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My Ratsun Datsun 521, now with L-20-B and a five speed


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The distance between the center of the two rear tires is 49.9" on the 521 and 50.4" on the 620. Now they might still be different WMS to WMS and have different wheel offsets to compensate. I don't know but on the face of it the 620 axle is only 1/4" wider per side.

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Rear axle repairs, installing differential carrier.

Rear wheel bearing removal.


I use Ratsun about every ten days or so to get a load of hay.  I would like to get it running.  I have enough hay for about seven or eight days.  I can get 11 bales of hay in my Ford Aerostar, but that causes a lot of clean up.  My hay supplier can also deliver hay, but that costs me an additional dollar a bale.   Another option is to take the complete axle from under Dragon Two, and put it under Ratsun.


But for now, I am going to work in Ratsun, using the hay deadline for extra motivation.


Last night, I used a wire wheel to clean remains of old gasket off the axle housing,



Notice the roll of paper towels in the lower left.  I scraped up the remaining gear oil, and after the housing was wiped clean, I went around inside the housing with a magnet.



I was able to get this gasket from Dick Hanna Nissan, my local Nissan dealer.



This is the 38320-B3002 gasket on the axle housing



Using the same rotary wire brush that I used on the housing, I cleaned the flange on the differential carrier.  Most of the flange is done, except fro one small spot.



Same area as above, but now clean.



I then put the carrier on the axle housing.



and the propeller shaft on the differential carrier pinion flange



I cleaned the drain plug, put some Teflon tape on the threads, and put it in.



And then I pumped some gear lube into the axle housing.


The following pictures is a sequence of rear axle wheel bearing removal to access the failed grease seal.

There is a tab in a notch on the nut that hold the bearing to the axle, centered between the two bottom studs.



Pry the tab out of the notch in the axle with a thin screwdriver.



This is the tab pried out of the notch in the nut.



You probably do not have the Nissan special tool to fit the notches in the axle nut, use a punch to drive the nut counter clockwise, both left and right axles.



This is the nut loose, ready to take off the axle.



That leaves the tabbed lock washer.  It just lifts off the axle.  There is an inner tab that fits into a notch on the axle.



Now, the only thing holding the rear axle bearing on the axle is a press fit.  Nissan again makes a special tool that bolts to the brake plate, and pushed the axle out of the bearing.   At one time, I made a plate out of 1/2 inch steel that would bolt to the brake plate, and allow you to press the axle out of the bearing.   But a guy in a auto machine shop showed me the following method.



In this picture, note the brake drum is still on the axle.  You can pull the axles out of the rear axle housing without removing the brake drum from the axle.   After removing the brake backing plate, with the bearing, the axle can be easily pressed out of the now empty brake drum.

But we are trying to get the wheel bearing off the axle.   Hold the brake plate with both hands, and bang the inner end of the axle straight down on the floor.  You may need to do this several times.  This will push the wheel bearing off the axle.



When the bearing is off the axle where it fits, it will fall to the floor



This is a spacer, on top of the wheel bearing, the tabbed lock washer, and the axle nut.



The reason I removed the bearing is to get to a seal in the bottom of the brake plate, below the wheel bearing race.   There was grease and oil all over inside the brake drum, shoes, and parking brake mechanism.



This is the left rear axle with the brake drum.   I could not get the brake drum off the axle with the axle in the truck, but it easily came out when I put the drum and axle wheel side up on my hydraulic press, and pushed on the axle.  


Edited by DanielC
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On Wednesday afternoon, I got new grease and oil seals for the rear axle.  I took the old grease seal out of the brake plate above, and tried to put the new one in.  It did not fit, It was too large.  There was also some damage in the bottom of the bore where the grease seal fits.

I did some yard work, and moved some hay down to the barn it is needed with Dragon.  Dragon is running, but not registered.  But I can drive Dragon on my property.


This Friday afternoon, I decided to pull the complete rear axle out of Dragon Two, and put that axle under Ratsun.  That will allow me to get Ratsun running again, and also open up garage space where Ratsun is jacked up in the air now.  That will allow me to take some more time to put the rear axle that was under Ratsun back together.  

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This is the left brake plate.RtBrakePlate.JPG


Here is a closer look at the grease that was on the brake drum and shoes.



With the brake plate off the axle, this is how I held it down to remove brake shoe springs.



I grabbed the lower spring with a pair of vice grips, and removed the springs that hold the middle of the shoes to the plate.



With the lower spring removed, and the middle shoe springs removed, you can just lift up on the lower end of the brake shoes, and slip them off the wheel cylinder.



Then I removed the four nuts holding the wheel cylinder on the brake plate.



Then turn the brake plate over, and take the wheel cylinder off the brake plate.



The Brake plate is now ready for cleaning.



This brake plate had some damage where the grease seal fits outside of the wheel bearing.  This seal keeps grease in the wheel bearing, and out of the brakes, If it is working.



This is the inside of the area damaged in the picture above.  I already used a brass punch to try to minimize the distortion in the lip that holds the seal.



I want to have Ratsun running, and free up space in the garage sooner than I can get all the repairs done on the axle that was under Ratsun. 

This is the axle that was under Dragon Two, another 521 long term project I have.  I decided to put it under Ratsun to get Ratsun running soon.



This is the brake drum that was on Dragon Two axle.  I think it is a 620 brake drum, it has a more rounded edge, and two holes to screw bolts into the jack the drum off the axle.


Edited by DanielC
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  • 4 weeks later...

Since I put the axle from Dragon Two under Ratsun, I have gotten 20 bales of hay four different days, and been daily driving Ratsun.   It had been running good. 

The emergency brake works a lot better, but that is expected because of the grease and gear lube that had worked its way into the brakes, and in the brake drum.  Those brake drums were cleaned with solvent, then taken to a machine shop to get cleaned, and turned.

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  • 1 month later...
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I ordered this gear shift lever boot from Amazon on December 6.



It arrived December 16.



This is a picture of a fairly new Nissan OEM boot, that is NLA from the Nissan dealer.



I have two 521 trucks with long shaft five speed transmissions in them.  I put a five speed transmission in my Green truck, named "Dragon"  in the late 1970's.  Earlier this year, I put a 1980 720 L-20-B engine and five speed transmission in my daily driver Datsun 521, named "Ratsun".

I pulled the transmission cover plate out of Dragon when I put the five speed in Ratsun, and left Dragon without a cover plate for a while.


This December 2019 I started work on a cover plate for Dragon, since I robbed the plate from Dragon.   I cut a round piece of 18 gauge sheet metal to fit the hole for the original shift lever location of a 521, Welded that in a shift cover plate, then I cut a smaller hole in that plate for the new location of the shift lever.   I just used a 3 inch hole saw to cut the new hole.

Notice the new smaller hole lines up with two screw holes to hold the plate to the transmission tunnel.



The new Thailand lever boot fits the original hole OK, but first I had to cut the parting line flash where two halves of the shift boot mold came together.



This is not the actual knife I used, it is just for illustration.



Time to make the actual new hole in the cover plate for the new lever boot.  I used a second OEM cover plate to draw a circle on the plate I wanted to put a new hole in.



This is the round hole drawn above.  Notice the outline of the hole runs into two of the screw holes that hold the plate in the cab.



I then freehanded drew lines about a 1/4 inch inside the two screw holes, and then added about 1/4 of an inch outside 90 degrees away from the screw holes.  The intention is to make the boot mounting hole slightly egg shaped to clear the plate mounting screw holes.



I used a 1/32 small cutoff disk in a die grinder to rough cut the new hole, undersized.



Then I used this drum sanding wheel to sand (grind) the hole to dimension, and to smooth the cutoff wheel gouges, and deburr the hole.



Then I used this flange,



and a punch, that looks very much like an old kingpin, and a hammer to flatten the metal around the new boot hole.



This is the hole, flattened.



This is the Thailand shift boot from Amazon on the modified cover plate.



The bottom of the cover plate, with boot.BootOnPlate2.JPG


and this is the cover plate, and boot screwed in the cab of Dragon.



First Gear



Second gear



Fifth gear






No it is not painted yet.  It was 40 degrees F in the garage, too cold to paint.  About 4.4 degrees C.


Edited by DanielC
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I did some work on the heater of Ratsun today, it is still 11:58 on Saturday Dec 28, 2019.

The original plan was to remove the front cover off the heater, and leave the heater in the cab.  Less work to remove the heater, no need to drain the coolant, no need to remove the heater hoses. 

If you need to remove your heater, it would be a good idea to have new heater hoses, and I believe they are currently NLA from the Nissan dealer.   Ask the dealer anyway, my thought is that if enough people ask the dealer for parts for their old Datsuns, they might be made again.

In the mean time, here is some useful numbers to make heater hoses.  Gates 18457, 18796, and a Four Seasons 84743.  You can cut sections out of the Gates hoses to make the bends.  the Four Seasons part number is a 1/2 inch (13 MM) to 9/16 (14 MM) adapter.  A four cylinder Datsun L-Engine has 14 MM connections for the heater hoses, and the Datsun 521 heater has 1/2 inch pipes on the heater core.


To remove the heater cover only, this was my original thought.

Remove the screw holding the knob on the hot water valve.  I used a number 0 phillips screwdriver, the screw is actually a number 1 phillips.



In my case, I had to pry the knob off the heater valve shaft.  Do this carefully, 50 year ons plastic parts can break.  This is a non stock knob that the previous owner of Ratsun actually made from a piece of aluminium.



There are three clips holding the cover on the heater box.  Two are visible in this picture.



Pry the clips away from the heater cover.   Put the clips somewhere you can find them.  they will fall off then heater box when you are not looking.



You also have to remove the rubber duct from the under dash air box to the heater.  there are two screws that hold it to the heater, and one screw that holds it to the air box.DuctRemoval.JPG


This is where the air box screw was.DuctRemoval2.JPG


With the duct off, you can see the fan, and you can see the third clip holding the cover on the heater box.  Remove the third clip, about 10:00 from the center of the fan.FanExposed.JPG

Now the cover will come off the heater.  The fan should be a white color.  This fan also had a crack in it.   You can clean the fan with a tooth brush, using dish washing detergent.  Be gentle, the fan is 50 years old also, and is very easy to break.  I use Ratsun to haul hay, notice some hay is in the heater box.



There is a screw that holds a clip, that holds the defrost cable.  Remove the screw, clip, and unhook the "Z" bend from the defrost door on the heater box.



At this point, I decided I need to remove the whole heater.  I am pointing to one of the four studs holding the heater in the cab, I have already removed the nut and washers.



Another heater box mounting stud.



I have already drained the coolant, and removed the heater hoses in this picture, there is another heater stud between the two hose connections.  the fourth stud is above, hidden by the wire harness.



The nuts and washers from the heater studs.



Slide the defrost hoses off the heater box connections.   The defrost hose is a nominal 1 1/2 inches, most auto parts stores carry carb air heat hoses in this diameter if you need new ones.   Pull the heater straight back, and then tip the top of the heater forward, and it comes out from under the dash.



Unplug the heater electrical connector.



I then carefully slid the heater core out of the heater box, and then blew air from an air hose up through the core to dislodge hay, insects, and other debris.  I used a pair of needle nose pliers to remove a few pine needles still in the core.


I previously have taken other Datsun 521 heaters apart, and happened to have a painted heater box ready to go, I used that to put back together, with the old core from the heater that was in Ratsun. 

I used this foam tape to seal the edges of the heater core.



This is the core in the heater box, notice the nice clean fan.  I put more foam tape on the front of the heater core.



Then I put the cover on the heater box, and put the three clips on the cover.CoverOn.JPG


Then I put some narrower foam tape on the defrost door.DeFrostDoor.JPG


Finally I put the heater in the truck.  I was painting some other stuff black, when I painted the heater boxes, and ran out of black paint in the spray gun.  This heater cover is painted black on the inside, but not on the outside.  I can easily replace this heater cover when I get one painted.


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Ahhh the 521 heater!!!! I survived Ontario winters in my '71 not because of the heater but in spite of it.



Did you see the other post where someone replaced the heater valve handle with one from a garden hose tap?



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Hey Daniel C


Everytime I log on here and I read about the more stock Datsun truck stuff being built and rebuilt...and then I see the pictures of the various parts that make up the old Datsun trucks...it makes me smile...takes me back to the 1980's when all I drove was a Datsun truck....


Love it love it love it...


Thanks for posting all the progress on your awesome little truck...



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Most of the trips I take Ratsun on are less than ten miles, or 16 kilometers to you Metric folks.  Ratsun barely gets a chance to warm up, but to speed up that process a little, I put sone cardboard in front of the radiator.  This also makes the heater work better when the truck does get warmed up.   By the way, this is with a stock 521 radiator, and a L-20-B engine.



Today, new years day 2020, Ratsun got another load of hay.  This is backed into the feedroom I store the hay in, and it is about 10 feet, (3 meters) from where the hay is stacked.



It may seem like I have not been posing much, but I am going through old posts, and getting rid of Photobucket links.

Edited by DanielC
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In this picture there are two 521 heater cover plates, and the shifter cover plate that is going back on Dragon.  The shift plate was sprayed with an epoxy primer, then a surfacer, and I sanded the surfacer.  The heater covers were sprayed with PPG DPLF epoxy primer, a while ago.  The instructions for DPLF  say it can be top coated within a week of spraying, without sanding, it has been much longer than that.   I sanded the two heater cover plates.



I mixed another small batch of DPLF, and sprayed that on the heater cover plates, both sides, and sprayed the top side only of the transmission shifter plate, to cover a few bare metal spots from sanding.  That was last evening.



This evening, I sprayed Alasta Centari 99A pitch black on the parts.  They are in the garage, under the PAR 46 lights for heat.



This post is pretty much a copy of the post in another thread, about another one of my 521 trucks.  One heater cover is going on Ratsun, the transmission shifter cover plate is going on Dragon, and I have other 521 trucks too.

Dragon's thread starts here.



Monday Jan 6, 2020 I painted the parts in the picture above, Thursday I put one painted heater cover plate in Ratsun.



Edited by DanielC
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  • 3 weeks later...

I did some more cleaning, and priming of random 521 parts last week.  There was a lot of sanding, some sandblasting, and using 3M clean and strip disks, and Nylox abrasive brushes, available at Ace hardware stores.   No pictures of cleaning the parts.


I have some smaller "DJ" type lights cans that hold a PAR 46 200 watt spot light.  Three of the light fixtures are in this picture.



After the parts were cleaned, I set them on a table, and turned on four spot lights on the parts.  Then they were sprayed with PPG 1791/1792 wash primer.



Some other parts.



After spraying the wash primer on the parts, I sprayed them with PPG DPLF epoxy primer.



Same parts, different angle.


That was Saturday night, and I quit there.  If you look at the pictures with the wash primer, you may notice I used wash primer on two air boxes, the part that is under the dashboard, above the heater on a 521.  when I moved parts around to spray the DP40LF epoxy primer. I had set the air boxes aside, and forgot to spray epoxy primer on them.


Sunday evening, I got the air boxes I missed spraying epoxy primer on, and checked the other parts I sprayed epoxy primer on for missed areas with the DP40LF.



Another set of air and heater boxes.



Hand brake brackets, and a brake and clutch pedal.



A pair of hood hinges, and a gas pedal.



Paint on these parts coming soon.

It's soon.







Three more pictures added Jan 31, some hand brake parts,



A brake and clutch pedal,



and three gas pedals.



Just a quick review of the story on this truck.  It was bought by me in April, 2011, as a parts truck for another one of my 521 trucks.  It turned out that it was easier to get this truck running then the truck I was going to use it's parts for.

It still need the floor replaced in it, but I have cut and bent some sheet metal for the floors.  As I was fitting the new floor pieces in this truck, it became apparent that to properly weld the new floors in the cab, I need to remove the cab from the truck.

I ended up buying another cab, that needed new floor also, but that cab's floor is not as bad as the cab on Ratsun, the name I gave this truck.

The small parts I have been removing rust and old paint from, and repainting are going to end up in this truck, probably when I do the cab swap. 

In many cases, if I have extra parts, is is not that difficult, or take much more time to prep and paint extra parts.  Then when i am working on another 521, I already have painted parts on hand.



This a quick edit on Feb 1, 2020.

It was unusually warm yesterday, about 60 degrees F, 15.5  C to the rest of the world.   


If you look at the parts on the table in primer, you might notice a pair of 521 hood hinges.   They were painted white yesterday, to match the cab they are going in.


When painting the hinges, I hung them off a bent piece of wire.  this allows you to paint both sides, the bottom, and top.  I used a second piece of wire in one of the bottom holes in the hinge to lift up the bottom of the hinge to paint that area.   I also propped a piece of cardboard behind where I was spraying, to catch some overspray.



The four spot lights were shined on the hinges to help cure the paint.  It may look like the spot lights are shining on the table, but they are actually shining past the hanging hinges, and lighting up the table.


Edited by DanielC
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  • 4 weeks later...

L block starters don't seem to last long anymore, I bet I have went thru 10 of them in the last decade or two in the work truck, whenever I see one at a Datsun swap meet that looks OEM I buy it, I can't seem to get a year out of a rebuilt one, I just changed one out again in the last two weeks, the one in it now came from the Brooks OR meet(Canby replacement).

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We are talking electrical, so may as well start with this.



There was a discussion about a month ago about batteries, and age of batteries.  This is the battery currently in Ratsun, a battery I got at Pick-n-Pull more than a few years ago.  I need to do some work cleaning corrosion off the hold down, and the negative cable clamp on the terminal of the battery.  Notice also how thick my negative battery cable is.



This is the positive battery cable.



Matt, and Mike, very good suggestions.


Why do I go to the trouble to make such big cables for the battery on my Datsun?

All electric motors, including the starter motor are designed to do a certain amount of work.  The amount of work an electric motor does is measured in Watts.  Watts is simply Voltage times Amperage.  If an electric motor is being supplied with 10 volts, and is drawing 100 amps, that is 1,000 watts of work.


All wires have some resistance.  Resistance impedes current flow, resistance tries to stop or reduce the amount of amps that can flow, and this happens because the wire loses voltage from one end to the other.


A small wire has a greater voltage drop than a thick wire.  A thick wire will deliver more voltage to the load it is connected to than a thin wire.  One example, thinner or longer wires will make your headlight dimmer. 


But electric motors are even more sensitive to voltage drop.  If you lower the voltage to an electric motor designed to do a certain amount of work, the motor compensates by drawing more current.  In the example above, if the motor only gets 9 volts, it will try to draw 111 amps to accomplish 1000 watts of work.  But it gets even worse, because you are drawing even more current through the resistance of the cable, the voltage drops even more.


The speed of an electric motor corresponds to the voltage supplied to it.  If you get more voltage to the electric motor, it turns faster.  It draws less current.  The battery voltage is also higher if the battery is supplying less current.


With battery cables that are "too big" the starter spins faster.  The battery actually has a slightly higher voltage, that also goes to the ignition system.  The engine starts sooner because of spinning faster, and haveing more ignition voltage.  Another benefit, because the engine started sooner, the battery is less discharged, and the alternator has less work to do to recharge the battery.


Enough electrical theory for one post.

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Ever try the TSI Starters(HiTorq I really think they are. 200.$

Troy Ermish sells the same one for $240 I seen

Denso motors used




I bought one but haven't installed it yet.

I found out that once I installed a starter relay my cheap starter seems to be lasting longer. Maybe I have been prematurely getting rid of them when the low voltage of the key switch makes the Click Click Click then I pull the starter

Edited by banzai510(hainz)
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1 hour ago, banzai510(hainz) said:

Ever try the TSI Starters(HiTorq I really think they are. 200.$

Troy Ermish sells the dame one for 240 I seen



I bought oe but haven't installed it yet.

I found out that once I installed a starter relay my starter seems to be lasting longer. Maybe I have been prematuly getting rid of them when the low voltage of the key switch makes the Click Click Click then I pull the starter

I have one in all my cars and worth every penny.

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My battery is 'I don't know how old' old. We scrapped our company van and the battery we bough new just 2 years ago... but side terminal. So I got some cables from a GM Pontiac van. Just look how thick the black negative wires are!!!! Rather than shorten and bolt to the usual place on the L head I used a starter mount bolt. What better place for it that right where it needs it. I think they were $10!!!!.





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