Who does (or knows how to do or has learnt how to do) double-clutching in 80's with a manual box? (1 Viewer)

[sunrk]

I'm staring down the pathway of a clutch job in the not too distant future due to the difficults of gear selection (esp 1st and 3rd), and have wondered about double-clutching for gear changing as a way to 'work around' the clutch issues while I'm fundless to get a shop to sort it out.

I've never done or tried double-clutching, but am I correct in this being the process:

- push clutch pedal
- Get out of gear into neutral,
- release clutch pedal
- push clutch pedal again
- go into desired gear

Seems that the idea is to rev-match the gearbox internals so gears mesh without crashing into each other or just being difficult to align when trying to get another gear (or get any gear from a standing start).

To get 1st, I have to push clutch all the way and be going very slow, or stopped, and it still usually is not a smooth engagement.

 

[NeverFinis]

Yes, that is the process for double clutching. It is used with transmissions without syncros.

Do you have a hydraulic clutch or a cable operated one? Check fluid on the former, and if the latter, the cable might need adjusting.

 

[TheBussman]

sounds more like a syncro issue, but also possible you need a clutch adjustment, need to do some testing.

 

[jayp2]

I'm staring down the pathway of a clutch job in the not too distant future due to the difficults of gear selection (esp 1st and 3rd), and have wondered about double-clutching for gear changing as a way to 'work around' the clutch issues while I'm fundless to get a shop to sort it out.

I've never done or tried double-clutching, but am I correct in this being the process:

- push clutch pedal
- Get out of gear into neutral,
- release clutch pedal
- push clutch pedal again
- go into desired gear

Seems that the idea is to rev-match the gearbox internals so gears mesh without crashing into each other or just being difficult to align when trying to get another gear (or get any gear from a standing start).

To get 1st, I have to push clutch all the way and be going very slow, or stopped, and it still usually is not a smooth engagement.

To getting 2nd before putting it into 1st

 

[BILT4ME]

First gear has no synchro's so you won't be able to downshift into first unless you match engine speed.

How about shifting with no clutch?
I have driven lots of old trucks and never used the clutch other than to start and stop.

You let up the clutch while in first to get going, then as you back off the throttle, you pull it out of first and gently and smoothly pull the shifter into 2nd. You will grind the gears as you learn to listen to engine rpm to match engine speed with transmission.

To downshift from a higher gear to lower gear (4th to 3rd) as you let up on the throttle to release the drive line pressure, you pull it out of the higher gear, then smoothly step on the throttle and increase the RPM to match the engine to the transmission speeds. Again, you do this by feel and watch your tach.

Eventually, you will be able to do it with little effort.

Double clutching typically was only used when heavily loaded and moving slowly. The idea is to keep the input shaft speed up for a smoother shift. It also increases wear on your throw out bearing and clutch faces.

 

[mudgudgeon]

@BILT4ME has it down!

@sunrk the important thing is not the double clutch action per se, its matching the engine revs, and input shaft speed to the gear speed for the gear you are selecting, and gear selection to road speed.

I've driven several vehicles I've owned without using the clutch. My first work ute as a teenager had a clutch cable break on my way to work. Drove 1hr + through Sydney traffic to get to work, then home again. Drove it for the rest of the week like this.

I've driven my 80s without using the clutch, mostly to know it can be done, but also to show my boy it can be done. He used this skill himself to get his subaru hinge, then to a mechanic when it had a clutch fork break.

Two things to think of,

1. you need to momentarily let the driveline go slack to slip out of gear.
2. Revs/throttle action.
- throttle DOWN to change DOWN.
- Throttle UP to change UP.

If your road speed is going UP, and you want to shift UP a gear, let the throttle UP.
There'll be a moment where the driveline goes slack,
While there's no pressure on the gear you are currently using, you can slip it to neutral,
Then slip n it into the next gear.
As you shift into the next gear, ease back onto the throttle.
Shifting up into a higher gear, the next gear will be rising at a slower RPM then the previous gear. It's easier/ more forgiving when trying to match engine speed.

If you delay getting onto the throttle, you'll have a rough gear change. Particularly with the torque of the diesel.
Timing of all these actions is important. The same as your would do if you were driving enthusiastically with the clutch.


If your road speed is going DOWN or you want to shift DOWN a gear, the process is slightly different.
If you coasting, or slowing down, engine braking will mean the weight of the vehicle keeps the driveline under load.
To unload the driveline, press the throttle DOWN, just a blip, and only for a second.
This will momentarily unload the drive line.
while it's unloaded, slip to neutral.
While in neutral, press the throttle down again, just a blip, and only for a second. This time to match engine RPM, and input shaft speed to the speed of the lower gear. The lower gear will be spinning at a higher RPM than the previous gear was. Engine speed needs to be higher to match.
As you slip into gear, press DOWN on the throttle to keep engine RPM matched to the new gear speed, then ease off the throttle to reduce vehicle speed as needed.

If you're downshifting because you need more power for a hill, a you shift into the lower gear, you can step on the throttle as much as you like to bring RPM up as quickly as you like to keep vehicle speed up.

Timing of the shift and use of the throttle is more critical downshifting. If you get this c wrong, the lower gear amplifies the torque off the diesel, and a bad shift will be jerky.
Shifting down, if you're too far off with matching engine revs, you just won't be able to get into a gear.

Get this right, you can drive just as smoothly, just as enthusiastically as you would with the clutch. It takes a lot of attention to engine noise, road noise, road speed etc and a lot of finesse with the foot work and hand coordination.

It can be fun.

If you had s total clutch failure, and needed to get the vehicle to a workshop, you can still do this.
To start driving, start with the engine off. When you're ready to move off, select 1st, turn the key and start the engine, apply throttle straight away to drive off as the engine fires up.
Then, shift as above.
To come to a stop, you can either stall the engine out as you come to a stop, or be ready to hit the key to turn off the engine as you come to a stop.

 

[BTLSHP]

First gear has no synchro's so you won't be able to downshift into first unless you match engine speed.

How about shifting with no clutch?
I have driven lots of old trucks and never used the clutch other than to start and stop.

You let up the clutch while in first to get going, then as you back off the throttle, you pull it out of first and gently and smoothly pull the shifter into 2nd. You will grind the gears as you learn to listen to engine rpm to match engine speed with transmission.

To downshift from a higher gear to lower gear (4th to 3rd) as you let up on the throttle to release the drive line pressure, you pull it out of the higher gear, then smoothly step on the throttle and increase the RPM to match the engine to the transmission speeds. Again, you do this by feel and watch your tach.

Eventually, you will be able to do it with little effort.

Double clutching typically was only used when heavily loaded and moving slowly. The idea is to keep the input shaft speed up for a smoother shift. It also increases wear on your throw out bearing and clutch faces.

That is how I was taught to handle the manual in a school bus as a summer job.

 

[mudgudgeon]

First gear has no synchro's so you won't be able to downshift into first unless you match engine speed.

The H15*F boxes have 1st gear synchros.

@sunrk the synchronisers are essentially a clutch for each individual gear. The friction as you engage a gear helps match the gear speed and adjust speed inside the box.

There's a limit to how much the synchros can do to match gear/ shaft speed, particularly if they are worn, which is why engine speed needs to match gear speed.

 

[manofthewoods]

I'm staring down the pathway of a clutch job in the not too distant future due to the difficults of gear selection (esp 1st and 3rd), and have wondered about double-clutching for gear changing as a way to 'work around' the clutch issues while I'm fundless to get a shop to sort it out.

I've never done or tried double-clutching, but am I correct in this being the process:

- push clutch pedal
- Get out of gear into neutral,
- release clutch pedal
- push clutch pedal again
- go into desired gear

Seems that the idea is to rev-match the gearbox internals so gears mesh without crashing into each other or just being difficult to align when trying to get another gear (or get any gear from a standing start).

To get 1st, I have to push clutch all the

Easiest way...
When shifting, treat neutral as if it is a gear, then immediately shift in the desired gear - all in a smooth motion.

Wanna save your clutch, master and slave cylinder, and throw out bearing?
Learn how to time the instant you let off the gas when the transmission has zero load, then shift. I do it for fun sometimes. Note: downshifting seems much more difficult..
Of course you'll be trading gear grinding for less clutch wear

way and be going very slow, or stopped, and it still usually is not a smooth engagement.

 

[sunrk]

sounds more like a syncro issue, but also possible you need a clutch adjustment, need to do some testing.

Need to save some money to get a local clutch shop to investigate, but in the meantime...

 

[sunrk]

Yes, that is the process for double clutching. It is used with transmissions without syncros.

Do you have a hydraulic clutch or a cable operated one? Check fluid on the former, and if the latter, the cable might need adjusting.

It's hydraulic. In 80's the clutch system is a totally seperate hydraulic circuit to the brake system, unlike my cars with manual boxes where the clutch and brake share the same fluid reservoir that feed their respective master cyl's.

 

[sunrk]

I find it very difficult to get 1st gear even when the motor is running and hot so the gearbox/clutch are also heated up. I can usually get 2nd gear ok at a standing start but on an upgrade 1st is sometimes needed. I have to work it to go in and usually I'm forcing it (with clutch pedal all the way down). I'll flush out the clutch fluid first as that's easy to do and step up from there.

If I'm *rolling* very slow in traffic (or not completely stopped when lights change) at the right sort of rev range getting 1st (or 2nd or 3rd) is easy.

 

[AussieHJCruza]

How long since you did a clutch fluid flush?

 

[mudgudgeon]

I find it very difficult to get 1st gear even when the motor is running and hot so the gearbox/clutch are also heated up. I can usually get 2nd gear ok at a standing start but on an upgrade 1st is sometimes needed. I have to work it to go in and usually I'm forcing it (with clutch pedal all the way down). I'll flush out the clutch fluid first as that's easy to do and step up from there.

If I'm *rolling* very slow in traffic (or not completely stopped when lights change) at the right sort of rev range getting 1st (or 2nd or 3rd) is easy.

This definitely sounds like a clutch issue.