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Patrick Francis
Prolific User
Username: jackpot

Post Number: 198
Registered: 11-2016
Posted on Friday, 10 November, 2017 - 07:22:   Edit PostDelete PostView Post/Check IP

Hi Guys
I have just installed a 4 speed Moss gearbox with overdrive in my Jag Mk2.
I find that the overdrive switch effects a smooth change when engaging, but a slightly abrupt change when disengaging. To satisfy my mechanical sympathy, I have been using the clutch to help engage and disengage.
Since I have never driven and overdrive vehicle before, I was wondering if it is normal to use the clutch with the overdrive, or if they were designed to work without?
Thanks
Patrick
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Mark Luft
Prolific User
Username: bentleyman1993

Post Number: 133
Registered: 10-2016
Posted on Friday, 10 November, 2017 - 07:47:   Edit PostDelete PostView Post/Check IP

Patrick, on my MKII overdrive went in and out by flipping the switch and letting up on the gas. Wasn't a Moss box though. I will say that when the overdrive is set up right, that was the sweetest setup I've ever had. I mounted the OD toggle switch on the gear shift, like a splitter in a large truck. OD on top two gears.
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Jonas TRACHSEL
Prolific User
Username: jonas_trachsel

Post Number: 149
Registered: 2-2005
Posted on Friday, 10 November, 2017 - 17:31:   Edit PostDelete PostView Post/Check IP

Patrick
I once had a Volvo Amazon with OD. Yes, you can shift the OD without using the clutch, but I think it hurts the OD in the long run. At least lift your right foot while switching on/off.
I also have had a Laycock OD retrofitted to my 20/25 HP. I always use the clutch when engaging or disengaging. I hate the jerk it gives without de-clutching, and that is not befitting a R-R.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1570
Registered: 5-2015
Posted on Friday, 10 November, 2017 - 22:32:   Edit PostDelete PostView Post/Check IP

An overdrive such as described works like an automatic gear box and can be changed under power.
But its good practice to lift off whilst changing in and out of overdrive.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1609
Registered: 9-2004
Posted on Friday, 10 November, 2017 - 22:43:   Edit PostDelete PostView Post/Check IP

Many years ago I ran a Jaguar with a four speed box I soon fitted a moss overdrive box and wired it up with the O/D working on 3rd and 4th.
had to wire up a cut out so it would not engage in reverse, it transformed the car for MPG and lower revs.
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Patrick Francis
Prolific User
Username: jackpot

Post Number: 201
Registered: 11-2016
Posted on Saturday, 11 November, 2017 - 03:52:   Edit PostDelete PostView Post/Check IP

Thanks guys.
Patrick, you are right. Mine was an auto, she is now a different car altogether!