Thanks for your time, I have had this truck for over twenty years but did not realize what I had until a year ago when I had to pull the tranny off to replace the clutch kit. The PO used this truck as a daily driver and wanted to run interstate speeds so I guess that's why he replaced the stock tranny? When in first gear the shifter almost touches the dash. Can you please explain the 1-2-4-3 shift pattern you mentioned. I have always shifted 1-2-3-4 rarely using the 4th speed in the city when driving under 50 mph. What is the difference between the overdrive gear and the straight thru gear?
Yup, lots of people want an overdrive transmission in the pursuit of better drive-ability and fuel economy.
The 4 speed manual transmission was a logical extension to the 3 speed manual gearbox that was prevalent from the 1890's to the 1940's. The 4 speed manual was available as early as the 1930's in the VW Beetle, but the US market didn't really get a 4 speed manual until the late 40's. For almost 100 years, the purpose of a transmission was to provide a gear REDUCTION in the drive train to produce more torque at lower speed, and allow you to keep the vehicle in the power band as you gain speed.
So in a typical 4 speed, first gear is the highest gear reduction, then 2nd, then 3rd, and finally 4th. But 4th gear isn't really a gear at all. 4th is "straight thru" or just a solid coupling. So in every 4 speed transmission built until about 1975... 4th gear is 1:1, or straight thru. Once you reach cruising speed, and the input shaft is coupled to the output shaft...you have reached maximum strength, and efficiency, and all of the gears inside the transmission are just idling and spinning and basically doing nothing. This is the ideal configuration for maximum durability at maximum exposure. So if you are going to drive at sustained speed on the highway...you want to be in "direct"
The traditional Ford Toploader 4 speed transmission follows this convention. First gear is typically 2.32, second is 1.69, third is 1.29 and fourth is 1:1. This is the configuration that everybody understands. And if you pull the top cover on a toploader, you can see the gears get smaller on the shaft as you vies it from back to front. The back gear has 32 teeth, then second has 28, then third has 25, and fourth has 23. Every T10, T98, T18, NP435, M20, M21, SM420, SM465, A833, you name it...follows this convention. Fast forward to the gas "shortage" of the 1970's and it became desirable to reduce engine RPM in search of improved fuel economy. Someone figured out that they could achieve an "overdrive" configuration" where the output shaft rotated faster than the input shaft by placing a large gear on the countershaft and a small gear on the main shaft...in the location traditionally reserved for "3rd gear." Your RTS (Remote Tower Shift) transmission is configured this way. So you get a 1:1 gear "reduction" in the fourth position, and an overdrive in the 3rd position. In order to achieve a logical shifting sequence, the 3-4 shift rail has to move backwards compared to normal.
There's a LOT of chicken vs egg in the discussion. Everyone understands the standard H-pattern (first toward the dash, second toward the seat, third toward the dash, fourth toward the seat) but it is an evolution that follows the shift rail mechanical logic. The shift rail on your T98 puts 4th toward the seat because the rail needs to move forward to engage 4th. So in order to keep the H pattern in your RTS, the 3-4 shift rail moves backwards. Nobody knows that it is happening, and it is transparent to the user. But it confuses the heck out of the service tech when the transmission shift tower moves backwards.
Hope that helps.
