Roadster transmission vs. Z transmission

[Pir0San]

I have been looking for a short throw shifter for the F4W71-A transmission, and so far, no Z shops sell a short throw shifter. I was searching on ebay once, and I noticed that the transmission in the datsun roadster looked very similar to the type a in my Z, and there were short throw kits for the roadster. Does anyone know the difference between the two, and if they'd work the same?

[Ron Carter]

Jeremy,

There are several types of transmissions for Z cars and Roadsters but to simplify this regarding this discussion there are "A" series transmissions and "B" series transmissions. There are plenty of short shift kits for the "B" series box. And nothing really available for the "A" series box. Most roadsters came with an "A" series box so a "short shift kit" doesn't really apply, I suspect that you are looking at a set of aluminum shift bushings that do not effect the shift pattern.

From the identifier you gave it sounds like your Z has an "A" series transmission. If you were to install a "B" series transmission there would be solutions out there for a short shifter....

Now that being said, there is not much benefit to a short shifter in a Z it can make the car much harder to shift because of a significant change in geometery of the shifter...again this is a preference thing. I had a short shifter on one of my 5 spd "B" boxes and never really liked it...I actually wound up taking it off in favor of a shortened shift lever that accomplished almost the same thing.

I hope this helps.

[Arne]

Ron is right, the "A" box has all the moving parts of the linkage built in to the transmission tail housing. It is impossible to design a short shifter for this without designing a replacement for the tail housing.

But on the other hand, your sig mentions that your car is a '72. I was pretty sure that by that time Datsun had switched over to the "B" transmission. Are you certain you have an "A" box?

[jmortensen]

There are several types of transmissions for Z cars and Roadsters but to simplify this regarding this discussion there are "A" series transmissions and "B" series transmissions. There are plenty of short shift kits for the "B" series box. And nothing really available for the "A" series box. Most roadsters came with an "A" series box so a "short shift kit" doesn't really apply, I suspect that you are looking at a set of aluminum shift bushings that do not effect the shift pattern.

That's odd. I had 2 "roadster" transmissions at one point and gave them to a friend. Actually what I had was the guts, I had no cases. One had a slip yoke type driveshaft and the other had a 2 piece with an output flange that was attached to the end of the main shaft. They both had steel synchros. He put the close ratio gears (they did match the roadster gear ratios for the close ratio box) on the slip yoke style main shaft and put that into a 280Z 5 speed case and then used a regular 510 driveshaft to put it in his 510.

I know that's all a little confusing, but the point is that I had been under the assumption that the roadster trans had the same internals as the "B" trans, and that this meant that they were the same. Maybe the internals are the same on the "A" and "B", but the shift linkage of the A and B is what is different. Doesn't seem right, but that's the only conclusion I could get out of this.

I am running a truck shifter (which apparently is the same as a 4 speed shifter) in my 5 speed and it shortens up the throw nicely. I also have shortened the shifter to about 7.5" from the pivot to the top of the shifter. This gives about a 4" throw from 1st to 2nd. Not sure I'd want it much shorter than that. MSA makes a short throw shifter that is WAY more drastic than the truck shifter. Raises the pivot about an inch, where the 4 speed shifter raises the pivot about 1/4". Seems like too much to me, but I haven't actually tried it.

[jmortensen]

Here's a way too drawn out discussion of short throw shifters in which I learned that the 4 speed and truck shifters are basically the same. The one mod I would do is to raise the pivot hole on the shifter if you can (depends on the ears for the particular case that you have). That prevents the shifter from hitting the edge of the shifter hole as discussed at the end of the thread. Even after all that extended discussion I still wouldn't bother with the aftermarket short shifter, but it is to some degree a matter of taste.

http://forums.hybridz.org/showthread.php?t=96707

[Ron Carter]

JM, sounds like you might have had an early nissan comp box with steel syncros.

I have a "B" box, steel synco trans with the a long tailshaft and output flange for a two piece driveshaft. The gear ratios are the same as a medium close roadster box. Explain that one!!

Like I said there are some odd ball transmissions running around out there but the basics are included in my post above....

Jeremy, the designation -A at the end of your transmission model number number indicates that it is an early style "A" box, which could have found its way into your car if it is a really early 72 or it if it had been replaced at one point.

As far as the truck shifter, thats a really good idea...I will have to file that one away into the memory banks :) thanks JM

[jmortensen]

I have a "B" box, steel synco trans with the a long tailshaft and output flange for a two piece driveshaft. The gear ratios are the same as a medium close roadster box. Explain that one!!

Is that the one with the 2.9 or 2.8:1 1st gear and the .8 OD? Because that's what I had.

[Ron Carter]

Yes, that would be it...I have only seen 3 of these transmissions ever! They are the early Japanese comp box pictured in "how to modify your datsun" pp148 of the old book.

[jmortensen]

Interesting. In the little bit of exploring I did into the roadster trans, I thought I had one of each of the ones that came with steel synchros (were those in the 2000???). There was one with the slip yoke that had a 3.3:1 first and .8 OD, then the other one.

[Pir0San]

actually, I've already done research into the difference between the type "A" and type "B" Z transmissions, and I actually have at least one of each. I had the original type "B" in my 72, until I decided that speed shifting was pretty cool, and I destroyed the transmission. It made a horrible noise when it died...but I ended up getting a rebuilt type "A" from a marine down at camp pendleton, and the transmission is excellent. Doesn't seem to have any of the notorious slop that I have heard that the "A"'s have, which would indicate at least new bushings in the shift linkage.

That was over two years ago that I swapped the transmission for the type "A", and about 6 months ago, I was given a spare 240Z block (which is in my Z right now, with 2 bad oil control rings) and two type "B" transmissions.

As for the short shifter, I had seen around the net somewhere a shorter shift lever, as well as bushings and such for the Roadster, and the kit looked like it was very close if not an exact match for the shift lever on my type "A" transmission.

On a side note, I was thinking that I might be able to modify the shift lever itself, in order to give it a shorter throw. I was thinking about removing an inch or so on a donor shift lever, bolt it onto my transmission, and see if my throw is shorter. I'm imagining that if the shifter length is reduced, the throw will effectively be reduced due to a shorter pivot point, if that makes any sense.

[Ron Carter]

Hey JM we should probably take our conversation off line as we are hijacking this thread....

Jeremy, effectively shortening the length would work... and your trans that died, well you probably broke the shift fork and lunched the transmission...If it was a late 5 spd some of them have aluminum shift forks and can break very easily....not a good idea to speedshift!

If you are looking for a transmission that can handle that abuse I would suggest finding a comp "B" box and have the shift forks double pinned to handle the strain...

R

[Pir0San]

Hey JM we should probably take our conversation off line as we are hijacking this thread....

Jeremy, effectively shortening the length would work... and your trans that died, well you probably broke the shift fork and lunched the transmission...If it was a late 5 spd some of them have aluminum shift forks and can break very easily....not a good idea to speedshift!

If you are looking for a transmission that can handle that abuse I would suggest finding a comp "B" box and have the shift forks double pinned to handle the strain...

R

Ron, you and JM don't have to take your conversation elsewhere, because when it's in a forum we can all learn :classic: . It was the type "B" 4 speed, and it made a horrible whining noise and would grind like nothing else. I ended up limping it to a friend's house, where it was leaking like crazy. When it was engaged in gear, it sounded like you could hear something smack against the inside of the gearbox. I never knew I could kill a transmission like that...