Leon Posted January 11, 2013 Share Posted January 11, 2013 If the pressure plate drags in release, the synchros have to do more work getting the clutch slowed down. There is always some drag on the clutch during shifts becase it still slightly contacts the flywheel and pressure plate. Minimizing that as much as possible will extend synchro life and give more positive shifts. My thoughts exactly. A lightweight flywheel could maybe help somewhat, but I just don't see if completely alleviating a syncro grind. TJ, did you bleed and adjust the clutch to FSM specs? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 11, 2013 Share Posted January 11, 2013 A lightweight flywheel could maybe help somewhat, but I just don't see if completely alleviating a syncro grind. Ever tried one? Makes a big difference. Google "light flywheel faster shifting" and see how many hits you get and read through some of the threads from all different makes and models etc. Quote Link to comment Share on other sites More sharing options...
Leon Posted January 11, 2013 Share Posted January 11, 2013 Ever tried one? Makes a big difference. Google "light flywheel faster shifting" and see how many hits you get and read through some of the threads from all different makes and models etc. Nope, but the next engine I'm putting in is getting the 10lb Fidanza I have sitting around. I didn't say anything about faster shifting, I just have my doubts regarding solving a syncro grind problem by purchasing and installing a lighter flywheel. Quote Link to comment Share on other sites More sharing options...
duragg Posted January 11, 2013 Author Share Posted January 11, 2013 Ok, I'm done working for the day. Heading down to the shop to swap the sauce... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 12, 2013 Share Posted January 12, 2013 I didn't say anything about faster shifting, I just have my doubts regarding solving a syncro grind problem by purchasing and installing a lighter flywheel. Faster shifting and grinding at very high rpm are related. The quicker the engine slows down, the less work the synchro has to do. If the grind is happening because the synchro can't slow the input shaft down quickly enough, then having the engine decelerate faster is obviously helpful. I think you'll love the flywheel BTW, and once you get used to it you'll find that you shift a lot faster even when driving calmly, just because it's smoother. Quote Link to comment Share on other sites More sharing options...
duragg Posted January 12, 2013 Author Share Posted January 12, 2013 (edited) No bueno. Maybe a little worse. Its only a 1-2 problem. Tranny is injured. Not sure when the injury came, or if my rebuild skills. Will find another 83 model to rebuild and swap, try again. Or maybe the SX swap.(Scratch that, too short gearing). Thanks for the great discussion. No type of gravy will fix a tough steak! Worth a try. Edited January 12, 2013 by duragg Quote Link to comment Share on other sites More sharing options...
Leon Posted January 12, 2013 Share Posted January 12, 2013 No type of gravy will fix a tough steak! Worth a try. Good metaphor! Quote Link to comment Share on other sites More sharing options...
duragg Posted January 12, 2013 Author Share Posted January 12, 2013 Maybe for the interim I will go the other direction and try some really crappy dime-store heavyweight stuff. Bottle the GMSMFM back up for future reference... Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 12, 2013 Share Posted January 12, 2013 I guess shifting at less than 7300 rpm is out of the question? Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 12, 2013 Share Posted January 12, 2013 If you're going to try some other fluids, the Swepco/ATF blend is definitely worth a shot. Fluids have a big impact. I had an old 78 5 speed that ground the 2-3 shift with Valvoline 75/90. Redline MT90 fixed that problem. Then I tried the MT90 in an old 1980 5 speed but still had a problem, with 1-2 and 2-3, so tried the Swepco/ATF blend. It raised my RPM limit before gridning, by about 1200 RPM (memory, may not match previous posts) over the MT90. This is on old worn, or rusted synchros, so may not apply to new. I used the Swepco based on JMortensen's recommendation's in past threads. He has a lot of history with the blend at 50/50. 50/50 felt a little thin to me so I upped the Swepco to 75%. Not cheap though, about $15/quart. The newer "syncromesh" type fluids are thinner, about 30W, from what I've picked up on the web. You need some higher viscosity to get things spinning, and the materials and synchroniser pieces are designed aorund a certain type of fluid. Re johnc's comment about new fluids in old design transmission's. Quote Link to comment Share on other sites More sharing options...
duragg Posted January 12, 2013 Author Share Posted January 12, 2013 I will review all the posts again. Heck I now have more money in fluid than I do in the Tranny! I got it free with the F54 L28 just for pulling it out. $150 for rebuild kit and here we are. Might try $10 bucks for some mole-asses since that is the opposite correction and basically free. Shifting at less than 7300 is not an option. My almighty 192whp was at around 7000 peak with the big chokes. Its all I've got... If I pull the motor out to do the tranny It will be expensive as I won't be able to resist a stroker rebuild while I have the motor out. Tempted to just get another shell, do nice body work,... and start swapping parts. I need to start drinking now as I am digging myself deeper in to projects. Quote Link to comment Share on other sites More sharing options...
duragg Posted January 12, 2013 Author Share Posted January 12, 2013 Please let me add. I am open to suggestion. If somebody wants to make a case based on experience I will make a further investment and do some testing. There was nothing on the magnet, no chunks or nothing. Quote Link to comment Share on other sites More sharing options...
dislexicdime Posted January 12, 2013 Share Posted January 12, 2013 its a long shot but here go's. how is the clutch line? I have had the clutch line swell when you pump the clutch but i dought it would only do it from 1st to second. I had a 78 truck 5 speed on a l18 that reved to 8500 and you couldn't shift from 1st to second over 7000 . I swapped in a zx na trans and had the same problem . I always just figured that L series 5 speeds could not shift between 1st and 2nd over 8 grand . Quote Link to comment Share on other sites More sharing options...
duragg Posted January 12, 2013 Author Share Posted January 12, 2013 Clutch line is all good. In fact yesterday I was feeling where the clutch engaged at idle by pulling out of gear a little and releasing clutch until it just starts to grab and you can feel the gears begin to turn then. Otherwise it is fully free. I clearly screwed something up when I rebuilt it. This is the 2nd 5sp I rebuilt, but I sold the first and never drove it (poor btsarard that bought it). 3rd time... I will do better. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 12, 2013 Share Posted January 12, 2013 (edited) Maybe your problem is related to why Nissan went to a dual-cone synchronizer. Might be cheaper in the long run to take the bellhousing from your ZX trans and do the 71C conversion. It would be interesting to see what the friction surface looks like on the 2nd gear ring when you take it apart. Another thought regarding the blocking ring is that all "brass" may not be the same. In other words, the coefficient of friction may be different between Nissan rings and aftermarket rings. Maybe just replace the 2nd gear ring with a factory Nissan ring. They're about $50 at courtesyparts.com. Edit - one of these might buy you a few RPM also - http://www.courtesyparts.com/nissan-motorsports-roller-bearing-pilot-bushing-p-341365.html Edited January 13, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
duragg Posted January 16, 2013 Author Share Posted January 16, 2013 (edited) Trying the other end of the spectrum for scientific analysis purposes. Edited January 16, 2013 by duragg Quote Link to comment Share on other sites More sharing options...
duragg Posted January 16, 2013 Author Share Posted January 16, 2013 Improved with O'Reilly GL4-140 Still grinds some at 7000 shift into 2nd, but less and goes in quicker. Can live with it till it breaks. Quote Link to comment Share on other sites More sharing options...
duragg Posted January 16, 2013 Author Share Posted January 16, 2013 (edited) Disregard Edited January 16, 2013 by duragg Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 17, 2013 Share Posted January 17, 2013 Thinking about brass, steel and shifting, the other teeth that grind are the splines on the coupling sleeve and the dog teeth, if I understand things. Maybe yours are rounded or damaged. That's the thing about rebuilding transmssions, it seems like you'd have to rebuild them before they start grinding, if you want like-new performance after the rebuild. Once they start grinding the parts that don't come in the rebuild kit are getting damaged. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted January 24, 2013 Share Posted January 24, 2013 Makes you wonder how manufacturers get away with the mass of a super long torque tube adding mass to the disc/input shaft combo that determines the amount of energy the synchros have to deal with. Quote Link to comment Share on other sites More sharing options...
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