Re: Replacing standard gearbox with an overdrive gearbox 1948 22nd Series

Posted by Ross On 2010/8/3 21:16:37

I would encourage you to do the work to install the overdrive. It will give the car much greater flexibility under all conditions, and will enable you to cruise at 70 with the same engine revs that used to provide 50. Helpful in the modern world. I am guessing that your car might already be geared 4.3 or 4.55 to one. The differential housing is stamped with the ratio at about the 11 o'clock position as you face to the rear of the car. The overdrive will give you an effective ratio of 72% of your axle ratio, or in the case of a 4.55, 3.28:1. That is a nice difference. And, you can always lock it out while traversing Snowdonia.