Locking 3rd vs shifting to 4th

[sae]

I don't remember my last trans ever even shifting into 4th, it would ride up close to 5k RPM and not shift. The new one shifts around 4400 and drops to 3000 which feels a bit early but still pulls much harder than before. I've experimented with holding 3rd a bit longer, to 4700-4800 or so and it feels like it continues pulling better but it's hard to say.

I see most people prefer locking up in 3rd over shifting to OD in a 1/4mi setting, is there any reason why this is? I was under the impression that locking up at wot is harder on the trans as well.

 

[Pro Built Automatics]

Re: Locking 3rd vs shifting to 4th

The vast majority of the time locking the torque converter clutch in the top of 3rd gear will not do anything as far as improving ET or MPH, but that is with naturally aspirated motors. With turbocharging that changes. You will have to try it and see what happens. Locking it up in 3rd gear will not hurt anything, just do not leave it locked up on a gear change, that is where it is very hard on parts. You want to lock it up at the top of 3rd gear just where you would normally shift from 3rd to 4th gear. Do not expect to see much in the way of improvements in ET or MPH, but there might be some slight gains.