Almost everything is going good on my first 12 miles! Other than small issues my total rebuild of everything and anything mechanical is going great!

When I decelerate in third gear it pops into neutral, I can hold it in 3rd with slight pressure,

Suggestions?

Thanks in advance

What transmission?

C

In the main plate of your gearbox are some bolts hiding a spring.. these springs hold a ballbearing in place witch are holding your gears in gear..

 

(Sorry if its bad english)

 

You have to place new springs or.. lengten those springs just a little.. you will see that if you have lengten them your gear will stay IN gear!  (Unless there is a lot of shaking going on.. instability in your drivetrain..

 

fwiw..

Mart

And the mainplate is that steelplate halfway your gearbox.. if you were wondering were that thing is!

It would help if you mention what model transmission you have and what you have done to it.

Like Martzedcars mentioned its most probably your 3rd, 4th detent spring in the adapter plate. There are three of them, one from the top and two from the side. The one you need to look at is the top one of the two side detents.

The springs are still available through Nissan (P/N: 32830-20100) and you can order all thre for less than $1.00. Most people don't replace them during a rebuild, but iss a very small price to pay to improve shifting.

 

While you are at it you may want to consider changing the centering detent springs. There are two, one fits inside the other. Its the detent that returns the selector to the 3rd - 4th line when you push the gate other to 1st - 2nd or to 5th - Reverse.

Inner P/N: 32852-24901

Outer P/N: 32856-24901

 

Gear selector bushing set

2x P/N: 32855-H1010

1x P/n: 32861-N4200

 

Chas

 

 

Great info, thanks guys! The car is a 1971 240Z, I did not go into the transmission when I rebuilt the car. Tell me where to look (on the transmission and on the pictures) to determine the model. Can any of these adjustments / repairs be done while it is in the car or do I have to pull it?

Eric

Your transmission, if still the original type, could be a F4W71A or the F4W71B 4 speed. The "early" 240Z (pre 09/1971) had the Type F4W71A and from 09/1971 they changed to the F4W71B. You can tell them apart by looking at the bell housing. The Type A has a seperate bellhousing (3-piece transmission housing) and the Type B has a two piece housing where the bell housing and front section are one piece.

The Type A also has the clutch fork with the return spring and adjustable slave cylinder pushrod. The selector is also very different from the later versions.

All this is nice to know, but the springs for the selector detents are all the same. You can access the springs from under the car. A 14mm spanner or socket set for the three detents in the adapter plate. The top one is hard to get at and you might need to drop the transmission mount a little to give you better access.

The centering detent needs a 19mm spanner.

The selector bushes are only for the F4W71B version. The A is different. To do the selector bushes you will need to remove the center console.

Here are some links to the online parts manuals for the 240Z and Courtesy Nissan to check availability.

http://www.carpartsmanual.com/datsuns30/DatsunZIndex/PowerTrain/tabid/1547/Default.aspx

http://www.courtesyparts.com/

And some more photos that might help.

Chas

Edited March 30, 20159 yr by EuroDat

WOW! Great info, I have the 3 piece transmission (2-71 man date on my 240), I am a little confused on where exactly  I have to go on the tranny , what I need to remove and what parts I will need to remedy the popping out of 3rd problem. 

For me (and the other non transmission savvy people) please go through the procedure and part numbers step - by - step

and what to expect. Thanks so much, I'm a aircraft mechanic and I get questions like this all the time, a clear, concise picture really helps to do the job correctly, the first time.

Eric

Are you using a phone and can't see the pictures and drawings?  I don't see how an airplane mechanic could not be able to get this done with what he's provided.

 

Here's a link to several Factory Service Manuals.  Open any Transmission chapter from any year, up to 1984, and you'll find many more excellent pictures.

 

http://www.nicoclub.com/datsun-service-manuals

 

 

Just saying - EuroDat laid it out on a platter with some nice garnish, and now you're asking him to cut it up and feed it to you.  Seems a little much.

Edited March 30, 20159 yr by Zed Head

Im not sure whats not clear. If you follow the manual and you should be fine. The manual describes it with the tranny out of the car, but you don't have to drop the transmission or drain the oil. All three detent springs are acessable from the passenger side of the transmission. Its the metal plate where the front and rear transmission housings come together. 

If you climb under the car and look just forward (6 inches) of the transmission mount you will see them, two on the side and one from the top. Unscrew the caps, remove the springs and catch the balls when they fall out. It may leak a little oil, but not much. The springs won't shoot off anywhere, but if you are outside on the ground you use a blanket or something like that to help find them if the fall on the ground.

 

One last photo of a FS5W71B, but the detents are the same.

 

Chas

This is for EuroDat, thanks very much for your help in resolving this problem I'm having, your help (without berating me)  has been very helpful. 

As I understand it I have a F4W71A type A 4 speed

I understand that the three caps that I need to remove to gain access to the detent springs are on the right side of the tranny (2 on the right side, 1 on the top).

The springs (P/N: 32830-20100) are available for 58 cents a piece from Nissan.

I'm assuming all 3 (one for 1st and 2nd, one for 3rd and 4th, and one for reverse) are the same P/N

Would you recommend replacing all three, or just the worn one?

The only figure (TM-14, labeled, Inter Lock Balls and Check Balls) that i find in the service manual is not very clear where the springs are.

Is there another figure that shows them more clearly? Or can you help me out as to their location?

Again, thanks for your help, I hope to have many years of enjoyable motoring in my Z.

I would do all three. Go all out and spend the $1.74 :: The springs and balls are all the same, you caný mix them up. It won't take much longer, maybe 10 - 15 minutes. You will probably spend more time jacking the car and putting it on stands then changing the springs.

 

Forget the interlock balls. You can't get to them anyway without dismantling the transmission and selector rods.

Btw: Its hard to stuff this up other than throwing the all parts in the bin and driving it without them. Even then it would just pop out of gear more often and every now and then drip a couple drops of oil.

 

If its still worrying you, just have a couple of beers and go for it

 

Sketch with springs coloured red.

Chas