Transmission questions

[zmanoside]

Hey guys. So, I have the stock 4 speed in my '70z and it needs to go. I want to go the cheapest route possible for a 5 speed because I plan to to a RB25 engine and trans swap next year. I just found a 1980 maxima 5 speed on Craigslist for 350 OBO. And he keeps reposting. I could probably pick it up for 200 bucks. From what I read these are a direct bolt on? The only thing I need to do is cut out some metal to make room for the 5th gear throw is what I gather? Also, excuse my ignorance here, but can my clutch from and flywheel from the 4 speed be used with this 5speed or is that completely different? Thanks in advance.--Z

[Patcon]

Why would you put money into a tranny swap if your gonna pull it all in a year? Just asking...these engines aren't afraid of RPM's for extended periods...

[Zed Head]

Should bolt right in.  Several threads on this forum about bending or cutting/welding shift levers so you don't have to modify your console or car body.  The clutch is an assembly of parts that is separate from the transmission.  There is nothing to "match".  Keep all of the parts you have or make sure any new parts you get are meant to work together.  But don't worry about the transmission, it has nothing to do with them, as long as the tip of the pivot ball is where it's supposed to be.

[zmanoside]

Yes sir I understand that. The clutch assembly fits inside the transmission bell housing correct? I didn't know if the clutch, flywheel is different sized for either trans, i.e. Didn't know if it would fit in the bell housing the same...I have searched a lot and can't seem to find compatible years that the maxima 5 speed will work for the Z car...to answer the other question. The 4 speed trans is pretty...terrible..If I can pick up a 5 speed trans for dirt cheap that will soothe my irritability with this sloppy 4 speed I think it's worth it

[Patcon]

A lot of times the slop in the handle is the little small bushings in the shifter. They disintegrate, they can be replaced with brass ones and that takes out a lot of the slop...and they're cheap

[Zed Head]

I was just trying to give another description of how the throwout bearing collar needs to match the pressure plate.  Since it's hanging on the nose of the transmission when it's pulled people, myself included in the past, tend to think it's matched to the transmission.

The 1980 Maxima transmission is the same one used on the 280ZX.  The Maxima manual is just not as commonly described.  The 1980 Maxima used a 2.4 liter L6 engine.  I think it has the same ratios, but not positive.  Hard to find Maxima information.

Edit - actually they have still been using the 1979 ZX ratios,which are the same as 77-78 280Z.  3.321, 2.077, 1.308, 1, and .864.  Don't forget to consider your diff ratio.

Here's a table from the interweb, but it's not quite completely right.  Shows 280Z in one entry with 3.592 first, which is not correct.  The rest seems on though.

http://newprotest.org/projects/510/gearRatios.pl

Edited April 30, 2016 by Zed Head

[siteunseen]

I'm going to "throw out"  something here.

My 280's bearing makes a slight whining noise when I'm in neutral and foot off the pedal so I'm guessing the bearing is slightly touching the fingers of the pressure plate?  If I shorten the adjustable rod under the dash wouldn't that take the bearing off the fingers and stop the whining? 

[Zed Head]

Are you sure it's the throwout bearing?  It's common, apparently, for the transmission countershaft bearing to do that.  Everybody has it.

[Captain Obvious]

To back up a little and add to Zed Head's info above...

It's likely that it's got nothing at all to do with the throw out bearing. Any time the engine is running and your foot does NOT have the clutch pedal pressed in, the input shaft as well as the countershaft of the transmission are spinning. Point is... When your not  pushing the clutch in, those two shafts are spinning and it's likely that the whining you're hearing is from the input shaft bearing, or the countershaft bearing, not the throw out bearing.

[siteunseen]

So that's something I'll just have to live with I guess, turn the radio up some more.  Now that I think about it I couldn't hear it until I had that resonator installed! 

[Mark Maras]

 Pull the return spring from the clutch slave cylinder and push and pull fork fore and aft. There should be a bit of free play between the top of the stroke and in to the point where resistance is felt. That free play is the distance between the throwout bearing and the pressure plate. If you have clearance the throwout bearing isn't turning.

[Chickenman]

7 hours ago, siteunseen said:

I'm going to "throw out"  something here.

My 280's bearing makes a slight whining noise when I'm in neutral and foot off the pedal so I'm guessing the bearing is slightly touching the fingers of the pressure plate?  If I shorten the adjustable rod under the dash wouldn't that take the bearing off the fingers and stop the whining? 

A stock 280Z uses a clutch slave cylinder that automatically takes up any slack With this type of hydraulic clutch adjustment the bearing is always in slight contact with the diaphragm springs There is never any : Free play " between the clutch rod and the clutch fork.

That is how they are designed and there is no way around that, ( without swapping out parts ). Trying to add clearance at the clevis to pedal side will not over ride the factory self adjusting function. And yes a failing TO brg with a self adjusting slave cylinder will start to whine in Neutral as they fail.

Note: Automatic slack adjustment slave cylinders should NOT have an external return spring attached. The slave cylinder has a weak compression spring inside that always apples slight  pressure to the non-threaded extension rod. This is how they self adjust.

Earlier styles ( up to 06/72 ) with the manual adjusting slave cylinder, use a different slave cylinder ( with no internal spring ), clutch fork and external return spring. With this style of clutch system, the TO bearing will not be in constant contact with the diaphragm fingers when the clutch pedal is fully released. The external spring pulls the clutch fork back and pushes the slave cylinder all the way to the bottom of it's travel. Then you adjust your free play with the ball and lock nut on the threaded rod.

Edited May 1, 2016 by Chickenman
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