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      10-04-2012, 01:52 PM   #4
Squadron Leader (Ret'd)

Drives: E91 330d SE & Mini Coupe JCW
Join Date: Aug 2010
Location: Cornwall

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Originally Posted by baz57 View Post
I'm showing my ignorance, but how do you mean lock up? On rapid acceleration the box is great. Fast smooth change. But when pottering around town, all changes are slightly ponderous, slow and a tiny bit jerky. I drove a jag with an 8 speed box which was super smooth too.
Traditional auto boxes use a torque converter instead of a clutch. This gives the smooth change, but also will cause revs to rise disproportionate to the speed when you accelerate a bit like a slipping clutch feels, but intentional. When the box is locked, the torque converter doesn't cause that 'slush box' slipping clutch feeling when you accelerate in gear.

Last edited by Falmouthboy; 10-05-2012 at 09:10 AM.