With an apropos ending...
(you can't expect Jeep guys to get it all right, do you?
)
(copy)
Speeding Up The Early Jeeps - Old School
Transmissions, Transfer Cases, And Overdrives - Speeding Up The Early Jeeps
By Willie Worthy
In the beginning, the Jeep was created with an off-the-shelf car transmission, designated as T-84 by its engineers. Tiny by any standards, and so were its capabilities. But serve it did through World War II.
With the advent of the civilian Jeep, the CJ-2A, a new stronger transmission was in order to replace the MB and GPW's failure-prone T-84. The replacement, a T-90 three-speed, was compact and actually over-designed for the horsepower and torque output of the flathead four-cylinder engine. So good was this transmission that Jeep stuck with it for a record 20 something years. Without a doubt, a bigger variety of engines was adapted to this transmission than any other in automotive and industrial history. For instance, Baker forklifts used it and Studebaker used the T-90 trans up into the early 1950s, which made swapping in a "Stude" six or V-8 that much easier. It's amazing that this little transmission designed for 60 hp would hold up well to V-8 power. Lloyd Novak started an adapter business with an adapter for this transmission.
When Jeep went to the V-6 Buick, they updated the design with helical gears and called it the T-86. While quieter in operation and smoother shifting, they soon found it wasn't up to the V-6's torque. Want to guess what the factory warranty fix was? Because the case dimensions were the same, the old T-90-style gears were a direct replacement. Neat thing about the T-90 was Jeep also used it in the utility wagon and pickups with their flathead-six. What made this great was that this version used a much longer input shaft that made building an engine adapter so much easier, as well as spacing the back of the then-popular Chevy V-8 with its rear-mounted distributor farther away from the firewall.
As good as the T-90 transmission was, it still required care if used behind a V-8. In reality, it was marginal. Much to my later regret, I once had a fuel-injected Chevy in front of a T-90. Needless to say, I got quite good at rebuilding it.
There were a few other transmissions used as well, but with 5.38 axle gears and 2.46:1 transfer cases, overall gearing was generally considered low enough. Jeep did offer the T-98 four-speed as an option on and off during the 1960s, and later, the updated version was called the T-18, but these were few and far between in the CJs. Contrary to information you may come across, there were some V-6s built with the T-98 four-speed on special order, and those that I have seen were all government vehicles. In the 1960s, the emphasis was on speed, not rockcrawling. Studebaker used the T-90, but in a column-shift version and there were some very early CJ-2As that had a column shift. One could use these cases and the then-popular Hurst shifters for faster gear changes instead of the cane and tower design. There were a few Ford passenger car three-speeds used with Hurst shifters, but these generally were one-off type of adapters. In 1960 or 1961, a Chrysler mechanic I knew built a few Chrysler automatic adapters for his friends.
The big change came when Brian Chuchua came out with his special adapter to use the Borg Warner T-10 four-speed. This was a performance trans used by Ford, GM, and Studebaker. It had an aluminum case, was fast-shifting, and, well, unfittingly high-geared. How does a 2.20 First gear sound? Yep, that's what replaced my T-90. A step backward in gearing from the 2.9 First gear in the T-90, but oh so much stronger and fun to shift. But again remember this was the 1960s, when high-performance muscle cars were in and off-road racing was starting up - not rockcrawling. In the later part of 1969, a start-up company called Advance Tooling and Engineering made its first adapter for the Muncie passenger car four-speed to the Spicer 18 transfer case. You may better know this com
(you can't expect Jeep guys to get it all right, do you?
)
(copy)
Speeding Up The Early Jeeps - Old School
Transmissions, Transfer Cases, And Overdrives - Speeding Up The Early Jeeps
By Willie Worthy
In the beginning, the Jeep was created with an off-the-shelf car transmission, designated as T-84 by its engineers. Tiny by any standards, and so were its capabilities. But serve it did through World War II.
With the advent of the civilian Jeep, the CJ-2A, a new stronger transmission was in order to replace the MB and GPW's failure-prone T-84. The replacement, a T-90 three-speed, was compact and actually over-designed for the horsepower and torque output of the flathead four-cylinder engine. So good was this transmission that Jeep stuck with it for a record 20 something years. Without a doubt, a bigger variety of engines was adapted to this transmission than any other in automotive and industrial history. For instance, Baker forklifts used it and Studebaker used the T-90 trans up into the early 1950s, which made swapping in a "Stude" six or V-8 that much easier. It's amazing that this little transmission designed for 60 hp would hold up well to V-8 power. Lloyd Novak started an adapter business with an adapter for this transmission.
When Jeep went to the V-6 Buick, they updated the design with helical gears and called it the T-86. While quieter in operation and smoother shifting, they soon found it wasn't up to the V-6's torque. Want to guess what the factory warranty fix was? Because the case dimensions were the same, the old T-90-style gears were a direct replacement. Neat thing about the T-90 was Jeep also used it in the utility wagon and pickups with their flathead-six. What made this great was that this version used a much longer input shaft that made building an engine adapter so much easier, as well as spacing the back of the then-popular Chevy V-8 with its rear-mounted distributor farther away from the firewall.
As good as the T-90 transmission was, it still required care if used behind a V-8. In reality, it was marginal. Much to my later regret, I once had a fuel-injected Chevy in front of a T-90. Needless to say, I got quite good at rebuilding it.
There were a few other transmissions used as well, but with 5.38 axle gears and 2.46:1 transfer cases, overall gearing was generally considered low enough. Jeep did offer the T-98 four-speed as an option on and off during the 1960s, and later, the updated version was called the T-18, but these were few and far between in the CJs. Contrary to information you may come across, there were some V-6s built with the T-98 four-speed on special order, and those that I have seen were all government vehicles. In the 1960s, the emphasis was on speed, not rockcrawling. Studebaker used the T-90, but in a column-shift version and there were some very early CJ-2As that had a column shift. One could use these cases and the then-popular Hurst shifters for faster gear changes instead of the cane and tower design. There were a few Ford passenger car three-speeds used with Hurst shifters, but these generally were one-off type of adapters. In 1960 or 1961, a Chrysler mechanic I knew built a few Chrysler automatic adapters for his friends.
The big change came when Brian Chuchua came out with his special adapter to use the Borg Warner T-10 four-speed. This was a performance trans used by Ford, GM, and Studebaker. It had an aluminum case, was fast-shifting, and, well, unfittingly high-geared. How does a 2.20 First gear sound? Yep, that's what replaced my T-90. A step backward in gearing from the 2.9 First gear in the T-90, but oh so much stronger and fun to shift. But again remember this was the 1960s, when high-performance muscle cars were in and off-road racing was starting up - not rockcrawling. In the later part of 1969, a start-up company called Advance Tooling and Engineering made its first adapter for the Muncie passenger car four-speed to the Spicer 18 transfer case. You may better know this com
Comment