FS5W71B - Questions

[boomer3]

Hey Guys, 

 

I have a '76 280Z, that originally came with the FS4W. I exploded the 4 spd a few years ago and picked up an unknown 5 speed, that supposedly came from a 720 truck. When I went to put it in the car, the hole pattern was out by probably 20 or 30 degrees clockwise when looking from behind the trans, so I swapped out the front case on the 5 spd with my 4 speed no problems.

 

I am sure that it is a FS5W71B, somewhere in the 81-83 range? It looks like the 71B may have even stayed in some trucks until '85 or so, but that could be wrong. Either way it looks most like the 81-83 rear case with the single ear and 6:00 bolt location on speedo as shown here:

 

 

I am pulling the trans soon to put in some new seals in the shifter assembly (looks like leak may be from there), as well as front and rear shaft seals while I'm at it. Where do you guys think the leak is from? It may be wise just to change all seals, it could really be coming from anywhere, hard to tell once wind has pushed oil around.

 

 

Final question; I don't have any useful casting #'s on this transmission case (ie 71B), but it does have "NMCA #5" cast into the left side of the rear housing, see pic below. My understanding is that this stands for "Nissan Motor Co., Australia". Interested in other input on what this means for this transmission. Was it common to the truck transmissions perhaps? I was planning on ordering parts for this off of one of these sites, but not sure how careful I need to be with this trans. It looked 71B through and through but I have read that 2nd gear synchro can differ (maybe this is only in the 71C?), advice on trans parts source would help too.

http://www.drivetrai...erhaul_kit.html

http://www.datsunpar...ts-and-Packages

http://www.manualtra...com/FS5W71.html

 

Edited April 5, 2017 by boomer3

[NewZed]

The bolt pattern would be different because it was on a VG30 engine.  So it's probably a 71C.  Did you have to do any machine work to get the shift rods to fit and clearance for the gears.  Swap bearings or enlarge the 4 sped housing hole?

 

Maybe the trucks did use the VG front case on 71B transmissions.

 

The casting letters and numbers don't seem to indicate much.  People have put guides out there but when you check against known transmissions, the codes don't work.  I think that the seals are the same across the B and the C and the G and the H....  They didn't change the shaft sizes over the years.  You can tell if the front seal is leaking because there's a weep hole in the front case that will have oil coming from it.

 

I had a leak from the clutch fork pivot ball.  Turns out the threads need to be sealed.  Someone took it apart and didn't do that.  The oil runs down the fork in that case.

[boomer3]

Maybe you're right, but the rear case is certainly 71B, so I haven't quite figured out the bellhousing alignment yet. Will be interesting if somebody can chime in on this one.

 

I think I have oil coming from a few locations now, likely the shift assembly at rear, but also a little oil up front. Good catch on the clutch fork bolts, I can't recall what I did there, so I won't be surprised if that is a culprit up front.

[NewZed]

I think the upgrade that Nissan made when they cast a new front case/bellowing to match the VG engine was to enlarge the countershaft bearing.  That's why I asked about the bearing.  They made other changes over the years and many of the "71C" transmissions are actually G or H or some other letter.  Double synchros, wider gears, double synchros on several gears, reverse synchros.  Many variations but all for the VG engine after, 1983.

 

The answers to the questions I asked will tell something.

[boomer3]

I did not have to swap bearings, or do any machining. It was a direct bolt-on from the 4spd to the 5 spd with the only difference being the bellhousing pattern. The rear case has the shift linkage design from the 71B, and looks to be the 81+ case given that picture description of speedo gear and number of ears on the tail.

[Eric JB]

81 and later trucks had the nap Z engine. It was slanted the opposite direction in the engine compartment. It's pretty common to have to swap bellhousings to put it behind an L motor. Also be aware that the truck transmissions had a lower 1st gear, so there will be a broader gap between 1st and 2nd. That is a 71B, since the shifter is different on the 71C.