Thread: How to recognise and repair 5th gear pop-out in a B13 or B14 transmission.

Table of contents

1) History of 5th gear pop-out and the Courtesy 5th gear pop-out "kit"
2) How to recognize if a transmission has 5th gear pop-out by looking inside
3) How to recognize if a transmission has 5th gear pop-out by driving the car
4) How to replace 5th gear once the transmission is out of the car
5) A total breakdown of the traditional 5th gear pop-out "kit" and what each part does
6) Alternative How To's

History of 5th gear pop-out and the Courtesy 5th gear pop-out "kit"

In the beginning, there was nothing.
Then we had SE-R owners coming out of the wood work with 5th gear pop-out. This became more common as the years and miles rolled on. Discussion on the SE-R mailing list centered around getting Nissan to fix the problem under warranty. The cause of the problem was blamed on poor engine mounts for the most part.

Lawrence (Larry) Weeks eventually developed 5th gear pop-out himself (year unknown right now) and went about ordering new parts from Nissan and did an incredible job documenting the process. During this time the community learned that Nissan had redesigned the 5th gear for the input shaft to combat the 5th gear pop-out problem (yet never issued a recall or repair edict).

In this description Larry lists the problem for 5th gear pop-out as the fault of the 5th gear synchronizer failing. This seems to have caused some confusion throughout the years as Larry isn't using the traditional naming of parts in this instance. The actual brass synchronizer does not fail, and does not cause this problem. He is referring to the 5th gear and coupling sleeve dog teeth as the "synchronizer". The failing of which is the cause. Technically a failing 5th gear synchronizer will certainly aggravate the problem, but even with a perfectly functioning synchronizer, you can/will develop 5th gear pop-out.

Larry also started a poll to see who was getting 5th gear pop-out, what year car they owned, and at what mileage it presented itself. The entry form for the poll is still present, but the form doesn't submit properly, and the original results page is sadly lost (possibly forever). Edit: The archived results have been found!

Apparently, since Larry was so thorough in his documentation and successfully remedied his 5th gear pop-out, Courtesy Nissan took his entire order (which included many extras not directly related to fixing the 5th gear problem) and labeled it the "5th gear pop-out repair kit" offering it for sale from then on.

Here is Larry describing how it happened:
Here is a link to the e-mail in the SE-R mailing list archives: http://www.se-r-list.org/new-archives/Week-of-Mon-20041018/018971.html

How to recognize if a transmission has 5th gear pop-out by looking inside

Facebook album permalink (in case the images don't show up in the future).

Once you have the case open (for those directions see section 4) you'll be looking at the gear stacks. I've labeled the 5th gear in this picture with purple.

I have this gear and the assembly above it on my desk that I've taken pictures of to help us out.

This is the 5th gear followed by the brass synchro and then the coupling sleeve. (From bottom to top).


Here is the stack again as they sit in the transmission.


Here is what it looks like with the coupling sleeve disengaged. My hand doing the job of the shift fork.


This is what it looks like with 5th gear engaged.


Here's what it looks like with the selector lifted off.


And with the synchro removed.


All three pieces separated.


This is the two main pieces of the coupling sleeve and hub assembly. Normally two ring springs and three retainers hold it together and allow them to slide up and down a bit.

Here they are together. The three open spots are where the three retainers go.


Here are the dog teeth on the coupling sleeve that have been torn up causing 5th gear pop-out.


Here they are again. Torn up. Chipped teeth.


More carnage.


Here is what the other side looks like that hasn't seen any use in it's life. This is what it should look like more or less.


More pics of the good stuff.


Here are the dog teeth on the 5th gear itself all torn up causing 5th gear pop-out.


Another picture of the beat up dog teeth. You should see now that with all this material gone the teeth don't have much left to hold onto.


Here is my brother's 5th gear that we replaced ahead of time before it could get 5th gear pop-out. It looks a lot better.


Again.


Good one on the left, bad on the right.


Here is the bad one again. You'll notice the distance between the gear teeth and the dog teeth is very small. Maybe 1mm at most.


The redesigned gear will have about 2mm between the gear teeth and the dog teeth. Basically they sit up higher. This means they penetrate deeper into the coupling sleeve and do not loose contact and slip or grind themselves up. Take a look back at the picture showing both gears next to each other. You'll see neither is the redesigned gear even though they both came out of 1994 transmissions.

Here is a comparison of the redesigned gear (on the left) and the original style (on the right).



Here are more pictures I was able to take with the redesigned gear (on the left) and the original style (on the right).








New style.


Old style.


If you have the gear with the "taller" dog teeth you're all set. Otherwise it's a time bomb. You'll know when you take it apart.

How to recognize if a transmission has 5th gear pop-out by driving the car

If you're driving the car in 5th gear and the shift lever pops out of the 5th gear location at any time you have 5th gear pop-out. Seriously, what else did you expect me to say?

Usually this starts to happen only under hard acceleration or engine braking while in 5th gear and it will get progressively worse until the transmission refuses to engage 5th gear at all.

How to replace 5th gear once the transmission is out of the car


Notes: When I say the "top" of the transmission in this post I'm referring to the transmission resting on the bellhousing/engine mating surface. The "top" usually points to the driver's side fender when the transmission is in the car.

1) With the transmission bellhousing facing down unbolt the 6 bolts on the top of the transmission that hold the small circular plate onto the transmission.

2) Unbolt the 12+ bolts holding the transmission case to the bellhousing.

3) Remove the small circular plate from the top of the transmission. It will be held on by grey RTV. Be careful. Don't lose the rubber o-ring either.

4) Use spreading C-clip pliers to remove the larger c-clip holding the outer bearing race on the output shaft to the top of the transmission case. This is a silver (not dark) c-clip down lower than the smaller c-clip you'll see on the end of the output shaft.


5) Remove the transmission case from the bellhousing. It will be held on by grey RTV. Be careful. There will be spots where you can "pry" with a thick flathead screwdriver or pry bar. Be careful lifting the case off of the bellhousing as it will not come straight off. Look through the hole at the top of the case to get an idea of how you need to remove it.


The two gear stacks and shift linkage should now be exposed. It should look like this (I like to call this the "back" of the transmission).

The "front" will have the shift linkage assembly in front of the two gear stacks. While looking at the "back" of the gear stacks in this picture, the part you'll be dealing with most is in the upper right hand section of the picture. That is where you'll find the 5th gear.
Here is another picture of the gear stacks from the "right".


And the "left".


6) Remove the long metal dowel that holds all of the selector forks in place. This should be lifted by hand. It should come straight out very easily. Once it is removed the gear selector forks will be resting on their respective coupling sleeves and the shift linkage assembly only. The metal dowel in question can been seen left of center in this picture.


Here it is removed (top in picture).


7) Slide the 5th gear shift fork around the gear coupling sleeve (making sure to keep the fork prongs inside the groove in the selector ring) to remove the fork from the shift linkage assembly. Be very careful. There is a small friction cap inside the "handle" of the fork that you do not want to loose. Keep track of this friction cap. Make sure not to disturb the other shift forks when doing this. They too have friction caps and you will want to make sure they don't get dislodged.

8) Remove the 5th gear retainment plate on the top of the input shaft gear stack. It has a C-clip holding it on that you'll need to remove as well.


9) Mark the top of the 5th gear coupling sleeve and hub assembly with a sharpie marker so you will know which side was "up". (You will want to reassemble this upside down.)

10) Remove the 5th gear coupling sleeve and hub assembly by sliding it off of the top of the input shaft gear stack. Be careful not to let it disassemble. It is held together by two ring springs and three retainers. Sort of a pain to put back together, but not too bad. If this doesn't come off easily because the bearing on the output shaft is preventing it from coming off you can lift the output shaft some and carefully spread the two gear stacks apart to get the wiggle room needed to remove it. If this fails you should disassemble the 5th gear coupling sleeve and hub assembly to remove it from the shaft. You do this by pulling the hub up and out of the coupling sleeve. Make sure not to loose the three retainers or the two ring springs.

11) Remove the 5th gear synchronizer by sliding it off of the top of the input shaft gear stack.


12) Remove the 5th gear by sliding it off of the top of the input shaft gear stack. This should be possible by hand but you might need a gear puller if you're the unlucky type.

Now you're basically going to reassemble the transmission in reverse taking care to replace all of the parts you removed with new parts if you have them. Keep reading though, there are some important details you won't want to miss.

13) Replace old 5th gear with new 5th gear by sliding the new 5th gear onto the input shaft.

14) Replace the 5th gear synchronizer with a new one if you bought one, or re-use the old one. (A new one is recommended).


15) Replace the 5th gear coupling sleeve and hub assembly by sliding it back onto the input shaft. Be sure to put it back on the opposite of how you took it off. This means what ever side was facing up before should face down. This is because this part will have worn out along with the 5th gear and you will want to use the "fresh" side. It has two sides, but only one is used.
Alternatively you could buy a new coupling sleeve and hub assembly and avoid re-using the old assembly (you can't buy just the coupling sleeve anymore). If you buy a new coupling sleeve and hub assembly you will have to disassemble the 5th gear selector ring/collar and inner spline ring assembly to re-use your old spring rings and retainers. This is not very difficult. Also, if you buy the entire kit it comes with two new ring springs and three new retainers for this assembly. You'll want to assemble all these new parts to replace the old if you bought the kit. (I don't feel this is necessary at all.)

16) Replace the 5th gear retainment plate on the top of the input shaft gear stack. Don't forget the c-clip.


17) Slide the 5th gear shift fork back onto the gear coupling sleeve (making sure to keep the fork prongs inside the groove in the coupling sleeve) and rotate the fork to put it back into the shift linkage assembly. Be very careful. There is a small friction cap inside the "handle" of the fork that you need to make sure is present and does not fall or dislodge itself during this step. Make sure not to disturb the other shift forks when doing this. They too have friction caps and you will want to make sure they don't get dislodged. Here's a picture of one of the friction caps. Here is where it should reside in the "handle" of the shift fork.

18) Reinstall the long metal dowel that holds the all of the selector forks in place. This should be fitted by hand. It should slide straight in easily aligning all of the shift forks back into place.
Here it is in the top of this picture.


19) Replace the oil spreader if it fell out. You may have noticed this piece in the transmission case.

Or you may not have even noticed it. If it is still in place where it goes, leave it alone. If it has fallen out, it's not readily apparent where it goes back. See the two tabs on the left hand side of the spreader? Those two tabs mount into the two small, oval holes in the bottom left of this picture.

See them right above the second bolt hole from the left? Good. That's where that thing goes.

Here is another picture showing the oil spreader installed in its proper location.



20) Clean all gasket surfaces. Clean the bellhousing mating surface and the transmission case mating surface of all Grey RTV material. Clean the small, circular cap of all Grey RTV and clean the side of the transmission case where this cap mounts. Be careful not to ruin the rubber o-ring if it is still in place.

21) Apply grey RTV gasket sealant to the bellhousing mating surface. Be careful to make sure you apply the bead to the "inside" of the bolt holes.

22) Replace the transmission case back onto the bellhousing making sure to tilt it and rotate it as it will not go straight down onto it. Look through the hole in the top to make sure you're avoiding everything and the oil spreader doesn't fall out as you do this.

23) Torque down the transmission case. I like to use an "inside out" torque method, not a star pattern.

24) Replace the C-clip that holds the outer race of the bearing on the top of the output shaft to the transmission case. If the output shaft is not tall enough and the groove in the bearing race is not showing you can lift the output shaft by hand (it should move easily) or pry it up with a screw driver to get the C-clip to seat.

25) Apply grey RTV to the top of the transmission where the small circular cap mounts.

26) Replace the small circular cap.

27) Torque down the bolts on the cap using a star pattern.

28) Take a break, grab a (root)beer and let the RTV cure. You are finished.

A total breakdown of the traditional 5th gear pop-out "kit" and what each part does

Breakdown of the traditional 5th gear pop-out "kit"

Here is Courtesy Nissan's 5th gear pop-out kit for the 2.0L transmissions: SE-R 5th Gear Pop-Out Kit :: CourtesyParts

Diagram of the parts you're buying: 5th Gear Parts :: Sentra / NX Parts (B13) 1991-1994 :: CourtesyParts.com




Cost right now is $341.41 for a total of 13 items (some items come with multiple pieces).




Here is Gspec's 5th gear pop-out kit: G Spec Performance - 5th Gear Pop out Kit

Here is Greg's picture of what you're buying.

Cost right now is $367.02 for a total of 16 items (some items come with multiple pieces).


As of now, these are the parts they have in common:

Driver's side axle seal.
Passenger's side axle seal.
Two (2) shift fork caps.
Coupling sleeve and hub.
5th gear shift fork.
Three (3) 5th gear shift inserts. (I call them retainers for the ring springs in my descriptions)
Two (2) 5th gear insert springs. (I call them ring springs in my descriptions)
5th gear baulk ring. (I call it the 5th gear synchronizer in my descriptions)
Input gear (5th).
Case cover O-ring.
Input shaft oil seal.


These are the parts that are in the Courtesy Kit only:

Striking rod oil seal.
Rod retaining pin.


These are the parts in the G-Spec kit only:

Output shaft upper bearing retainment C-clip.
Unknown circular seal (rear main seal?)
Unknown dowel with key way.
Reverse position switch.
Neutral position switch.


What each part does

I know it can get confusing when parts aren't always called the same thing. Nissan has official names for their parts that make sense most of the time, but then cause confusion other times. Their naming convention for their synchronizers is a perfect example. They call their synchronizer a "baulk ring". That might make sense to someone, but to me and most others it is a terrible name. The part is typically referred to as a synchronizer, and that's what I've been calling it in my descriptions. I'm going to try and use the best name for a part I can. It might be the official Nissan name, or it might not be. It should be descriptive however, and leave no confusion. If you are confused, please let me know and I will make it less so.

As of now, these are the parts they have in common:

Driver's side axle seal - Creates a seal around the axle preventing gear oil from leaking out of the transmission case and road debris from entering the transmission case. This is a wear item but can be re-used if in good condition.
Passenger's side axle seal - Same as above.
Two (2) shift fork caps - The shift linkage has levers that lift the shift forks up and down. The shift fork caps provide a connection between the levers and the shift forks to reduce friction and allow pivoting. These are technically wear items but wear very slowly and shouldn't need replacing.
Coupling sleeve and hub - These pieces transfer torque from the input shaft to the floating 5th gear on the input shaft. The coupling sleeve slides up and down with the shift fork. When the shift fork is raised up the sleeve raises and disengages the dog teeth on the input gear (5th). When the shift fork is moved down the sleeve moves down and engages the dog teeth on the input gear (5th). The dog teeth on the sleeve suffer heavy damage on transmissions with 5th gear pop-out so you will need to flip the sleeve over to use the unused "good" side or purchase a new one. This is one of the two main parts that are damaged when you have 5th gear pop-out.
5th gear shift fork - This transfers the lever movement from the shift linkage to the coupling sleeve. In some rare cases this can be bent by an overly aggressive driver trying to keep their transmission in 5th gear when they have 5th gear pop-out. This piece should not need replacing except in the most extreme cases.
Three (3) 5th gear shift inserts - These little pieces install into the coupling sleeve and hub facilitating in their sliding movement. These are technically wear items but wear very slowly and shouldn't need replacing.
Two (2) 5th gear insert springs - These springs retain the three 5th gear shift inserts and help facilitate the sliding of the coupling sleeve and hub. These do not need replacing.
5th gear baulk ring - This is the synchronizer. It is a wear item and is likely worn more than usual in a transmission with 5th gear pop-out. It should be replaced.
Input gear (5th) - This is the input gear on the input shaft for 5th gear. When engaged with the coupling sleeve above it transfers torque from the input shaft to the output shaft via the 5th output gear. The dog teeth on it are heavily damaged in transmissions with 5th gear pop-out and it needs to be replaced. If your transmission has 5th gear pop-out you almost certainly have an old style 5th input gear and it should be replaced with the new style of 5th input gear.
Case cover O-ring - This seals the transmission case where the small, round cap is bolted to the top of the transmission case. It prevents gear oil from leaking. If you are not very careful in disassembly you will likely ruin this piece so you should get a new one to replace it with.
Input shaft oil seal - Creates a seal around the transmission input shaft on the bellhousing side to prevent gear oil from leaking into the bellhousing. This can be re-used but is good to replace "while you're in there".


These are the parts that are in the Courtesy Kit only:

Striking rod oil seal - Creates a seal around the shift actuator rod (or striking rod) to prevent gear oil from leaking out of the bellhousing. This can be re-used but is good to replace "while you're in there". If you replace this you will need a new rod retaining pin.
Rod retaining pin - This locates and holds the shift actuator lever arm onto the shift actuator rod (or striking rod). If you replace the striking rod oil seal you will need a new one of these as it is usually ruined in the removal process.


These are the parts in the G-Spec kit only:

Output shaft upper bearing retainment C-clip - This locates and holds the input shaft bearing towards the top of the gear stack in place on the top of the transmission case. The c-clip fits into a groove in the outer race of the bearing and rests on top of a circular ledge on the transmission case. When opening the transmission case this needs to be removed and usually suffers no damage so it can be re-used. A new one is not essential unless you ruin yours.
Unknown circular seal (rear main seal?) - I need to ask Greg what this is.
Unknown dowel with key way - This might be the rod retaining pin. I need to ask Greg.
Reverse position switch - This switch tells the ECU when the transmission is in reverse. This can be re-used but is good to replace "while you're in there" because they tend to leak with age.
Neutral position switch - This switch tells the ECU when the transmission is in neutral. This can be re-used but is good to replace "while you're in there" because they tend to leak with age.

Alternative How To's

1) tsuruser has compiled another How To with great pictures (some of which I have now used with his permission) and more step-by step directions.
Link: http://www.sr20-forum.com/general-maintenance/40644-transmission-case-5th-gear-fix.html

2) NissanEgg did the job back in 2008 and took plenty of good pictures that survived the Photobucket apocalypse.
Link: http://www.sr20forum.com/driveline-transmission/234817-b13-5th-gear-pop-out-overhaul-pics.html

good to see my photos are being put to good use!! and thanks for this HOW TO to end all!

Yah junknstuff, thanks so much for the pictures, they are great. I'm just sad I didn't know exactly where the oil spreader went when you asked in your thread at the time. I know the answer now. =/
I hope everything turned out well with your transmission. http://www.sr20-forum.com/all-motor/3970-transmission-gears-56k-users-extinct-we-should-ok.html

Added Lawrence Week's quote to the History section from a SE-R mailing list message in 2004 where he explains why the Courtesy kit includes what it does, and his recommendations for what does, and what does not need to be replaced.