Datsun 5-speed 5th to reverse lockout?

[cygnusx1]

Every trans that I have had so far had a lock out for reverse gear, where you have to pass into neutral before you can get into the reverse fork. This used trans that I just installed is allowing me to go from 5th to reverse. Mind you, I haven't driven it yet and it has been sitting for many, many years. The old oil was clean but the trans was very gunky and the shifter was "sticky" until I cleaned it and lubed it from the outside. With the car on stands and running, I ran it through all the gears, and it seems very smooth and quiet. I think it's a solid trans, other than the lockout.

 

I can't remember if the trans has a "rocker" gate inside or is the lockout done with the ball-detents? It may start working again after I put new oil in the trans and drive it a little. Could it simply be sticking from sitting for so long?

Edited March 27, 2012 by cygnusx1

[NewZed]

What year car is the 5 speed from?

 

I had a 78 5 speed transmission with a similar problem. I posted a question about it on the forum, about 2 years ago, but got no responses. An 83 I had and the 80 transmission I'm using now both have firm reverse lockouts. The 78 had essentially no resistance from 5th to reverse, just dropped straight down if I wasn't careful. I've seen some comments around the various forums about improvement in the lockout in the later 5 speeds, but don't know the details of the improvements.

[cygnusx1]

I am not sure about the year of the trans but I assumed it was from an S30, based on some of the features, compared to the other later one's I've had..

[NewZed]

The early/late 5 speed pictures are at the bottom of this link - http://www.geocities.com/inlinestroker/ratio.html

 

You might be able to figure something out from the FSM deawings.

[HowlerMonkey]

I seem to remember my buddy had a brand new 280zx in 1979 and hearing him catch reverse for a second as he removed it from 5th.

 

From that, I will guess the early s130 did not have lockout.............or my friend was truly a bad driver.

[cygnusx1]

It's an early model.  My other early 5-speed has a definite lock-out.  You cannot go from 5 to R without dipping into neutral first.  I seem to remember from 20 years ago that there was a rocker type of mechanism inside the trans that achieved this.  I looked at the exploded views in the FSM already and can't seem to be able to visualize the part I was thinking of.  Maybe it was a different trans.  If it's the detent balls that achieve the lock-out, I may be able to fix it without pulling the trans back out.

 

 

 

 

Thanks for that link!

 

 

Edited March 27, 2012 by cygnusx1

[NewZed]

You're welcome, and good luck with it.

 

After looking at the drawing again myself, I would vote for a weak reverse return check spring. "Return check spring" must mean something. I have the 78 5 speed out now and will probably take that plug out tonight and see how it looks.

 

Edit - I was looking at the 4 speed drawing (1978 FSM has both). On the 5 speed it's just called the return spring plug. But they're in the same spot, so probably have a similar function.

 

Edit 2 - the return spring plunger just re-centers the striking assembly. The plunger rides in a groove on the striking rod, the plunger is pushed out of the groove against the spring when the striking rod is rotated as the lever is pushed left or right. No direct effect on reverse, except that with a light touch it will pull the lever back to the center. No lockout effect though. Out of ideas.

Edited March 28, 2012 by NewZed

[cygnusx1]

You're welcome, and good luck with it.

 

After looking at the drawing again myself, I would vote for a weak reverse return check spring. "Return check spring" must mean something. I have the 78 5 speed out now and will probably take that plug out tonight and see how it looks.

 

Edit - I was looking at the 4 speed drawing (1978 FSM has both). On the 5 speed it's just called the return spring plug. But they're in the same spot, so probably have a similar function.

 

Edit 2 - the return spring plunger just re-centers the striking assembly. The plunger rides in a groove on the striking rod, the plunger is pushed out of the groove against the spring when the striking rod is rotated as the lever is pushed left or right. No direct effect on reverse, except that with a light touch it will pull the lever back to the center. No lockout effect though. Out of ideas.

 

 

 

 

Yeah me too. I saw a photo of a 5 speed taken apart and noticed a brass thing-a-ma-jig that hooked onto the selector rods. It looked like what I remember from rebuilding a transmission years ago. I had rebuilt an early 80's 200SX unit for my Z. I seem to remember that placing the shift lever into 5th caused a rocker to swing in the way of the 5-R selector rod so that it could not move into R. When dipping the shifter into neutral, that part would swing back out of the way. However...I don't see that part in any of the transmission diagrams for S30 or S130. Baffled...I may have to take this thing apart.

 

 

 

[cygnusx1]

After some research:

 

77-79 - no lock-out from 5th into R

 

80-83 - mechanical lockout from 5th to R

 

 

[duragg]

I've rebuilt a 1977 5 speed and a 1983 5 speed and I recall them both having the little cam to help prevent nicking reverse. But it can still be done if you are determined.

 

The lockout cam is hard to figure out which way it goes together. When I rebuilt my 83 5speed last year I took pics of this exact part to verify. I have them somewhere if you want.

 

Also have pics of the 77 I can dig up from somewhere.

[duragg]

Its a fitting into the right side of the case if I recall with a spring and funky cam thing that only works one way.

[cygnusx1]

If you can find a pic post it. I am curious. I remember something similar when I rebuilt a 200SX transmission a looong time ago. I have asked a few people that are running S30 5-speed units to test 5th to R for me and they can go straight down into reverse, like mine.