gearbox help

[datzenmike]

haha i hope not too.. ive already had this engine/transmission in and out 2 or 3 times in the past week haha

 

 

 

the diesel box didnt come with a clutch fork or throwout bearing collar

 

 

 

correct wayno

 

ill give you the story from the start

 

bought the 1985 nissan datsun 720 with z22 motor, 220mm clutch flywheel assembly and 5 speed gearbox to suit.

 

water pump shit itself and blew the head gasket between the cylinders, which in turn cracked the block

 

bought a z24 engine from a nissan pathfinder and swapped everything from the original z22 over onto it (sump, 220mm flywheel/clutch assembly, 5 speed box etc).

 

ran flawlessly for a few months and then the gearbox gave way.

 

swapped the flywheel out with a 240mm one and new clutch disc/pressure plate assembly to suit the 240mm flywheel.

 

bought a gearbox from a 1985 nissan datsun 720 diesel. swapped the front casing and counter bearing over from the original gearbox. also used the clutch fork, throw out bearing collar from the original gearbox, replaced the throw out bearing with an identical new one. used the original clutch slave cylinder and rod from the original gearbox.

 

See here you say you changed from a 225mm clutch to a 240mm one but no mention of changing the release collar. Release collars are matched to the clutch size. If changing to a 240mm clutch you need a collar for one too.

[Bambam91]

 

 

See here you say you changed from a 225mm clutch to a 240mm one but no mention of changing the release collar. Release collars are matched to the clutch size. If changing to a 240mm clutch you need a collar for one too.

 

That must be where I've gone wrong.. Is there any way to fix this without changing the collar?

[wayno]

That must be where I've gone wrong.. Is there any way to fix this without changing the collar?

 

 

I would try a longer rod myself, not saying it's going to work, but I would make one out of a long bolt with about the same size shaft that had about 1mm(1/16") play when the clutch slave was bottomed out before I pulled the transmission, keep in mind you have to force the clutch arm backwards to get the rod into position, I use a crescent wrench.

This is all a little strange, it seems to me that the smaller clutch cover(225mm) would be shorter(not stick out as far from the flywheel surface), so the collar would need to be longer, therefore if you used that collar on a 240mm cover, you would actually have the problem of the stock rod being to long, not to short, but maybe it works the opposite of the way I am thinking.

[datzenmike]

The clutch arm geometry works properly through a specific range of motion. The arm is swinging through an arc or curve which is small when the arm is at right angles to the transmission input shaft. But if you increase the slave push rod length the collar end swings forward but also curves to the right as viewed from above. Far enough and it will un-clip from the release collar.

 

To keep the clutch arm at close to right angles to the input shaft the collar is shortened with a taller pressure plate (240mm) and lengthened with a shorter one. (200mm)

 

If you use a longer (200/225mm) collar on a 240mm PP the arm will be pushing the release bearing too far forward and the clutch may not engage fully and slip.

 

If you use a shorter 240mm collar on a 200/225mm PP the opposite is true and the clutch may not disengage properly and drag.

 

Not saying a rod length change won't work, it might, just that Nissan didn't do this.

 

 

 

From your description you are not disengaging fully so I would try to bleed it more or measure the stroke length on the slave again.... should be about 1.18"

[Bambam91]

The clutch arm geometry works properly through a specific range of motion. The arm is swinging through an arc or curve which is small when the arm is at right angles to the transmission input shaft. But if you increase the slave push rod length the collar end swings forward but also curves to the right as viewed from above. Far enough and it will un-clip from the release collar.

 

To keep the clutch arm at close to right angles to the input shaft the collar is shortened with a taller pressure plate (240mm) and lengthened with a shorter one. (200mm)

 

If you use a longer (200/225mm) collar on a 240mm PP the arm will be pushing the release bearing too far forward and the clutch may not engage fully and slip.

 

If you use a shorter 240mm collar on a 200/225mm PP the opposite is true and the clutch may not disengage properly and drag.

 

Not saying a rod length change won't work, it might, just that Nissan didn't do this.

 

 

 

From your description you are not disengaging fully so I would try to bleed it more or measure the stroke length on the slave again.... should be about 1.18"

 

i tried making the rod length longer, now the clutch slave cylinder is bottomed out in normal state.

 

without the clutch pedal being pushed in, i measured 30mm between the edge of the slave cylinder casing and the clutch fork. while have the clutch pedal pushed, i measured 48mm between the edge of the slave cylinder casing and the clutch fork.

 

still no joy. ive tried bleeding the line multiple times. im at a loss here.

i wouldve thought having the longer 225mm collar on the 240mm pressure plate, like you said, the clutch may not engage fully and slip. but this seems the opposite. i cant get the clutch to disengage.

[datzenmike]

i wouldve thought having the longer 225mm collar on the 240mm pressure plate, like you said, the clutch may not engage fully and slip. but this seems the opposite. i cant get the clutch to disengage.

 

That's right. Well somethings odd here...

[Bambam91]

 

 

That's right. Well somethings odd here...

 

Is that enough travel to disengage the clutch? It feels as though the throw out bearing is hard up against the pressure plate diaphragm springs

[wayno]

I am sorry to say this, but I beleave you are going to have to tear the transmission out again, something is wrong, all the symtoms appear to point to the clutch disc being put in backwards, no matter how far one pushes the clutch cover arms in, it will never fully disengage.

But it is difficult to put in backwards, as the section that sticks out hits the flywheel/flywheel bolts holding the clutch cover out farther than normal, and when the bolts are tightened on the clutch cover, the fingers of the clutch cover drop in towards the flywheel dramaticly.

This would cause the need of a much longer rod, and even if you could get the clutch disc to disengage, it would make a lot of noise while the flywheel bolt heads were grinding away at the disc center if the engine was running but the truck was in gear but not moving.

You need a Z24 collar anyway, so unless you can figure out it is something else like a bad slave or master, there are not many other avenues to take. :crying:

[Bambam91]

I am sorry to say this, but I beleave you are going to have to tear the transmission out again, something is wrong, all the symtoms appear to point to the clutch disc being put in backwards, no matter how far one pushes the clutch cover arms in, it will never fully disengage.

But it is difficult to put in backwards, as the section that sticks out hits the flywheel/flywheel bolts holding the clutch cover out farther than normal, and when the bolts are tightened on the clutch cover, the fingers of the clutch cover drop in towards the flywheel dramaticly.

This would cause the need of a much longer rod, and even if you could get the clutch disc to disengage, it would make a lot of noise while the flywheel bolt heads were grinding away at the disc center if the engine was running but the truck was in gear but not moving.

You need a Z24 collar anyway, so unless you can figure out it is something else like a bad slave or master, there are not many other avenues to take. :crying:

 

I'm 100% sure the clutch disc isn't around the wrong way. There's no noise while the truck is running.. And I remember looking at the disc when I bolted it all together and thinking that there's only one way this is going to fit properly so it must go this way.

 

I might just pull it apart on my next days off and double check everything.

[datzenmike]

I've looked at this before with spare clutches I have. I don't think you can get the pressure plate bolts to start into the flywheel if the disc is on backwards.

[Bambam91]

I've looked at this before with spare clutches I have. I don't think you can get the pressure plate bolts to start into the flywheel if the disc is on backwards.

 

you're right, its just not possible

 

i may try adjusting the pivot ball out and see if that makes a difference?

[datzenmike]

without the clutch pedal being pushed in, i measured 30mm between the edge of the slave cylinder casing and the clutch fork. while have the clutch pedal pushed, i measured 48mm between the edge of the slave cylinder casing and the clutch fork.

 

Well that 18mm of travel. Manuals all say 1.18" or 29.9mm. So you really only have just under 2/3 of normal travel. Before removing the trans I would try to get at least an inch of travel.

[Bambam91]

Well that 18mm of travel. Manuals all say 1.18" or 29.9mm. So you really only have just under 2/3 of normal travel. Before removing the trans I would try to get at least an inch of travel.

 

so what are my options to try and get that? adjusting the pivot point out would give a larger range of motion for the clutch fork. maybe check the seals on the cylinders?

 

my other option i had in mind was to slightly loosen the pressure plate bolts, these were torqued up to spec but that's the only other thing i could think of.

[wayno]

How exactly are you bleeding the slave?

When you push in the clutch, are you using a stick to hold it down?

When you open the bleed screw on the clutch slave, the arm moves towards the slave, correct?

Can you post a photo of the clutch fork arm in the rest position, and with the clutch pedal pressed to the floor, as what I want to see is the angle of the arm coming out of the bellhousing.

[datzenmike]

The ratio of input movement to actual release collar movement will remain the same because the pivot point doesn't move side to side.

 

 

 

Loosening the bolts isn't the way to go they hold 10 pounds of metal spinning up to 6K.... you don't want that coming loose..

[Bambam91]

How exactly are you bleeding the slave?

When you push in the clutch, are you using a stick to hold it down?

When you open the bleed screw on the clutch slave, the arm moves towards the slave, correct?

Can you post a photo of the clutch fork arm in the rest position, and with the clutch pedal pressed to the floor, as what I want to see is the angle of the arm coming out of the bellhousing.

 

With someone else in the car, and myself under the car, i get the "driver" to press the clutch. then i (the bleeder) crack the bleed screw releasing some fluid. i then tighten the bleed screw and the "driver" then releases the clutch pedal.

when i open the bleed screw, the slave cylinder recedes into the casing and the arm moves towards the cylinder.

 

when i get the chance, i will take a video of the clutch fork in the rest position, then moving whilst the pedal is being pressed, and then back to rest position. i will also bleed the slave to show you what happens and how i am bleeding it.

The ratio of input movement to actual release collar movement will remain the same because the pivot point doesn't move side to side.

 

Loosening the bolts isn't the way to go they hold 10 pounds of metal spinning up to 6K.... you don't want that coming loose..

 

i would've thought turning the pivot point out would bring the fork closer to the pressure plate giving it that extra movement whilst the clutch is pushed?

 

does the torque on the clutch cover bolts affect the operation of the pressure plate?

[wayno]

I could only imagine the damage that could be caused by the clutch cover coming loose, but it would likely slip so bad before it let loose, that you would have already quit driving it before it flew apart.

Don't loosen clutch cover bolts, EVER!

Flywheel and clutch cover bolts are some of the few bolts I double and triple check before putting together, like the lugnuts, it's something you don't want coming loose.

[Bambam91]

I could only imagine the damage that could be caused by the clutch cover coming loose, but it would likely slip so bad before it let loose, that you would have already quit driving it before it flew apart.

Don't loosen clutch cover bolts, EVER!

Flywheel and clutch cover bolts are some of the few bolts I double and triple check before putting together, like the lugnuts, it's something you don't want coming loose.

 

yes i double check mine too. i actually put threadlocker on them just to be sure. i didn't mean loosen them to the point of being finger tight. just back them off slightly, maybe ive done them too tight. i dont think you can really go wrong with a torque wrench

[wayno]

yes i double check mine too. i actually put threadlocker on them just to be sure. i didn't mean loosen them to the point of being finger tight. just back them off slightly, maybe ive done them too tight. i dont think you can really go wrong with a torque wrench

 

 

The only way they would be to tight is if you broke them, that would be to tight. :lol:

I hope you figure this out soon without having to pull it apart, it's a bad sign when one starts telling everyone how fast you can remove and replace your transmission. :lol:

[Bambam91]

 

 

 

The only way they would be to tight is if you broke them, that would be to tight. :lol:

I hope you figure this out soon without having to pull it apart, it's a bad sign when one starts telling everyone how fast you can remove and replace your transmission. :lol:

 

Lol so the tightness on the clutch cover bolts don't affect the pressure plate at all?

 

Haha yeah I'm getting pretty quick at it :p

[Bambam91]

right, well i finally got around to having another go at the ute.

 

i removed the motor again and changed the flywheel, clutch, pressure plate etc. back to the original 220mm. new gearbox with the old petrol bellhousing stayed in.

 

dropped the motor back in, bolted everything up, started her up, everything works a treat. clutch works fine, gear shifts are fine, drives fine.

 

so the problem had to be something to do with the pressure plate or the slave cylinder not being strong enough maybe? im not really sure.

 

heres a link to the clutch kit i used:

 

http://www.ebay.com.au/itm/160591117048?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

maybe thats the wrong one?

 

i have the z24 engine/flywheel with the 240mm friction surface, so i figured thatd be the one to use

[Bambam91]

Good luck to you, I hope it is not a collar/sleeve issue, as that will require removing the transmission.

You need to use the collar that was on the motor you have. It's matched to what ever clutch you have and has to stay with it.

 

If one came with the diesel 5 speed do not use it.

 

any ideas why that clutch wouldnt work?

[wayno]

Did you use the same throw out bearing collar that you used with the 240mm flywheel/disc/cover on the recently installed 225mm flywheel?

If you did use the same collar, then that is likely the issue, you were using the wrong collar on the 240mm hardware.

[Bambam91]

Did you use the same throw out bearing collar that you used with the 240mm flywheel/disc/cover on the recently installed 225mm flywheel?

If you did use the same collar, then that is likely the issue, you were using the wrong collar on the 240mm hardware.

 

the T/O bearing collar i have is from the 225mm flywheel. i used that with the 240mm flywheel and i could not get the clutch to disengage. the 240mm T/O bearing collar is shorter than the 225mm one. so if anything, my problem should be that i could not get the clutch to engage. but if fact it is the opposite.

[Bambam91]

just an update for anyone whos interested.

 

ive used the 240mm flywheel with new clutch kit. the new gearbox and ive used the original t/o bearing collar from the 225mm flywheel combo.

 

what i did to remedy the problem was i packed 3 washers on the pivot point. problem solved. thanks for all your help guys.