'78 280Z 4-speed odd transmission issue - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 26 (permalink) Old 06-11-2016, 10:52 AM Thread Starter
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'78 280Z 4-speed odd transmission issue

This one has me stumped. The 4-speed manual will go into reverse with a slight bit of effort, but it loads up the engine against the transmission as if there's something like a brick or a chock under the wheels. It does not roll backwards. It is like a trans-brake if anyone has ever used on at a drag strip where the transmission goes into forward and reverse at the same time so you can load up the engine rpm's without launching.

Clutch seems to be fine as it will go into first and move forward with zero drama.

Any ideas?

I'm based in Houston so I'll need to figure out who can work on a 4-speed here. I can pull it and reinstall it, but I'll do nothing but butcher it if I take it apart. I used Kin at Reliable Dependable Auto Repair last time. Nice guy, but I never got an estimate and when I picked the car up it was quite a bit more than I expected. Probably a communication issue more than anything.

HS
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post #2 of 26 (permalink) Old 06-11-2016, 11:55 AM Thread Starter
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I'd put the car in neutral and rolled it last night. So this morning I rolled it out of the garage....viola. Problem is gone. Weird.

Drove it several miles and grabbed some donuts for my boy and his friends that slept over (holy crap maple bacon donuts are unbelievable). Zero drama.

vroom vroom....

HS


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post #3 of 26 (permalink) Old 06-11-2016, 12:34 PM
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Sounds like you had it in reverse and a forward gear at the same time. I do not know if that is even possible (or not) on your transmission, just a thought. Or it could have been something jammed in the gears. In any case I would pull the drain plug and see if there are metal chunks on the bottom of the case. If not new lube may help it shift easier.

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post #4 of 26 (permalink) Old 06-11-2016, 12:40 PM Thread Starter
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Sounds like you had it in reverse and a forward gear at the same time. I do not know if that is even possible (or not) on your transmission, just a thought. Or it could have been something jammed in the gears. In any case I would pull the drain plug and see if there are metal chunks on the bottom of the case. If not new lube may help it shift easier.
I guess that's possible, although I was able to put it into first and move it forward easily, but it sure did act just like a trans-brake and that's what a trans-brake does so you may be right.

Good call on checking the fluid. I'm due for an oil change so I might as well go through all the fluids.

Thanks for the response!

HS


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post #5 of 26 (permalink) Old 06-11-2016, 04:52 PM
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have you checked the drain plug lately for metal? Maybe something got loose and hung up in the reverse gear.
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post #6 of 26 (permalink) Old 06-11-2016, 05:41 PM
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When you say "loads up the engine" do you mean the RPM drop? Since the clutch is disengaged, there's nothing to load against. All that's left is internal drag. Could be that one of your reverse gear shafts is binding, maybe a bearing failed or is failing.
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post #7 of 26 (permalink) Old 06-11-2016, 10:51 PM Thread Starter
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have you checked the drain plug lately for metal? Maybe something got loose and hung up in the reverse gear.
I have not but will go through all the fluids.

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When you say "loads up the engine" do you mean the RPM drop? Since the clutch is disengaged, there's nothing to load against. All that's left is internal drag. Could be that one of your reverse gear shafts is binding, maybe a bearing failed or is failing.
Yes...there clearly was drag and it was solid...full bind if that was the case. Literally like a trans-brake...forward and reverse at the same time. Without gas, engine dies. Give it throttle and it was as if the bumper was up against a brick wall.

I rolled the car backwards a few feet and viola...no issue. That's about what I know at this point. Drove the car around this morning without issue, but it is bothersome so I'll check the fluid to be sure there's no bits floating around.


Thanks for posting, gents.

HS


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post #8 of 26 (permalink) Old 06-11-2016, 11:31 PM
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I would stop thinking in terms of "transbrake". It's a manual transmission. When the gears are engaged the only thing stopping the car from moving is the clutch. Which is disengaged when you press the pedal. So if your clutch is working correctly the engine and transmission are completely disconnected from the differential. Completely.

Not even sure what you mean when you say "Give it throttle and it was as if the bumper was up against a brick wall." Is this with the clutch engaged? That sounds more like clutch slippage. Or are you giving it throttle with the clutch pedal down? If the pedal's down, where does the brick wall come in, since you shouldn't be expecting to move anyway? If you mean that you have to give it throttle n reverse to keep the engine running, that sounds like internal drag. Something's wrong in there. Not clear what "full bind" means either.

p.s. A viola is a string instrument.
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post #9 of 26 (permalink) Old 06-12-2016, 02:35 AM Thread Starter
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I would stop thinking in terms of "transbrake". It's a manual transmission. When the gears are engaged the only thing stopping the car from moving is the clutch. Which is disengaged when you press the pedal. So if your clutch is working correctly the engine and transmission are completely disconnected from the differential. Completely.

Not even sure what you mean when you say "Give it throttle and it was as if the bumper was up against a brick wall." Is this with the clutch engaged? That sounds more like clutch slippage. Or are you giving it throttle with the clutch pedal down? If the pedal's down, where does the brick wall come in, since you shouldn't be expecting to move anyway? If you mean that you have to give it throttle n reverse to keep the engine running, that sounds like internal drag. Something's wrong in there. Not clear what "full bind" means either.

p.s. A viola is a string instrument.
I owe you a thanks on two counts: 1) for the definition of what a manual transmission is and how a clutch functions, as well as, 2) how to spell.

This is the triple disc carbon carbon clutch we installed in my challenger. It only puts down about 1100-1200rwhp in TT trim so please be patient with me so I can keep up while I'm getting a lesson on how to work on and drive a stick car.



Secondly, spell check is a real bear. A little tolerance goes a long way, chief.

To be crystal clear...foot off clutch, rpm's well over idle....the engine was loading the drivetrain with the shifter in the reverse position and the car did not move. There was load on the motor.

I've been on an american muscle car forum that's a tough place for several years now. My skin is thick. I find guys that post like you do are very different when in person at the track and in front of me.

HS


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post #10 of 26 (permalink) Old 06-12-2016, 12:54 PM
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They're just jokes. I'm the same in person. Your skin is thinner than you imagine. Get over it. Don't give a squat about your "muscle" car experience. Good luck.
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