TR2/3/3A TR3/4 clutch adjustment and shifting into 2nd

[bigjones]

Say you are going down the road and are about to turn onto a side road that goes uphill. You would naturally shift from 4th to 2nd, right?

Well, I can't seem to do this - there is much gnashing of gears. Is this normal for the TR3/4 gearbox?

I've just adjusted the slave cylinder to give 10 thou end float - is that right? I mean this is a TR3A but has a TR4 gearbox (all synchromesh, ar, ar!) Incidentally, why would the clearances be different - the TR3A spec is 87 thou. Anyway that didn't make any difference.

There is no other issues at all with the clutch/gearbox.

Many thanks for any suggestions!

 

[Moseso]

I would naturally shift from 3rd to 2nd... If you're going from 4th to 2nd, you're either lugging the car in 4th, or really going to hit the revs in 2nd.

In any case, it's a big jump. The TR syncros need time to change the speed of the input shaft. It's a feel thing. You have to pull (push) the lever against the syncro, sort of gently, hold it there a "moment," and then follow through.

I double clutch, up and down, almost all the time -- so I don't often have that problem.

.010" end float on the slave push rod is kinda tight, to my way of thinking. There's no harm in having it even as much as .100". You don't want to pinch the slave cylinder...

 

[Twosheds]

Heel-and-toe.

And double clutch.

 

[bigjones]

Moseso and Twosheds,

Fair enough. I'll make it 0.100".

I found an explanation of heel and toe and declutching here:

https://en.wikipedia.org/wiki/Double_clutch

I'll give it a go but it sounds like it needs serious practice to master.

Cheers!

PS. That link provides another link that references Click and Clack discussing double declutching. They said it was unnecessary and wore out the clutch prematurely. I remember listening to that episode. This link says the opposite! It actually minimzes wear.

 

[TR3driver]

Personally, I like having the slave adjusted kind of tight. The only downside, IMO, is having to adjust the clutch more often. The clearance goes down as the friction plate wears away, and as Moses said, you don't want to let it go to zero. But it's easy to check while doing a chassis lube (just grab the pushrod and see if you can shake it) and easy to adjust if it needs it.

Sounds to me like your 2nd gear synchro is a bit tired, or perhaps the springs in the shift hub need to be shimmed up a bit. Not worth tearing down the box for that, so just do a quick double clutch in cases where you know the synchro isn't going to cut it. Fortunately, since the synchro is still working to some extent (otherwise you'd also get clashing when upshifting), all you have to do is spin it up to roughly the right rpm, then be sure to press the clutch again before putting it in gear (so the synchro can deal with any small mismatch).

You could also try giving the synchro a bit more time to "catch up". Start the shift into 2nd with the clutch depressed, and when you feel that resistance about halfway into gear, let up a bit so it stays there for a second. Or just don't pull so hard on the lever for the whole shift

Something else worth trying, IMO, is switching to Redline MT-90 lubricant. It is designed to optimize synchro operation (according to Redline), and several people (including myself) have reported a definite improvement.

Double-clutching might increase clutch wear slightly but not enough to be significant, IMO. And certainly it will reduce wear considerably if it prevents gear clash.

PS, yet another way, if it only happens when skipping a gear, is to go ahead and shift into the intermediate gear. You don't have to go all the way, or let the clutch out, just shift towards 3rd enough to engage it's synchros and spin the input shaft up a bit.

 

[bigjones]

Good info Randall!

I'll try the various suggestions.

Yeah, I'm using the RedLine MT 90 - everytime I order from Moss Motors I include a bottle of the stuff, for top up purposes.

Cheers!