1970 Corvette Silver Sport Transmissions

A few months ago, I purchased a 1970 Corvette with the intent of installing a TREMEC Magnum 6 speed transmission in it.  My Corvette was an LT-1(370 HP) with a 4 speed and 3.70:1 Rear Axle Ratio.

C3 Corvette TREMEC Magnum PerfectFit KitIn addition to the transmission, we also installed a hydraulic clutch actuator and our new SST Advanced Friction™ STR clutch kit.  The STR is designed for engines up to 450 ft. lbs. of torque and to provide light pedal effort and smooth street characteristics.

We completed the install, the day before our Christmas vacation and I decided to drive it home to show my family and friends.  Home is 890 miles away (Knoxville, TN to Pryor, OK).  This is a fairly daunting trip when you consider the car is 48 years old and we had only driven it a few times around the plant.  But, I had a lot of confidence in our team and our products so I took off for Oklahoma.

The trip home provided a great test of our products.  Although it was mainly highway driving (I40), the route took me over the Cumberland Plateau (6% grade) and the cities of Nashville and Memphis during the peak rush hours.

Prior to the TREMEC Magnum, 2000 RPM would get me 44 MPH in high gear (4th).  With the Magnum, I could get 54 MPH in 5th and 69 MPH in 6th.  At 2300 RPM, this increased to 62 MPH in 5th and 79 MPH in 6th.  I can’t imagine making this trip without the advantages of an overdrive transmission.

The Magnum transmission handled the mountains very easily in 6th gear…even the steepest grades.  And, on the open road, it was easy to keep up with or pass the other vehicles.

5th gear was especially important when driving in heavy traffic, like rush hour in Memphis and Nashville.  It allowed me to operate in overdrive a relatively slow speeds when my engine couldn’t handle the 6th gear overdrive ratio.

Many times, we are asked what the advantage of the Magnum is over the TKO and this is the big advantage to me.  You will be able to use overdrive more often if you have the option of a .80 overdrive in addition to a .63 or .64.

All of the equipment performed flawlessly.  The clutch was very friendly, it has nice street characteristics.  The pedal effort was light, no chatter and it gripped very well.  The hydraulic actuator felt really nice and it will never need to be adjusted.  There were no vibrations and the car ran smoother than it ever had.

It is clear why our customers tell us “This is the best upgrade my car ever had”

Jack Silver Grizzly Silver 1970 Corvette

1970 Corvette Silver Sport Transmissions TREMEC Magnum