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Correct Shifting Technique?


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#16 samuelw

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Posted Oct 20 2013 - 08:16 AM

Some time ago I tried to research this topic on the net.  The best info I found was a discussion on The Nostalgia Forum at the autosport site.  The Nostalgia forum is populated by persons devoted to auto racing history at least at the hobby level.  I believe some of the Nostalgia Forum contributers have authored books on the subject.  At any rate the consensus was double de-clutch on downshifts and upshifts are performed quickly with throttle blip and without use of the clutch.  This was the most reliable information I could find.  Of interest was the claim that Graham Hill did not skip gears on down shifts,ie he would not directly downshift from 5th to 2nd but rather went 5-4-3-2.  I guess this was to avoid locking up the rear and spinning.  I'm just not quick enough yet to do this at Monaco.  Plus if I spin I don't die.

I believe some of the information above is incorrect.  A dog box has straight cut teeth rather than the angled teeth on our current synchronized daily drivers.  The important points are that the teeth in a dog box are larger and stronger.  Dog boxes also are not synchronized resulting in a simpler more reliable transmission for high powered racing if shifted correctly.

About a year ago (inspired by a post by Remco Hitman) I resolved to quit paddle shifting, secured an h-shifter (Thrustmaster TH8 rs), and started to learn the art of double de-clutching.  After a year of double de-clutching downshifts in my daily driver  and race sims I can do it pretty well if not quite as second nature.  ( In tense situations I still tend to forget)

If anyone has better info I'm interested.

Happy racing
Samuel

#17 DuncanS

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Posted Oct 20 2013 - 12:51 PM

As said before, I think you'll find the clutch was used for upshifts too.

#18 samuelw

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Posted Oct 20 2013 - 01:25 PM

Google dog box transmission sometimes called a crash box. http://automotivethi...ox-and-dog-box/  Don't claim expertise in subject but fellows at Nostalgia Forum seem pretty knowledgeable wrt Grand prix history.
Samuel

#19 Wozza_UK

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Posted Nov 09 2013 - 01:18 PM

View Postsamuelw, on Oct 20 2013 - 08:16 AM, said:

Some time ago I tried to research this topic on the net.  The best info I found was a discussion on The Nostalgia Forum at the autosport site.  The Nostalgia forum is populated by persons devoted to auto racing history at least at the hobby level.  I believe some of the Nostalgia Forum contributers have authored books on the subject.  At any rate the consensus was double de-clutch on downshifts and upshifts are performed quickly with throttle blip and without use of the clutch.  This was the most reliable information I could find.  Of interest was the claim that Graham Hill did not skip gears on down shifts,ie he would not directly downshift from 5th to 2nd but rather went 5-4-3-2.  I guess this was to avoid locking up the rear and spinning.  I'm just not quick enough yet to do this at Monaco.  Plus if I spin I don't die.

I believe some of the information above is incorrect.  A dog box has straight cut teeth rather than the angled teeth on our current synchronized daily drivers.  The important points are that the teeth in a dog box are larger and stronger.  Dog boxes also are not synchronized resulting in a simpler more reliable transmission for high powered racing if shifted correctly.

About a year ago (inspired by a post by Remco Hitman) I resolved to quit paddle shifting, secured an h-shifter (Thrustmaster TH8 rs), and started to learn the art of double de-clutching.  After a year of double de-clutching downshifts in my daily driver  and race sims I can do it pretty well if not quite as second nature.  ( In tense situations I still tend to forget)

If anyone has better info I'm interested.

Happy racing
Samuel

Are you sure that's correct? How would you blip on an upshift? I thought they were only for downshifts. Surely if anything it should be "At any rate the consensus was double de-clutch on UPSHIFTS and DOWNSHIFTS are performed quickly with throttle blip and without use of the clutch."

#20 Bob Simpson

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Posted Nov 09 2013 - 01:34 PM

On an upshift, you can rev the engine while the stick is in the neutral position so that the gears about to mesh are going roughly the same rotational speed.  I'm just not sure that's the fastest way to shift.  That could be done on a downshift too, but I'm definitely sure that would be slower than using a clutch.  But I'm no expert.

#21 Paddy the Irishman

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Posted Nov 10 2013 - 09:10 AM

Sorry Bob, but you are not correct. The  quotation in # 20 is rather more correct, though for grammar pedants it isn’t !

Take the words in red, to read correctly there should be a comma between “downshifts” and “and”.  If you  are a grammar pedant, use the comma without the “and” -- "double de-clutch on downshifts, upshifts are performed quickly with throttle blip and without use of the clutch"

The ‘upshift’ details seem a bit off though, why the blip ?

Basically a gearbox has two shafts, the mainshaft and the layshaft.  The mainshaft  goes through from the the clutch to the the output end which drives the differential.  It is not a solid shaft, being split so that the two parts may turn at different speeds and has other gearwheels ‘floating’ on it which are meshed with the gears on the layshaft, these will be locked on to the 'front' of the mainshaft provide the different ,‘gears‘, ‘first’; ‘second’; etc. The two ends of the mainshaft are  locked solidly together in ‘top’ gear if it is “direct drive”.

The layshaft  is engaged and driven all the time by the front of the mainshaft, and has corresponding gears,solid on the shaft, meshed to the 'floating' gears on the mainshaft which can be 'solidified' to that shaft by dog-clutches.

A ‘blip’ with the clutch engaged and the gearbox in neutral, increases the rotational speed of the layshaft The layshaft needs to be slowed down on the upshift and sped up on the downshift.  

To synchronise gear/dog-clutches for engagement, on an upshift the throttle must be closed, on a downshift it must be opened.  The double de-clutch with a blip, means that the gears move through the synchronising point as input revs are falling, which means that they slip into engagement more easily than if power was being applied on input without having to be exactly synchronised

The ideal for downshift is to push down on the throttle pedal to the point where the revs of layshaft and mainshaft gears synchronise while moving the gearstick quickly through with a double clutch movement.  (This is much easier to achieve if you are faced with a car slowing down when going uphill and you are faced with the necessity to change down).

Changing up, if the throttle is lifted correctly, can be done without the clutch but with the clutch it does not need to be as precise and is easier on the gearbox (in real life anyway).




#22 benzman

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Posted Nov 10 2013 - 01:04 PM

View PostPaddy the Irishman, on Nov 10 2013 - 09:10 AM, said:

Sorry Bob, but you are not correct. The  quotation in # 20 is rather more correct, though for grammar pedants it isn’t !

Take the words in red, to read correctly there should be a comma between “downshifts” and “and”.  If you  are a grammar pedant, use the comma without the “and” -- "double de-clutch on downshifts, upshifts are performed quickly with throttle blip and without use of the clutch"

The ‘upshift’ details seem a bit off though, why the blip ?

Basically a gearbox has two shafts, the mainshaft and the layshaft.  The mainshaft  goes through from the the clutch to the the output end which drives the differential.  It is not a solid shaft, being split so that the two parts may turn at different speeds and has other gearwheels ‘floating’ on it which are meshed with the gears on the layshaft, these will be locked on to the 'front' of the mainshaft provide the different ,‘gears‘, ‘first’; ‘second’; etc. The two ends of the mainshaft are  locked solidly together in ‘top’ gear if it is “direct drive”.

The layshaft  is engaged and driven all the time by the front of the mainshaft, and has corresponding gears,solid on the shaft, meshed to the 'floating' gears on the mainshaft which can be 'solidified' to that shaft by dog-clutches.

A ‘blip’ with the clutch engaged and the gearbox in neutral, increases the rotational speed of the layshaft The layshaft needs to be slowed down on the upshift and sped up on the downshift.  

To synchronise gear/dog-clutches for engagement, on an upshift the throttle must be closed, on a downshift it must be opened.  The double de-clutch with a blip, means that the gears move through the synchronising point as input revs are falling, which means that they slip into engagement more easily than if power was being applied on input without having to be exactly synchronised

The ideal for downshift is to push down on the throttle pedal to the point where the revs of layshaft and mainshaft gears synchronise while moving the gearstick quickly through with a double clutch movement.  (This is much easier to achieve if you are faced with a car slowing down when going uphill and you are faced with the necessity to change down).

Changing up, if the throttle is lifted correctly, can be done without the clutch but with the clutch it does not need to be as precise and is easier on the gearbox (in real life anyway).
Paddy,
  Part of my miss-spent youth involved driving old trucks with crash gearboxes, so I am well acquainted with double-declutching, both in theory and practice.  Everything you say in your posting is absolutely correct.

#23 Paddy the Irishman

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Posted Nov 10 2013 - 04:00 PM

I managed the crash box quite adequately on a 1911 Sunbeam that my uncle owned,  NEVER manged to get a clean change on an afternnon in 1928 bus that had a rev range from 900 to 1200 rpm ! :dino:

#24 David Wright Lo67

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Posted Nov 10 2013 - 04:46 PM

I would suggest there is no consensus.  Gearchanges could be made without the clutch, with a single clutch depression or with a double clutch depression.

#25 samuelw

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Posted Nov 25 2013 - 06:10 AM

FWIW here's an article on point: https://docs.google....qSJE/edit?pli=1
SW

#26 John Woods

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Posted Nov 25 2013 - 08:19 AM

View Postsamuelw, on Nov 25 2013 - 06:10 AM, said:

FWIW here's an article on point: https://docs.google....qSJE/edit?pli=1
SW

Well...thereyahgo.
.

#27 David Wright Lo67

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Posted Nov 25 2013 - 03:03 PM

I bought Weekend of a Champion the other day about the 1971 Monaco GP.  Stewart uses a single press of the clutch on both upshifts and downshifts.

Edited by David Wright Lo67, Nov 25 2013 - 03:04 PM.


#28 John Woods

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Posted Nov 25 2013 - 04:14 PM

Not sure if this technique has been described, but recall reading about it somewhere long ago, based on not having to use a clutch to take a car out of gear.
The idea is to drop the clutch at the same time as shifting out of gear, so the pedal is down just at the moment the shift lever is ready to go into the next gear, then click it in and let the pedal out. With practice, a shift happens in the same time it takes the driver to engage the clutch and let it out. This happens while the driver matches engine revs and trans speed, (as if not using the clutch), so shifts are very smooth, quick, clutch is pressed only once per shift, and there's no clutch slip.
Apologies if someone already commented about this technique, even more if its not accurate, although I've done it for years so know it works even if not correct.

#29 TurboMan

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Posted Sep 29 2017 - 04:17 PM

Is it correct to downshift moving the stick from 5th to 3rd? In general, downshifting in a non-sequential way. Did the gearbox of the period allow this?

#30 leon_90

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Posted Sep 29 2017 - 05:52 PM

View PostTurboMan, on Sep 29 2017 - 04:17 PM, said:

Is it correct to downshift moving the stick from 5th to 3rd? In general, downshifting in a non-sequential way. Did the gearbox of the period allow this?

Ferrari's didn't. The others I believe they did




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