Forcing the torque convertor to lock up under power.

[2JZR31]

I always thought the convertor lock up function was piss weak and would not handle power loading, but some people are saying you can hook it up to a button and get it to lock up under load in say 3rd gear at the drags to get more power to the wheels.

Does anyone know more about this? If the trans shifted gear with it locked would something be likely to break?

[stradlater]

Sounds Nasty to me....

[2JZR31]

I would have thought so but 1JZ-747 said he does it and he somewhat knows what he is talking about.

[CrUZida]

He also has a heavily modded transmission.


I have always been under the impression thats its bad for a stock tranny to be under power while the TC is locked. Which is why it unlocks as soon as you use a bit more throttle.

[Norbie]

The fact that any factory auto engages the lockup clutch only at cruise (ie light load) speaks volumes. The clutch is pretty weak, I can't imagine it holding the full onslaught of 2JZ torque for very long.

[2JZR31]

That's what I am thinking. I wonder what 1JZ747 has to say about it.

[1JZ.747]

i say ring michael at mv and ask him as he is the professional.

built gearbox aside. the lock up is in the convertor, i simply have a toyota convertor with bent fins to raise the stall and a bigger rear cover to allow them to fit. there is nothing special about my convertor so that would lead me to believe that it isnt a problem.

i would suggest that norbies theory is partly right, but i would think it more that the gerbox is sensing you need more power via raised revs to combat a hill or upslope or more revs to accerlate faster to overtake. i doubt its anything else.

i do know that if you have the trans locked on ger changes you will fuck things very fast.

[2JZR31]

built gearbox aside. the lock up is in the convertor, i simply have a toyota convertor with bent fins to raise the stall and a bigger rear cover to allow them to fit. there is nothing special about my convertor so that would lead me to believe that it isnt a problem.

Yeah, the lock up mech is where the strain will be. The stock unit must be up to the task if yours is holding up.

i would suggest that norbies theory is partly right, but i would think it more that the gerbox is sensing you need more power via raised revs to combat a hill or upslope or more revs to accerlate faster to overtake. i doubt its anything else.

i do know that if you have the trans locked on ger changes you will fuck things very fast.

I was also under the opinion that it unlocks to provide more torque so as not to labor the engine at low revs more than to protect the convertor. I suspected that gear changes would be a no no with it locked. I can't see how it could damage the trans in anyway providing its not locked on a change though. The fluid damping would act like a big shock absorber when it changes gears. It would probably be a bit like trying to change gears with out the clutch on a manual gearbox.

Do you cross the line in 3rd?

[1JZ.747]

yes.

100 rpm of rev cut 7400 rpm

[Mos]

How will you know when to unlock it before a gear change?

I was always curious about the torque capabilities of this clutch. It's not very big looking at the toyota diagrams, but it is a large diameter thing in constrast to the clutch packs inside the box.

Mos.

[1JZ.747]

How will you know when to unlock it before a gear change?

I was always curious about the torque capabilities of this clutch. It's not very big looking at the toyota diagrams, but it is a large diameter thing in constrast to the clutch packs inside the box.

Mos.

mos, i only lock it in third gear on the track, or in 4th gear on the freeway. mines on a push button switch on the steering wheel for my left thumb.

there is no point locking it up for a poofteinth in 1st or second gear so i dont know why people are talking about it.

[chris davey]

I will be able to give some advice in a few weeks.

Stock auto, manualised and lockup to be used in 3rd at the drags