Lock-up in the auto box

BanziBarn · 02-18-2010, 02:35 AM

Saw mention of this in another thread. What exactly is it and when does it engage?

Cheers!

zltm089 · 02-18-2010, 11:08 AM

hmm...never heard of this term before....what is it???

Dave_3 · 02-18-2010, 11:17 AM

In older Automatic gearboxes the torque converter was a fluid coupling to damp out the input, and prevent stall when coming to rest.

In the older boxes when you start from rest, or accelerate hard you are going through the torque converter and will really feel that buffer effect- i.e. rising/flaring revs, matched slowly by progress.

In the latest ZF boxes, when you are up and running it can directly (mechanically) "lock" in a gear, so you have direct drive from engine through the gearbox and not buffered trhough the torque converter. You don't need to do anything - it is designed that way.

That is why the new automatic boxes will feel very crisp in uptake compared to those in older cars.

D.

dxb335d · 02-18-2010, 11:19 AM

Quote:

Originally Posted by Dave_3

In older Automatic gearboxes the torque converter was a fluid coupling to damp out the input, and prevent stall when coming to rest.

In the older boxes when you start from rest, or accelerate hard you are going through the torque converter and will really feel that buffer effect- i.e. rising/flaring revs, matched slowly by progress.

In the latest ZF boxes, when you are up and running it can directly (mechanically) "lock" in a gear, so you have direct drive from engine through the gearbox and not buffered trhough the torque converter. You don't need to do anything - it is designed that way.

That is why the new autoboxes boxes will feel very crisp in uptake compared to those in older cars.

D.

+1

I hate old autos.

BanziBarn · 02-18-2010, 12:10 PM

Very interesting. So does the drive only become viscus when the car is going too slow and about to stall?

In 'D' the car seems undirect to me quite a lot of the time - perhaps this is because it doesn't use 1st gear (as far as I can tell) so in slow traffic the car will be playing catchup to the revs quite a lot of the time.

Does this also mean that in gear, the auto should be as quick as the manual?

Dave_3 · 02-18-2010, 12:19 PM

Quote:

Originally Posted by BanziBarn

Very interesting. So does the drive only become viscus when the car is going too slow and about to stall?

In 'D' the car seems undirect to me quite a lot of the time - perhaps this is because it doesn't use 1st gear (as far as I can tell) so in slow traffic the car will be playing catchup to the revs quite a lot of the time.

Does this also mean that in gear, the auto should be as quick as the manual?

What age is your 330D ? You have the LCI from your tag ?

If it is not the LCI version you will have a slightly older gearbox than the latest versions in the 335i/d. The newer spec box is also fitted to some of the newer Jaguars too.

When it is locked up you will have direct physical/mechanical connection from engine to propshaft. As quick as the manual ? Depends if the gear ratio you are in (and final drive ratio in the Diff) are identical to the manual version you should. Most older automatic cars had a slightly taller final ratio (=slower acceleration, more relaxed cruising) and lower geared gearbox ratios. Haven't looked closely at the BMW setup.

The direct lock-up will not be engaged all the time. Only over a certain speed/load. Stop - start, you will be using the torque converter, you can feel it disengage as you come to a rest (badly programmed versions in the Jaguar and 5 series caused lurches).

D.

HighlandPete · 02-18-2010, 12:26 PM

The older boxes of E46/E39 models with the 5HP24 series box had an on/off lock-up operation, you could clearly see/feel the 5th gear lock-up as revs dropped, some even thought they had a 6th gear.

The current 6HP26 series uses a stepped lock-up, so more smooth in both engagement and disengagement. Obviously the clutch must disengage at low revs and has other electronic interfaces, such as minumum oil temperature before becoming active.

Low revs and pulling away is still using torque multiplication in the torque converter, but is more closely controlled than older boxes and keeps much closer to the 1.1:1 coupling speed, ahead of lock-up.

HighlandPete

BanziBarn · 02-18-2010, 01:14 PM

Yep, I have an LCI - didn't know I had a newer box as well as a newer engine. Good to know

BanziBarn · 02-18-2010, 03:46 PM

Very interesting. So does the drive only become viscus when the car is going too slow and about to stall?

In 'D' the car seems undirect to me quite a lot of the time - perhaps this is because it doesn't use 1st gear (as far as I can tell) so in slow traffic the car will be playing catchup to the revs quite a lot of the time.

Does this also mean that in gear, the auto should be as quick as the manual?

SoYank · 02-20-2010, 07:53 AM

Quote:

Originally Posted by dxb335d

+1

I hate old autos.

Me, too. That's why I avoid them even today and opt for a manual. Only two of my nine cars have had automatics.

02-18-2010, 02:35 AM	#1
BanziBarn Lieutenant Colonel 110 Rep 1,800 Posts Drives: BMW 330D E90 LCI Msport Join Date: Sep 2009 Location: London iTrader: (0)	Lock-up in the auto box Saw mention of this in another thread. What exactly is it and when does it engage? Cheers! __________________ Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.
	Appreciate 0 Tweet Quote

02-18-2010, 11:08 AM	#2
zltm089 Banned 261 Rep 7,686 Posts Drives: 335i SE Coupe Space Grey Join Date: Nov 2008 Location: LONDON iTrader: (0) Garage List 2006 BMW 335i [10.00]	hmm...never heard of this term before....what is it???
	Appreciate 0 Quote

02-18-2010, 11:17 AM	#3
Dave_3 Brigadier General 658 Rep 3,447 Posts Drives: G22 M440D Join Date: Oct 2006 Location: CH / SCO iTrader: (0) Garage List 1973 Escort RS2000 MK1 [10.00]	In older Automatic gearboxes the torque converter was a fluid coupling to damp out the input, and prevent stall when coming to rest. In the older boxes when you start from rest, or accelerate hard you are going through the torque converter and will really feel that buffer effect- i.e. rising/flaring revs, matched slowly by progress. In the latest ZF boxes, when you are up and running it can directly (mechanically) "lock" in a gear, so you have direct drive from engine through the gearbox and not buffered trhough the torque converter. You don't need to do anything - it is designed that way. That is why the new automatic boxes will feel very crisp in uptake compared to those in older cars. D. __________________ Escort Mk1 RS2000 (2.1 2x44IDFS, BVH, Kent FR32, 5spd, 180 BHP) : M440D ¦ Previously : F32 435D : F32 430D M Sport sDrive, 335D E92 2006
	Appreciate 0 Quote

02-18-2010, 12:10 PM	#5
BanziBarn Lieutenant Colonel 110 Rep 1,800 Posts Drives: BMW 330D E90 LCI Msport Join Date: Sep 2009 Location: London iTrader: (0)	Very interesting. So does the drive only become viscus when the car is going too slow and about to stall? In 'D' the car seems undirect to me quite a lot of the time - perhaps this is because it doesn't use 1st gear (as far as I can tell) so in slow traffic the car will be playing catchup to the revs quite a lot of the time. Does this also mean that in gear, the auto should be as quick as the manual? __________________ Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.
	Appreciate 0 Quote

02-18-2010, 12:26 PM	#7
HighlandPete Lieutenant General 6550 Rep 15,857 Posts Drives: BMW F11 535i Touring Join Date: Mar 2007 Location: Scotland, Highland Region iTrader: (0)	The older boxes of E46/E39 models with the 5HP24 series box had an on/off lock-up operation, you could clearly see/feel the 5th gear lock-up as revs dropped, some even thought they had a 6th gear. The current 6HP26 series uses a stepped lock-up, so more smooth in both engagement and disengagement. Obviously the clutch must disengage at low revs and has other electronic interfaces, such as minumum oil temperature before becoming active. Low revs and pulling away is still using torque multiplication in the torque converter, but is more closely controlled than older boxes and keeps much closer to the 1.1:1 coupling speed, ahead of lock-up. HighlandPete
	Appreciate 0 Quote

02-18-2010, 01:14 PM	#8
BanziBarn Lieutenant Colonel 110 Rep 1,800 Posts Drives: BMW 330D E90 LCI Msport Join Date: Sep 2009 Location: London iTrader: (0)	Yep, I have an LCI - didn't know I had a newer box as well as a newer engine. Good to know __________________ Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.
	Appreciate 0 Quote

02-18-2010, 03:46 PM	#9
BanziBarn Lieutenant Colonel 110 Rep 1,800 Posts Drives: BMW 330D E90 LCI Msport Join Date: Sep 2009 Location: London iTrader: (0)	Very interesting. So does the drive only become viscus when the car is going too slow and about to stall? In 'D' the car seems undirect to me quite a lot of the time - perhaps this is because it doesn't use 1st gear (as far as I can tell) so in slow traffic the car will be playing catchup to the revs quite a lot of the time. Does this also mean that in gear, the auto should be as quick as the manual? __________________ Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.
	Appreciate 0 Quote