cooprasupra Posted December 17, 2016 Report Share Posted December 17, 2016 Noob question. Got a 70 521 here with an L16 and stock transmission. Have a rebuilt motor that has no clicking sounds from the transmission. After doing quite a bit of searching on the subject here I am a bit at of a stopping point after trying all that was suggested. When motor is running I am getting grinding in all gears when clutch pedal is depressed. It does shift freely when motor is off. I went ahead and replaced the clutch master and slave cylinders to no avail. I have bled the system dozens of times to ensure that all air is out. The issue still persists. The slave cylinder is only moving the clutch fork about 3/4 of an inch and from what I have read an inch and an 8th seem to be normal. With the slave cylinder removed the clutch fork does have some play, is this normal? Still keep bleeding it with no luck. At this point I am thinking my only option is dropping the transmission and replacing the clutch, pressure plate, and throw out bearing. Sadly I have no information from the previous owner whether the transmission was working prior to purchasing. Do y'all think this is a transmission or hydraulic issue? Any help would be greatly appreciated. Quote Link to comment
wayno Posted December 17, 2016 Report Share Posted December 17, 2016 How much play dies the clutch pedal have, do you feel resistance in the first half inch or do you have to press it farther before feeling pressure? Quote Link to comment
datzenmike Posted December 17, 2016 Report Share Posted December 17, 2016 Doubt it's the transmission. Grinding is the inability of the synchronizers to match 'gears' moving at different speeds and allowing them to mesh quietly. Normally just the weight of the input shaft and clutch disc is spinning and the synchros can easily speed up or slow down this mass. But if the clutch is not being fully disengaged the entire drive force of the flywheel and engine internals makes this impossible, and this over powers them. Clutch not fully disengaged can be the clutch, the wrong release bearing collar, the slave, the master or an adjustment. So has this ever worked properly????? Yes.... we can eliminate the release collar as the problem No..... we cannot eliminate it as the cause yet. Quote Link to comment
cooprasupra Posted December 17, 2016 Author Report Share Posted December 17, 2016 How much play dies the clutch pedal have, do you feel resistance in the first half inch or do you have to press it farther before feeling pressure? I would say about an inch, there is definitely resistance and I can push it no further in the direction that is supposed to go. Quote Link to comment
datzenmike Posted December 17, 2016 Report Share Posted December 17, 2016 Play should be only a couple of mm about 1/16" when pushed down with your thumb before there is firm resistance. The push rod on the clutch pedal must be removed and adjusted. Pull the clevis pin out, remove rod, loosen the lock nut, turn the rod to lengthen it, tighten the lock nut, DO NOT FORGET THE COTTER PIN TO HOLD IT IN PLACE. Check adjustment. If you have carpet make sure the clutch pedal is not stopped by it. Did this ever work properly? Quote Link to comment
cooprasupra Posted December 17, 2016 Author Report Share Posted December 17, 2016 Doubt it's the transmission. So has this ever worked properly????? Yes.... we can eliminate the release collar as the problem No..... we cannot eliminate it as the cause yet. As far as I know it has not, just hoping for other suggestions before I rip out the transmission which I would rather not do. We have messed with the slave and master quite a bit, only thing we have not adjusted is the travel in the pedal travel. Quote Link to comment
cooprasupra Posted December 17, 2016 Author Report Share Posted December 17, 2016 Play should be only a couple of mm about 1/16" when pushed down with your thumb before there is firm resistance. The push rod on the clutch pedal must be removed and adjusted. Pull the clevis pin out, remove rod, loosen the lock nut, turn the rod to lengthen it. You are right, I over guessed the travel it is a 16th of an inch. I did trim down the rod from the master cylinder to the pedal because it would not fit initially. I did not want to cut it too much as I did not want to put pressure on the master cylinder when the pedal is not being pressed. Should I shorten it further? Quote Link to comment
datzenmike Posted December 17, 2016 Report Share Posted December 17, 2016 Shouldn't need to cut, it's threaded and adjustable. Maybe the slave travel is also different. Measure it. If 1 inch I would say it's all good. Quote Link to comment
DanielC Posted December 17, 2016 Report Share Posted December 17, 2016 Do you have the slave cylinder with the external spring on it? Does the slave cylinder have a push rod that goes through the throw out lever on the transmission? Go to this page, http://www.davidcmurphy.com/olddat/620tech.htm go about 2/3 down the page. click on the link for Datsun 521 body and chassis manual, to down load the PDF manual. Everything you need to know about the clutch service, and adjustment is in the chapter titled "Clutch", in the 521 manual. Quote Link to comment
cooprasupra Posted December 18, 2016 Author Report Share Posted December 18, 2016 Shouldn't need to cut, it's threaded and adjustable. Maybe the slave travel is also different. Measure it. If 1 inch I would say it's all good. Would adjusting it further negatively effect the master cylinder? Slave travel is less than an inch at the moment. Quote Link to comment
cooprasupra Posted December 18, 2016 Author Report Share Posted December 18, 2016 Do you have the slave cylinder with the external spring on it? Does the slave cylinder have a push rod that goes through the throw out lever on the transmission? Go to this page, http://www.davidcmurphy.com/olddat/620tech.htm go about 2/3 down the page. click on the link for Datsun 521 body and chassis manual, to down load the PDF manual. Everything you need to know about the clutch service, and adjustment is in the chapter titled "Clutch", in the 521 manual. There is an external spring and it does have a rod that goes through the throw out lever. I will also be consulting my shop manual. Quote Link to comment
Crashtd420 Posted December 18, 2016 Report Share Posted December 18, 2016 I could be completely off here but He never really said the clutch wasnt disengaging?? so does it shift freely while driving or do you feel it drag? Here's a question? If the grinding only happen when the clutch pedal is depressed maybe just the throw out bearing itself is worn. Couldnt you put the truck in gear and push in the clutch and see if will it roll? Wouldn't you feel the clutch drag if it wasn't fully disengaging? Just a thought. I've had my clutch completly slipping and it still sounded good but my clutch release bearing would make a nasty grinding sound.. Quote Link to comment
cooprasupra Posted December 18, 2016 Author Report Share Posted December 18, 2016 I could be completely off here but He never really said the clutch wasnt disengaging?? so does it shift freely while driving or do you feel it drag? Here's a question? If the grinding only happen when the clutch pedal is depressed maybe just the throw out bearing itself is worn. Couldnt you put the truck in gear and push in the clutch and see if will it roll? Wouldn't you feel the clutch drag if it wasn't fully disengaging? Just a thought. I've had my clutch completly slipping and it still sounded good but my clutch release bearing would make a nasty grinding sound.. The vehicle is not driving, it shifts freely when the motor is off however if the engine on it grinds when shifting into gear. Quote Link to comment
wayno Posted December 18, 2016 Report Share Posted December 18, 2016 I would say about an inch, there is definitely resistance and I can push it no further in the direction that is supposed to go. You can push the pedal to the floor, correct? Can you get a photo and post it of the slave/pushrod/clutch arm in the clutch pedal pushed in position, and the not pushed in position? I am trying to figure out if the rod is adjusted correctly. The pedal adjustment is also important, if it has too much play before it has resistance then one will run out of travel(pedal hits floor) before the clutch is released. Can you pump the clutch pedal fast a few times and then shift without issues? Quote Link to comment
cooprasupra Posted December 18, 2016 Author Report Share Posted December 18, 2016 You can push the pedal to the floor, correct? Can you get a photo and post it of the slave/pushrod/clutch arm in the clutch pedal pushed in position, and the not pushed in position? I am trying to figure out if the rod is adjusted correctly. The pedal adjustment is also important, if it has too much play before it has resistance then one will run out of travel(pedal hits floor) before the clutch is released. Can you pump the clutch pedal fast a few times and then shift without issues? I can press to the floor and it does have resistance. I can post pics of the adjustment in the morning. From what I can tell it does nothing if I pump the pedal as far as shifting. Quote Link to comment
cooprasupra Posted December 18, 2016 Author Report Share Posted December 18, 2016 What is normal play for the clutch fork? Quote Link to comment
datzenmike Posted December 18, 2016 Report Share Posted December 18, 2016 I could be completely off here but He never really said the clutch wasnt disengaging?? so does it shift freely while driving or do you feel it drag? Here's a question? If the grinding only happen when the clutch pedal is depressed maybe just the throw out bearing itself is worn. Couldnt you put the truck in gear and push in the clutch and see if will it roll? Wouldn't you feel the clutch drag if it wasn't fully disengaging? Just a thought. I've had my clutch completly slipping and it still sounded good but my clutch release bearing would make a nasty grinding sound.. He did say grinding while placing into gear with the engine running. If there is gear clashing when trying to put in gear with the engine running then the clutch must be dragging or rubbing or in some manner not releasing. There may be enough rub to grind but not enough to prevent the truck rolling. If I suspect the clutch were rubbing I try to shift into a non synchro gear like reverse. Only takes a second or so for the counter shaft to stop spinning (it's immersed in thick gear oil) when the clutch is depressed, then softly place or try to place in gear. It should never grind going into reverse if everything is working. Quote Link to comment
datzenmike Posted December 18, 2016 Report Share Posted December 18, 2016 Clutch fork play is again... a few mm, just enough to be sure that the arm is fully back and the slave retracted. Quote Link to comment
wayno Posted December 18, 2016 Report Share Posted December 18, 2016 What is normal play for the clutch fork? If you push on the rod till it is bottomed out in the slave, it should have a 1/16th inch play without the spring connected. 1 Quote Link to comment
glorydime Posted December 18, 2016 Report Share Posted December 18, 2016 Just curious with the slave cylinder off the transmission, how much play would the clutch fork have? Would an inch of play be a sign of something wrong in the bellhousing? Quote Link to comment
DanielC Posted December 18, 2016 Report Share Posted December 18, 2016 The clutch fork will have a lot of play, without the slave cylinder. Even more, if the clutch disk is new. Quote Link to comment
Roadster-ka Posted December 18, 2016 Report Share Posted December 18, 2016 Clutch disk in backwards? Quote Link to comment
Eagle_Adam Posted December 18, 2016 Report Share Posted December 18, 2016 Sounds like the wrong throw out bearing collar was used .... Quote Link to comment
datzenmike Posted December 18, 2016 Report Share Posted December 18, 2016 This is very possible. But as this means taking the transmission out all other causes must be eliminated first. Clutch disk in backwards? I've tried this and it's impossible to do. Quote Link to comment
Eagle_Adam Posted December 18, 2016 Report Share Posted December 18, 2016 I've tried this and it's impossible to do. Challenge accepted!!! 1 Quote Link to comment
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