Gearbox Gear Ratios

During my first test-drives, I discovered that the gearing of the beetle gearbox is a litle low for this Alfa engine. I can rev the engine very long in each gear, I can rev to 50 km/h in second gear easily for excample. It isn't a real problem, I now have the choice to drive very steady and quiet at low revs, or rev it up high and make the engine scream.
But I am having cooling problems, this might be caused by this low gearing. Because the waterpump pully is sized that way that it will give the coolant enough flow at certain revs. A certain speed is coupled to a certain rev count and that should give amount X of cooling air in gear Y. But, the beetle gearing is lower than that of the Alfa Romeo 33. At least, in my beetle, because it is a "S" model with 1600 engine and the lower geared gearbox.

The next beautiful tables are courtesy of Custom and Speed Parts.

This is the rev-speed table of my beetle's gearbox with 175/70 15 tires fitted:

And this is the table of the Alfa Romeo 33 1.4 i.e.:
(NOTE: this is the gearbox of the 1.4 Alfa, the 1.5 and 1.7 Alfa 33 has a different (lower) differential value, namely 3.888)

You'll have to compare the 4th gear of the beetle with 5th gear of the Alfa. As you can see there is about 10 km/h difference per rev number! Quite a lot. This means the waterpump is turning at a lower speed with the beetle gearbox than the Alfa gearbox at a given speed. This, while, the engine is working harder to turn that lower gear. That doesn't sound good.

I don't know how much impact this all has to the cooling system. But I have an AM gearbox lying around in my garage, which will give me these gear ratios:

Again, compare 5th Alfa gear with 4th beetle gear. These numbers are much closer to the Alfa gearing!
Maybe I will give this gearbox a try, it will probably improve acceleration a lot!

edit 22-07-2007: Started cleaning the other gearbox a bit.

Man, what a mess it made! All this mud mixed with gearbox oil went everywhere. I discovered I have to transfer the nosecone of the current gearbox to this gearbox. This gearbox has the old-style front gearbox mount.

edit 15-08-2007: This week I started to take the beetle apart to change the gearbox. I started with this:

Than with a plan-off-attack (in dutch):

It's even prioritized!

I took the engine out:

And after that the gearbox:

I had to transfer the nosecone of the original AT gearbox to the AM gearbox:

The front gearbox mounting is different.

Both nosecones off:

And the AT nosecone on the AM gearbox:

Now I have to put it all back in.

edit 19-08-2007: When I was ready to install the AM gearbox, I noticed that the clutch levers where different:

The one on the left is the AT gearbox, the one on the right the AM. Notice that the AT lever is longer! And the throw-out bearing axle is thicker too. After I put the engine back in I noticed that his shorter clutch lever caused the clutch to operate a little heavier.

Here's the gearbox back in:

And the engine back in:

Done!
After a test run it turned out it didn't matter a thing for the cooling. Apperently a 10% in waterpump speed doesn't matter.
But, this drives a lot better. The engine pulls and revs better. The downside is that the cluth operates a little heavier now.