Torque Converter Stall vs. Engine Size

[transman]

Let's say I find one of the LU A999's. What controls the lockup on these? Is it all hydro/mechanical, or would I need to retrofit an on/off switch of some kind?

I'm not a builder, but maybe Rusty or one of the other builders on this board can give you that kind of information.

 

[TT5.9mag]

Let's say I find one of the LU A999's. What controls the lockup on these? Is it all hydro/mechanical, or would I need to retrofit an on/off switch of some kind?

A904 lock-up wiring - Page 2 - Slant Six Forum

 

[dusterbing the peace]

Let's say I find one of the LU A999's. What controls the lockup on these? Is it all hydro/mechanical, or would I need to retrofit an on/off switch of some kind?

It's hydraulic

 

[vynn23]

It's hydraulic

Thanks. Yeah, my research today says the switch is for disabling the LU TC, and even then only needed on trucks (for towing and such), so one less thing to worry about.

 

[dusterbing the peace]

Thanks. Yeah, my research today says the switch is for disabling the LU TC, and even then only needed on trucks (for towing and such), so one less thing to worry about.

The one in the ebay add I shared looks to be the three wire hydraulic as it's missing the separate single-wire electronic connection...but I could be mistaken.

The posting below shows pretty good detail of it for reference:
Lockup 904 transmission

So, you're still correct, one less thing to worry about as you'll have functional lockup as intended, without needing to run a switch...and you'll have the lower gearset.

 

[vynn23]

The one in the ebay add I shared looks to be the three wire hydraulic as it's missing the separate single-wire electronic connection...but I could be mistaken.

The posting below shows pretty good detail of it for reference:
Lockup 904 transmission

So, you're still correct, one less thing to worry about as you'll have functional lockup as intended, without needing to run a switch...and you'll have the lower gearset.

I can't wait. I might even leave the 3.23's in for a little bit before I swap for the highway gears. For science, y'know.

 

[Woody500]

That ^^^^ to me screams overdrive trans. There is no single modification that will make the car more enjoyable to drive AND no single modification that will return a mileage benefit like it. I won’t build another car/truck without one.

I also wondered why no OD trans in your plan? Do you need to change tunnel for it to fit.
I've got a 1990 5.2(roller cam) w/od trans out of a van that I'll put in my '65 Barracuda someday.
I'll have to search here for mods list.

 

[Woody500]

AJ, why don't you post a long post......

His posts long but informative & this one easy to follow because it's not over my head!

 

[Woody500]

Thanks. Yeah, my research today says the switch is for disabling the LU TC, and even then only needed on trucks (for towing and such), so one less thing to worry about.

Lock-up should help mileage, acting like a solid clutch with no torque multiplication, and using less HP to turn trans, hence better mileage.
Question is, how to get it to automatically unlock when slowing down, because forgetting to flip the switch could cause engine to stall, sorta like not pushing the clutch pedal in.

 

[Charrlie_S]

I could be wrong, but I think the LU 904/998/999 type trans with the electrical connector, allows disabling the LU at speeds where you would normally have LU. But LU is still disabled by the internal valve body when the vehicle speed drops below the setpoint. The external switch is only to "prevent" LU under extreme loads to preven damage to the converter clutch, and allow torque multipication for added pulling power.

 

[Woody500]

I could be wrong, but I think the LU 904/998/999 type trans with the electrical connector, allows disabling the LU at speeds where you would normally have LU. But LU is still disabled by the internal valve body when the vehicle speed drops below the setpoint. The external switch is only to "prevent" LU under extreme loads to preven damage to the converter clutch, and allow torque multipication for added pulling power.

Thanks for the explanation.

 

[vynn23]

I also wondered why no OD trans in your plan? Do you need to change tunnel for it to fit.
I've got a 1990 5.2(roller cam) w/od trans out of a van that I'll put in my '65 Barracuda someday.
I'll have to search here for mods list.

Well, since you asked...

OD would be nice. I've even bought some parts and done tons of research over the decades to prepare for it. However, I turn 60 this November. I've come to the realization that, although I'll still be wrenching on my car moving forward, I'd rather focus on enjoying/driving the car NOW.

I also don't have the performance/acceleration standards that most on this board have, so "better" is good enough for me. The current 273, Eddie AVS2/SP-2P intake and duals are MORE than enough power for my needs. I LOVE driving the car as-is. The only reason I'm swapping in the 5.2 Magnum is because I have a hot-running/coolant-loss condition I can't resolve, minimal down-time for the car, and (maybe) a little better fuel economy.

Although they are REALLY cool and I salute those who make these mods, I no longer want to spend huge amounts of time/energy/money on dream upgrades like modern hemi swaps, aftermarket K-member suspensions, and OD's in the coming years the way I used to. I coated/sealed and sound-deadened the car's floors a few years ago, and don't want to undo that work by modifying the trans tunnel. I also no longer want to cut up/reinforce/fabricate the crossmember and trans mount to make it fit. OD's (trans or Gear Vendors) conversions also cost thousands of dollars I'd never recover in my lifetime. Again, I applaud those who have the ability and resources to do so, but that ain't me.

I think that replacing the well-worn A-904 with a freshened-up A-999 and swapping the axle ratio to the 2.74's or 2.92's (that I already have in the garage) will get me from the current 16 mpg highway to the 18-20 I'm hoping for with way less time/effort/$$$, so I can continue long drives with my teenage son while I can still spend time with him. Wish me luck!

 

[273]

and allow torque multipication for added pulling power.

More Hp equals more pulling power, torque ain't a bonus power.

 

[TT5.9mag]

Well, since you asked...

OD would be nice. I've even bought some parts and done tons of research over the decades to prepare for it. However, I turn 60 this November. I've come to the realization that, although I'll still be wrenching on my car moving forward, I'd rather focus on enjoying/driving the car NOW.

I also don't have the performance/acceleration standards that most on this board have, so "better" is good enough for me. The current 273, Eddie AVS2/SP-2P intake and duals are MORE than enough power for my needs. I LOVE driving the car as-is. The only reason I'm swapping in the 5.2 Magnum is because I have a hot-running/coolant-loss condition I can't resolve, minimal down-time for the car, and (maybe) a little better fuel economy.

Although they are REALLY cool and I salute those who make these mods, I no longer want to spend huge amounts of time/energy/money on dream upgrades like modern hemi swaps, aftermarket K-member suspensions, and OD's in the coming years the way I used to. I coated/sealed and sound-deadened the car's floors a few years ago, and don't want to undo that work by modifying the trans tunnel. I also no longer want to cut up/reinforce/fabricate the crossmember and trans mount to make it fit. OD's (trans or Gear Vendors) conversions also cost thousands of dollars I'd never recover in my lifetime. Again, I applaud those who have the ability and resources to do so, but that ain't me.

I think that replacing the well-worn A-904 with a freshened-up A-999 and swapping the axle ratio to the 2.74's or 2.92's (that I already have in the garage) will get me from the current 16 mpg highway to the 18-20 I'm hoping for with way less time/effort/$$$, so I can continue long drives with my teenage son while I can still spend time with him. Wish me luck!

That’s a great reason. Go enjoy your car with your son.

 

[vynn23]

That’s a great reason. Go enjoy your car with your son.

Although he'll only grudgingly help me wrench, he LOVES riding with me and listening to music for mile after mile. So I'm savoring every moment I can, while I can.

 

[Charrlie_S]

More Hp equals more pulling power, torque ain't a bonus power.

HP=TQ X RPM
increase torque=increase horsepower at the same revs.

 

[273]

HP=TQ X RPM
increase torque=increase horsepower at the same revs.

Not with a stall and or gearing, an increase in torque by those is met by a decrease in rpm so no increase in hp, stall and or gearing don't multiply hp, there're there to just try to match engine power (band) to the task at hand.

 

[Charrlie_S]

Not with a stall and or gearing, an increase in torque by those is met by a decrease in rpm so no increase in hp, stall and or gearing don't multiply hp, there're there to just try to match engine power (band) to the task at hand.

? That statement does not make sense to me. In general, when you increase the stall speed of the converter, you also increase torque multiplication. A LU converter in LU mode has zero torque multiplication. When unlocked there is torque multiplication, up to the point of stator lock up.

 

[Woody500]

Not with a stall and or gearing, an increase in torque by those is met by a decrease in rpm so no increase in hp, stall and or gearing don't multiply hp, there're there to just try to match engine power (band) to the task at hand.

I don't remember increases being mentioned.
What was said is that the lock-up converter saves the extra drag it takes to torque multiply in the converter all the time. Less heat too.
You then are not wasting whatever amount that is, to Propel Vehicle Forward instead, or at cruise saving that power(or whatever technicality you want to use) & increasing your mileage.
And that is what OP has asked about & you seem to have not read the whole post or didn't comprehend it as it was meant.
I didn't call you out before, but you keep going on about it.

 

[273]

I didn't call you out before, but you keep going on about it.

Kept going on about it ? I replied only once, other than my original statement lol then he replied with a question mark obviously not getting my point so I dropped it.

I don't remember increases being mentioned.

"Charrlie_S said:
and allow torque multipication for added pulling power."

Multiplication and Added is the same as "Increase", in this context, is it not ?

What was said is that the lock-up converter saves the extra drag it takes to torque multiply in the converter all the time. Less heat too.
You then are not wasting whatever amount that is, to Propel Vehicle Forward instead, or at cruise saving that power(or whatever technicality you want to use) & increasing your mileage.
And that is what OP has asked about & you seem to have not read the whole post or didn't comprehend it as it was meant.

Kewl but doesn't change that his last part of the statement is wrong and when I pointed that out he didn't clarify and or said I miss read etc.. he doubled down

? That statement does not make sense to me. In general, when you increase the stall speed of the converter, you also increase torque multiplication. A LU converter in LU mode has zero torque multiplication. When unlocked there is torque multiplication, up to the point of stator lock up.

True but that doesn't make more "Power", pulling or otherwise.

 

[Woody500]

Going on & on again