K, here's the deal. I got my car with 36K last year and since then have just passed 70K miles. Probably right around 60K...I can't really remember, My shifter started to slip VERY EASILY out of 3rd and 4th gears. and when put into gear with the clutch depressed, it wouldn't "click-in" like the other gears....it can even fall out of gear sometimes, when the car in in gear with the clutch out...and I'm off throttle. The car still seems fine besides that...and there's no vibration or grinding noised coming from the tranny....somebody help.

 

That nice "click in" sound and feeling when you engage a gear comes from a part of the transmission called the detent assembly. When you move the shifter from Neutral into any gear you are moving one of three shift rods. There is a separate shift rod for each plane in the shift pattern: one for 1/N/2, one for 3/N/4, and one for 5/N/R. Each shift rod has three deep notches in it. A spring-loaded steel ball settles into one of those notches and produces the "click in" sound and feel. These parts (the notched rod, steel ball, and spring) compose the detent mechanism. The detent helps the driver know the shift has been completed, and it also helps to keep that gear engaged until the driver moves the shifter again.

Your symptoms suggest that either ...
(a)you are unable to fully engage 3rd and 4th gears so the detent never clicks in, or ...
(b)the detent is broken.

Case (a) might arise if the shifter is damaged or the engine mounts are defective. These parts are external to the transmission.

Case (b) might arise if the ball has broken or the spring is weakened. These parts are internal to the transmission. Here's where you get lucky... maybe...

Raise the front end of the car and support it on sturdy jackstands. Slide under and look at the part of the transaxle case which faces the front of the car. You will see the lubricant fill port. Below that port, and slightly toward the driver's side of the car, you will see the heads of three bolts. They look like ordinary bolt heads but they are actually the detent plugs. The one nearest the driver's side of the car is the 1/N/2 detent, and the one in the middle is the 3/N/4 detent.

Remove the 3/N/4 detent plug. A small coil spring and a steel ball should come out. If they don't, a small magnet may be used to coax them out. As soon as these parts come out the gear lube will pour out. You may immediately install the plug without the spring or ball to stop the loss of fluid.

Examine the steel ball and spring. If the ball is damaged, replace it. If the spring is broken or crushed, replace it. When the new parts are in hand, remove the detent plug, insert the ball, the spring, and reinstall the plug. You should be able to feel the difference in the shifter immediately, even without starting the engine or taking the car off the jack stands.

 

Great info Dan. I was wondering what that was that shot out of my tranny when I disconected the wrong bolt. Get this, At first I just found the spring and put it back in the tranny, then I was refilling my tranny fluid later{with the same fluid I just drained} and at the very bottum of the bucket I see a circular steel ball{bearing} and I was like what the hell? Then I realised that it must have shot out with the spring. So I drained the fluid again and luckily put it all back together proparly. Anyways you made me feel a lot better because I was not sure if I messed something up by doing this.

 

Thanks so much for the info Daniel. I was thinking about taking it in to get it diagnosed...and they would have probably told me that I needed my tranny re-built. From what you said, it is almost definitely the 3/N/4 detent that is broken. I'm going to try and fix it. I'll post what I find out. Thanks again...you are a lifesaver.

 

If your 5-speed now shifts and "feels" right, no harm was done. Enjoy the ride!

 

Daniel, I took a LONG long at the tranny today....and I can't seem to locate the three bolts that you are talking about. I did find three that are in the same area near the fluid filler plug...and the middle one holds a clip that secures the reverse light sensor wire....could these be those three misterious detent plugs?? They are not equally spaced or anything though. I also think I came up with a theory on what happenend to the 3/N/4 detent...I had the car in for service last fall (I do my service now as much as I can..thank god) and they replaced a leaky reverse light sensor....now since that clip is held on by that middle bolt, (probably the detent plug) when the smelly mechanic removed it, he probably inadvertantly let the spring and ball fall out....and since the fluid was already drained...he didn't notice that they had fallen out and just replaced the plug WITHOUT the spring or ball. Now, the reason that I suspect this is becuase AS SOON as I left the dealer that day was when I noticed that it wouldn't "click" into 3rd or 4th anymore. I thought nothing of it (stupid, I know), becuase I figured they didn't open the tranny...so how could they have messed up something inside. Stupid me. Now my question is....would I have that same problem that I've been having if the spring and ball were simply MISSING...or would it be worse....or not work at all?? Thanks so much for all your help....

 

another update.....I removed the middle plug (one with the clip for the reverse light sensor wire) and guess what I fould........NO SPRING AT ALL. The ball was there....but there is no spring to be found. so It seems that my theory just might work out after all....I lost a little gear lube in the process....would that be a problem? It's not even enough to cover the bottom of my oil catch bucket. I ordered the spring and a new ball from nissan today....total cost: 3 bucks....and they said they'll have them in on wednesday...so I'll post then when I get this all sorted out...again..thanks for all your help daniel....

 

Aha! Now we know who did it, and when!

 

Daniel B Martin is totally the man! Wow that was really informative. I was just browsing, and well whatever, I don't even have a MTX, but it was still cool. And good t okeep in mind because my mom has a '96 SE.

Thanks, DBM!

 

It would be no problem if we knew the tranny had been full beforehand. However, the doof who lost your detent spring may also have lost some gear lube and not bothered to replace it. Please... just to be on the safe side... top off your tranny when you install the replacement detent parts. You might even want to replace the gear lube at that time rather than top it off. Five bucks worth of gear lube, not a major expense. For instructions with photos, see http://vbxmaxima.8m.com/mtoil.html

 

Dan-

Even though I don't always have the problems that are listed, I always learn something from your replies. You also lay out most of of your replies in a way that there's hope that we shadetree mechanics can fix at least some of the stuff ourselves! Thanks for the continued assistance you give to me and everyone else!

btw, BriGuyMax, if you're just topping off, you might want to wait until the transmission is cool before topping, the fluid tends to expand a bit after it heats up.

 

Thanks for all the tips guys.....especially Dan....I couldn't have done it without you!!