5AT lock-up question.

Was wondering, anyone know how the 5AT on the LGT decides when to lock-up the torque convertor? e.g. above 2k rpm at X speed etc etc.

Thanks!

Also 05-06 lockup: 3rd-5th gears

07-09+ (5eat) lockup: 2nd-5th gears

Also 05-06 lockup: 3rd-5th gears

07-09+ (5eat) lockup: 2nd-5th gears

Thanks. So does that mean that for 2-5th gears, it is always locked up?

I was asking this because I read that for the new Jaguar autos, the box is programmed to always lock up after 2000rpm. Was wondering how ours worked.

Thanks. So does that mean that for 2-5th gears, it is always locked up?

 

I was asking this because I read that for the new Jaguar autos, the box is programmed to always lock up after 2000rpm. Was wondering how ours worked.

Our cars are not on/off lock-up, its a gradual lock-up. Its all clutches and disks, no pressure plate. So it will gradually apply lock-up pressure until its fully locked, dont know what rpms and most likely depends on load and driving conditions.

Happens a few times but cruising at low speeds in 2nd gear below 3k and I floor, it feels slow to accel and it kicks, the lock-up disengages and now goes into torque multiplication mode, then I can feel the powaa!! (In manual mode, not downshifting into 1st)

underground: Does that mean that the 07+ 5eat does not have a 2nd gear hold in manual?

Im sorry its been a few months since I took a transmission class. What do you mean 2nd gear hold in manual?

on must AT cars, TQ converter lock up only happens during cruise or very light accel or deccel. tq converter clutched are not like MT clutches. they can only hold a small amount of the tq the engine makes. so they are used for fuel efficiency and drivability aids.

actually the torq lock up clutch takes the full power of the engine !

the torque lock up actuation depends on many variables.

engine coolant temp

tranny oil temp

if either of them are low the torq lock up will not lock up

if either of them are high it will lock up earlier than at normal temperatures.

torqlock up only works in 3rd 4th and 5th gear

in 5th gear minimum speed is 60 kmph or aboot 38 mph for lock up

4th is aboot 50 kmph 30 mph

i have data logs showing the lock up engaging while going down the 1/4 mile. you can also see this if you go into manual mode 3rd at 30 mph and floor it the rpms wll jump up to the "stall speed " of aboot 3500 rpm untill the tranny input shaft reaches aboot 800 rpm less than that then engine rpm will rise untill aboot 5500 rpm where it will jump down seaming like its shifting then there is a direct lock between crank shaft and axels just as if its a manual tranny.

when i did dyno pulls with my lgt 5eat i used 4th manual mode waited for the lock up then floored it and it pulled the entire rpm range locked.

but this is also a concern for people who put a tranny cooler with no thermostat. the tranny temp may take longer or not ever reach its normal orperating temp causeing the lock up to never engage or engage very late. i noticed this problem simply by lowering my fan turn on temperatures since the tranny cooler lines are in the bottem ( cold side of the rad ) the tranny would practically never lock up.

I mean in manual mode, you can start from 2nd and it will hold 2nd gear without downshifting until you shift.

Yes you can do that on the 05-09+ 5eat, this is mainly used for low traction conditions, and stall speed test

actually the torq lock up clutch takes the full power of the engine !

 

torqlock up only works in 3rd 4th and 5th gear

 

i have data logs showing the lock up engaging while going down the 1/4 mile. you can also see this if you go into manual mode 3rd at 30 mph and floor it the rpms wll jump up to the "stall speed " of aboot 3500 rpm untill the tranny input shaft reaches aboot 800 rpm less than that then engine rpm will rise untill aboot 5500 rpm where it will jump down seaming like its shifting then there is a direct lock between crank shaft and axels just as if its a manual tranny.

 

when i did dyno pulls with my lgt 5eat i used 4th manual mode waited for the lock up then floored it and it pulled the entire rpm range locked.

Up to 06, lock-up occurred only in 3rd+, 07+ lock-up occurs in 2nd gear

Yes and no about lock-up taking full use of the engine...Automatics are a lot heavier and have more rotating mass than a manual transmission. In manuals you can slip the clutch and get it moving then (lock-up) when your moving. Having a higher rotating mass you will loose more power because more power will be required to moving it

Automatics are completely different. Before stall speed does not mean the engine is slipping from the transmission. From idle until stall speed the TQ is multiplying the torque from the engine, instead of slipping it. Our transmission multiply upto 3.5x, or producing over 700ft-lbs of torque. This high toque is what makes your car moves from a stop. (Something about Newtons law that it takes more energy to move something from a stop then to keep it moving)

Yes lock-up will make 1:1 from the engine to transmission, but not necessary means its better. Having a high stall speed is much better then being in lock-up. Low lock-up rpm means better gas millage

In racing situations those 1000hp drag cars, the TQ is always multiplying all the way down the 1/4 mile, they never go into lock-up

In racing situations those 1000hp drag cars, the TQ is always multiplying all the way down the 1/4 mile, they never go into lock-up

not any more ! torqlock up converters are makign thier way into the racing world !

I use the lock up on my 4t65ehd tranny out of a grand prix supercharged in my sunbird to increase effiency. with out lock up i run aboot 112 mph in the 1/4 mile and with 117 mph thats probably a 80 hp increase

also cars with a cvt have a typical torq converter that locks up at a certain speed.

but in our lgt the converter is made to hold the power of the engine. as many new cars do mostly because the converters are very high stall compared to the old stuff.

the high stall only help off line acceleration the rest of the time its a big thing that converts mechanical energy into heat.

the tq also multiplys torque output.

its not the same as sliping the clutch at a higher rpm.

what it does is it uses a "stator " to circulate the oil.

as the oil leavs the driven turbine it smashes into the driven turbine.

as the rpm increases you get more oil smashing into the driven turbine.

its kinda weird but just imagine taking off in 5th gear with manual tranny ..

and 5th gear auto tranny the auto will kick ass !

its kinda weird but just imagine taking off in 5th gear with manual tranny ..

and 5th gear auto tranny the auto will kick ass !

at least give them a chance, use 4th its close to 1:1

I use the lock up on my 4t65ehd tranny out of a grand prix supercharged in my sunbird to increase effiency. with out lock up i run aboot 112 mph in the 1/4 mile and with 117 mph thats probably a 80 hp increase.

We got confused somewhere...

You can control lock up? (I know its possible). This I can understand, because at stall speed and above the TQ is slipping from the engine (w/out lockup) so lockup would be good here. Yes lockup increases efficiency vs not having lockup, thats why we have lockup now.

But you do not want to engage lockup before stall speed, if you do this you would decrease efficiency. Like I said before lockup for our cars (before stall speed) we can multiply engine torque (make more torque), and for the 5eat it can be up to 3.5x more torque. Not slipping. It works like how frank_ster says

We got confused somewhere...

 

You can control lock up? (I know its possible). This I can understand, because at stall speed and above the TQ is slipping from the engine (w/out lockup) so lockup would be good here. Yes lockup increases efficiency vs not having lockup, thats why we have lockup now.

 

But you do not want to engage lockup before stall speed, if you do this you would decrease efficiency. Like I said before lockup for our cars (before stall speed) we can multiply engine torque (make more torque), and for the 5eat it can be up to 3.5x more torque. Not slipping. It works like how frank_ster says

Well the lock is is used often below stall speed ! At cruse

The only thing the higher stall torque converters help is off the line and it can make it so that you would not need to shift down a gear.

I used the torque lock up at the top of each gear ie 6500 rpm engage it and the engine will drop down to ~ 5500 pull that then shift next gear while un locking the torq then all over again. Essentially making the 5 speed into an 8 speed or my 4 speed auto into a 7 speed ( because not all speeds have lock up available 4t65e cannot lock up in first gear )

The reason I didn't leave the lock up engaged is because the gear spread is to much for the autos it would pull the engine down out of the power.

With the converter yes make more torque but at hp loss!

I understand it multiplies. But it does not multiply the same through the entire range...IOW it does not multiply torque 3.5X from 700rpm to 3500 RPM. I just mean that it's not as simple as engine torque X 3.5 = torque to transmission. My point is that if you ride the clutch and keep the engine at 3500 rpm in 5th, you can take off...you just burn the hell out of the clutch. It is just a simple way of thinking of the way it works. I know it is not at all mechanically similar to a manual clutch. It's just an analogy.

 

I think it is right however that you would want your stall speed at your peak torque so that the engine would maintain as close to the peak torque as possible for as long as possible.

 

Frank_ster: would you be able to mess with the stall speed with the megasquirt?

Nope stall speed is a mechanical designe thing the shape of the stator ( pump ) affects the flow speed of the oil

When they do stall change they change / modify the stator to have larger or smaller angle also the clearances between the turbines.

I had my tranny guy mod mine but he said he did what he could but it would need a diffrent stator. The converter is actually as high stall as most of the race one he makes it's just the small motors arnt making the torq as the 400 cubic inch motors we normally use

I get aboot 3500 stall out of mine now out of boost

I didn't know that these converters make a 3.5 ratio most of others only make a 2-1 ratio.

Mega shift can control lock up how ever right now the soft and firm ware is quite basic related to lock up I'm talking on the forums for getting more control for lock up it will happen it's only a matter of time

My sunbird and my camaro I have the lock up on a switch on the shifter so I engage when ever I like it's a function that I want manual control of it allows me to do 30 mph smoke shows and better economy because I drive the car as if it's a manual.

I am curious to see if I can get lock up in second or even first with my manual control on the gm tranny it's hydraulically not able with out valve body modification in first it's a fail safe incase the lock up sol fails in the on position so the car can still be driven.

Mega shift can control lock up how ever right now the soft and firm ware is quite basic related to lock up I'm talking on the forums for getting more control for lock up it will happen it's only a matter of time

My sunbird and my camaro I have the lock up on a switch on the shifter so I engage when ever I like it's a function that I want manual control of it allows me to do 30 mph smoke shows and better economy because I drive the car as if it's a manual.

I am curious to see if I can get lock up in second or even first with my manual control on the gm tranny it's hydraulically not able with out valve body modification in first it's a fail safe incase the lock up sol fails in the on position so the car can still be driven.

I do believe IPT mods the behavior of the lock-up by beefing up the responsible clutches and also how it engages and disengages. Someone correct me if I am wrong.

In my experience, torque lock-up, all other things being equal (oil/atf temp, load etc) engages above 1500rpms in any gear. I am not sure why some say it won't do it in gears lower than 3rd, I can definitely tell when it is locked up in 2nd. I will try it again just to be sure. Either way, it will kick out of lock-up at 1500rpms or below. Watch the revs decrease steadily then drop suddenly at idle speed once 1500 is reached.

I do believe IPT mods the behavior of the lock-up by beefing up the responsible clutches and also how it engages and disengages. Someone correct me if I am wrong.

In my experience, torque lock-up, all other things being equal (oil/atf temp, load etc) engages above 1500rpms in any gear. I am not sure why some say it won't do it in gears lower than 3rd, I can definitely tell when it is locked up in 2nd. I will try it again just to be sure. Either way, it will kick out of lock-up at 1500rpms or below. Watch the revs decrease steadily then drop suddenly at idle speed once 1500 is reached.

i know my 05 lgt 5 eat doesn't lock up what so ever in frist or second and it also stated in the manual.