Why does double clutching work without a revmatch?

[charlieR]

My 2.0 d4d Avensis t27 has a very hard to engage first gear and a very high minimum speed (12mph) in second gear. This makes it very hard to drive around town because if you want to go from second gear to first gear, then you basically have to come to a complete stop first. However today i randomly tried double clutching WITHOUT a rev match and first gear was a lot easier to engage while rolling to a giveway line. Why did double clutching help without the revmatch? It doesn't make sense to me because i dont see how going to neutral without a revmatch would it make it easier for first gear to engage. Any help is much appreciated!

[Haliotis]

The synchromesh in the gearbox would have helped in this respect. Although, without achieving a “rev match”, prolonged use of this method would put increased wear on the synchromesh.  Double-declutching is intended to allow achievement of the rev match - letting out the clutch allows the gears to be matched by means of the accelerator - and when the practice is perfected the gears will slide into place smoothly at the next depression of the clutch, and releasing it will produce little or no shudder in the transmission.

My first car was a 1938 Standard 9, which I bought in 1953, and double-declutching was essential to move through the gears without crunching them.

I once had to drive a hire car with a seized clutch from the Welsh coast to Leicester.  Changing up or down was done by relaxing the accelerator, moving the gear stick into neutral and engaging the next gear by accurate timing of the engine.  

Stop and restart was done by knocking the great stick into neutral and switching off the engine.  The restart was done by engaging first gear and then turning on the ignition, which caused an immediate move forwards.

[AndyN01]

Ah, the joys of matching revs to gear to speed. 👍

Those who have ever had a clutch cable break or, on my case on a Chrysler Sunbeam, the locating lug pull completely through the bulkhead, will have vivid memories of using that particular "skill."  😀

[Cyker]

2 hours ago, charlieR said:

My 2.0 d4d Avensis t27 has a very hard to engage first gear and a very high minimum speed (12mph) in second gear. This makes it very hard to drive around town because if you want to go from second gear to first gear, then you basically have to come to a complete stop first. However today i randomly tried double clutching WITHOUT a rev match and first gear was a lot easier to engage while rolling to a giveway line. Why did double clutching help without the revmatch? It doesn't make sense to me because i dont see how going to neutral without a revmatch would it make it easier for first gear to engage. Any help is much appreciated!

I had that with my Mk1 Yaris too! Never understood why it helped but I also found it somehow did!!

I could also help it by revving the engine up a lot before trying to move into 1st (A lot being 2000-2500rpm, which is a fair amount for a diesel  ), but going to neutral and releasing the clutch first seemed to make it that much easier.

I still don't understand why it makes any difference!

One thing I love about my Mk4 is I don't have to deal with weird idiosyncrasies like that any more  

[charlieR]

4 hours ago, Cyker said:

I had that with my Mk1 Yaris too! Never understood why it helped but I also found it somehow did!!

I could also help it by revving the engine up a lot before trying to move into 1st (A lot being 2000-2500rpm, which is a fair amount for a diesel  ), but going to neutral and releasing the clutch first seemed to make it that much easier.

I still don't understand why it makes any difference!

One thing I love about my Mk4 is I don't have to deal with weird idiosyncrasies like that any more  

I also tried the just revving it method with the clutch down, but then the gear felt like it gone in but it hadn't fully and then i got some grinding 🤦. The double clutching works a lot better. Like you i find it odd that the double clutching works without the revmatch. Maybe the synchromesh is only just starting to go so it helps it out just enough 🤷

[Haliotis]

15 hours ago, charlieR said:

I also tried the just revving it method with the clutch down, but then the gear felt like it gone in but it hadn't fully and then i got some grinding 🤦. The double clutching works a lot better. Like you i find it odd that the double clutching works without the revmatch. Maybe the synchromesh is only just starting to go so it helps it out just enough 🤷

When the clutch is depressed, the engine is effectively isolated from the gearbox.  Letting the clutch out again allows the engine to be used to match the revolutions of the primary shaft to those of final drive shaft, through the lay shaft.  With the clutch let out, depending on whether you are changing UP or DOWN the gears, you either allow the engine to momentarily idle so that the primary shaft is rotating slower than the final drive shaft, or increase engine speed until the primary shaft is rotating faster than the final drive shaft.    The “skill” is in judging when the two shafts are running at the “match revs”, when the gear change is smooth and without jerking.  It takes time and patience, but there is a satisfying buzz when perfection is achieved.😃