owenst7
1/2 ton status
http://www.truckinweb.com/tech/0510tr_sw_performance_transmissions_install/index.html
I'm looking at each ring gear on my bench right now, and that's got to be exactly what they did. I saw somewhere on the internets (of course I didn't think to save the picture), of the back of the same ring gear. There was a weld bead right about the same location where you'd graft the two together. The ODs of the planetaries are the same, so the clutches would fit just fine, and the sun gears are the same splines between the two trannies...The planets fit the same on my sun gear.
There is a snap ring right behind the helical ring gear teeth so that the plate + shaft splines remove from the actual ring, FYI.
I initially saw that picture and thought, "well that doesn't help me at all, it doesn't show what is actually modified". I'm sure the SW Trans told them not to publish a picture of the back of the ring gear, or it would be obvious what they did...maybe they want the idea to themselves, or maybe TCI has a patent issue with aftermarket ratios
The 700r4 ring gear fits fine inside my TH350 case, park pawl works with it like it was designed to (not that modifying the pawl would be difficult anyways, hell you could make a new one, it's just stamped steel and not even a live part).
There are 34 teeth on the sun gear in either tranny. The TH350 uses a 66 tooth ring gear, and the 700r4 uses a 78 tooth ring gear. In first gear, the TH350 uses both gearsets for a compound reduction. The front accomplishes 1.3:1 while the rear accomplishes 1.94:1 (66/34=1.94), so first gear ends up as 2.52:1 (1.3*1.94, rounding). Using the 700r4 rear planetaries (gear reduction of 78/34=2.29), the new first gear ratio would be 2.98 (1.3*2.29). Second gear would remain 1.52:1, as the rear planetaries idle and the first sun gear is held.
I'm looking at each ring gear on my bench right now, and that's got to be exactly what they did. I saw somewhere on the internets (of course I didn't think to save the picture), of the back of the same ring gear. There was a weld bead right about the same location where you'd graft the two together. The ODs of the planetaries are the same, so the clutches would fit just fine, and the sun gears are the same splines between the two trannies...The planets fit the same on my sun gear.
There is a snap ring right behind the helical ring gear teeth so that the plate + shaft splines remove from the actual ring, FYI.
I initially saw that picture and thought, "well that doesn't help me at all, it doesn't show what is actually modified". I'm sure the SW Trans told them not to publish a picture of the back of the ring gear, or it would be obvious what they did...maybe they want the idea to themselves, or maybe TCI has a patent issue with aftermarket ratios
The 700r4 ring gear fits fine inside my TH350 case, park pawl works with it like it was designed to (not that modifying the pawl would be difficult anyways, hell you could make a new one, it's just stamped steel and not even a live part).
There are 34 teeth on the sun gear in either tranny. The TH350 uses a 66 tooth ring gear, and the 700r4 uses a 78 tooth ring gear. In first gear, the TH350 uses both gearsets for a compound reduction. The front accomplishes 1.3:1 while the rear accomplishes 1.94:1 (66/34=1.94), so first gear ends up as 2.52:1 (1.3*1.94, rounding). Using the 700r4 rear planetaries (gear reduction of 78/34=2.29), the new first gear ratio would be 2.98 (1.3*2.29). Second gear would remain 1.52:1, as the rear planetaries idle and the first sun gear is held.
Last edited:
