Dropping Revs over 80k's per Hour

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19th February 2011, 06:14 PM
Bigrig

Dropping Revs over 80k's per Hour

Howdy

quick one - I've had this since I had the car, but never really paid that much attention to it till now. I drive with the overdrive on, so after about 70-80k's per hour, it will usually drop out of third and down into over drive. The usual drop in revs and happy days ... thing is, over about 80, it seems to drop into overdrive (drops from say 2400 rpm in third to about 18-1900) and then a second or so later, drops another 200 or so rpms - no issue as such, but has no real power at this point, if I put my foot into the accelerator slightly, then it just very slowly responds, and usually I end up putting the boot in so it drops back to third. Here's the other thing .. if I do what I just said and slowly accelerate, its like I have limited power available, however if I take my foot completely off the accelerator then put it back on slightly, its like it picks up that 200 or so rpms again that I was talking of earlier for a second or two and then dies back again ...

Not the best explanation in the world, but let's start from here ... hope you know sorta kinda what I mean!! Is it just a "feature" that I should be happy with?? LOL - as said, not causing me any drama's, just thought it time to ask the question in case I need to have something looked at.

Thanks in advance!!!!
19th February 2011, 06:39 PM
YNOT

What you are feeling is the torque converter locking up.
The torque converter is a fluid coupling that fits between the engine and the gearbox, where the clutch would be in a manual. it's a bit hard to explain exactly how the T/C works but like a clutch it has one element connected directly to the crankshaft and another element connected to the gearbox. The two elements are only connected by transmission fluid, there is no direct coupling. Under normal conditions there will always be an amount of slip between the engine and transmission which is inefficient, so manufactures started installing lock up clutches in torque converters to eliminate the slip under cruise conditions.

What you have described is exactly the conditions under which the T/C will lock and unlock, right down to the T/C unlocking on deceleration.

Tony
19th February 2011, 07:31 PM
Sir Roofy

hi big rig
yep mine does the same thing
you think to your self whats goping on then the next thing
away we go
19th February 2011, 07:34 PM
Bigrig

Quote:

Originally Posted by YNOT

What you are feeling is the torque converter locking up.
The torque converter is a fluid coupling that fits between the engine and the gearbox, where the clutch would be in a manual. it's a bit hard to explain exactly how the T/C works but like a clutch it has one element connected directly to the crankshaft and another element connected to the gearbox. The two elements are only connected by transmission fluid, there is no direct coupling. Under normal conditions there will always be an amount of slip between the engine and transmission which is inefficient, so manufactures started installing lock up clutches in torque converters to eliminate the slip under cruise conditions.

What you have described is exactly the conditions under which the T/C will lock and unlock, right down to the T/C unlocking on deceleration.

Tony

Thanks a million mate - so no drama then? As said, wasn't overly concerned as it's had the full Monty done to it to check it out, but better to be sure.
19th February 2011, 07:36 PM
Bigrig

Quote:

Originally Posted by roofy

hi big rig
yep mine does the same thing
you think to your self whats goping on then the next thing
away we go

Yep - that's the feeling .... Seems strange as that last couple of hundred revs (to me at least) would be just what it needs to hold gear going up long inclines (not hills as such, just slopes) ... That said, if it's a feature, then that's what it is!!
19th February 2011, 07:43 PM
Sir Roofy

Quote:

Originally Posted by bigrig

yep - that's the feeling .... Seems strange as that last couple of hundred revs (to me at least) would be just what it needs to hold gear going up long inclines (not hills as such, just slopes) ... That said, if it's a feature, then that's what it is!!

try your a.t button push it forward to power then see the difference,once at the top just put it back in the centre
19th February 2011, 07:53 PM
Bigrig

Quote:

Originally Posted by roofy

try your a.t button push it forward to power then see the difference,once at the top just put it back in the centre

Will do mate - thanks!
19th February 2011, 08:32 PM
Finly Owner

just fit manual and feel real power........
19th February 2011, 08:35 PM
Bigrig

Quote:

Originally Posted by Finly Owner

just fit manual and feel real power........

Not hijacking (my own thread?? LOL) - can start a new thread, but since having it tuned properly for LPG etc, and the extractors and exhaust installed, I don't reckon a TB42e manual would come close to doing me off the mark!! Or am I fooling myself?? LOL
19th February 2011, 09:51 PM
Finly Owner

Quote:

Originally Posted by Bigrig

Not hijacking (my own thread?? LOL) - can start a new thread, but since having it tuned properly for LPG etc, and the extractors and exhaust installed, I don't reckon a TB42e manual would come close to doing me off the mark!! Or am I fooling myself?? LOL

no reply is what u get from me on this
19th February 2011, 09:52 PM
Bigrig

Quote:

Originally Posted by Finly Owner

no reply is what u get from me on this

So it's true then!!! LOL
19th February 2011, 09:54 PM
Finly Owner

Quote:

Originally Posted by Bigrig

So it's true then!!! LOL

I repeat last statement