Automatic Gearbox 3N71B Help

mick280

Well-Known Forum User
Refitted the gearbox after restoring my 280ZX and have no drive in any gear.:confused:
The fluid levels are correct and the gear change is adjusted correctly. The gearbox worked fine before being removed. Using Dexron 2.

Any advice, ideas or suggestions (no I'm not going to convert it to manual, need to keep the auto)?

Or do you have a working auto box forsale?

Thanks.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I'm no expert on this but I'm guessing that the Torque Converter isn't transmitting drive from the engine.

Could it just need priming with fluid?

As I say I'm not an expert.
 

bigblock

Well-Known Forum User
No idea about your model autobox and if following applies,but are you sure you have engaged the torque converter correctly into the box,,,,on the GM turbo hydramatics you have to manipulate and twist the converter to engage input shaft,reaction shaft and oil pump rotors(you feel them click into place in turn),also there can be a delay in getting pressure if the converter is virtually dry(should generally install filled) as mentioned previously about priming.If the converter is correctly fitted i normally just run through the gears with footbrake/handbrake and wheels chocked,i have come across a couple where it has taken a few mins to build pressure.There are many other reasons.
 

mick280

Well-Known Forum User
Thanks for the replies. When the torque converter was installed I checked the installed distance, as per the Nissan quoted figure. I installed the converter dry, so maybe this is the concern. I'm going to remove the gearbox on Monday, check and reinstall as per you suggestions. I'll feedback result. Again, thanks.
 

Northerner

Club Member
H'mmm interesting why did you install it dry? I am also not an expert but the auto's that I have changed, I have filled the TC with fluid which is usually quoted in the manual. Just checking but did you bolt it to the flywheel?
 
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mick280

Well-Known Forum User
All the manuals I have, do not state filling the torque converter before installing. The torque converter could only be half filled at best anyway. Sourced the hydraulic drawings for the gearbox. The outer case of the converter bolts to the flex plate and this outer case also meshes with the pump drive. When the engine is running, the pump primes and fills the torque converter (via the pressure valve). The gearbox is coming out tomorrow, so hopefully should be work ot / correct what is wrong. When the convert is being reinstalled, I'll fill the torque converter as suggested. Fingers cross it's something as simple as that. Want the car on the road ASAP, it's been off for too long!!
 

mick280

Well-Known Forum User
Removed the gearbox and checked torque converter installed distance, manual valve connection, selector adjustment etc, as expected all OK. Checked the flexplate distance from the mounting face, all OK. At this point noticed that the flex plate torque conveter mounting is offset.........Yes I'd installed the flex plate the wrong round, so as the converter was bolted up, it disengaged it from the pump (the difference is approx 10mm). Feel a bit daft but glad it was something simple, and not to expensive. Thanks to everybody for the suggestiions, it kept me motiviated and focused.
 
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