1981 720 budget knuckle dragger.

[wayno]

That looks like a pre 1980 transmission to me.

[datzenmike]

It's very possible it IS a zx 5 speed.... just not a close ratio.

 

'79 280zx was a mid ratio

'80-'83 280zx (non turbo) was a close ratio.

[Thisolddatsun]

Ive heard there's closed and open ratios and the open is more sought after but i might have it backwards

[datzenmike]

Wide ratio has a 3.592 first gear. That's 3.592 engine turns for one drive shaft turn. Very good for multiplying start off torque for a truck with a load and/or small displacement engine. Large drop in engine RPMs per shifts

 

Mid ratio has a 3.321 ratio first gear. Slightly more effort on take off, slightly less RPM drop on shifts. Good for truck with 4.11 or more differential.

 

Close ratio* has 3.062 ratio first gear. More effort needed on take off, even less RPM drop between shifts. Good for lighter vehicles or vehicles with larger displacement like a six cylinder or 2.4 liters with lots of torque..

 

 

*The close ratio transmissions have an insane over drive of 25.5% where most 5 speeds are half this. If your rear end is 3.70 or lower you may find it difficult to maintain highway speeds into the wind or going up hill in a truck. For example if your cruise speed is 60 MPH at 3,000 RPMs shifting into 5th drops it to 2,235 RPMs. Will your engine have the power to drive into a 15 MPH head wind or climb a 5% grade.

[Thisolddatsun]

If it is a mid that will be perfect in my truck as it has 4.11 gears and i didnt plan to change them anytime soon. I will get the info/picture for you soon.

[Thisolddatsun]

Wide ratio has a 3.592 first gear. That's 3.592 engine turns for one drive shaft turn. Very good for multiplying start off torque for a truck with a load and/or small displacement engine. Large drop in engine RPMs per shifts

 

Mid ratio has a 3.321 ratio first gear. Slightly more effort on take off, slightly less RPM drop on shifts. Good for truck with 4.11 or more differential.

 

Close ratio* has 3.062 ratio first gear. More effort needed on take off, even less RPM drop between shifts. Good for lighter vehicles or vehicles with larger displacement like a six cylinder or 2.4 liters with lots of torque..

 

 

*The close ratio transmissions have an insane over drive of 25.5% where most 5 speeds are half this. If your rear end is 3.70 or lower you may find it difficult to maintain highway speeds into the wind or going up hill in a truck. For example if your cruise speed is 60 MPH at 3,000 RPMs shifting into 5th drops it to 2,235 RPMs. Will your engine have the power to drive into a 15 MPH head wind or climb a 5% grade.

Heres a picture for you mike. I couldnt find really any numbers on the side which i found a little odd.

[datzenmike]

Made before 1980, so '79 280zx probably. NOT close ratio as they only came on the '80-'83.

 

To confirm the internal ratios is easy.

 

Place in first.

Mark the input and output splines.

Rotate the input spline exactly 20 times.

Have a helper count the output turns.

 

Wide ratio 3.592 first gear................. 5.5 turns. Used in the '79 620 and '80 2wd 720

Mid ratio 3.321 first gear.................... 6.0 used in the '77-'78 620, '77-'78 280z, '79 280zx, '77-'79 810

Close ratio 3.062 first gear................ 6.5 used in the '80-'83 non turbo 280zx

[Thisolddatsun]

Made before 1980, so '79 280zx probably. NOT close ratio as they only came on the '80-'83.

 

To confirm the internal ratios is easy.

 

Place in first.

Mark the input and output splines.

Rotate the input spline exactly 20 times.

Have a helper count the output turns.

 

Wide ratio 3.592 first gear................. 5.5 turns. Used in the '79 620 and '80 2wd 720

Mid ratio 3.321 first gear.................... 6.0 used in the '77-'78 620, '77-'78 280z, '79 280zx, '77-'79 810

Close ratio 3.062 first gear................ 6.5 used in the '80-'83 non turbo 280zx

Mike it is a mid ratio 280zx transmission also the bearings were the same so the transmission went right together no problem. working on posting a update here in a few

[Thisolddatsun]

Alright so I polished my crank and reassembled the z24 no I didnt send it in for machine work I used 320 grit emery cloth. used a scotch brite type pad to clean my head and headgasket and threw a new set of rods in. I also swapped bellhousings on the wide ratio 280zx transmission I have bearings were all good and the same size and it went together no problem. heres pictures now. all thats left to do involves rolling the truck in and putting it all together.

[Thisolddatsun]

Alright shes back together clutch pedal in. Running and timed. Waiting to see if she drives and finishing up the exhaust system. Electric fan wired up. Working on photos cause im to excited to have her running again killed the starter then got a new one and shes on the spot with timing and all. Carbs tuned. Cant wait for the drive. 6 months later since i spun the rod. now thats something i can drink to. No i didnt pull the dash to swap pedal assemblys. It wasnt easy but i pulled the rod and swapped the pedals/rods out.

[Thisolddatsun]

Shes running and moving under her own power. I have a starting issue im working with but she runs great hit the rpms just right and she had that perfect sound manual transmission is in and going i couldn't love this truck anymore than i do now. The feel and everything ooh baby shes going good just a few things to work out now.

[Draker]

Nice work man!

[Thisolddatsun]

Nice work man!

Thank you very much. Bled my brakes and coolant system some more today drove it to work. Ive got a mystery starting problem new starter but sometimes it takes a couple trys to start it got the speedo working again. Now its just a matter of tuning and and what not.