Auto-box irritation!

shropshire-ranger · May 23, 2012

Late 99 4.0 litre - box does't change up to 4th (top) until road speed of 50-54 mph. Kick down & downshifts seem fine. Oil & filters changed as per rr schedule, oils coming out clean.
No leaks, anyone got any thoughts? I can live with it but on the roads down here in deepest Shropshire, it means I spend a lot of time in 3rd which uses more juice!

wammers · May 23, 2012

Think you will find it changes to top a lot sooner than that. The apparent change you get at 50 mph plus is torque convertor lockup.

Brian S · May 23, 2012

I thought the same, but while doing 45 drop the gear down to third and you will notice the revs rise.
As said, you are in top but the lock up seems to drop the revs as well and it feels like another gear change.

Saint.V8 · May 23, 2012

Brian S said:
I thought the same, but while doing 45 drop the gear down to third and you will notice the revs rise.
As said, you are in top but the lock up seems to drop the revs as well and it feels like another gear change.

Thats because following the Lock-Up, torque convertor slippage is removed, hence the drop in revs.

goonarmy · May 23, 2012

wot wammers sed

goonarmy · May 23, 2012

also this is good for fuel consumption, so id say not an irritation

john-sussex · May 23, 2012

Don't forget that the converter only locks when the oil is warm, mine takes a couple of miles before it locks.

shropshire-ranger · May 24, 2012

Thanks Wammers & Brian S,reason I say it's not changing into 4th is because the revs don't drop until the change has happened. There are 2 points in the change-up, first as i hit about 52mph the revs drop back by about 500, then in 2-3 secs, there's a further drop in revs, which I assume is the T C lockup.

Auto-box irritation!

shropshire-ranger

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wammers

No longer with us, RIP

Brian S

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Saint.V8

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goonarmy

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goonarmy

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john-sussex

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shropshire-ranger

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