Lets talk, transmission gears and tire size.

[CaveManDave]

Hi Guys,
Is there anyway to know the gears in my 4 speed Transmission without opening it up?? What is the Gear ratio needed for a 30" height tire?

 

[Loner]

1. Raise left wheel off ground.
2. Set motor to TDC.
3. Make chalk mark at exactly 12 oclock at highest point of tire.
4. Put tranny in fourth gear.
5. Slowly turn rear pulley on motor and count the number of revolutions it takes to make the tire do one rotation (be precise).
6. If your count says about 3.60 revs, you are lucky you have a 3.875 ring and pinion ratio. If your count indicates 3.67 revs (see why the precision?), you have a 4.12 ring and pinion.

Whatever the tire height, the highest ratio you can get (i.e., 3.875 ratio) will always be best. If you don't have that you can decide if that little bit of extra higher gearing is right for you. (Cost would prohibit the gain in my book!).

Hope I remember that right. Good luck.

 

[DeathBySnuSnu]

Yeah a 30 inch tire is big.
That in itself is a large gearing increase.
The vw evolved and got larger engined and taller gears through the years.
Lots of stuff interchanges and from the outside looks almost the same.
Beetles
First is it a swing axle?
Up to 66 4.375 ring and pinion.
Some 66 and 67 swings and after all the irs had 4.12 ring and pinion with taller 3rd.

Ghias had some different 4th gears ( heavier car).

The late model beetles with the single side cover gear box were mostly 3.88 ring and pinion

Unless you have a modified engine a regular 4.12 box with them 30 inch tall tires should be plenty gear.

I run a lot of gear, but, i also run modified engines.