Beginning my next project

[mshort07]

The truck and the car are close to finished so I thought it was time for my next project. I’ve never built a motor from start to scratch, so I decided an engine swap in the 520 would be a nice project. I did some research and got advice that a L20B should fit (with some cutting and welding) in my truck. 
 

 

 

I picked up a 77ish L20B and 5 speed (is that an L5 transmission?) but might have picked up a bigger project than originally planned. The motor was free turning but hadn’t run in many years. The transmission was stuck and not turning. 

 

#4 cylinder will need machine work. 1-3 cylinders, the crank, and crank journals are in good condition and within spec so I think the motor is worth rebuilding. 
 

The transmission on the other hand is most likely shot. There’s a lot of rust in the front half. Rust on the gears and won’t shift. 
 

Here’s my question. What tranmissions will bolt, with no mods, up to the L20B?

 

Will my stock 4-speed transmission in my 520 bolt to the L20B?  There’s not a lot to choose from where I live. 
 

thanks for the info. 

[datzenmike]

No, the sock 4 speed is for a J series engine, you need one for an L series.

 

All L series transmissions will bolt up to the L20B with no modifications.

 

If you mean the least modifications to the 520 then the 4 speed from a 521, a 510 or the '73 620, all 710s and the  '78-'79 A10 are identical shape and length and fit L series engines.

 

If you want a 5 speed the FS5W63A from a first gen S10 (200sx) is the same length but you will need to re-work the transmission mount. The FS5W63A is just adequate for the L20B in a car so if in a truck commuting only. These are quite rare and well used so finding one difficult and it should be rebuilt I would think.

 

The FS5W71B are strong enough for a fuel injected Z car 6 cylinder engine and the same ones were also used in the 620 for their strength. Many ,amy more of these were made so not at all as hard to find. There is also some choices in gear ratio sets and over drives. they are about 5.5" longer so the 520 drive shaft has to be shortened and... the transmission mount modified. L series FS5W71Bs are found in...

 

'77-'79 620 (optional)

'80 720 2wd (optional)

'78-'84 810 and Mazima

'77-'78 280z (optional)

'79-'83 280zx non turbo (optional only on '79)

 

 

 

[mshort07]

Where do you find the model number of the transmission? I found “L5” by the fill plug. Front housing, tail housing, or center plate?

 

wouldn't call this “rusty gold” just a rusty mess. 

 

 

[mshort07]

Need some help identifying this transmission. I was told it was from a 77ish 620 pickup mated to the L20B. It is a 5 speed. 
 

only identification i found was “L5” cast into the front case next to the reverse switch. Also a “hand written looking” raised Text on the tail housing (upside down) that says “#3_2_8”. And stamped in the bell housing right on the top next to where bolted to the engine block “7226939”. 
 

any ideas?

[datzenmike]

Show me pictures of the right, or passenger side, of the front and rear cases.

 

 Looks like it was stored under water. Hope you got it for free.

[mshort07]

Part of a package deal. I got it all apart. It might clean up. 
 

 

 

 

 

 

 

[mshort07]

 

 

[mshort07]

On 1/5/2020 at 6:05 PM, datzenmike said:

Show me pictures of the right, or passenger side, of the front and rear cases.

 

 Looks like it was stored under water. Hope you got it for free.

So what do you think datsenmike? Is it a correct era FS5W71B for a 77 620? 
 

Did the ‘77 FS5W71B have the oil gutter that went through the mid plate to the gutter rail in the tail housing? This transmission did not when I opened it up. I saw a YouTube video of a rebuild that indicated this oil gutter insert that passed through the mid plate. The video was of a later 280z trans. Found this pic online. 
 

 

[wayno]

This post is of my personal experience, that is a pre-1980 transmission, at least the rear case is, I have diesel engines in a couple of my trucks, I have found the early 5 speeds like what it appears you have have a different 5th gear than the later transmissions which are good for diesel engines, meaning that the if I were going 60mph in the transmission you posted photos of I would show 3000+rpms, if I had a 1982 5spd out of a 720 at 70mph I would be showing 3000rpms, so us diesel guys avoid these early transmissions because they just don't like being above 3000rpms.

That said that transmission appears to be of the late 70s era, it will work fine behind an L block.

[datzenmike]

I see nothing to disagree with it being made in 77 definitely a pre '80s transmission and it was in a truck.

 

wayno the two overdrives in the 620 were 11.8% and 13.6%. The later 720s used 17.7% and 18.7% over drive. These gas engines were larger displacement and the diesel got the 18.7% OD.

[mshort07]

Any thoughts on the missing oil gutter? Is the oil gutter through the mid plate found in the early 5 speeds? Or just in the later 80’s 5 speeds?

[mshort07]

Does anybody know how to remove the “dog leg” off of the shift rail from a ‘77 FS5W71B? I saw a YouTube video where the trans the guy was working on had a bolt hole in the rear of the housing where he could reach in and knock the pin out of the dog leg. My tail housing doesn’t have that hole. I removed the nut but the pin won’t budge and I can’t get an angle on it to knock it out. Any ideas?
 

 

 

[datzenmike]

ALL 71B 4 and 5 speeds had the oil gutter and ALL 71Cs. If yours is not there, the hole will be, it probably fell out and was ground up by the gears.

 

I wouldn't use the tern 'dogleg' as there are transmissions called that for their shift pattern with reverse above first. This makes a bend in the 1 to 2 shift

R 2 4

1.3.5

That's the striking lever and it bolts to the striking rod. I wouldn't remove it as there's nothing wrong with it.

 

[mshort07]

I wanted to remove the striking lever to pull the rod because the seal around the striking rod at the rear of the housing was leaking quite a bit. Thanks for the correct terminology. 

[mshort07]

Ok. Some more questions - I need some help finding where to get some replacement parts for the transmission. I was able to find the seals, o-rings, and oil gutter from Nissan. I can’t find the tail house bushing in picture 1.

and I can’t find this synchronizer ring (Part 18) for the overdrive main gear seen in the pictures below. 

 

Any ideas where to source these parts?

[mshort07]

From what I’ve read, my ‘77 ish FS5W71B trans has Borg Warner synchros on gears 1-4 and Servo type synchro on 5th gear. I need one of these “Servo” type synchros. Mine’s chewed up and need a new one. I found a website, datnissparts.com, that states the “X Steel Synchronizer Ring” is the same for roadster 5th gear in fs5c71a, fs5c71b, and some FS5W71B overdrives found in the 620. But... is no longer available from them. I see the servo ring on Datsunparts.com but it’s $150 (for a roadster). Is there any other options or places to purchase?

[datzenmike]

 

Early transmissions like the 521/510 and the 71B 4 seed used in the z car and 620 had a replaceable bushing but I think they had to be reamed to size after installing it. The 71B 5 speeds they did away with the bushing and either did without it or just used the aluminum case in place of it.  

[datzenmike]

 

Part 18 is called a Warner type synchro ring 32361-20100 (on the roadster parts list) and used on the '77-79 620 5 speed.

 

Also used on the Roadster to '70, the '77-'78 280z 5 speed, the '79 (only) 280zx 5 speed, '79 810 5 speed*, on the 720 through Nov. '79**, on the S110 200sx through Oct '79**

 

*The Maxima began in Jan '80 which would suggest the 810 stopped the month before and this synchro.

 

**looks like this synchro stopped being used in late '79 build dates. Just barely into some '80 model year vehicles but not after the new year.

[pdp8]

I think these guys were where I picked up my rebuild kit.  It wasn't wildly complete but it did have synchros and the cost for the kit was less than buying the bearings and seals separately.

https://www.drivetrain.com/parts-catalog/manual-transmission-rebuild-kits-and-parts/nissan-4-speed-transmission-parts

 

Based on what datzenmike said about the tailshaft bushing, if you pressed it out and measured it, and then measured the shaft where it passes through, any machinist should be able to turn you an aluminum bushing or brass bushing to press in.  Your original was likely babbitt  faced and that will be trickier to replace exactly.  I'd be tempted to make one out of Super Oilite as a compromise if I couldn't source an original.

[Stoffregen Motorsports]

Steel synchros have not been available for years, but there are guys out there who hoard these hard to find parts. Think Ermish or Epperly.

 

For the rear slip yoke bushing, you could try one of the transmission parts houses. All Trans in Portland (Oregon) would be a good place to start.

[mshort07]

Got some progress done. The 5 speed trans is all rebuilt. The L20B has been to the machine shop and bored over for .40 pistons. The bottom end has been assembled. Now I’m sourcing my replacement accessories. 

Edited April 22, 2020 by mshort07

[mshort07]

I need some carb knowledge passed along to me if anyone is willing. The carb that came with the L20B looks completely shot. Not worth the effort to rebuild it. I’ve found a Weber carb that fits the engine but then I got to thinking about the carb on my j13 that will be coming out of my 520 for the L20B to go in. Can that carb be used on the L20B?
 

The carb on the j13 is a Nikki and seems to be in good condition. Will it fit the L20B? Will it work on the L20B? Any thoughts? Thanks

[docbainey]

Use a weber 32/36, the carb off the j13 will be to small and will need re-jetted.

 

Where did you end up finding a 5th gear steel syncro ring? $$$?

 

Typically you should replace the ring, blocks and bands as a unit as all of those parts are the 'synchronizer'.

 

Nice Roadster

[datzenmike]

You can always use a smaller carb than needed but performance will always be the big looser. If you run too large a carburetor there are some performance gains but mileage, starting, idle and low and mid range... what I like to call drive ability, suffers. An L20B with a J13 carb will not reach it's potential. It will run fine but basically perform like there is a block of wood under the gas pedal limiting how open the carburetor is.

[iceman510]

I have numerous Weber 32/36 carbs if you are interested.  Some of them probably jetted for L20B already.