I have a tav2 torque converter. I am looking to keep the unit in low gear until the engine reaches about 3500 rpm. I have tried all 3 settings of the spring on the driven unit. In position 3, it helps a little bit but also reduces top end. After studying how the unit works, I have come to the conclusion that what really needs to change are the 2 springs on the driver unit that control the weights. Stronger springs would create a higher stall speed and keep the unit in low longer. It turns out that Manufacturing Supply has 2 versions of heavier springs available. The part numbers are 216111A for the Yellow/Blue springs and 216115A for the Blue/Silver springs. Has anyone tried these springs with the stock zinc weights? Thanks in advance for your replys.
Heavier springs on tav2 driver unit
the stiffer springs will make it engage at a higher rpm this may effect your low speed driveability unless you just want to use it as a drag bike. you may be better off going to a larger rear sprocket. it all depends on how you use the bike. On mine I use a chain clutch and a large gear on the jack shaft to really gear it down low. It tops out at about 25 mph but it has crazy power and acceleration with the 6 horse Tecumseh. But since I ride at low speeds in hilly areas or just driving around the back yard pulling wheelies it works out well for me.
I realize that low speed drivabililty may suffer and belt life may be shortened. In stock form, the unit works well. It gets off the line well, can climb any hill, and tops out at 40 mph. But it does not have the midrange acceleration that the same motor would have with a chain drive and clutch using the same final drive ratio of 6 to 1. This is because the driver expands the working diameter of the belt too soon. Heavier springs would help delay this and give better midrange performance.
you might want to try the larger 7" driver,if you are using the 6" 20 or 30 series converter. also try letting off the throttle when you are at mid range speed this will slow the engine enough to disengage the converter . Then when you hit the throttle the belt will be low in the driver and might give that quick snap of speed you are looking for. If you can move the engine to change the belt tension [like on a Rupp] that may do some thin too. Something like this is trial and error,if the driver spring is easy to change then give it a shot and see what happens.