Another 4 speed to 5 speed swap question

[Neal G]

Ok, I read and read the other thread and have gotten tons of info. But can someone verify the following.

When changing out a 4 speed from a "72" you can bolt right in a "77" to "79" 5 speed and get pretty much the same first 4 drive gears with another for the highway. You reuse the 4 speed throw out bearing and fork/ collar and the 4speed speedo drive gear. Do you need to reuse the 4 speed shifter, or the 5 speed shifter?

Next

If you use an "80" to "83" 5 speed you get better acceleration because the gears are more evenly spaced (no big change from 2nd to 3rd) but you need to change out the diff to take advantage of it. Also the shifter is too far forward and you have to either cut metal and or plastic to make it work, or you change out the shifter for a rather hard to find part. Or you cut and weld one of your own. There still seems to be a question if MSA's short shift kit will help with the clearance.

My confusion began when the discussion turned to type "A" and type "B" trannys. Not too mention my lack of ability to understand the gear ratios. It gets too jumbled in my head and hurts.

Last

Z car source of arizona sells an "84"-"86" to 240z swap out for $1900 (ouch) and other 5 speed trannys. What do I want? Who can help me?

Thanks,

Neal G

[e_racer1999]

type A & B refer to the 4-speeds. the cutting is involved in the earlier cars that had the type A 4speeds.

you're basically right on the ratios, but the 1-4 of the early trans is wider than the 4-speed (correct me if i'm wrong). plan on replacing the diff with a ~3.7 anyway.

as for the collar and fork, use the 240 fork and the collar will match whatever clutch/PP combo you are running

[Sailor Bob]

I just did the swap for 77 and put in the 82 5 spd - 1st two gears are definately different - used the collar of the old throwout for the 4 spd setup.

I am wondering about the differential change as well. Is the change to a 3.7 from 3.545 straight up?

[Arne]

Don't worry about the differential change until you're done and you've driven it with the five-speed. Depending on your driving style and conditions, you may not feel you need the diff change.

[Sailor Bob]

I put about 150 miles on mine since the tranny change - I like it in the first four gears, but the fifth is boggy. I am finding that I need to exceed the highway speed limit to make use of it - which defeats the purpose a little (not that I never exceeded the speed limit befor). So I thought the higher input dif would make the 5 spd more practical.

Sorry for thread jacking.

[sblake01]

type A & B refer to the 4-speeds. the cutting is involved in the earlier cars that had the type A 4speeds.

you're basically right on the ratios, but the 1-4 of the early trans is wider than the 4-speed (correct me if i'm wrong). plan on replacing the diff with a ~3.7 anyway.

as for the collar and fork, use the 240 fork and the collar will match whatever clutch/PP combo you are running

You're correct about ratios though somewhere apparently it is mis-stated that they are the same because people keep saying that. First of all, before anyone mentions it, we can throw the Borg Warner T-5 completely out of this discussion. I've done much reaearch in that area and have even posted charts showing the differences. By Nissan's definition the A trans is the 70-71 with the 'monkey motion' shifter which has the pin on the bottom holding it in place and the B is the 72 and up with the horizontal pin and E clip with nylon bushings holding it in place. The confusion on the 'A and B' thing comes in because people sometimes refer to the five speeds a A (77-79), B (80), and C (81-83 ZX, 84 Maxima). Technically, all five speeds would be type B by Nissan's definition. The shifter on all type B four speeds and all five speeds are in the same position so no cutting would be necessary for any five speed in a 72 and up. Use the 4 speed shifter. Also, if you use the 80-83 trans, you'll need to use your 4 speed speedo gear but put it in the 80-83 collar because of the offset.

[sblake01]

I put about 150 miles on mine since the tranny change - I like it in the first four gears, but the fifth is boggy. I am finding that I need to exceed the highway speed limit to make use of it - which defeats the purpose a little (not that I never exceeded the speed limit befor). So I thought the higher input dif would make the 5 spd more practical.

Sorry for thread jacking.

I've had that setup in my 78 for years now. Late 5 speed/3.54 diff. I like it since it does create a little better highway mpg. But I will admit that the 810 with the same trans and it's 3.70 does pull a little better in 5th gear. I just think that if you go too much lower (higher numerically) with the differential that would also be defeating the purpose of having the 25.5% overdrive. I guess I don't notice it too much in the Z because here in California, the average traffic flow (when it's flowing) is always above the speed limit anyway.

[240ZMan]

http://www.geocities.com/z_design_studio/transmission.html

This is a great tool to try out different ratios and see how they affect your speed in gears, etc.

As for changing the diff, if you like to shift often and wind into higher revs, then you should consider changing to higher ratio diff. Also, if you plan to make engine mods that move your powerband up the rpm band, same thing. But if you will leave the engine mostly stock, then 3.36 or a 3.54 (easy to find and not a lot of $$$) are good. It's hard to find inexpensive 3.70, 3.90 and 4.11 diffs in good condition.

[Sailor Bob]

The 3.9 is probably a better match according to the calculator - it would make 55 a usable speed with rpm above 2k in 5th.

Going from a 3.545 to 3.9 - Is that a straight bolt on or is there a conversion kit required?

[janaka]

i know with my 5spd and the 3.90:1 rear end I have to be over 60mph before i can use 5th gear, otherwise the car bogs pretty good as the RPM's are too low to have any power in 5th. where i cruise its a lot of back roads where most people cruise at 50mph ish.... drive me bonkers in 4th gear at 3k rpm and not being able to up-shift...

edit: i've got a bigger cam/exhuast/head work for what thats worth

[240ZMan]

Going from a 3.545 to 3.9 - Is that a straight bolt on or is there a conversion kit required?

If you find a 3.90 r180 diff, it's a straight bolt in. You may have to move the flanges from your old diff to the new one, but it's not hard to do.

If you switch to an R200, then you need to change other parts as well. This has been discussed many times here and on hybridz.org so I won't repeat it. Unless you plan to make major mods to your L6 (such as a turbo), I'd stay with the r180 as it's lighter and an easier swap.

[240ZMan]

i know with my 5spd and the 3.90:1 rear end I have to be over 60mph before i can use 5th gear, otherwise the car bogs pretty good as the RPM's are too low to have any power in 5th. where i cruise its a lot of back roads where most people cruise at 50mph ish.... drive me bonkers in 4th gear at 3k rpm and not being able to up-shift...

edit: i've got a bigger cam/exhuast/head work for what thats worth

I have a similar situation (cam etc), even with a 4.11 as I also live above 6k feet altitude. After 2nd gear, I never drive below 2k rpm - engine just isn't happy. From 3k on though, that's another story