Need to double clutch = Slave Cylinder or ?? (1 Viewer)

[78crzr]

My new 40 was delivered today, and a couple of undisclosed tech. issues are readily apparent, one of which is the need to double clutch to avoid a very rough shift to 2nd gear. Is this a symptom of a tired slave cylinder or something else? It shifts fine into every other gear. The transmission was rebuilt by TLC just a few thousand miles ago according to the doscuments/receipt that came with the 40. Thoughts?

 

[Roboosfj40s]

78? with a 4 speed I would think a bad slave but I would guess it would be leaking. Check the boot on the slave cyl. and see if it is full of fluid. Other wise it sounds like the 2nd gear sync has a problem if all other gears are smooth. Just a thought.

 

[bikersmurf]

Should be smooth as silk. Are you loosing fluid?

I'd bring it back to TLC and ask them what's wrong.

Or, just shift 1,3,4...

 

[Fast Eddy]

If you can hold down the clutch with the engine running, stopped and shift in and out of 1st repeatedly, it's not the clutch.

A rebuild would not necessarily include the syncros. They're expensive.

Both of my h41s and a previous h42 were just a bit finicky about 2nd gear. If I don't do it just right I get a bit of grind. Your's sounds much worse though.

 

[1973barnfind]

Or, just shift 1,3,4...

Lucky... i only have 1,2,3.
mine does the same thing only, it grinds from 2 down to 1.
double clutch doesn't help. I just have to stop completely

 

[78crzr]

78? with a 4 speed I would think a bad slave but I would guess it would be leaking. Check the boot on the slave cyl. and see if it is full of fluid. Other wise it sounds like the 2nd gear sync has a problem if all other gears are smooth. Just a thought.

The "new" one is actually a '76. I had a '78 when I joined Mud, which I sold. Just getting back into 40's.

Thanks for the replies above. I will get under it tomorrow and take a look at the slave. It shifts in and out of every other gear nicely, and is perfectly smooth after the double clutch. I was hoping it wasnt the synchros but it sounds like it could be. I need to dig out the receipts for the transmission rebuild and see if it details what was done or just a general description. I've got a couple of other minor issues (undisclosed by the PO) to address, but on the bright side, it is bonding time with the 40.

 

[1973barnfind]

Hmm....
now that I think about it, I leave mine in Neutral when stopped because my slave cylinder does what has been described in the above posts.

If i keep the clutch held in too long, the engine boggs slightly, and the clutch starts burning. I guess thats what 37 years does to moving parts

 

[78crzr]

I should have noted that it has the issue on upshift, as I havent noticed it on downshift yet.

 

[1973barnfind]

Huh. my 3 speed is like butter in upshift, if I smash the clutch. downshift, 2-1 grinds.
Oh, and I have a strange habit of when i'm stopped in N, I slam it into 2nd, then 1st.
because if I go from N to 1, it grinds... Quarky old thing

 

[Fast Eddy]

Lucky... i only have 1,2,3.
mine does the same thing only, it grinds from 2 down to 1.
double clutch doesn't help. I just have to stop completely

No 1st gear syncro in a 3 speed. When shifting from neutral to first, hit 2nd briefly to line it all up. This trick also works going from neutral to reverse in a 4 speed.

 

[Pin_Head]

If it doesn't grind going into R when stopped with the clutch pedal down, then the slave and clutch adjustment is OK and the grinding on down shifting is because the synchro brake rings are weak. Double clutching or slowing down before down shifting should help. The idea with double clutching is to match the input gear speed with the output gear speed.

 

[1973barnfind]

No 1st gear syncro in a 3 speed. When shifting from neutral to first, hit 2nd briefly to line it all up. This trick also works going from neutral to reverse in a 4 speed.

IT all makes sense now!!!
I always thought my 3spd hated me until I figured out that trick.
I guess 1973 was a different world from 2011. I just "expect" 2nd will shift into 1st. lol aint America's new generation great?

 

[bikersmurf]

Huh. my 3 speed is like butter in upshift, if I smash the clutch. downshift, 2-1 grinds.
Oh, and I have a strange habit of when i'm stopped in N, I slam it into 2nd, then 1st.
because if I go from N to 1, it grinds... Quarky old thing

Don't mean to step on anyone's toes...

Do you know any truckers who could teach you how to double clutch with a non syncronized transmission? I learned to double clutch and smoothly shift a fifteen speed rig...

The trick when down shifting is (when traveling a constant speed):
Push in the clutch and shift from second to neutral
Let the clutch out, and bring up the engine revs aproximately 650 rpm
Push in the clutch and it should slip right in if you've got the revs right

It'll take a little practice, but I've even shifted from low to high range while moving without grinding (I don't recomend it though). Once you get the hang of it, it'll become second nature and you'll be able to do it by feel.

If you've got a tach, you can learn to relate the speed it rpm for each gear... If things are turning at the right speed, the clutch almost becomes unnesecary... (use it anyway though).

 

[bikersmurf]

Huh. my 3 speed is like butter in upshift, if I smash the clutch. downshift, 2-1 grinds.
Oh, and I have a strange habit of when i'm stopped in N, I slam it into 2nd, then 1st.
because if I go from N to 1, it grinds... Quarky old thing

Rigs often have a clutch brake to help you get it into 1st from neutral for just this reason. It is engaged if the clutch is pressed all the way down.

 

[bikersmurf]

My new 40 was delivered today, and a couple of undisclosed tech. issues are readily apparent, one of which is the need to double clutch to avoid a very rough shift to 2nd gear. Is this a symptom of a tired slave cylinder or something else? It shifts fine into every other gear. The transmission was rebuilt by TLC just a few thousand miles ago according to the doscuments/receipt that came with the 40. Thoughts?

It sounds like the syncros are going for first to second shift. If you let your RPMs drop the right amount, I believe it's around 650 rpm, the syncros won't need to match the speed. It should help.

 

[Roboosfj40s]

Mine is a 3 speed and I do as you are saying Smurf no problems down shifting at least with this new rebuilt tranny and t case. I have driven a few over the road rigs long time ago and an old trucker told me the same thing you suggested.

 

[1973barnfind]

Don't mean to step on anyone's toes...

Step on my toes, I'm still learning about these old machines

 

[Roboosfj40s]

Step on my toes, I'm still learning about these old machines

Dude I don't care how much of an expert some think they are. WE all learn something new everyday working and driving these puppies! And if they say they know it all.....They are not being honest lol! I am 58 years old been in 2 wars and lived in 6 countries and I learn something every day of my life even if it is as simple as not trusting a fart after 50 haa haa!

 

[bikersmurf]

If you think grinding it into first is bad, you should try trying to get it into fith while in down town traffic during rush hour... On the second lesson. Meanwhile, the instructor is breaking off, "quit F...ING around and get it into gear..." ...he got to take a break for a while after that.


X2 we never stop learning.

 

[78crzr]

It sounds like the syncros are going for first to second shift. If you let your RPMs drop the right amount, I believe it's around 650 rpm, the syncros won't need to match the speed. It should help.

Anyone have an idea of what it should run to have a shop install new synchros? I've experienced the issues with other non-synchro transmissions (like my TR3) but never had the issue while unshifting. I appreciate the responses as now that we've likely narrowed it down I can work on the fix. Don't want to do a lot if driving in Houston traffic having to wait for RPM's to drop. The tractor us slow enough already! Wish everyone else would just slow down. Lol!