Gear swap in a L20B 4 speed

[DailyDato]

I have found that the Z tranny will bolt to the L block and be crooked like hell, but my question is, Has anyone tried to get the Z 5 speed and house it in the L 4 spd case? Hopefully making a bolt in 5 speed for the L block?

[erichwaslike]

im no expert, nor do i know anything about either trans, but it would appear to me that u have one too many gears in ur equation... 5 into a 4.

 

y wont this thing fit!!!!!!

 

 

[datzenmike]

I have found that the Z tranny will bolt to the L block and be crooked like hell, but my question is, Has anyone tried to get the Z 5 speed and house it in the L 4 spd case? Hopefully making a bolt in 5 speed for the L block?

 

 

You could take the Z series transmission and remove the front case half and put the front case from the 4 speed onto it and you would have an L 5 speed. There are a couple of things to watch for.

 

1/ The Z series counter bearing was increased in size in '85. If you have an earlier one you are good to go. If you have the larger bearing simply remove and swap the 4 speed one on and good to go. Very easy, just a simple gear puller.

 

The 1st/2nd shift rod was increased in diameter from 14mm to 16mm after '85, so you will need to drill the 4 speed case out to this size to get it to fit. No matter what you do you should use the 4 speed cover plate to match the smaller bearing.

 

This is the 5 speed case with the larger counter bearing (bottom) and the larger shift rod (top one of three) The 4 speed case needs the shift rod hole increased and the smaller counter bearing for it to fit. I doubt very much that you will have this 5 speed but you never know if the tranny was swapped by a previous owner.

 

 

 

2/ I have reason to believe that the reverse light switch on the 4 speed is about an inch further to the back on the case than the 5 speed reverse switch. This can be drilled out and tapped and an old switch used to plug the hole.

 

This is a 5 speed reverse light switch location. The 4 speed case is more or less identical. You can see where the reverse light switch would be mounted. About an inch to the rear.

[Braden]

if anybody would know it would be mike!!!! nice answer, and nice pictures as usuall.

[datzenmike]

:D

 

Here's the correct way to loosen the cover plate after removing the bolts. Use a socket extension and gently hammer against the clutch arm pivot ball.

 

[erichwaslike]

ok so it can be done, by chance this isnt the z 5 speed that is the t5 is it?

[datzenmike]

No. The Borg Warner T-5 was known as the FS5R90A. The tranny we are talking about are the FS5W71B

 

 

FS5W71B left and FS5R90A right

 

 

.

[erichwaslike]

thats wat i figured. im familiar with a the t4/5 trans but not the other

[DailyDato]

Wow! datzenmike that is quite some detail that you got there, Thanks... What about using the newer K series 5-speed with a swapped housing, seems the length is a lil better of a fit, just a lil shifter mods and i think it would be okay With my 77 having the 190 rear could i swap the third member in the rear as well from the same hardbody/720 to get some better highway options? that match the tranny, or is that a hard strain on my L20?

[datzenmike]

K series? Not familiar with them for use with late '60s through late '90s 4 cylinders. What's it in? Got a picture?

[DailyDato]

86.5-97 Nissan hardbody pick up. some early still came with Z series 2.4 I made it in a fuelie version of the Z 2.4.... later models came with a Ka24d, i think late 89-94 came with 2.4l 2400 12 valve, even laters came with Ka24de twin cam 2.4 L. 16 valve also known as KA series, bell housing of both bolt together with that of a Z series, i am working on a Ka24de to put in a 720 pickup I own, I have a spare hardbody short shaft tranny layin around, would be good donor parts just a lil unfamiliar when it comes to the gutting and swapping of manual trans.... series number for the tranny in a hrdbody would be a FS5W71C i believe if I remember correctly, I was thinking that the only lenght differnce is in the front half of the case, maybe a lil in the rear section, but hell even with a driveshaft shortening, I can still move my crossmember to the rear holes in the frame brackets and make something work, maybe even a custom crossmember, but if it goes that short, I can always bolt a 240sx front shaft half to the stock rear section of the drive shaft and shorten out several inches ....whadda ya think?

[datzenmike]

86.5-97 Nissan hardbody pick up. some early still came with Z series 2.4 I made it in a fuelie version of the Z 2.4.... later models came with a Ka24d, i think late 89-94 came with 2.4l 2400 12 valve, even laters came with Ka24de twin cam 2.4 L. 16 valve also known as KA series, bell housing of both bolt together with that of a Z series, i am working on a Ka24de to put in a 720 pickup I own, I have a spare hardbody short shaft tranny layin around, would be good donor parts just a lil unfamiliar when it comes to the gutting and swapping of manual trans.... series number for the tranny in a hrdbody would be a FS5W71C i believe if I remember correctly, I was thinking that the only lenght differnce is in the front half of the case, maybe a lil in the rear section, but hell even with a driveshaft shortening, I can still move my crossmember to the rear holes in the frame brackets and make something work, maybe even a custom crossmember, but if it goes that short, I can always bolt a 240sx front shaft half to the stock rear section of the drive shaft and shorten out several inches ....whadda ya think?

 

Ah, got cha. The FS5W71C... never heard it called a K is all. The first FS5W71C was used in the 300zx in '84, all others were after 86.5 in the 200sx, D-21. and '87 for the WD-21. The D-21 and WD-21 were the shortest but still longer than the FS5W71B that it replaced. The 200sx and 240sx were even longer. There may be 3 different lengths.

 

 

The very top one is from the D-21 the other is from the S13.

 

 

The differences in length are ALL in the tailstock. The KA/CA/VG front cases can all be swapped to interchange them. The L and Z series front case halves can be swapped onto the FS5W71C.

[DailyDato]

So with putting the FS5W71C tail on the L front, is there any real issuse I would need to address as there were with the L and Z swap?

[datzenmike]

Yes there are a couple of things. The B front counter shaft bearing is 56mm in diameter so the B case will only have a 56mm hole in it. Note the distance between the lower counter bearing and upper main shaft holes below.

 

 

This is the 62mm counter bearing hole just like the C tranny. See how the holes are closer?

 

 

You can simply swap the 56mm onto the C and it will fit the B case. OR Have it milled out to size as you will need to have some machine work done anyway. Here's why: The gears in the C are wider (so less space front to back) and just behind the counter bearing is a thin toothed spacer that I like to call an oil slinger. The C case has room for it but the B case does not. The B case will need to have some material removed for the oil slinger to fit.

 

Below is a B case modified to have clearance for the oil slinger. The bearing hole was increased to 62mm at the same time :

If you choose to go with the larger 62mm bearing you must use the C front cover to fit over the bearing:

 

 

 

One more thing. The C uses a larger 1st/2nd shift rod that sticks through and is supported by the case. The B case top shift rod hole must be increased from 14mm to 16mm so it will fit. Simply use a hand drill. Below is a C case. Note that the upper shift rod hole is larger than the other two. Also note the clearance around the counter bearing hole for the oil slinger.

 

 

 

 

 

 

 

 

 

.

[DailyDato]

So in reality, if i were to create a 5-speed for my 620 pickup, with having no real luck on getting a maxima trans or a 280 trans, What is the best and easiest " build" from manner of opinion, also looking for better highway gearsets, I can get any and all the machining done that needs it, but for simplistic reasoning, whats the best route to go, and is there any gearsets that fit the L case the best, and what is the best gears out of the series of trannys that can be used for the best highway/sporty options? Can i change out shift rods and scyncros and fit other gears, or go all out and disassemble like three or four trannys for certain gears for this and that and what not, or is it too involved, to keep in mind I'll be running a pretty beefy built L20B, with one off fuel injection and possible type of forced air induction turbo in highly in mind. might just drop my twin cam I built in it

[DailyDato]

Hot damn..... pullapart shows to have a '76 280 will that tranny work if so ill go buy it tomorrow, if its a five speed, i bet its auto.

[datzenmike]

OK here are the possible FS5W71B 5 speeds that will 'drop in' to your '77 720....

 

'77-'79 620

'77-'78 280z

'79-'83 280zx

'79-'84 810/Maxima gas or diesel.

'80 720 2wd.

 

Failing to find one you could use one of the following 5 speeds and swap an L series 5 or 4 speed front case onto it....

 

'81-'86.5 720 2wd Z series gas or SD22 or SD25 diesel engine

'80-'83 200sx w/Z series engine

'84-86.5 200sx w/CA20e or CA18ET motor

 

The L series front case from the F4W71B can be found on the following.....

 

'74-'79 620

'74-'78 280z

'79 280zx

'78-'80 810/Maxima

 

What is the best and easiest " build" from manner of opinion, also looking for better highway gearsets, I can get any and all the machining done that needs it, but for simplistic reasoning, whats the best route to go,

 

The best thing is to swap in what you want. A "better highway gearset" not sure what better is for you. All 4 and 5 speeds have the same 4th gear ratio of 1:1 or straight through. This only leaves 5th gear overdrive which is only intended for cruise speeds on the highway to slightly lower the RPMs for economy sake. 5th should never be used for towing, climbing steep hills or passing. 5th is not an acceleration gear for top speed, rather it's solely for steady cruise speeds. So you have to decide is my motor strong enough (or in the case of the 280z/zx) is it large enough to pull the car along at a reduced RPM at highway speed. I would advise not using a 280zx 5 speed with it's monster overdrive 5th gear on a small L16. To be sure it will work but slight hills and head winds will require down shifting to 4th for more torque to push the car. Just a thought.

 

...and is there any gearsets that fit the L case the best, and what is the best gears out of the series of trannys that can be used for the best highway/sporty options?

 

Well here is where wide ratio and close ratio terms are used.

A wide ratio gear set would have a very low first gear set, perhaps 3.592:1 with the other two equally spaced between it and the 4th 1:1. This would give good strong take offs but long pulls through each gear and big RPM drops on every shift. Ideal for heavy cars or trucks with loads, small motors or stop and go city driving.

 

A close ratio gear set would have a much higher first gear set, perhaps 3.021:1 with less 'distance' to 4th 1:1. This would give a poorer take off acceleration but once moving quicker revving through the gears and less RPM drop on shifts thus keeping the motor revved higher and making more power after every shift. A close ratio transmission is great for a lighter car, a larger stronger motor or racing where the car never or rarely has to stop and take off.

 

Naturally both wide and close ratio transmissions would be equal in 4th but each would have an advantage over the other under certain conditions. Either application will work, it's just that one will be slightly better depending on your intended use.

 

Wide Ratio FS5W71B 5 Speeds

 

1st.... 3.592

2nd... 2.246

3rd.... 1.415

4th.... 1.000

5th.... 0.882 ..... '79 620, diesel 720s, '84-'86.5 CA18ET 200sx

 

 

 

Middle Ratio FS5W71B 5 Speeds

 

1st.... 3.321

2nd... 2.077

3rd.... 1.308

4th.... 1.000

5th.... 0.864 ............ '77-'78 620, '77-'79 280z/zx, '79-84 Maxima, '84-'86.5 CA20E 200sx

 

 

 

Close Ratio FS5W71B 5 Speeds

 

1st.... 3.062

2nd... 1.858

3rd.... 1.308

4th.... 1.000

5th.... 0.745..... '80-'83 280zx

 

 

Unfortunately you cannot mix gears except in sets. The 1, 2 and 3 gears are determined by the counter shaft ratios. The countershaft is a one piece gear set with 1st, 2nd and 3rd gears on it. The corresponding 1st, 2nd and 3rd on the main shaft above it MUST match the counter gear below. 5th gear sets can be swapped because they are separate and removable.

[DailyDato]

pull a part was a total fail today, i just need to find one to buy...I could assemble one, but buying one seems to be the easy route.... I dont know, it will be a few eeks till i get my truck on the road anyways, maybe i can come across something in the mean time, or get some parts....

 

 

[DailyDato]

Diggin through my pile o' stuff, I came across a tranny that i didn't ever remember having, but am having a lil trouble figuring out what it is, If you look back at the sixth picture that you posted, the top transmission in that pair, is what it looks like, the Housing sticker has 7S21378 , the side number is ZL 71B #2 with NMCA just under it, any I dea, or what do you know about this particular tranny? Thanks.....

[DailyDato]

I am told it is a truck tranny, it has the speedo hole, but what throws me is the it has the six bolt shiter much to that of a 240sx, the plugs look a little new for the series, but I am unsure what year, thinking like 86.5 and up?? I know that the plugs on an 80-86.5 just have wires, this has connectors on it.....

[datzenmike]

 

The very top one is from the D-21 the other is from the S13.

 

 

 

 

Says right up top what it is.

[Master-O-Turbonics]

OK here are the possible FS5W71B 5 speeds that will 'drop in' to your '77 720....

 

'77-'79 620

'77-'78 280z

'79-'83 280zx

'79-'84 810/Maxima gas or diesel.

'80 720 2wd.

 

Failing to find one you could use one of the following 5 speeds and swap an L series 5 or 4 speed front case onto it....

 

'81-'86.5 720 2wd Z series gas or SD22 or SD25 diesel engine

'80-'83 200sx w/Z series engine

'84-86.5 200sx w/CA20e or CA18ET motor

 

The L series front case from the F4W71B can be found on the following.....

 

'74-'79 620

'74-'78 280z

'79 280zx

'78-'80 810/Maxima

 

 

 

The best thing is to swap in what you want. A "better highway gearset" not sure what better is for you. All 4 and 5 speeds have the same 4th gear ratio of 1:1 or straight through. This only leaves 5th gear overdrive which is only intended for cruise speeds on the highway to slightly lower the RPMs for economy sake. 5th should never be used for towing, climbing steep hills or passing. 5th is not an acceleration gear for top speed, rather it's solely for steady cruise speeds. So you have to decide is my motor strong enough (or in the case of the 280z/zx) is it large enough to pull the car along at a reduced RPM at highway speed. I would advise not using a 280zx 5 speed with it's monster overdrive 5th gear on a small L16. To be sure it will work but slight hills and head winds will require down shifting to 4th for more torque to push the car. Just a thought.

 

 

 

Well here is where wide ratio and close ratio terms are used.

A wide ratio gear set would have a very low first gear set, perhaps 3.592:1 with the other two equally spaced between it and the 4th 1:1. This would give good strong take offs but long pulls through each gear and big RPM drops on every shift. Ideal for heavy cars or trucks with loads, small motors or stop and go city driving.

 

A close ratio gear set would have a much higher first gear set, perhaps 3.021:1 with less 'distance' to 4th 1:1. This would give a poorer take off acceleration but once moving quicker revving through the gears and less RPM drop on shifts thus keeping the motor revved higher and making more power after every shift. A close ratio transmission is great for a lighter car, a larger stronger motor or racing where the car never or rarely has to stop and take off.

 

Naturally both wide and close ratio transmissions would be equal in 4th but each would have an advantage over the other under certain conditions. Either application will work, it's just that one will be slightly better depending on your intended use.

 

Wide Ratio FS5W71B 5 Speeds

 

1st.... 3.592

2nd... 2.246

3rd.... 1.415

4th.... 1.000

5th.... 0.882 ..... '79 620, diesel 720s, '84-'86.5 CA18ET 200sx

 

 

 

Middle Ratio FS5W71B 5 Speeds

 

1st.... 3.321

2nd... 2.077

3rd.... 1.308

4th.... 1.000

5th.... 0.864 ............ '77-'78 620, '77-'79 280z/zx, '79-84 Maxima, '84-'86.5 CA20E 200sx

 

 

 

Close Ratio FS5W71B 5 Speeds

 

1st.... 3.062

2nd... 1.858

3rd.... 1.308

4th.... 1.000

5th.... 0.745..... '80-'83 280zx

 

 

Unfortunately you cannot mix gears except in sets. The 1, 2 and 3 gears are determined by the counter shaft ratios. The countershaft is a one piece gear set with 1st, 2nd and 3rd gears on it. The corresponding 1st, 2nd and 3rd on the main shaft above it MUST match the counter gear below. 5th gear sets can be swapped because they are separate and removable.

 

Maxima FS5W71B transmissions have a .752 5th. I verified this on 82 and 84 transmissions and that is what the 84 Maxima service manual says. I did not check the other gears.