5sp Shifting Problems

[rossiz]

5sp from '81 zx non-turbo

came with an engine that i re-built, was said to be fine, so all i did was replace the front & rear seals before installing. noticed 2 things during install:

 

1 - the return spring plug was removed and in a bag of misc parts along with the shift lever pin & boot. the plunger was missing, so i poached the one from my '78 4sp along with the matching springs & plug. 

 

2 - when i checked shifting (before putting in boot cover) the striking rod pulled out exposing the o-ring seal. the stopper guide pin was out (i found it in the aforementioned bag of goodies). i rotated it back/forth a bit until i could jigger it back in, then installed the pin & e-ring.

 

car shifts horribly, 1st is fine (whines) very difficult to get it into 2nd (misses into false neutral) third is fine

 

i do need to bleed clutch, as i think i pulled in air when the slave cylinder expanded out when tranny was removed.

 

 

did i pull something out of engagement/alignment when the striking rod pulled out? am i dropping this tranny or do these symptoms sound fixable in situ?

[Zed Head]

Most people don't even know those plugs and springs, return or check, even exist, and only find out after they have problems and get on the forums.  The fact that yours was out is a bad sign.  Along with the stopper guide pin.  Nobody ever removes those  unless they're trying to fix something.  They are the first two steps of transmission disassembly.

 

How are the shifter bushings?

 

 

[EuroDat]

Hi Rozzi,

 

You mentioned exposing the o-ring and you also mentioned a shifter lever pin, but was the stopper guide pin in place? It stops the striking guide from coming out. The striking guide should rotate and return to centre by the return plunger on the left side. It shouldn't move back and forward. Sounds like your stopper pin is missing or damaged in some way.

 

I have posted a this in a couple of threads. I would start by replacing all the check balls and springs and return checker plunger and spring. You can't change the interlocks without dismantling, so don't worry about ordering them.

While you are at it. Buy all the shifter bushes (2x side bushes and the end cup). All this stuff will set you back $20 at your local Nissan dealer.

 

Its all "do"able without dropping the transmission. The top check ball and spring are a pita. I bent a ring spanner to get to it easier. You will need to remove the console to get to the shifter.

I know some people will say that there could be wear inside the transmission. True, but this is often enough to return the system within spec and eliviate the problem.

 

Parts list

2x Shift lever side bushes.

2x Shift lever lower (cup) bush

1x Shifter lever pin (Optional)

3x Check balls

3x Check springs

1x Set Return checker springs

1x Return checker plunger (Optional)

 

Don't bother ordering the o-ring or the little oil seal on the striking rod. You need to dismantle the shifter assemble/transmission to get to them and I don't think you need to do that at this stage.

There are more things that can cause shifting problems, but your description of the state it was in when you got it, I would start with these easy/cheap fixes.

 

Another thing is to use a sealant on the the spring caps to prevent them leaking and coming loose. Doesn't hurt to use silicone sealant around the stopper guide pin. Its on the transmission side of the o-ring an can leak a little oil. 

An hours work and your should done. An aircraft technician managed it . Zed will understand that .

 

Chas

 

 

[EuroDat]

Rossi,

 

Here are some other threads with similar problems. The first one has a lot of pictures

 

http://www.classiczcars.com/topic/51155-tranny-piping-out-of-third/

 

http://www.classiczcars.com/topic/45755-shifter-return-spring/

 

http://www.classiczcars.com/topic/46725-weak-return-to-center-spring/

[rossiz]

update: bled the clutch and flushed out what looked to be 30+ year old fluid. it shifts through all gears now, but not well under load. i think i still don't have quite enough throw at the slave rod to throwout fork. i'm going to pick up the correct adjustable rod and wind out some of the slack.

 

if i shift gently it goes through all the gears smoothly, but it grinds horribly if i try to upshift or downshift under load.

 

the lever and bushings are from my 4sp - i had replaced all 3 bushings recently.

[rossiz]

chas - thanks for the helpful posts, i had read that earlier and it was next on the list. 

i ordered the correct adjustable throwout rod and will now try to source the check balls & springs.

[Zed Head]

I had a similar grinding problem with a junkyard 1980 5 speed.  I also had a 3rd gear grind with a 1978 5 speed.  Fixed the 78 by switching from Valvoline fluid to Redline MT90.  Moved the RPM range up substantially on the 1980 by using a 75/25 blend of Swepco 201 and AT fluid.  The 1980 also got better with usage after the final switch.  I thnk that there may have been rust on the gear cones.  It had sat for a long time.

 

Short post - try another fluid.

 

On the throw - the later slave cylinders automatically adjust to max throw since its hydraulic.  The fork can only push it back so far, to its new starting point.  If the rod was too short the hydraulics would just push the cylinder out of the bore.  The rubber boot is the only thing holding the cylinder in the bore with the newer slave cylinders.  I don't know how the old ones are designed.  Loss of potential throw would be at the MC rod and pedal adjustment.  Pretty sure that's right, from my memory of past clutch problems.

 

Posted a picture of a 1978 nonadjustable.

Edited July 3, 2015 by Zed Head

[Zed Head]

 

An hours work and your should done. An aircraft technician managed it . Zed will understand that .

 

The memory is fuzzy, but I think I feel a little bit bad about that...

[rossiz]

zed, thanks for the helpful posts. the tranny was empty when i got it - probably sat for a year in total between when the PO pulled the engine/tranny and when i filled it (last week) with redline MT90. by throw i don't mean increasing the total amount that the rod moves, but getting the starting point of the throw closer to the engagement point so the available throw is all useful vs. wasting the first 1/2" of rod travel.

 

gonna go out and check the detent springs - who knows, they may be missing... 

[EuroDat]

Rossi,

 

Chickenman quoted GM transmission oil (Friction modified) in another thread. Maybe he will chip in, I can't find the thread atm.

It must be the friction modified version. I can't get it here so I can't talk from experience.

 

Im using Redline MT90 like ZedHead and I find it to be a very good oil for these transmissions. My experience.

 

What do you expect to accumplish with an adjustable push rod? How much free travel do you have on the slave cylinder?

If you push the clutch fork into the slave cylinder, you should get around 10-15mm free travel. Depends on clutch disc wear and pressure plate/throw out bearing collar combinations.

 

The balls and spring will help the shifting, but won't do anything for the grinding into gear. That can be a synchro issue or a clutch disengagement issue. Even a dry spigot bearing in the crankshaft or dry clutch plate splines can cause extra drag where the weaker synchros with give up and cause grinding.

 

EDIT: Found the thread: http://www.classiczcars.com/topic/51698-how-should-a-71-240-4-speed-feel/

Edited July 3, 2015 by EuroDat

[Zed Head]

 

if i shift gently it goes through all the gears smoothly, but it grinds horribly if i try to upshift or downshift under load.

 

With more pondering - I think that you're screwed.  If you're already using MT90 and still using the word "horribly", on both upshfits and downshifts, odds are the synchros are worn out, or even broken. Only being blunt 'cause I know you can take it, but hate to see you waste your time.  The guy started to take it apart then stopped.  People don't take apart transmissions that work fine.

 

The best sign of proper clutch operation, I think, is entry in to reverse.  If you can press the pedal down and quickly pop it in to reverse, your clutch and clutch actuation are working.

[rossiz]

yup, agreed. synchros are the likely culprit at this point.

i fabbed up an adjustable clutch rod and wound out all the free play up to ~10mm and the clutch is brand spankin' new. the detent springs & balls were fine - i checked 'em against the ones from my 4sp which works perfectly. it still grinds horribly when shifting under load (both up and down).

 

gonna swap my 4sp back in and contemplate whether its worth re-building the 5sp - never cracked a tranny open before and not sure if it's better to just buy a re-built one...

 

sux because i really want to drive that new engine!