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Zx 5 speed rebuild


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Without a complete professional heat treat afterwards, there's no way I would put welding heat to an internal transmission gear like that.

It's just a reverse idler, right? Only engaged when you shift into reverse? I'm no transmission guy, but unless it looks like one of the teeth is going to come off and get wedged between other teeth (and avalanche), I would just run it the way it is.

Make sure your clutch is adjusted properly, come to a complete stop before shifting into reverse, and put the trans into any forward gear first right before you grab reverse. Do those and it won't get any worse.

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27 minutes ago, Captain Obvious said:

Without a complete professional heat treat afterwards, there's no way I would put welding heat to an internal transmission gear like that.

It's just a reverse idler, right? Only engaged when you shift into reverse? I'm no transmission guy, but unless it looks like one of the teeth is going to come off and get wedged between other teeth (and avalanche), I would just run it the way it is.

Make sure your clutch is adjusted properly, come to a complete stop before shifting into reverse, and put the trans into any forward gear first right before you grab reverse. Do those and it won't get any worse.

The concern about heat treat is what exactly?

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You want the gears to be hard enough to be "tough" and "wear resistant" but not so hard that they're "brittle". And you want the heat treat to be predictable through the part.

Welding heat would definitely take the metal above the temperature where the original heat treat would be changed. And without knowing how it changed, it's risky. After welding, it might be harder, softer, or exactly the same. It's all a crap shoot and the only safe thing would be to start over. And even that comes with issues because you don't know what the original spec was.

I just see the whole thing as risky. I mean, not that I've never done risky stuff, but, you know...

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I wouldn't weld it. It could make the chipping worse.

The chips are not as bad as I thought they were. I assure I have seen worse and they worked fine for thousands of miles without giving any trouble.

The most I would do is clean them up a little with a dremel grinder. Be a little carefull using reverse and definitely don't try pulling it into reverse while the car is still rolling forward.

The most probable cause of those chips is people hitting reversewhen they come outof 5th to go back to 4th. It tends to happen more when the selector bushes are worn.

That is why they added the reverse lockout in the later version of the FS5W71B and C transmissions.

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  • 3 weeks later...

So here is where we're at

This a panoramic photo which is why it has some distortion

20210508_165210.jpg

My concern right now is on the front side (left) of the main plate. the first two gears don't line up very well. All the rest of them line up pretty good. Now I haven't torqued anything down yet

20210508_165120.jpg20210508_165124.jpg

I thought we might have had the countershaft gear on backwards but I've double checked my pictures and I think it's right side out. Also the snap ring on the inside of the bell housing plays a part too

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That seems normal. When the input shaft is fully installed with circlip it does not bottom out like it does now in the photo.

What you can do to check if its not too rxcessive is measure the distance between the front faces of the two gears. Then install the front transmission housing. Push the input shaft in until it bottoms out and measure the difference between that position and the position with circlip installed. The difference should be pretty close to the gear faces measurement.

Screenshot_20210509-194916.jpg

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Excellent! We'll try that

Any recommendations on how to torque the shaft nuts? Nissan had a special adapter tool

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1 hour ago, Patcon said:

Excellent! We'll try that

Any recommendations on how to torque the shaft nuts? Nissan had a special adapter tool

You can do a couple things.

1. Make a tool out of a ring spanner and weld a nut on the spanner shaft at 100mm from the centre of the ring. Use a tension wrench on that. There is a formula to calculate the required torque, but if you use a wrench whereyou dial in the NM, just reduce it by 10%

2. What I do is use a ring-open end combination spanner. Measured the distance to from center of shaft to a position on the spanner where I could attach a bucket to.

Calculate the required wieight. Spec is 14 to 17kg/mtr with tool. If you use a spanner direct on the shaft nut, than add 10% (15.4 to 18.7). If the spanner is 500mm long than calculate 1000mm ÷ 500 = 2.

2 x 15.4 = 30.8kg en 2 x 18.7 = 37.4kg. Fill a bucket with what ever you can find to make 31kg to 37kg. The weight of the spanner won't make much difference and you have a fairly wide tolerance of 6 kg in this example.

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I purchased a 1 1/2 inch crowsfoot wrench and attached it to my 1/2-inch torque wrench so that it was at right angles. This did not change the length of the torque wrench appreciably so the torque value I dialed in should be somewhat accurate. Maybe a little underestimating the torque if you consider the length from the center of the nut to the handle is slightly longer than the center of the wrench head to the handle. Lets see Pythagorean Theorem, a2+b2=c2, a 2 + b 2 = c 2 , can be used to find the length of any side of a right triangle.

PXL_20210509_194758880.jpg

Edited by Jeff Berk
Picture added because description was confusing.
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+1 on the 38mm / 1.5in crowfoot cocked 90deg to the side. It's not exact, but if you shoot for the middle of the torque range you will be fine. 

My gears were lined up just like yours are. In one of the how-to videos I watched it was said that they lined up perfectly, which mine obviously didn't. When I looked at them closely, it seemed that flipping the countershaft gear might make things better, so I did that. It was a pain - the woodruff keys kept wanting to fall out - but I did it. Mine was definitely NOT flipped to begin with, but my transmission had definitely been half-assed rebuilt at one point so I wasn't really confident that it was assembled right. After looking at lots of pictures and diagrams, I decided that the the countershaft gear was originally was indeed right, so I put it back.

As @EuroDat said, once you secure the mainshaft bearing to the front housing with the big circlip and make sure you have the right countershaft bearing shims in place, everything lines up pretty well. It's still not perfect, but it's good. 

As an aside, the reason I rebuild my WR 5-speed was that it sometimes slipped out of 2nd gear. I actually never drove it much (maybe 20 miles) before the engine and transmission came out for other reasons, but it slipped out of 2nd a few times so I decided to learn about transmissions while the engine was being worked on. Sadly ... it still slips out of 2nd (rarely) and 4th (occasionally, when I rap it out in 3rd then drop it into 4th and coast). I had thought the problem was probably due to worn detent balls/springs (which I replaced) or worn baulk rings (which I also replaced), but apparently there's something else that causes the problem. I did look carefully at the 1-2 and 3-4 selector rods and forks and they looked fine (to my untrained eye). Otherwise, the transmission shifts great and it "feels" really good. 

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28 minutes ago, pogden said:

+1 on the 38mm / 1.5in crowfoot cocked 90deg to the side. It's not exact, but if you shoot for the middle of the torque range you will be fine. 

My gears were lined up just like yours are. In one of the how-to videos I watched it was said that they lined up perfectly, which mine obviously didn't. When I looked at them closely, it seemed that flipping the countershaft gear might make things better, so I did that. It was a pain - the woodruff keys kept wanting to fall out - but I did it. Mine was definitely NOT flipped to begin with, but my transmission had definitely been half-assed rebuilt at one point so I wasn't really confident that it was assembled right. After looking at lots of pictures and diagrams, I decided that the the countershaft gear was originally was indeed right, so I put it back.

As @EuroDat said, once you secure the mainshaft bearing to the front housing with the big circlip and make sure you have the right countershaft bearing shims in place, everything lines up pretty well. It's still not perfect, but it's good. 

As an aside, the reason I rebuild my WR 5-speed was that it sometimes slipped out of 2nd gear. I actually never drove it much (maybe 20 miles) before the engine and transmission came out for other reasons, but it slipped out of 2nd a few times so I decided to learn about transmissions while the engine was being worked on. Sadly ... it still slips out of 2nd (rarely) and 4th (occasionally, when I rap it out in 3rd then drop it into 4th and coast). I had thought the problem was probably due to worn detent balls/springs (which I replaced) or worn baulk rings (which I also replaced), but apparently there's something else that causes the problem. I did look carefully at the 1-2 and 3-4 selector rods and forks and they looked fine (to my untrained eye). Otherwise, the transmission shifts great and it "feels" really good. 

Thanks for that reply. Very helpful

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Could the slipping out of gear be related to a damaged shifting insert spring? That was a suggestion a mechanic gave me when I was having problems with 5th gear.

On a side question... What is a reasonable price for a 5-speed that is sold as is with minimal opportunity to inspect it? I have someone who is considering buying a junked car and offering me the transmission if I throw in some money for the car. I'm not sure if there is an opportunity to pull the transmission first.

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Could the slipping out of gear be related to a damaged shifting insert spring? That was a suggestion a mechanic gave me when I was having problems with 5th gear.


I replaced the insert springs with new ones, but the inserts are NLA. I looked carefully at the springs and inserts from both the 1-2 and the 3-4 synchro hubs and they seemed fine. But I replaced the springs anyway.

Sent from my KB2005 using Tapatalk

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  • 2 weeks later...

So I did some measuring

Current gear offset is .112 (2.84mm)

With the case on and the shaft down as far as it will go the projection into the bellhousing is .110 (2.79mm)

With it pulled forward for the snap ring the projection is .195 (4.95mm)

The difference is .085 (2.16mm) so the gear offset appears to be .027 (0.69mm)?

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  • 4 weeks later...

So we have most of the tranny reassembled.

We are working on the cases. I have two O rings for the shifter. One is easy to replace

20210613_184328.jpg

The one on the OD there. But I suspect there is one internally as well. Should I drive out the rear cap that is staked?

20210613_184325.jpg

Also is there any particular way to orient the new Omega bushing? It has a hole but I didn't know if there was a specific orientation because the existing one didn't have a hole

20210613_184422.jpg20210613_184412.jpg20210613_184417.jpg

@EuroDat

 

20210613_184328.jpg

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For the selector seals you will need the o-ring on the outside of the striking rod (32721N) P/N:32710-14600 size:24x2.5mm

and

The inner lip-seal for the striking rod (32850H) P/N: 32858-U6702  size:14/20x2mm.

You will need to push the cap off using the striking rod. It will come off easily and can be re-staked with little problem. You can use a tiny amount of sealant to create a god seal.

The omega bush can be fitted in both directions. The hole is not used in the datsun extension housing.

Screenshot_20210615-203936.jpg

Edited by EuroDat
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Another small improvement for when you assenmle the transmission.

On the top rear of the extension housing is the locating pin/circlip for the striking rod. It is actually located on the oil side of the O-Ring seal on the striking rod. It can weep oil.

It is not much, but a little sealant around the pin (32847) and its circlip will stop it and keep the area dry and clean.

Screenshot_20210615-205052.jpg

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