Hi all
I have just purchased a '95 disco V8 Auto. My first LR. I have a million questions.... I find that the torque converter locks up at about 85km/h in 4th. What causes it to lock up? Is it speed dependant? Does it lock up in low range as well? Can you get it to lock up in any other gears?
Thanks
Jimmy
On or around Wed, 12 May 2004 22:25:41 +0200, "Jimmy Sanby" enlightened us thusly:
speed dependent, 85Km/h sounds about right. It only locks up in 4th, it's done by a clutch in the torque converter which is driven by a speed sensor in the 'box.
It'll also lock up in 4th Low range... not that this is a lot of use.
There's not much to be gained from locking it in intermediate gears, anyway. The slippage in the converter is part of how the 'box works. The lock-up gives lower engine revs at cruising speeds, and slightly more efficiency to boot.
Sorry to be a smartarse but it doesn't have a clutch, the lockup effect is produced by reversing the oil flow direction through the torque convertor. What's really sad is that I can also tell you which valves are used to do it :-)
cheers
Dave W.
On or around Wed, 12 May 2004 22:43:45 +0000 (UTC), Dave White enlightened us thusly:
OK, well, I'll bow to your superior judgement (sad man...:-)) - in the schematic of power-flow I've seen it implies a clutch.
Thanks for your input, I suppose Dave's explanation exaplains the reason that the torque converter appears to lock completly on some occasions and appears to have about 200rpm slippage under other occasions. This is apposed to the +/- 750 rpm slippage when not locked up. I am not sure if slippage is the correct wording....
Extract from LR WS Manual"A three element torque converter delivers power to a four speed epicyclic transmission. ~~ Adirect drive clutch, integral within the torque converter operates to engage fourth gear (Sect 44 Pg 1 of LR Pub LRL 0079)
Peter
You are both right - the direction of oil flow through the oil cooler does change direction when the TC locks up. But the TC locks up due to a hydraulic clutch that is internal to the TC.
On or around Thu, 13 May 2004 21:28:47 +0100, "Simon Atkinson" enlightened us thusly:
aha. I thought it had.
Having now actually read the manual rather than relied on memory your are correct :-)
There is a clutch in the torque convertor, it is operated when the oil flow through the torque convertor is reversed. The governor operates the DDC control valve which then reverses the flow which in turn operates the clutch. I always thought the reverse oil flow acted on the stator and used that to lock it up - I'll know next time though !
cheers
Dave W.
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