shifting rpm solution
Thread Starter
Intermediate
Joined: Sep 2011
Posts: 40
Likes: 0
From: Virginia
shifting rpm solution
Recent change from a TH350 to a 700R4 using stock 3.07 rear end in 1980. Through no fault of the transmission, the torque converter locks up cruising at steady 45 mph showing rpm's of 1000. It also shifted from 3rd to 4th a little too quickly, almost like it was in a hurry to get into 4th gear (for fuel economy?)? Felt the rpm's were too low and looked for an alternate solution besides changing rear end gears to 373's and losing highway mpg's.
Installed the 700-R4 Lock-up Control Module from Bowler Transmission/w new gasket/filter ($179.00). It basically delays the torque converter from locking up for 8-10 seconds (uses a plug in timer). If you tap the brakes or accelerate at a certain rate with the torque converter locked, the torque converter then unlocks and begins a new 8-10 second cycle before it will allow the converter to lock back up. This is great for in town driving, keeping the torque converter from locking up and dropping the rpm's.
A side note is that now it seems to slightly delay the shift into 4th, staying in 3rd slightly longer. A benefit as the transmission now feels "right".
Bowler Transmission very helpful and quick shipping!
http://bowlertransmissions.com/produ...ontrol-Modules
Installed the 700-R4 Lock-up Control Module from Bowler Transmission/w new gasket/filter ($179.00). It basically delays the torque converter from locking up for 8-10 seconds (uses a plug in timer). If you tap the brakes or accelerate at a certain rate with the torque converter locked, the torque converter then unlocks and begins a new 8-10 second cycle before it will allow the converter to lock back up. This is great for in town driving, keeping the torque converter from locking up and dropping the rpm's.
A side note is that now it seems to slightly delay the shift into 4th, staying in 3rd slightly longer. A benefit as the transmission now feels "right".
Bowler Transmission very helpful and quick shipping!
http://bowlertransmissions.com/produ...ontrol-Modules
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
A 3.08 rear gear is pretty low for use with the 700R. If the range shifts happen at rpm's where the car wants to 'lug n chug', you might want to change out the tranny governor so that all shifts will happen later (higher rpm). Or, you could just leave the gear shift in 3rd range while in city traffic conditions.
My car...with 3.36 gears...will shift into 4th at about 42 mph (1500 rpm), then go into lockup at 1300 rpm. That's about as low an rpm level as I think the car will run without any lugging/surging.
But, at 70 mph, you'll be cruising at about 1900 rpm!!
My car...with 3.36 gears...will shift into 4th at about 42 mph (1500 rpm), then go into lockup at 1300 rpm. That's about as low an rpm level as I think the car will run without any lugging/surging.
But, at 70 mph, you'll be cruising at about 1900 rpm!!
