521 Taillight rebuilding

[DanielC]

Last year, I cleaned and rebuilt the taillights for my 521 pickups.

Removal of taillights
I started by getting the taillights off my three Datsun pickups I own. I also found some old taillight lenses. The taillights on the pickups were a little difficult to remove, the screws that held them were rusted to the pickup bed. There was also clearance issues with the wrap around bumper that was on the green truck, pictured. You will want to clean the screws as best you can, and then put some penetrating oil on them. Letting the penetrating oil sit for a while is not a bad idea



The screws that hold the taillights to the truck are 10-32 screws, with a Phillips head. Some of the screws go into a nut that is welded to either the pickup bed, or they have nuts that are loose on the back side. The nuts on this truck that were free, used a 3/8 inch wrench.

Dissassembly
The Datsun 521 pickup taillight assembly can be taken apart easily, except for the problem that they have had road grit, and water thrown on them for the last 40 years. Again, you want to clean the threads on the studs as best you can, and put penetrating oil on them. The studs can be broken off pretty easily.
Even though the taillights are fairly well sealed they will probably have some dirt inside them, both on the reflectors, and the inside of the lenses. There might also be some rust on the frames. The whole taillight assembly assembly is held together with a metal frame, that has eight 8/32 studs welded to it, and uses flat washers, lock washers, and nuts to clamp the white plastic reflector to the frame. The lenses, both red and clear are separate plastic pieces also clamped between the metal frame, and the back reflector, with a gasket in between the two plastic parts.

Here is a picture of the back of the taillights, with an extra taillight wire harness in the top of the picture.


After getting all six taillights off the trucks, I then took them apart. The bulb sockets just twist counterclockwise, and come out. The old bulbs will just twist counterclockwise out of the bulb sockets, it they are not corroded too badly. The ground wire on the taillight on the taillight wiring harness can then be removed from the taillight assembly by removing the 8/32 nut that hold it to the stud on the taillight frame. I used a 5/16 deep socket to get to the nuts. A metric 8 MM deep socket will also work.

Here is a better picture of the nut that holds the taillight wiring harness ground wire to the taillight frame. Notice this wire is under the second stud in from the inside, on top of the taillight assembly.



Remove the other seven nuts on the taillight frame. You probably will need to clean the studs as best you can, and put penetrating oil on the studs before you remove the nuts. A little care and patience now will save you from breaking a stud off the taillight frame and having to repair that later. After getting all the nuts off, carefully pull the frame off the taillight assembly. You now have a white plastic taillight back, and the taillight lenses, and there is a gasket between them. Carefully pull the two apart, and watch the gasket between the two parts. Be careful, and you can prevent ripping the gasket. Gently pull it off of the lenses, and reflector.

 

EDIT:  the clear lens is a right and a left.  There is a part number on the clear lens, 220-23429L and 220-23429R. The "L" is for left, and the "R" is for right.  

As near as I can tell, the only two parts that is unique to each side is the metal taillight frame, and the clear reverse light lens. The eight holes in the parts that go on to the studs on the taillight frame are symmetrical, from top to bottom. The red colored lenses can be used on either side. The gasket can be used on either side. The white reflector can be used on either side. The wiring harness can be used on either side. On the taillight frames, two of the holes used to mount the taillight assembly are closer to each other. This is the turn signal end of the taillight frame. On the other end of the frame, there is a small tab that goes into a small cut out hole on the reverse light lens. The reverse lights go toward the center of the truck, the turn signals go to the outside.

You can see the tab for the reverse lens on the left side of the top frame, and on the right side of the bottom frame.



You can see the cutout in the reverse lamp lens in these pictures.





I then cleaned the plastic parts. I used a detail brush, and one of my favorite cleaning products, a very little bit of Dawn dish washing detergent in a spray bottle filled with water. I then rinsed everything made of plastic, throughly with running water, and then blew the remaining water off with compressed air. The outside of the taillight lenses were polished with rubbing compound, and a rag, by hand.

This picture is the red lenses after I cleaned and polished them. One of the Taillight assemblys I had came with a seperate turn and tail/stop signal lenses. I am thinking there are probably some 521 Datsun pickups with orange rear turn signals. Probably not too many in the USA.



Electrical Stuff
After cleaning the lenses, I worked on the wires. When I did this as a web page, I had a nice little chart here, as an HTML table. I can not do that here, so maybe this will help, with the electrical information.

The turn signal and reverse lamps are 12 volt, 25 watt. The SAE trade number for the bulbs is 1073. For a pair of 521 taillights, you need 4 bulbs.
The stop and taillight lamps are 12 volt, 8 watt, and 25 watt. The SAE trade number is 1034 or 1157. You need two of these bulbs.
The wire colors are as follows, on my 521. Yours may be different. The turn signal wires are Green, with a red stripe, both sides. The stop light wire is Green with a blue stripe, and the taillight wire is red with a blue stripe. The tail, turn, and stop lights end with a three pin plug, that plugs into the wiring harness on the truck. The reverse light Red with a black stripe, and has a separate connection to the wiring harness on the truck.

The black wire on the lamp sockets is obviously the ground wire. The lamp sockets are sitting in the middle of the white plastic taillight housing, and cannot ground, without it. When the truck was new, this black wire connected the lamp sockets to the taillight frame, and ended there. The idea was that the taillight frame was bolted to the truck bed, that attached to the truck frame, that attached to the engine, that finally got back to the battery negative post.

On a forty year old truck, the grounds may not all make a good connection. The battery grounds the engine, by the fuel pump, and to the cab, by one of the screws holding the voltage regulator to the fender well. This ground wire is important, because if this ground goes bad, your truck may try to ground itself through the throttle cable, and the choke cable. These cables then get hot, melt the plastic, and lock the cables in whatever position they are in. Add an extra ground from the engine to the frame.

Now, back to the taillights. When you assemble them, put an extra black wire under the stud on the taillight frame, that will go back to the frame of the truck, when you put the taillight assembly back on the truck.

I then worked on the taillight wiring harnesses. I cleaned up the harnesses I had a little, and put new bulbs in them. I had a bad bulb that was corroded tight into at least one socket, This is how I dealt with that. I broke the bulb in the socket. Then I broke out as much of the glass in the base of the bulb as I could, I then pried the brass bulb base away from the socket, so I could grab the metal part with some needle nose pliers. I could then turn the bulb base counter clockwies in the socket, and peel the corroded parts away from the socket. I then used a new clean battery brusk to clean out the socket. Make sure you check that the spring in the bottom of the socket is not broken.

I put new bulbs into the sockets. I ran a pair of wires from a 12 volt battery, to the taillight wiring harness, and tested them to see if all the lights work. It is much easier to check these on a bench, than it is to work on them while you are under the truck.

Painting the frames
One of the frames I had to straighten. I took a piece of 2 x 6 lumber, a little longer than the taillight frame, and drilled eight holes in it to match the studs on the back of the taillight frame. I then put another block of wood on top of the taillight frame, and pressed, or lightly hammered the blocks together to straighten the frame
I then cleaned, primered, and painted the taillight frames. I used an electrolysis process to clean the frames. The electrolysis cleaned off a lot of the rust on the frames, but they were not perfectly clean. The electrolysis did greatly reduce the amount of sandblasting the frames needed to clean up perfectly. The frames were primered with a wash/rust preventive primer, an epoxy two part primer, and then a single stage enamel, gloss black.

Reassembly
Finally, time for reassembly. I took the two best white plastic reflectors I had, and set them on the bench face up. Both are the same, no right or left. The turn signal side has the shiny reflector in it, and is larger than the reverse light side. I then put the gasket on the taillight reflector. Look at the picture of the gaskets, you see three pencils pointing at notches, or cutouts in the gasket. These go down in the assembled taillight. If it seems like you only have two right or left gaskets, turn one end for end.


Now that you have put the gaskets on, you have a right and a left taillight. In this picture, the top assembly is the left taillight, the bottom is the right.


Put the taillight lenses on the assembly you have.


Carefully put the frames over the reflector and lens assembly. The rounded end of the frame goes down. The reverse light end of the frame has the little tab that lines up with the hole in the reverse lamp lens.

Turn the assembly over, and put it face down on a clean cloth on the bench. I added some number 6 flat washers to spread out the stress of clamping the whole assembly together. Do not forget to put the ground wire on to the assembly. The ground wire lug goes over one of the studs above the top of the Tail/ Stop reflector. Use the one closer to the reverse light. Here is the pile of hardware I used to put the assembly back together.



Now you can put the lamp sockets back into the reflector. The reverse light has a red with black wire on it. The dual filament bulb goes in the stop/tail light reflector, The green with red wire is the turn signal. Notice that the free end of the wiring harness goes toward the turn signal end of the taillight assembly.



This is the completed taillight assembly, ready to install.



Before I installed the taillight assemblies, I retested them. I just wanted to eliminate problems before I had to deal with them when I was under the truck. As it turned out, I had to add a ground wire from the taillight assembly to the frame of the truck to get the taillight on the left side to ground correctly.
I was able to get some Stainless Steel 10-32 screws to mount the taillights back on the truck.


I think I am done with this, but I might edit it in the future, if Ratsun will still let me.

[fisch]

Thanks for the writeup Daniel! +1

[patd]

Good Thread, I removed my tail lights to clean them a few weeks ago, they had forty years of grime on them and I could not clean them as good as I wanted to as I was afraid I would crack the lens, my right hand side tail light is cracked and missing some pieces and looks like it will fall apart, so now I can remove it and super glue it from the inside and clean the inside of the left one thanks to your article. I am going to the Datsun museums car show/swap meet this Sunday and i am hoping someone might have a lens to sell. Thanks for posting it.

 

[jrock4224]

Thanks for the right up gonna clean up my stockers and see how they look beofre i try and source some newones

[DanielC]

Thanks for the kudos!

The editing has continued. I am choosing to change the original post, rather than add bits and pieces as this thread goes along.

[DanielC]

I think I am finished with this.

Hope it helps you all.

[NSRz32]

Awesome write up. Looks like something I'll have to do in the spring :)

[DanielC]

I thought I would bump this to the top.  It has been three years since I last edited it.

 

Sorry about the blurry pictures.  This thread was started before my digital camera, and was done with film, that was developed, transfered to a CD, and finally to here.

 

If you have ANY parts from 521 tail lights assemblies, I can use them.  I would even be interested in paying you shipping for them, and a reasonable price for the parts.

[Rocket Dog]

Daniel, I have a few questions please?

 

1. Can I pay you to refurbish tail light frames? Specifically to repair the missing studs and clean up the threads. I can clean the paint and prime them, etc.

 

2. Would you pass along the info on the rubbing compound you use to buff out the tail light lenses?

 

3. I noticed on my tail light back piece (the white section that holds the light fixtures, attaches to the lens) that the backup light portion of the fixture is a different kind of plastic, or for some reason deteriorates far more than the rest of the fixture. Have you hit upon a process for repairing that "divider" between the backup bulb and the rest of the light fixture? Is that even necessary for the operation of the light?

 

4. Again on the white light fixture, sometimes the "interlock" where the bulb fixture attaches to the light back piece, the tabs are deteriorated or just broken. I guess this is the same question as number 3, how to repair portions of the light fixture?

 

Would pictures help?

 

You sir, are Lord of all things Datsun.

 

 

[Tucson620]

Thanks for a great thread Daniel - used it to rebuild my 521 lights a couple months back.  Problem in AZ, for sure, is the white housings are all rotten.  Took my 2 + 2 junkyard lights to make one decent set.  I've got the remains still if you wanna look at it, though it all looked pretty rough to me.

 

Rocket Dog, don't think I have any pics, but I had to reconstruct the housing in a couple places due to rot.  Tabs gone or crumbling, bulb socket had nothing to enage.  I used a combination of new material and epoxy to rebuild the white housing where the bulbs mount.  Also to reinforce some cracks.  I'll check if I have some pics.

 

What I did: Found similar white vinyl/plastic material at hardware store.  Material needs to be of similar thickness to original.  I copied the hole pattern from another hole, then dremeled with tabs to match.  Then I epoxied the new material in place as the new bulb locking spot.  In my case, the "ears" and rim of the hole were reasonably solid, but the hole was gone.  So I dropped in a new round piece.  Kinda like my mspaint job below:

 

[Tucson620]

Thanks for a great thread Daniel - used it to rebuild my 521 lights a couple months back.  Problem in AZ, for sure, is the white housings are all rotten.  Took my 2 + 2 junkyard lights to make one decent set.  I've got the remains still if you wanna look at it, though it all looked pretty rough to me.

 

Rocket Dog, don't think I have any pics, but I had to reconstruct the housing in a couple places due to rot.  Tabs gone or crumbling, bulb socket had nothing to enage.  I used a combination of new material and epoxy to rebuild the white housing where the bulbs mount.  Also to reinforce some cracks.  I'll check if I have some pics.

 

What I did: Found similar white nylon/plastic material at hardware store.  Material needs to be of similar thickness to original.  I copied the hole pattern from another hole, then dremeled with tabs to match.  Then I epoxied the new material in place as the new bulb locking spot.  In my case, the "ears" and rim of the hole were reasonably solid, but the hole was gone.  So I dropped in a new round piece.  Kinda like my mspaint job below:

 

 

 

Also - my "divider" was broken too.  I think it just separates the light from different sections of the fixture.  Probably don't need to fix it.

[Tucson620]

One other thing to add.  Googling around, came across this Rockauto newsletter that suggested boiling old brittle nylon parts as a restoration technique.  http://www.rockauto.com/Newsletter/archives/62112.html (scroll down to boiling parts section)

 

I soaked the housings in near boiling water and think it helped!  Your results may vary.

[.sunlover]

I thought I would bump this to the top.  It has been three years since I last edited it.

 

Sorry about the blurry pictures.  This thread was started before my digital camera, and was done with film, that was developed, transfered to a CD, and finally to here.

 

I have the tail lights. Is this the truck you needed the front turn signals for?

 

If you have ANY parts from 521 tail lights assemblies, I can use them.  I would even be interested in paying you shipping for them, and a reasonable price for the parts.

[DanielC]

A quick reply.  It is probably getting warm enough to put some primer and possibly paint on Ratsun today.   I am sure by 4:00 PM it will be too cold again.

 

I have not found a way to repair the deteriorated white reflector base.

 

It theoretically should be possible to weld new 8-32 studs on the taillight frame.

 

So far, I have disassembled various taillight assemblies,  and used good parts off one to repair another. 

I have bought damaged taillight assemblies from Pick-N-Pull, sometimes out of one taillight i will just get a good wiring harness, or a good red or clear lens, or a good white reflector, you get the idea.   What you think is a bad taillight assembly may have some, or even one good part on it.

 

As far as polishing the lenses, I do not think the polish is critical.  I think I used a Meguire's Heavy cut cleaner, followed by Meguire's swirl remover.  What is important is to NOT get the plastic warm.  Do NOT use a powered buffer, with high speed, or lots of pressure.  Using a soft cloth, by hand is fine.

[.sunlover]

I've got a pair. Were you able to use those front turn signals I gave you?

[Rocket Dog]

Thanks very much. I'll try the reconstruction method. McMaster Carr or Tap Plastics probably has the materials for patching (?)

[JoeCool]

Good writeup. I did all that to my taillights when I replaced the busted lenses and also spray painted inside bright silver as mine was dirty and stained very dark. I Does anyone know how to fill a small crack in the lens? My front corner has a small crack.

[DanielC]

.son,

I actually have parts for four 521 trucks, but not all the parts.   The front park lamp assemblies you gave me, I think I moved one amber lens to Ratsun, one of my project trucks, and put the rest of the assemblies in storage, for a future project.

 

But for now, I am trying to get Ratsun on the road.  The licence plate renews in February, and since it has not been registered for several years, DMV recommended I wait until March 1, before I renew the registration.  So that is my main focus right now.

 

I do not know what I would use to fill a small crack on either the taillight, or the parking light.   If I have all the pieces, with no gaps, I think I might try using Superglue on a broken, or unusable, to see how it looks, and if I like the results of that experiment, try to fix a useable one by Supergluing it.

[.sunlover]

Well if you need a lens, I've got one

[DanielC]

I have mentioned it before, but I have parts for four 521 trucks, but not taillights for all four.   When I got Ratsun, this truck,

http://community.ratsun.net/topic/30606-my-ratsun-datsun-521/

it's taillights were in sad shape.  I took a pair of taillights I had already rebuilt, and put them on Ratsun.

I put the taillights from Ratsun into storage.

Last fall, I also grabbed the taillights off a 521 truck that was at Sherwood Pick-n-Pull, but they were also in poor shape, but had some useful parts on them.  But Sherwood P-n-P only charged me $15. xx or so for each one, so it was worth it.

So I had two pairs of taillights, one from Ratsun, and one pair from Sherwood.

 

When I bumped this thread, .sonlover mentioned he had some 521 taillights.   Long story short, we traded a good 521 heater motor and fan and some dollars for a pair of 521 taillights.

 

Today, I decided to see what I had for good, or useable parts for 521 taillights.  I took all three sets of taillights apart.  I wanted to get down to the metal frames, I have another set, of both one side,but good taillights.  But several broken studs on the metal frames.  

 

I ended up with two pair of frames, with all eight studs good.  The two other frames have only one broken stud each.  But the frames were bent.  Because I have a few bent frames to straighten I took a piece of 2 x 6, and drilled eight holes in it to match the studs.

The eight holes match the eight studs.

I also made this block from a piece of scrap steel.

The notches in the block clear the studs on the taillight frame, and I put the steel block under the taillight frame, on the wood block.

and I used this to help straighten the taillight frames that were bent. 

 

Tonight, I also washed the good lenses in the kitchen sink.  I have two good red lenses, a useable red lens, and four clear lenses.

I also noticed tonight, the clear lens is a right and a left.

[71Hustler]

Thanks for this write up Daniel! I know this thread is a couple years old now, but PM me if you're still interested in misc. tail light parts -- no matter the condition! 

 

I took my existing not-great tail lights and two more I bought at Canby to piece together two nicer ones. I neglected to take before photos, but they're definitely a lot cleaner, and the reverse lights have some housing to latch on to -- my existing housing for reverse was totally shot.

 

 

Still have cracked lenses, but was able to glue a few bits back on and add some tape in the gaps.

 

I don't get why the reverse lights and their housing appear to be so different than the rest of the tail light. The housing plastic is super crumbly, and the sockets are a mess of rust, whereas the other ones seem fine. I sprayed the housing with plastic primer, hoping it will act as an adhesive and hold things together a bit longer:

 

Here's an example of my sad reverse lights. Anyone know where to get these sockets? RockAuto only seems to have the dual contact run/brake sockets, and I don't want to buy a whole harness assembly. 

[DanielC]

Yes, I will still take taillight parts. 

You can use the turn signal lamp holders in the reverse position, but you need to do some rewiring.

I believe the plastic deteriorates around the reverse lamp quicker because the reverse lamp is in a smaller area, and heat builds up more.

I do plan on going to the Blue Lake meet.

[DanielC]

One of my old posts, but by adding this, it brings to higher in the pile of search items.

 

[Oilspot]

Just a note. I just got done redoing the tailights on my 521 this morning and the studs on my frames are M4x0.7. 

 

 

Edited January 13, 2022 by Oilspot

[Matt H]

Hey @DanielC I have the same issue where both of my reverse lights are corroded beyond repair. The housing of the lights is salvageable so i'm just in need of two single point sockets. Appreciate any guidance you might be able to offer. It looks as though finding a replacement wiring harness might be tough. 

Is it possible to use something like this and just file down some of the grooves in the locking mechanism to get it to fit?

https://www.ebay.com/itm/133567541812?hash=item1f193ef234:g:l40AAOSwrNBfpJEZ&amdata=enc%3AAQAIAAAA4E907rxOaQpnr26tko5%2FFbYv93x17x4Z5PIqIRRJdsnGUY%2FVXUjXyAlazAukFLW8gRCkw6VMPL%2FlQ5i2pa1uHHJ797bESPC41wZljhFVOsB8ib0HK5VizB0UXX0MOX8zVlYgeZIW3BY5s%2FrkvbCUOL4XVXhgCNmueSelqR7UayODXiUcaP9YqyjTj2C5MO6x%2FSiCA%2BRxWKKGpGHezGUrPc%2FmuXXp5DRxwShlEBXe35PwLIBlfgUo4MfCvz8eKHwo1YUMLInsd8eeyYzHdPwrqWoFJ8BxNjrio9NR1xfmjSRV|tkp%3ABFBM2IC7-IBi