Reverse Lock Out In A Five Speed

[RLJ]

What Datsun five speed transmissions with the standard gearshift pattern(5th above reverse) had a reverse lock out so you couldn’t grab reverse when downshifting from fifth?

Did the close ratio gearbox have this feature?

Seems the early five speed gearboxes didn’t have this feature. 

[datzenmike]

L series or all Nissans?

 

L series...

'80 810

'81-'84 Maxima

'80 720

'80-'83 non turbo 280zx

 

Other

All 720 Z series and SD diesel engines

All S110 200sx Z series engines

All S12 CA series engines

[RLJ]

L series

Do all the close ratio five speeds have it?
80-83 non turbo 280zx is close ratio?

[RLJ]

What’s your thoughts on running a close ratio gearbox in a 510 with an L20b that’s 2.3 displacement?

Torn between which five speed to run.
Like the thought oh the lower ratio fifth in the close ratio but wonder on normal street drivability. Referring to the spread between fourth and fifth. Never drove a 280zx with one to have any feel for it

[datzenmike]

All close ratio boxes have the reverse lock out called the reverse check sleeve.

 

A close ratio box has a first gear closer to 4th gear than a mid or a wide ratio, thus on take off it's more like starting in second gear. This is extremely exaggerated of course. A mid or wide ratio box has more turns of the engine in first, second and third so torque is multiplied more making take offs easier and acceleration faster. The close ratio box was used on the zx because the engine is much larger displacement, higher HP and torque and can make use of it.

 

Now, having said all this, the 510 has one good advantage over most Datsuns, it's light weight, at around 2,100-2,200 pounds. Putting a close ratio box in my 2,700 pound 710 would not be a good idea. Your engine choice is another, it has more displacement and torque to go along with it.

 

While most over drives are 12%-18% the close ratio is a massive 25.5% making 5th almost exclusively useful only out on the highway. If you drive only around town it won't get much use.

 

 

 

[RLJ]

Good clarification Mike. 
 

Thank you!

[RLJ]

What was the horsepower and torque difference between a 280z and a 280zx? Reading specs on the web they’re stating the zx had less horsepower and torque. 
Both models are 2.8 liter fuel injected. Confusing 

Is it safe to say the 280z could have run the close ratio box also?

[datzenmike]

At one time the engine was rated 'gross HP'. This was measures at the crankshaft and in later years during the horsepower wars where everyone was claiming to have the most, often parasitic losses were removed such as the alternator and water pump even the exhaust manifolds were replaced to improve the numbers over the completion.  Eventually this was changed to the more believable NET HP numbers using real world engines in the vehicle with all drive line losses included. My '76 L20B says 110 HP but my '78 L20B was 93.

 

The difference is very roughly 17%. If you have a gross hp number just multiply by .17 to get an approximate NET hp rating.

 

Early 240z engine were rated at about 150 gross hp. 150 gross x 0.17 = 24.65. 150- 4.65= 124.5 NET

The much later 280zx was about 145-ish NET hp