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63a dogleg rebuilt - Gets stuck in 4th gear?

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I picked up an 63A short dogleg to rebuild. It was stuck in 3rd gear. It was obvious the shift sleeve key/strut/detent popped out and prevented the sleeve from returning to the neutral position.

 

I bought a rebuild kit and went through the tranny. replaced bearings and syncro's. Got it all back together, and still have the same issue except for in 4th now, it gets stuck in forth because the sleeve moves too far in 4th and the key's pop out.

 

Anyone have experience rebuilding these doglegs and know what could cause this? Seems to be just 4th having the issue now.

 

Pics coming

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Before rebuild:

 

20171001_132627.jpg

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After:

 

20171105_175710.jpg

 

20171105_175437.jpg

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At first I thought it was getting stuck in the same gear before and after the rebuild.. but pics show its clearly a different gear.

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I picked up an 63A short dogleg to rebuild. It was stuck in 4th gear. It was obvious the shift sleeve key/strut/detent popped out and prevented the sleeve from returning to the neutral position.

 

I bought a rebuild kit and went through the tranny. replaced bearings and syncro's. Got it all back together, and still have the same issue, it gets stuck in forth because the sleeve moves too far in 4th and the key's pop out.

 

Anyone have experience rebuilding these doglegs and know what could cause this? Seems to be just 4th.. 

 

Pics coming

 

What limits the travel into 4th then?

 

Shift fork fingers worn? roll pin broken?

 

The hub has a thicker side that should be facing to the rear of the transmission. Can't tell in the picture.

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What limits the travel into 4th then?

 

Shift fork fingers worn? roll pin broken?

 

The hub has a thicker side that should be facing to the rear of the transmission. Can't tell in the picture.

Forks looked good. The detent in the slide rails should limit the travel. If I shift gently, it's ok. But we know that isn't going to happen.

 

I'm wondering if the alight mentioned of the gear sets could be slightly off from the center section. But would have to be just a slight amount since other gears are ok. 4/5th are also the only gears to use the shift pivot arm in the tail section. Wonder if there is anything wrong with that. Although I didn't remove it.

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Maybe them key things are worn out.

I do know when I had one of these L series doglegs lock up and I pulled it apart them key things fell out onto the ground when I separated the case, I looked that them lying on the ground and then thru the whole thing in the scrap pile, I didn't even look at it anymore, I was done with L series doglegs, I went thru 4 of them in 5 years.

That was when I figured out how to make a short shaft 5 speed out of the 85/86 Nissan 720 regular cab short box truck transmission and a 1980 Datsun 720 front case, best thing I ever did in my life L series transmission wise, them doglegs don't last, the truck transmissions do last, well they last longer than doglegs.

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ZYpjZet.jpg

 

 

.H66XjWJ.jpg

 

 

Centering rockers or 'shift dogs'. These are from a 71B but I think the dogleg uses the same synchro rings as them.

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They aren't worn out. The hub is clearly moving too far and they pop out.

 

Springs are only used in 1st/rev. The others use big C style springs that sit inside the hub, I replaced all of those and the springs with OEM springs from the dealer.

 

Now if the shift dogs were directional, that certainly could be part of the issue, but I think they are uniform.

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I think I might have a spare, I can check that one and see. But every time I've seen these get stuck in gear, it's because these damn things pop out.

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When building a racing Datsun transmission, one of the items on the to-do list is setting the stops. Overshifting is pretty common on old, worn out transmissions and there are ways to fix the problem.

 

The shift rails have factory set stops in the front cover and in the tailhousing, but these are rarely adequate. A quick way to tighten up the stops at the front of the trans is to remove the front cover gasket and replace it with RTV. The rear stops can be a bit more tricky as they are in the tailhousing. You can weld onto the rear of the shift rails and grind away as needed to make sure the travel is enough and the gear fully engages. This obviously should be done before sealing up the trans and installing it.

 

So there are ways, but you're going to have to remove the trans to get it done. Your trans may be having a different problem, like a worn out shift sleeve and maybe you flopped it over when you reinstalled it, which would explain why it used to happen in 3rd, now it happens in 4th.

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When building a racing Datsun transmission, one of the items on the to-do list is setting the stops. Overshifting is pretty common on old, worn out transmissions and there are ways to fix the problem.

 

The shift rails have factory set stops in the front cover and in the tailhousing, but these are rarely adequate. A quick way to tighten up the stops at the front of the trans is to remove the front cover gasket and replace it with RTV. The rear stops can be a bit more tricky as they are in the tailhousing. You can weld onto the rear of the shift rails and grind away as needed to make sure the travel is enough and the gear fully engages. This obviously should be done before sealing up the trans and installing it.

 

So there are ways, but you're going to have to remove the trans to get it done. Your trans may be having a different problem, like a worn out shift sleeve and maybe you flopped it over when you reinstalled it, which would explain why it used to happen in 3rd, now it happens in 4th.

 

 

Wow.. thanks for posting this! I'll check into the stop positions in the case.

 

It's 100% possible.. I could have flipped the sleeves.

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The forward facing of the sleeve was for the then mentioned 4th gear. It may or may not apply to the later one you mentioned. I'll try to look up the procedure when I get home.

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The forward facing of the sleeve was for the then mentioned 4th gear. It may or may not apply to the later one you mentioned. I'll try to look up the procedure when I get home.

I know the hub itself was directional. I didnt see anything about the sleeve. I'll have to reread the manual as well.

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The 5th/4th hub is thicker towards the rear

The 3rd/2nd hub is thicker towards the front

1st/rev I don't know but only first has a synchro, maybe it's obvious... 

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I don't think you can physically put the hubs in backwards and have everything spin on the shaft.

 

The sleeves should be reversible, by design.

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I got the hubs on correctly. I measured them and made sure. 

 

I didn't have a chance to work on this last night. Will take another look at it soon and report back. Thanks for the info.

 

It's been abut 8 years since I rebuilt a manual tranny. I don't have a use for this tranny at the moment. This project was more just for the experience than anything. 

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I don't remember where I saw it but I remember seeing a couple of Datsun boxes that had the shift rails machined with a small groove so they could fit a circlip to prevent the shifter from over traveling. As the syncros get worn it's not uncommon for the shift rail to over travel and rather than the bits falling out they wedge the collar on the hub. My Ultra-close 4 speed did this and it took a bit of doing to get them apart...........I feel your pain.

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I think I got this fixed. It was a deep on my part. I would bolt the cases together but I never bolted on the front plate in the bell housing. That's what stops the tranny forks from moving too far. Bolted that plate on and it shifted like butter!

 

Thanks everyone for your input. It definitely helped!!

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You, those are the forward stops. Would affect Rev, 3rd, 5th ?

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You, those are the forward stops. Would affect Rev, 3rd, 5th ?

 

Didn't seem to effect those gears at all no matter how hard I shifted it. Just 4th.

 

It was a good learning experience. Still have a little more to put together before it's ready to go in a car.. but it shifts fine now. We'll see if it grinds or does anything weird once its in a vehicle.

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You, those are the forward stops. Would affect Rev, 3rd, 5th ?

On a dogleg, the front cover is the stop for 1st, 3rd and 5th.

 

The stops for the rest of the gears are in the tailhousing.

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Reverse and 1st are.... reversed right at the shifter striking rod and the shift rod.

 

On the underside of the rear case is a large nut that holds a post with a lever on it up inside. You've probably all seen this nut on the doglegs. This lever turns a forward motion to a reverse on the reverse/first shift rod to give the distinctive reverse above first.

 

R..2..4

-- N --

1..3..5

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It has been so long since I've rebuilt a dogleg (I hate that term), that I honestly don't remember.

 

Explain that nut and post again.

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4/5 are on this lever mechanism in mounted to the rear of the tranny via a large nut. If I had a picture hosting service worth a shit.. I'd post it. (working on it)

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