The History of Speed Gems

Speed Gems Transmission Adapters started as businesses often do, to fill a void or a need in a market place. We evolved from a full service transmission shop.  We grew to specialize in antique and obsolete transmissions.

We started building engine to transmission adapters for two reasons. One is that it is getting extremely expensive to rebuild the original transmissions. Not only are some of the parts getting scarce, but the knowledge level of the people available to rebuild these units competently is diminishing. Transmissions had more internal changes back in the 50’s than they do today. To most people, four speed Hydramatics appear to be the same from the outside, but many of the internal parts (mostly hydraulic control) were not interchangeable from year to year, or from model to model.

These transmissions had extremely touchy throttle pressure linkages that required them to be adjusted correctly or a failure would occur. Carburetor swaps usually made adjustments very difficult, if not impossible. These adjustments are very similar to the detent cables used in 700R4 and other modern transmissions. They control all internal pressures inside the transmission. Throttle pressure must raise quickly when engine load increases. Out of adjustment one way (low pressure) and you will have burned clutches and bands; out the other way (high pressure) and you can break shafts and splines. Vacuum modulators changed the way transmissions received their information about engine load. Linkage & cables became just “kickdown” devices.  Electronics made external adjustments obsolete. There are no longer any mechanical adjustments. All pressure and shift timing is now taken care of by computer. Changes internally to today’s transmissions are usually well documented not only by the manufacturer, but also by technical subscription to a number of aftermarket companies.  

The second reason that we are designing and building adapters is that we would like to see more people run alternative engines in their cars rather than just small block Chevys. The original V8 engines that many of us fondly remember from our youth are making a long overdue comeback in the way of the Resto-Rod.  

Hot Rodding started as a very creative hobby. Working with what one could afford at the time, cars were built with a lot of imagination. The trend to drop a small block Chevy engine into Hot Rods today shows that the hobby/sport has totally changed.  It is now common to see the same type of build out at local car shows.  Where can we go from here?  That’s what we are interested in.  We like to see what no one else has ever done before. 

Here at Speed Gems Transmission Adapters, we adapt the old motors to modern transmissions so you can use an engine with some personality, plus get a lot better gas mileage with an overdrive gear, whether it is a manual or automatic application. We plan to lead a revolution against the trend of planting small block Chevy motors into everything that moves.