personally shave the thing off. i'd also balance the shaft and all that jazz too.