Just as it is not uncommon to suffer “cascading failures” like the one where I recently broke a motor mount, and the resulting vibration was enough to cause the transmission mount to come loose, which allowed enough motion to break the exhaust hangers and destroy the muffler, it is also common to find yourself caught in the wallet-emptying cycle of “cascading enhancements” when working on cars.
You know, I was going to replace the cylinder head because it was cracked, but while I have the motor apart, I might as well rebuild the very tired top-end, and well, add higher compression pistons, and hmm… why not a cam! Let’s see, I’m really going to need a bigger carb to feed this setup… Of course I don’t want to take it apart again anytime soon, so I need a new clutch, and with all this new power, maybe I should upgrade the brakes, and suspension and… so it goes, on and on, you just have to stop yourself.
The Need for (5)Speed
With that being said, I couldn’t stop myself. You see, a while back I replaced my differential with one that had lower gearing (it went from 3:64 to 3:9 if that means anything to you). This change made the car pretty zippy around town, but the top speed was lowered significantly, and it was already pretty high-revving on the freeway as it was.
Well, I must admit that when I put that 3:9 rear-end in, I did it with the long term plan of replacing the stock and ill-shifting 4-speed transmission with a 5-speed overdrive unit from an early 80′s 320i, and yes indeed, yesterday I went to a junkyard and harvested a gen-you-ine Getrag 245/5 !
This transmission will pretty much bolt right up to my 1973 2002 motor with a few minor mods in shifter bracketry, and some judiciously inflicted blows with a sledge hammer to the tunnel. The drive shaft will need to be sent out to be shortend and ballanced, since the 320i gearbox is a bit longer than the original.
When I get my car back on the road, gearing should be ideal.