Overdrive Selection advice

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Rev Light
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Overdrive Selection advice

Post by Rev Light » Mon Apr 29, 2019 1:27 pm

I was watching a video on the 'Tube' whereby a certain Car journo was driving another person's classic car. It was fitted with overdrive and the owner requested that the 'journo' depress the clutch before selecting overdrive.....Never heard of this? What will it achieve? Also, I think even the 'journo' found it a bit odd, but did, apparently drop the revs a bit before selecting overdrive.

Any comments from the experts?

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Old and Slow
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Overdrive Selection advice

Post by Old and Slow » Mon Apr 29, 2019 2:13 pm

Yes, I was "taught" to do this, also, never engage overdrive (without using the clutch) when under acceleration, as it puts undue stress on the sun and planet gears.
I reality, I probably use the clutch 50% of the time, but I try never to switch in overdrive whilst accelerating, I feather back the throttle instead.
Only my view, of course.


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Nick
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Overdrive Selection advice

Post by Nick » Mon Apr 29, 2019 2:23 pm

There should be no need to pussy foot an overdrive provided you stick to 3rd and 4th gear . All the overdrive does is apply a brake to the outer ring gear to change to ratio. No need to de clutch. If anything I would have though de clutching would apply more shock load.


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chrisgallacher
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Overdrive Selection advice

Post by chrisgallacher » Mon Apr 29, 2019 4:24 pm

Interesting. I have a J-type overdrive and I've never used it in conjunction with the clutch - isn't that one of the joys of dropping the overdrive in and out especially when driving around town in 3rd gear? The clutchless, instant gear-change?

I don't pop the overdrive in when under full foot-to-the-floor acceleration, but I find I get the smoothest & quickest change if I'm under mild/moderate acceleration. It doesn't feel as if I'm stessing anything. Am I fooling myself?


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Overdrive Selection advice

Post by TrevorG » Mon Apr 29, 2019 4:26 pm

I was always taught not to select overdrive when experiencing hard acceleration. Likewise, don't deselect when hard braking. Probably because I had a succession of powerful 1950s cars with overdrive. But any driving trait that creates unnecessary stress to an older vehicle could lead to problems anywhere in the moving parts......owner's choice i suppose.
I remember shearing my engine mounts on one of Dave Caswell's lake district jaunts in the 80s, probably due to overloading the scimitar drivetrain.



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Overdrive Selection advice

Post by peter freeman » Mon Apr 29, 2019 6:42 pm

I agree with Trevor an select and de-select with the power at neutral - you know its right when there is no jerk when selecting and deselecting - got to be better for the car.



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Old and Slow
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Overdrive Selection advice

Post by Old and Slow » Mon Apr 29, 2019 7:50 pm

Forgot to say,
Mine has the Moss gearbox with overdrive (Mk 2 Jag) so it might be different internally to the "standard" Reliant fit.


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peter freeman
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Overdrive Selection advice

Post by peter freeman » Mon Apr 29, 2019 8:01 pm

Same rules apply do they not.



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Overdrive Selection advice

Post by halfpenny » Mon Apr 29, 2019 8:05 pm

I think a neutral throttle change is best practice, and avoids an unecessary torque reversal. Can't see the point of dipping the clutch.



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Roger Pennington
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Overdrive Selection advice

Post by Roger Pennington » Mon Apr 29, 2019 8:18 pm

I've always followed Chris' principle. I don't get a jerk, it's always been pretty smooth.


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chrisgallacher
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Overdrive Selection advice

Post by chrisgallacher » Mon Apr 29, 2019 9:36 pm

It's funny, I've been driving overdrive cars for two decades now (all J-type overdrives) and it's just second nature that I don't think about it.

I happened to have taken the Sabre with me to work today, so on the drive home I concentrated on how I used the overdrive. As I thought, dropping it in was almost always under gentle-ish acceleration with no feathering of the throttle resulting in a nice smooth, snatch-free, pretty much instant take-up. Disengaging was different, almost always done with very light or no throttle which again gave a smooth change. This was dictated more by the practicalities of needing to disengage as I'm slowing down, than anything else.


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Overdrive Selection advice

Post by efi_sprintgte » Mon Apr 29, 2019 10:42 pm

I used to full throttle shift overdrive at 6k in 3rd and 4th with 200 bhp. :lol:

Dad has done many many many thousands of miles with 1.5 tonnes of trailer on the back you still get smooth changes using the overdrive under-load.

It’s not a fragile overdrive in my experience.


JC

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