Av8ferg

5 Speed Transmission inspection and possible rebuild.

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    I finally picked up that 1982 280zx transmission and differential that I purchased a while back.

    Fist impression is that it looks rough on the outside.

    I wanted to start a thread so I can get the guidance and advice as I analyze and open this up for inspection.

    Thy last time I looked inside a manual transmission was 1980 when my dad pulled the tranny out of our 1974 Corolla to repair it. I was 10 then and was the hand me the tool, hold this flashlight helper.

    So just like my methodology I had with the engine rebuild, I don’t want to put an Unknown quantity in the car. Just like I found the protruding valve seat on my P79 head, I’d prefer to get ahead of possible problems. I want to at least inspect the inside and determine if it requires an replacement parts. I’m in no rush. The car should be in my new garage in about 5 weeks and as soon as it get here I’m going to pull the old engine and drive train. I’m hoping to get it off to body work then.

    So. I’m guessing some will say it’s probably good so don’t waste time opening it up and going through all that extra work. First this is a labor of love. Secondly, I want to to be a reliable tranny that I don’t have to go back and fix later. Finally, it’s an opportunity to learn and expand my knowledge and skill.

    With that all said, I’m hoping you all can guide me through the pitfalls and help me see the blind spots as I pull this thing apart. Here are the pics.

     

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    3509aa4226b07f841be7c6636d215d2f.jpg

    0882cac2469d7d4ad3a4f4211894bde0.jpg

     

     

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    People keep bringing me 5 speeds with chucks of bearing cage on the magnetic drain plug. Been the mid plate countershaft bearing in every case so far. At the very least I’d replace the bearings. Wish I was closer.

     

    DA7B37C5-03A5-410F-9A3B-00667507FE32.jpeg

    Aren’t the balls supposed to be inside the races? Not always I guess.

    The good news is that the cage pieces haven’t reaped havoc with the rest of the rotating parts in any of the examples so far....

    Edited by zKars

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    I used those rubber caps and oven cleaning foam, hot water pressure wash to clean mine. Then carried it to a friend who has a transmission shop. He opened it up replaced the seals and said it looked fine. I put it in then filled with Redline MT90. Works great for my jaunts around here.

    transmission cap.jpg

     

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    Odd that the front case has a different tone than the back one.  It might have already been opened at least once.  Who knows, it might have had a "dirty" rebuild.  Check the bearings and synchros they might already be newish.  It's pretty easy to split the cases and pull the gear cluster out without special tools.

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    Thanks guys. ZH, I noticed the same thing regarding color. I also noticed some black RTV where the bell hosing connects to the case so someone might have been inside before. When I get it open I’ll take a bunch of pics and a video and go from there.

    Of note. This salvage yard has been sold. The owner is attempting to crush all the cars buy 1 Sep for scrap metal. He said rate not is about $4 per 100 lbs. He’s got seven L-28 engines and six 5 speed transmissions in those cars . What a waste. I might try and make a deal with him. At $4 per 100 lbs that puts a Z bringing him about $115. I wish I had a place to put one of those Z’s and get some of the transmissions and engines.

     

     

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    3 hours ago, Zed Head said:

    Odd that the front case has a different tone than the back one.  It might have already been opened at least once.  Who knows, it might have had a "dirty" rebuild.  Check the bearings and synchros they might already be newish.  It's pretty easy to split the cases and pull the gear cluster out without special tools.

    I notice the difference in tone as well. Funny, I have an 82 close ratio and it has the same tones in the casting. It looks like they made the castings in two different factories, if that was possible.

    +1 for @siteunseen cleaning method and then open it up and have a look. You will be just guessing untill you crack it open and have a gander.

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    I started tearing apart this transmission, I have never done this before so I’m in uncharted waters.  The FSM is vague and poorly discusses the tear down procedures so I’m trying to figure out why the rear casing is not coming apart.  

    Take a peak at the video I posted and let me know if you see something I missed.  

     

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    Well, I figured it out. The transmission must be in neutral which I already knew but I must have moved it accidentally back into gear543f4430e7be385923326094ddff1bb3.jpg
    . It must be in neutral so you can rotate the portion where the actual stick inserts. Once rotated you can pull the casing right off. Looks pretty clean inside this thing.


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    @Mark Maras and @EuroDat and @zKars probably know for sure.  I can't remember what might be holding the back half on.  I'm pretty sure though that you can get the front half off without removing the back half.  If you wanted to split that case off of the adapter plate while you're waiting.

    It might be that you need to rotate the shift lever to get the reverse lockout mechanism free on the back case.  That was the "spring thing' that you removed.  Look inside the hole and you might see what's getting hung up.

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    Timing...

    Be careful with the oil gutter on the other side.  It gets bent often.

    image.png

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    4 minutes ago, Av8ferg said:

    Well, I figured it out. The transmission must be in neutral which I already knew but I must have moved it accidentally back into gear543f4430e7be385923326094ddff1bb3.jpg
    . It must be in neutral so you can rotate the portion where the actual stick inserts. Once rotated you can pull the casing right off. Looks pretty clean inside this thing.


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    I just received a notification and while watching the video see you already found the reason while.

    The striking rod needs to move from left to right after the case comes away from the adaptor plate. Once you remove the reverse check lock out "thingy on the side" it will allow you to move the striking rod past the selectors and pul, the extension housing off. I generally use a large philips head screwdriver in the shifter to giggle it around past yhe 5th/Reverse position and them it will come free.

    Btw: The manual says to use a hammer to tap it off. What they mean is break it loose from the adaptor plate and extension house bearing.

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    Thanks guys. To an untrained eye this transmission internals looks nice. I suspect this may have be rebuilt before. It’s a clean as one could imagine for a car with 192k miles. Give aways were the gasket sealant, black paint rear housing and gasket under the front cover. It doesn’t look OE but again this is a guess.
    I need to get the front and rear case off for cleaning on the auto shop on base and get it back together before I forget where all these parts go.
    I may need help on that anyway.

    Here’s a video of the internals.




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    Looks very good. I'd say it's been apart twice before judging by the staked nuts. Take a good look at the brass synchro rings. The pointy end of the teeth should come to a sharp edge rather than be rounded over.

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    Thanks for the feedback. Here’s a close up of one of the synchros. They all look about the same.

    7ece6cde7daa9a5e78305d8f575f6a35.jpg


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    There are a few other things you can check without taking it apart.  The roll pins that hold the shift fork to the shaft.  Sometimes they can wear or break or wallow out their holes.  Make sure the forks are tight on the shafts.

    I looked at your video but didn't see the oil gutter.  If it's gone the reverse gear or maybe the idler will get dry. 

    Check the straight cut reverse gears for chips.  They don't really matter but it gives an idea of abuse.  

    The gutter is a mmysterious thing, it's only shown in the 4 speed drawing but it exists on all of them. It's a trough that catches oil and transfers it through the adapter plate.

    image.png

    image.png

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    Thanks ZH. I will check all that out. What the best way to clean up some residual debris I see in between the gears and along the shaft? High pressure air? I guess using something like carb cleaner my not be a good idea due to removing oil but I don’t know. As all as you re-lube it all well it might be fine. It will sit open for about a week until the cases are blasted clean. I’m ordering a new throw out bear release that attaches to the fork. Since I don’t have a press I’m buying it already built. RockAuto sells them for about $39.


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    Looks like the bearing have been cheaply replaced. Why I say cheaply? They reused the nuts. I wonder if they changed any of the seal while they were at it.

    It looks very good from the video. Reverse gear is still in good condidtion (the idler spur gear), but that is generally due to the reverse lock out device helps prevent accidently hitting reverse on change down in the close ratio transmissions.

    You can take some measurements without striping it down any further. It will take a bit of fiddling, but it can be check without dismantling. That will give you a better idea of the condition.

    Baulk rings: The grooves inside the baulk ring do all the work getting the gears to similar speeds. The teeth on the outside of the baulk ring do the last step by aligning the teeth. It the grooves are worn down, the gears will be at different speeds and the teeeth will grind. That is the wear that Mark is talking about, but it started at the worn grooves.

    Screenshot_20200524-092434.jpg

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    Gear end play: The next thing you can check is gear end play. If you are driving and take your foot the throttle and the transmission goes clunk. That can be other things like the diff, but it can also come from the gears snapping back.

    Screenshot_20200524-092403.jpg

    Screenshot_20200524-092525.jpg

    While you are in the transmission, I would put changing all the seals and the oil gutter ZH mentioned on my priority list. Those oil gutters can get damaged during rebuilds and can take so much benbing back before they break off. They only cost 3 or 4 dollars.

    I have a list of all the seals with Nissan part numbers and sizes so you can source them locally.

    The check springs in the selectors would be nice to change now.Screenshot_20200524-095702.jpg

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    Here is a list of the parts when I did the close ratio I had. The seals are what you want. The seals, springs and oil gutter are listed in their sections according to the parts manual cross section drawings.

    I think I will clean up that list and post it in the technical articles later.

     

    Tranny_Rebuild_FEB2012.pdf

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    Hey, thanks for all this information. I’ll start going through all those procedures and inspection points. Lots of information to digest especially when I really don’t understand how this thing really works. This is how you expand your knowledge; by diving in and learning. Sure helps to have some experts on this forum to keep you from making some fatal errors.
    Thanks for the parts list. I was looking online and I’m hoping most are easily sourced. Will start ordering some of that stuff. My hope is I don’t have to do any further work other than the aforementioned.


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    Visually it looks in good order and it looks like someone did the bearings in the past.

    Seals: If you buy aftermarket seals (o-rings and lip seals) remember to ask for NBR or Viton rubber. Sometimes they have EPDM.

    Check springs: I don't know if you can still get the check springs, but they do make a difference in the selsctor movement. My old ones were about 2mm shorter than the new ones and lost a lot of tension. They gave it that kind of click sensation when the shifter goes into the gear.

    If you can't get the springs, you can try a couple of small washers with the same outside diameter behind the old springs to increase the pressure. Be carefull not to go overboard or the springs could bind and loose function.

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    looks like the adapter plate counter shaft bearing has a seal on it. I don't think that is a good idea, pretty sure that is supposed to be an open bearing. You would want gear oil to freely flow through out the trans. I don't know if I would tear it down just to replace that, or try to pick it out, or just leave it. the trans looks good after all.

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    On 5/23/2020 at 4:20 PM, Zed Head said:

    Timing...

    Be careful with the oil gutter on the other side.  It gets bent often.

    image.png

    About this oil gutter.  I don’t have one on my transmission.   I looked at the FSM and it appears that the 4 speed exploded view show an oil gutter but the 5 speed does not.  I also looked around and could fin one available, for sale.  Are they hard to find,  and are we sure the 5 speed ZX transmissions had them?  See attached pics from FSM. 
     

     

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    C840EE02-6D2E-4FEE-AB9E-71DD85D718D2.png

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    grannkyknot has also rebuilt a 5 speed.  EuroDat posted some pictures in his thread.

    I opened up the 1982 FSM and found a similar issue where they don't show it in the diagram but do describe it in the reassembly text.  It's an odd little chunk of folded stamped metal.  You could probably make your own pretty easily.  I don't think that there's much engineering in it.

    image.png

    image.png

     

     

    Edited by Zed Head

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    19 hours ago, Dave WM said:

    looks like the adapter plate counter shaft bearing has a seal on it. I don't think that is a good idea, pretty sure that is supposed to be an open bearing. You would want gear oil to freely flow through out the trans. I don't know if I would tear it down just to replace that, or try to pick it out, or just leave it. the trans looks good after all.

    I've had bearing come with those seals. Absolutely remove the seal. Just pick them out, they are not held in tightly at all. 

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    Is there grease inside?  Supposedly they are filled with super duper grease designed specifically for the bearing.  The purpose is to keep them lubricated when they are used in areas that can't be reached for regular maintenance.

    The bearings are C3 tolerance which is loose, to allow crud to slip out, as I understand things.  but, this reference says it's to allow expansion.  Trivia...

    https://www.bearing-king.co.uk/article/why-are-your-bearings-c3

    More stuff.  I'm learning.

    https://www.skf.com/cn/en/products/bearings-units-housings/principles/general-bearing-knowledge/bearing-basics/internal-clearance/index.html

    Edited by Zed Head

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