Big power is more popular than ever, with motors growing in size all the way up to 155ci-and there's no end in sight. With so much power from the motor making contact with the street through high-torque clutches, the peak load is on the transmission gears. Most stock transmissions just can't hold together under that kind of stress, so JIMS came up with the new Fat-5.
If you want strong, the Fat-5 is one of the toughest gearboxes made. JIMS took advantage of new, more compact shifter technology to increase the width and strength of every gear. The width increase varies from 18 to 53 percent, depending on the load each gearset must carry. We wanted to see just how this new super-tough transmission went together, and JIMS was kind enough to show us the trans from the inside.
Assembly began with the individual...
Assembly began with the individual gears on the shafts. Ray, the lead shop man, started with the mainshaft and First gear.
Next came the mainshaft, Third...
Next came the mainshaft, Third gear, and the shift ring between both First and Third gears.
The gears were then installed...
The gears were then installed on the countershaft. Here is Second gear.
Snap rings were installed...
Snap rings were installed to hold the gears in position on the shaft.
The shafts were pressed into...
The shafts were pressed into the trap door. Here is the mainshaft sub-assembly.
Then the countershaft sub-assembly...
Then the countershaft sub-assembly was pressed into the trap door.
The locknuts were tightened...
The locknuts were tightened to proper torque spec to properly retain the shaft.
Some of the shift forks needed...
Some of the shift forks needed to be installed before the gear cluster was slid into the case.
After positioning the gasket,...
After positioning the gasket, the gear kit was then carefully installed in the transmission case.