Reply To: Overdrive versus High Speed Gears?

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I have had installed, but not yet driven, a Gear Vendors unit in my 1932 Model 54 eight cylinder Club Sedan. It cost $3000 (gulp), and of course the considerable installation labor was additional. Some of the pluses and minuses (some already mentioned by others) that I see for gear-set and Gear Vendor overdrive units are:

Gear-set

Looks original – provides what some would say is a more useable first gear – is a “new” unit – provides an excellent opportunity to inspect and replace the rear end and rear axle bearings – when successful, is cheaper and easier to install than a Gear Vendors overdrive – provides engine braking without going through an additional clutch. Phil Hill unit does require some grinding of the housing.

Gear Vendors Overdrive

New, very strong, and yet light weight units – leaves all your original ratios intact, but adds two more (second overdrive and third overdrive – first overdrive is not useable – the second overdrive is what is called gear splitting) – is actuated electronically at any speed over 20 mph by the driver and is engaged hydraulically. Using it only results in about one quarter of one percent inefficiency (some other overdrive units result in much more). If my memory is right (better check!), one can get a 1.22, a 1.25, or a 1.28 ratio GV tech phone service is very good. There are also what in my thinking are significant disadvantages compared to a gear-set and some other overdrives. I wanted to keep my original transmission because I want my car to feel like an original Pierce-Arrow, so there was not room to mount the GV unit onto the transmission itself, which in my opinion would have been the simplest and most desirable approach. So we had to use what Gear Vendors calls a “remote” installation. From the rear of the transmission, first comes a universal joint, then the shortened drive shaft, then another universal joint, then the GV unit, then a third universal joint, and finally the yoke attached to the pinion gear. Unfortunately, the original positioning of the torque arm is not far enough off-center to clear the GV unit. So the torque arm was moved farther to the side, a mirror image torque arm was constructed, and the GV unit was set between the two. Luckily for me, one of the mechanics doing the installation is also a machinist. Other than costly installation, another disadvantage is that I can only use the GV unit over about 20 mph. I would have much preferred an overdrive that I could use at any speed, but due to what GV calls the unit’s hydraulic requirements, this can’t happen. Also due to the hydraulic requirements, it is not recommended to use second over for engine braking or deceleration; second or third gear is recommended for this. I haven’t given thought to how freewheeling fits into the discussion. After all this, I sure hope the xxxx thing works good!