4 speed vs 5 speed info?

[Pop's Z]

A couple of thoughts: I put a 5spd from a Maxima (same as a '81-'83ZX) in my '73 and also put in an R180 diffy from a 200SX (4:11-1). I bought a red pinion gear to match the rear end from Oliver at Z Specialties and I had to rotate the pinion housing 180 degrees and cut a new slot in it with my Dremel to secure it for the pinion to engage the drive gear inside the tranny. I did NOT have to make any cuts in the trans tunnel for the shifter to clear (I believe that is only required for early series 1 cars). I used the shifter from my 4spd. I am running 205-60/15 Bridgestones on 15X7 Rota RBs and my speedo is accurate. It has been a very successful swap, fairly easy to do and a lot of fun in the canyons around northern Colorado.

Cheers, Mike

[Carl Beck]

Chris is using the wrong word for the speedo drive gear. The pinion gear is in the rear diff and is a major event and you do not want to fool with it at all at this time.

Well - one "pinion" gear is in the differential.

Item #58 in the below Parts Catalog Page is "Assembly - Pinion Speedometer" Item #65 is the Speedometer Drive gear.

While the speedometer pinion gears, no matter how many teeth are all the same in both the 77-80 and then 81-83 transmissions. There are two slightly different "assembly sleeves" used, between the two types of transmisisons. See Item #59 in the diagram..

FWIW,

Carl B.

[sblake01]

The overthinking that takes place in these threads can be quite entertaining...........

[IdahoKidd]

The overthinking that takes place in these threads can be quite entertaining...........

Roger that!

At my house, when one starts talking about changing rear end ratios and then brings up the pinion gear, it is assumed that it is in the differential. I didn't want the poor fellow to think he had to change the pinion in the diff to get his speedo to work out correctly. One never knows what background the poster might have or what mechanical aptitude may be there.

On the other hand, if it is on the internet, it must be true!

[Walter Moore]

Apparently the "correct" speedometer gear depends upon both the differential and the speedometer. The factory service manual for the 1971 240Z shows a 17 tooth gear for the 3.364 differential and a 19 tooth gear for the 3.9 differential.

The P.O. of my car had installed a 16 tooth gear when they put the series B transmission in it, and the speedometer was way off. After checking the FSM I bought and installed a 17 tooth gear, which brought it back into calibration.

[Jetaway]

Chris is using the wrong word for the speedo drive gear. The pinion gear is in the rear diff and is a major event and you do not want to fool with it at all at this time.

Keeping the speedometer correct

Everyone gets confused about how to calibrate the speedometer after swapping differentials, it's actually very easy. The speedometer is metered by a plastic, toothed cog on the end of the speedometer cable that screws into the transmission. This cog is paired with the differential, not the trans. So it doesn't matter which trans you have, all you do is select the proper cog for the rear-end ratio you have in the car. While they are colored for easy identification, the Nissan dealer only has them in their parts list as "17, 18, 19, 20, or 21" tooth cogs.

(Above edited)

I used the term pinion gear because that's what my 1971 240Z Autobook manual used and it had been referred to as such in earlier posts. Perhaps I should have used "speedo pinion gear" to eliminate confusion.

The original question was about swapping a transmission, not a differential. While you are correct in that the "plastic, toothed cog" (aka speedo pinion gear) is paired with the differential, that pairing refers to the factory installed transmission and differential (or otherwise correctly paired tranny / differential). However, when the transmission is changed, it is no longer the same pair and a speedo pinion gear of the correct ratio will need to be installed in the transmission.

I'm sure you know this. But approaching this as someone with relatively little experience (which I am) and assuming the same of the original poster. I can easily see how the your first two sentences after "Keeping the speedometer correct" could lead one to conclude that no change in the speedo pinion gear is needed after a tranny swap. After all, the differential didn't change.

I may well have been incorrect when I said to take the pinion gear from the 4 spd and put it in the 5 spd. For all I know, the fit is different, so that wouldn't work. The color (# of teeth) put in the 5 spd. should be the same as that of the color currently in the 4 spd., however.

Chris

[Carl Beck]

Apparently the "correct" speedometer gear depends upon both the differential and the speedometer. The factory service manual for the 1971 240Z shows a 17 tooth gear for the 3.364 differential and a 19 tooth gear for the 3.9 differential.

The Parts Catalog shows:

up to 10/71 = 17 teeth 3.36

11/71 to 11/74 = 16 teeth 3.36

12/74 280Z forward = 17 teeth 3.54

FWIW,

Carl B.

[tlorber]

Chris, just to clarify, changing out just the tranny does NOT require a different speedo gear than the original one. In fact you would WANT to use the original one. However, as you alluded to, the manufacturer paired the trannys and the diffs together so as to provide cars that would launch off the line adequately but not have to over-rev on the highway.

Changing one of these two components (tranny for example) does not MANDATE that one must change the diff to compensate for the different gear ratios, but one would probably want to. It is at only at this point where the speedo gear needs swapping.

[72240Z]

Ok, aside from the speedo gears, to get back to my question, how do I identify a 5 speed? Obviously i'ts going to have 6 possibilities for the shifter to move into. I'm likely to scrounge up one buried in somebody's garage along with other piles of car parts. I don't have my 4 speed sitting here to compare it to. Are there numbers stamped on it or cast into it?

Devin

[Jetaway]

Chris, just to clarify, changing out just the tranny does NOT require a different speedo gear than the original one. In fact you would WANT to use the original one. However, as you alluded to, the manufacturer paired the trannys and the diffs together so as to provide cars that would launch off the line adequately but not have to over-rev on the highway.

Changing one of these two components (tranny for example) does not MANDATE that one must change the diff to compensate for the different gear ratios, but one would probably want to. It is at only at this point where the speedo gear needs swapping.

Different issues. Four and five speeds (and different five speeds, apparently) came with different rear end ratios and different speedo pinion gears keyed or matched to the rear end ratio. If you are going from a 4 spd. to a 5 spd. you'll need to remove the speedo pinion gear from the 4 spd. and put it in the 5 spd. to keep the speedometer accurate (assuming it physically fits, otherwise the same color gear for a 5 spd.) Maybe just semantics, but in this case, from the perspective of the the 5 spd., it would have a new / different speedo pinion gear, but from the perspective of the car body (or rear end) it would be the old / original speedo pinion gear.

You've brought up the issue of overall multiplication ratios. I have a 1972 with the original (4 spd.) differential but a 5 spd. from a 280 ZX (don't know for sure which version of the 5 spd., but suspect the earlier version based on Idahokids description of the 2nd to 3rd gap and relatively small rpm drop going from 4th to 5th). It still makes for a very long legged car, pulling barely 3000 at 70 mph. Yes, it is a bit sluggish off the line, but somewhere during the previous 30 years dropping a drive line went from an amusing story to share with friends to a flat-out PIA, so it doesn't bother me much. OTOH, Smiling Jack is out there hammer and tong on my 75 mile (one way) work commute and I suspect that some of his strong punch when launching from 50 mph to 70 mph is due to the tall gearing. And, I've got to admit, I love ramping up and then maintaining a closing rate of 2-3 mph on the speedy boys (especially pickup trucks) who passed me on the flats while cranking over the Altamont. I know, its semi-evil and somewhat immature, but I get a kick watching them try to rebrake and go with me, but quickly run out of revs on the downshift and simply don't have the power to keep up in a higher gear. Yeeeaaahhh buddy, I'm doing 80 and at 3400 revs, I'm just getting into the power curve.

So ... you may want to swap in a higher numerical rear end. Or not. It depends on your driving style and usage. With my long commute, I'll take the better gas mileage, lower engine wear, and high speed kick that comes with a tall geared car. OTOH, if I could walk to work, I'd probably be looking for limited slip 4.XX+ differential.

Chris

[Racer_Z_]

I skimmed, but did not study each reply. In your OP (original post) you asked about gear ratios and fitment. I saw some good links to places I had been before. Good reading there. I saw some other good inputs as well.

The 4-speed and 5-speed from the 240, 260 and 280 Z are interchangeable with no modifications needed. The B/W (Borg Warner) 5-speed used in the later turbo's will fit with some modification. The B/W is a heavy unit and the weight should be taken into consideration.

The gear ratios the 4-speed and 5-speed are the same (B/W excluded). The difference is that the 5-speed has an OD (overdrive) gear added to it. The first four gears have the same ratios. Fifth is an OD. This is a good thing on the highways.

There are two versions of the 5-speed that will fit with no modifications. There is a minor, and I mean minor, difference in the gear ratios. For street purposes it hardly matters and you will probably never notice the differences.

Because the only real difference between these transmissions is the OD, it's not a necessary change. If your old tranny is worn out and you're looking to replace it, then it might be something to look into. Keep in mind that a used 5-speed is about $500 while the 4-speed is $50.

We rebuilt our 4-speed for about $150.

The other thing that seems worth noting is the shifter bushings. The shifter has bushings that wear out. I think the factory used plastic bushings. Anyway, this makes it seem as if the transmission is worn out. I bought a set of brass bushing on eBay for $10 and replaced them with the tranny in the car. What a difference.

A bunch of miles later we started to hear a whine. Even though the tranny shifted and worked well, we rebuilt it and the whine went away.

[Zedyone_kenobi]

Well the 3rd gear in my type A four speed has been whining since I got it. It drives and shifts wonderfully smooth. I have a replacement type A ready to go in, but I have no idea if it is better or worse than what I have, so I left it in until it goes pop.

I would like to keep it an original car as long as possible. One day I may be forced to switch to a later Type B 4 speed or 5 speed, but until then I am going to ride it out.

Seems when looking to get my type A rebuilt, nobody locally would touch it, as they said they could not even get parts for it anymore. So threads like these make me keep looking for what I will do when I get up the nerve to do a swap.