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dozenhundred

Any transmission gurus?

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On my way home today my trans got stuck in 4th gear. Can't get it out at all. If I try to force it it feels like something is rubbing on something else not Turing the same speed. Hard to describe. I'm guessing a synchro is gone. It's a stock four speed with who knows how many miles. I want a five speed but right now I'm feeling like selling it I'm so frustrated. Anyone had this happen? What did you do? What suggestions are out there? UGH

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I would just ignore it until tomorrow. When you calm down, then re-assess the situation. If its a blown 4 speed.... big deal. I'm sure you could find another one pretty easy. If I sold a car every time it gave me issues... I'd have no cars. These things are old! They break.. big deal. 

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Paging DM... in 3.. 2.. 1..

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Not much you can check or do from the outside I'm afraid. Fourth 'gear' isn't a gear at all really. It's a solid connection of the input shaft to the mainshaft directly through the transmission front to back. A one to one direct drive. Possibly a shift insert has jumped out of place and the synchronizer hub and the coupling sleeve can't slide together.

 

Pull it out I guess and look for another. Maybe it's time for the 5 speed. There were 3 for the A series, 2 doglegs and a regular shift pattern.

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I had a roadster 4 speed get stuck in 4th, There was a half tooth on one of the gears that chipped itself off.

locked it in 4th.

Trying to find pics but no luck yet, Ill post em up if I find them.

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My 521 4 speed wouldn't shift when I pulled off the highway after driving 50 miles. Had to slip the clutch a lot to get home. This was '77 ish. Never fixed it just pulled it and let it sit for three weeks. Found one for $20 already out. I wonder why 4th??? It has the least wear, use and abuse.

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My 5 speed in Smurf got stuck in 4th gear, similar symptoms. It wasn't the transmission, a spring from the clutch hub broke in three pieces, wedge inside the clutch cover couldn't dis- engage clutch. Put side pressure on the mainshaft, wouldn't shift even with the engine off. Had one hell of a struggle just getting the transmission off the back of the engine. Replaced clutch disc and trans worked fine. One for the "sometimes it's just weird" list.

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Does clutch disengage correctly still? If not(cant start engine cause its in gear), that sounds like clutch spring or something wedged between press plate and disc.

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Clutch disengagement or engagement should not affect shifting the transmission into neutral or any other gear with the engine turned off.  Try this. Turn engine off and leave the clutch pedal up. You can still pull the lever out of gear as long as you are not using the engine to hold the vehicle on a grade.

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It must great to be right aaaaaaall the time!

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Thanks for all the thoughts. It will not come out of gearr running or not. Clutch does disengage fine. Had to slip it a lot to get home. I had a clutch facing explode in a Toyota pickup I had swapped a dual cam dual carb 18RG in once. That one happened when I shifted into second, went to hit third and all the clucth material came apart and jammed the pressure plate. Wouldn't engage after that. Thi one is internal for sure.

 

I found a local with a 63A five speed I can get for 350. Problem is the clutch fork exits on the passenger side. I think I could do a longer hose for that, but from what I see on Datsun1200.com I may need an automatic driveshaft. Anyone done this swap that could chime in? I know I'd have to fab a mount. Ain't skeered of that.

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The dogleg is likely 26" long so compare that to what you have. Automatics are usually 26"long as well.

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The 63A is a nice one for the 1200, albeit fairly large for the manual tunnel. There may be some "massaging" involved with a hammer. The clutch disc needs to be changed to the b210 one, which I believe is 1"x24T, 180mm. The shifter should pop up in the shifter hole in the body. The driveshaft can be modded with the yoke from a 510, or similar. just check the free play between the through out bearing and the pressure plate.

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