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DanielC

My Ratsun Datsun 521, now with L-20-B

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Another step in swapping the L-20-B engine into Ratsun was hooking up the exhaust system.  A few years ago, I replaced the exhaust system myself.  Details here:  http://community.ratsun.net/topic/61167-how-i-replaced-a-521-exhaust-system/?hl=exhaust

I put a flange connection in the exhaust system, about two feet from the enf og the exhaust manifold on the engine.  With the flange in the pipe, I just remove the short down pipe to either remove the engine, or the transmission.  It makes changing a clutch way easier.  Tubing, mandrel bends, and flanges here:  http://www.mandrelbends.com/

DownPipes.JPG

 

This is the flange.  I should of got one about two weeks ago, but I did not.
PipeFlange.JPG

 

I did have a piece of 5/16 steel plate.  This is how I made a flange.
SteelPlate.JPG

 

I held the flange on the plate, and marked around it with a Sharpie felt pen.
Flange1.JPG

 

Found the center of the flange, and center punched it.  The first center punch was not really centered.
Flange2.JPG

 

Drill an 1/8 inch pilot hole, notice the cup of oil at the top of the picture.  The oil is just old gear lube.  With the 1/8 hole drilled, I then enlarged the hole to 1/4 inch, to make a pilot hole for a hole saw.
Flange3.JPG

 

The hole saw has a a set screw to hold a 1/4 drill, but the set screw does not really hold the drill secure enough to drill a hole in metal.  But once the 1/4 hole is in place, the hole has only to center the hole saw.  In fact, after the hole saw has started to cut, the 1/4 drill is no longer needed.  I also used a lot of gear oil on the hole saw.  The drill I used on the hole saw is heavy duty 1/2 corded and keyed chuck Milwaukie drill.  A drill press would be even better, but I do not have a drill press.
Flange4.JPG

 

With the 2 inch hole in the plate, I used a spare piece of pipe to center the old pipe and flange on the plate, and located a 5/16 hole to hold the flange to the flange on the pipe on the rest of the exhaust system.
Flange5.JPG

 

Here I am drilling the second of three holes to hold the flanges together.  Notice I have the bolt in the first hole to locate the second hole accurately.  I also used the spare piece of pipe to help locate the small holes.
Flange7.JPG

 

I drilled the third bolt hole, using two bolts in the first two holes to locate the third hole.  With all three holes drilled, I deburred the holes.

Flange8.JPG

 

Then I bolted the old pipe and flange to the steel plate I was making a new flange with.
Flange9.JPG

 

and then, a cutting torch to cut the flange from the steel plate.
FlangeA.JPG

 

then I used a 9' angle grinder to smooth the edgers of the new flange, and then smaller grinders to finish the flange more.
FlangeB.JPG
More grinding,
FlangeC.JPG
and then remove mill scale of the mating surfaces of the flange, and to make eventual welding easier.
FlangeD.JPG

 

That was Saturday, I was hoping the exhaust system would go together easily.  It did not.  In hind site, I should of enjoyed the rain in Canby.  I did go out there for the banquet, and to hear Pete Brock.

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This is the pipe mismatch with the exhaust pipe from the 720 truck that the engine came out of, looking up.
PipeMismatch1.JPG
 
This is from the side. 
PipeMismatch2.JPG
 
The down pipe was too low, I put a jack under the 720 down pipe to bend it up.  
PipeMismatch4.JPG
 
I used an old main bearing cap to push the pipe up.
PipeMismatch5.JPG
 
I had a 2 inch 90 degree mandrel bend, after deciding it would be easier to use it, I tack welded it to the 720 down pipe, bolted on the L-20-B engine.  This is looking from the side.
DownPipeBend.JPG
 
The straight piece of pipe is not welded to the flange I made on Saturday, I bolted the made flange to the existing exhaust pipe to check alignment.  Good alignment, looking up.
PipeMatch1.JPG
 
New pipe elbow tacked to old 720 down pipe.  It ended up too high.
NewBendTack.JPG
 
I had to grind out three tacks on the elbow to down pipe, and bend it down slightly.
PipeMatch2.JPG
 
This is how I adjusted the location of the pipe.
BendAdjust.JPG
 
With that done, I could cut a new piece of straight pipe to go between the elbow and the existing exhaust system. 
PipeMatch5.JPG
 
I am preparing to weld the straight pipe to the new flange.
FlangeTack1.JPG
 
This is a tack weld joining the straight pipe, and the new elbow.
PipeLengthTack.JPG
 
Tack weld on flange, on one side
FlangeTack2.JPG
 
Tack welds on flange the other side.
FlangeTack3.JPG


With the downpipe tack welded, I removed it, and welded the flange, straight piece of pipe, the elbow, and the exhaust manifold connection together.  Then grind the welds off, and put it back on the truck.
Downpipe1.JPG
Other side of the down pipe.
Downpipe2.JPG
With the downpipe in place, it looked a little too close to the speedometer cable.
SpeedCable1.JPG
 
I took the transmission end of the speedometer cable off, cleaned the cable, and rerouted the cable outside of the steering column.
SpeedCable2.JPG

 

With Ratsun getting close to running and driving again, It was time to take all the stuff out of the bed of Ratsun.  This is the second L-20-B Engine I got in March.   I put a four speed 521 transmission on it, put a starter on it, and then bolted it to the engine test stand I built.  Sometime I will do a compression check on this engine, and see what it needs to be a running engine again.  I then set the L-20-b engine and trans on the pallet.
L20B_413.JPG

 

I was thinking that I could also put the L-18 engine I pulled out of Ratsun and a transmission on the same pallet.
L18D2.JPG
I used a fork lift attachment on the tractor to move them both.  That did not work.  It made the tractor do wheelies.
2Engines2Trans.JPG

I ended up putting the L-18 engine and dogleg transmission back into the bed of Ratsun, along with the five speed 720 transmission.  I had to go to work that evening.

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This is a 521 carburetor I found in a junkyard, on a 620.  The carb looked rebuilt, but it had some issues.  when I got the carb, the accelerator pump was jammed, and I fixed that by putting a different accelerator pump plunger from another carb in it.  The engine would start, and run with a lot of choke, but not idle without the engine dying.  I decided to pull the carb off the L-18 engine I just pulled out of Ratsun, and try that carb on the L-20-B .  This is also the carb that was on the L-16 engine that was on Ratsun when I bought it. 
Carb removal steps follow.
JyCarb1.JPG
A small tuna fish, or pineapple can makes a good cap to prevent dropping stuff into the carb.
JyCarb2.JPG
Use a Phillips head screwdriver to remove the inner choke cable from the lever it pulls,
JyCarb3.JPG
Remove the outer cable clamp.
JyCarb4.JPG
and remove the choke cable.
JyCarb6.JPG
Remove the fuel line.
JyCarb5.JPG
Use a 12 MM wrench to loosen the throttle cable lock nut
JyCarb7.JPG
Unscrew the other nut off the end of the throttle cable.  Then the inner throttle cable can be slid out of a slot on the throttle cable anchor.  Then unhook the barrel on the end of the inner cable from the throttle cam.  Sorry, no picture of this, all my hands were being used to remove the barrel from the cam.  If you hold open the throttle shaft, the cable is easier to unhook from the throttle cam.
JyCarb8.JPG
Throttle cable unhooked.
JyCarb9.JPG
It is not necessary, but if you unscrew the collar holding the cable to the firewall, the throttle cable hangs down close to the firewall, and is harder to damage.  More important if you are removing the engine.
JyCarbA.JPG
Remove the distributor vacuum line from the carb.
JyCarbI.JPG
 
Unplug any wires that go to the carb.  None of the wires were hooked up on this carb.
 
Loosen the two outer carb nuts.  The carburetor nuts are M8-1.25 but with a JIS standard, 12 MM across the flats.  M8-1.25 nuts that are 13 MM across the flats are much more common, but are too big to get a wrench between and parts of the carburetor.
JyCarbB.JPG
Yes, there is a nut under there.  Trust me.  Do not remove these nuts yet, just loosen them.
JyCarbC.JPG
 
This is a 12 MM wrench I put a 90 degree bend in, and then ground the outside of the jaws down to get to the two inner close to the engine carb nuts.
JyCarbD.JPG
 
I hook a second 12 MM wrench on the unbent end of the bent wrench to loosen the inner carb nuts.
JyCarbE.JPG
this is right after the picture above. 
JyCarbF.JPG
This picture gives you an idea of how the bent wrench fits the carb nuts.
JyCarbG.JPG
Same as picture above, after turning the nut 1/6 of a turn.
JyCarbH.JPG

 

The nut under the accelerator pump is hard to get out, it tends to fall behind the stud.  I use a magnet to fish it out.
JyCarbK.JPG
This nut is easy to reach, just unscrew it with your fingers.
JyCarbJ.JPG
With both inner nuts removed, and the outer nuts loose, but not yet removed, you can the inner edge of the carb up, and grab the two washers with your fingers.
JyCarbL.JPG

This outer nut at the front you can remove with your finger also.
JyCarbM.JPG
The nut under the secondary vacuum diaphragm is also very hard to reach.  but you can loosen it and hopefully leave it on top of the throttle cable bracket.
JyCarbN.JPG

the flash on the camera washed this picture out, but there are two lock washers and one nut on the throttle cable bracket.
JyCarbO.JPG
With all the nuts loose, you can remove the carburetor.
CarbLessMani.JPG

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This is the original carb that came with Ratsun.  The carb insulator and its gaskets were in good shape, I just reused it.
RatCarb1.JPG
To install the carb nuts, I put the throttle cable bracket on first.  No nuts or washers, jut hook it over the studs.
RatCarb2.JPG
Next, I put the washers and nuts under the accelerator pump, I just start the nut a few turns.  I am using a small shaft screwdriver on the top of the stud to guide the nut in place.  The nut is put on the shaft of the screwdriver, the end of the screwdriver is held on the top of the stud, and the nut is allowed to slip over the stud, and turned a few turns with my fingers.  Then I put washers and nuts on the rear inner carb stud, that is easy to reach.  Start this nut a few turns.
RatCarb3.JPG
Lift the outside of the carb, and put a washer and nut on the outer studs.  Put the nut and washer under the vacuum diaphragm first.  If you put the front outer nut on, you cannot lift the edge of the carb as high, makes it harder to put the nut under the diaphragm on.  The two outer studs only need a lock washer.  The throttle bracket acts as a flat washer.
RatCarb4.JPG
The inner nuts need a flat washer, and a lock washer.
RatCarb5.JPG
Tighten the two inner nuts first.  Not real tight, but pretty snug.  Tighten the outer two nuts, and recheck the inner nuts.
RatCarb6.JPG
Then hook up the fuel hose, the distributor vacuum hose, the throttle and choke cables.
RatCarb7.JPG
 
The reason for changing the carbs was the carb I tried first on the engine would not allow the engine to idle.  I reached inside the cab of the truck, and my plan was to crank the engine to fill the float bowl, check the level of the gasoline in the float bowl, and then get in the truck, and use the choke and throttle to start the engine.  But after about 10 or 15 seconds of cranking, the engine started and idled without touching the throttle or choke.
 
With the engine idling, It was time for a short test drive.  But I still had the L-18 engine, with a dogleg five speed bolted to it, and the 720 five speed transmission, and some other accumulated stuff in the bed of Ratsun.  I took the L-18 engine, with trans, and lifted it in the garage, and set it on a pallet on the floor of the garage.  I drove Ratsun out from under the hanging engine, got a pallet, and the tractor in the garage, and set the L-18 on the pallet.  Then I drove the tractor out to where Ratsun was parked, and set the 720 five speed transmission on the pallet next to the engine.
 
IL18TwoFives.JPG
 

I took Ratsun back into the garage, and cleaned the remaining stuff out of its bed,
EnginesOutBed.JPG
 
BedPWashed.JPG
 

Next, I pressure washed the bed of Ratsun,
L-20-BInandRun.JPG
 

and put this hood on Ratsun.  This is a different hood, the hood that was on Ratsun had a stripped out bolt hole.
HoodOn.JPG

 

and finally a short test drive.  I have a slight exhaust leak, the clutch needs adjusting, and some other details to having this a reliable daily driver again.

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Nice carb wrench. I made one for mine too, except I use the 12pt side, and ground both the thickness and diameter. The double bend is to clear the valve cover on the inner nuts.

 

8XVqQC9.jpg

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I did some minor work on Ratsun again today.  Put a coolant catch can on it, topped off the radiator, and brake fluid.  I took the down pipe off the engine, and exhaust system, and put a short piece of pipe inside the junction between the down pipe and the rest of the exhaust system.  The exhaust leak is still there.  It might be the plug that was in the exhaust manifold EGR port, or the connection between the down pipe and exhaust manifold.  I put some gear lube in the transmission since it was up off the floor for exhaust work.  I set the ignition timing with a timing light.

 

I took Ratsun for an almost 10 mile test drive.  All on back roads, but with a few spots where I could get up to about 55 MPH.  My first impression with a L-20-B 521, it really needs a five speed transmission.  The L-20-B definitely does not like to run in the RPM range a L-16 likes. 

 

I took the test drive about 5:30 PM to 6:00 PM.  Today was a warm day for Oregon, about 85 or 90 degrees.  The temperature gauge on Ratsun stayed just below the middle mark.  When I got home, after letting Ratsun sit for a minute or two, I turned the key on, and rechecked the temperature.  Slightly above the middle mark, and the upper radiator hose had some pressure in it. 

 

This evening, I put new spark plugs in the engine.

NewPlugs1.JPG

 

I took the old Bosch plugs out.

NewPlugs2.JPG

 

While the plugs were out of the engine, I did a compression test on the engine.

CompNumbers.JPG

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I had a 6 year old '71 back in the day. Put a car L20B in it. Biggest difference was the torque without revving it out like the L16.

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I drove Ratsun to work yesterday, and I needed a little work on the brakes. I adjusted the fronts, they were not too far out. The pedal still went down too far.

If you set the hand brake, that should make a noticeable difference in pedal travel, but it did not. The brake system had air in it.

You bleed brakes starting with the farthest from the master cylinder, right rear.

After bleeding that cylinder,the brake pedal was good.

 

Drove Ratsun today, about 11 miles. I took an old Kimball organ to Goodwill, and donated it.

Then I got groceries. I live on a hill, not very high, but there is a a steep 16% grade on one road up the backside of the hill, coming home. Ratsun used to need 2nd gear to drive up that hill. With the L-20-B, easily went up the hill in 3rd.

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Hi Daniel,

I'm happy to hear that you're getting to drive Ratsun.

I just wanted to add a note on the bleed sequence.  On some of the trucks, the brake line to the rear actually goes down the passenger side of the frame.  In those cases, the driver's rear is actually the farthest from the m/c since the line has to cross the truck twice.  I think they started that on the 620's.

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Damn I would have like to meet up with you at Canby Daniel and a few others. That's it... next year I'm wearing a name tag that doesn't say SMOKE. 

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Table of contents on this page added June 23, 2018.
A comment to last post on page 23.
Exhaust pipe to manifold connection question.
Ratsun moving yard debris.
 
I too would liked to have met a lot of people at Canby.
My poorly chosen plan was to bring Dragon to Canby, this truck : http://community.ratsun.net/topic/49698-my-dragon-datsun-521/
However, it became apparent that Dragon was not going to make it to Canby, about June 1.  It was then I decided to push getting the L-20-B engine in Ratsun, so I could make it to Canby with a Datsun.  If I had started the engine swap on Ratsun about a week earlier, I possibly would have been able to take it to Canby.  Canby was June 8,9, and 10, I made the first test drive with the L-20-B in Ratsun June 18.
 
I did go to the banquet at Canby to listen to Pete Brock.
 
A few more details on Ratsun need to be done, then I am back to working on Dragon.  I am also considering putting the five speed transmission that came with the L-20-B engine in Ratsun, when it was in the 720 in the junkyard.  In hind site, I should of also got the rear axle "pumpkin" from that 720.

 

This is the exhaust manifold and down pipe connection.  It is leaking.  If you take a hose, hold one end of the hose to your ear, and the other end of the hose where you suspect an exhaust leak, you can hear exactly where the leak is.  Is there a gasket or some other sealer used at this connection?
ManiDownpipe.JPG
 

This is my front yard.  There are four fir trees next to the road, the fourth tree trunk is barely in the bottom right of the picture.  These four trees had mostly dead branches hanging down to the ground, it made then difficult to mow the lawn under.  I trimmed the branches off the trees, and loaded the debris in Ratsun.
FrontYard.JPG
 

This is the walkway between my house and garage.  Wide enough to drive a Datsun 521 through.
HouseGarage.JPG

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Almost three weeks since the last update on Ratsun.    I have driven Ratsun about 170 miles, the yard debris was disposed of, and I have been dealing with a few minor issues on Ratsun.   I also had some issues with the forum update, caused by my E-mail address changing since I first joined Ratsun in 2012.

 

After about a week of driving Ratsun  on short trips, I noticed a lot of corrosion around the battery.  I checked the voltage on the battery, and it was overcharging, and pushing some battery fluid out of the battery.  I tried changing the voltage regulator, but that did not fix the problem.  I then put an internally regulated alternator I had in Ratsun.  i also decided to put a voltmeter under the dash on Ratsun.

 

This is a panel I had in my spare parts collection, and I put it under the dash, just to the left  of the steering column.



I ordered this volt meter from Amazon,  actually I ordered two voltmeters, the second one will go into Dragon, another one of my 521 trucks.

VoltMeter.JPG

 

The voltmeter is really easy to wire in.  The gauge metal case is grounded, so to measure volts, you need only to add one wire to the voltmeter.  The blue wire is long enough to reach across the  dashboard to the right side of the truck, and go forward to the fuse box.

VoltWire.JPG

 

Then I put the voltmeter into the panel I installed earlier,

VMeterInPanel%20.JPG

 

I connected the fuse box end of the blue wire to the fuse box.  The two right terminals on the fuse box are always hot, the two left terminals on the fuse box are ignition switched hot.  Right and left perspective is from this picture, NOT the trucks right and left.

VoltFuseConn.JPG

 

And this is the voltmeter showing a charge.

VoltCharging.JPG

 

Now, time to wire the volt meter light.  This is the lamp holder, and lamp that came with the voltmeter, after I added a piece of wire to the lamp wire.  This wire only need to reach to the space under the ashtray in the top center of the dash board.

VoltLamp.JPG

 

There are four wires under the ashtray, all four wires have female bullet connectors on them.  I put a male bullet connector on the lamp wire,

VoltLamp2.JPG

 

The red wire with a blue stripe is hot when the lights are on, park lights, or headlights.  I plugged the volt meter lamp wire into that connector.

VoltLamp3.JPG

 

I turned the trucks light on, and the voltmeter lit up. 

VoltLamp4.JPG

 

I turned the key on, engine off, with the lights on.  Volt meter still works.

VoltLamp5.JPG

 

I also retorqued the head bolts to about 55 foot pounds, on a  cold engine, and checked the valve lash adjustment.

To do that, you obviously have to remove the cam cover.  This engine has the three bolt thermostat cover, and the washer under the thermostat cover bolt is really close to the cam cover.  I removed that bolt, and ground a flat spot in the washer, so I can remove the cam cover without removing the thermostat bolt.

TStatWashGround.JPG

 

Edited by DanielC
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Sweat truck Daniel.  Nice work.  You will like the L20B.  The 5 speed will be nice if you hiway drive.  The rear end ratio for the 720 L20B 5 speed regular cab short bed is 3.89 and the King cabs had 4.11 with the 3 speed automatic trans.

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Friday, July 13, in the morning, I loaded some fence tools, and boards into Ratsun, and went to work on this fence.

OArenaFence1.JPG

 

This is more of the fence done.   It was a hot day by Oregon standards, so I only worked until about 12:30 PM

OArenaFence2.JPG

 

After fence work, I drove Ratsun out to Clackamas Steel, to get a few pieces of steel.

SteelYard.JPG

 

This is the transmission mount and bracket for a 521.

TMountandBracket.JPG

 

I am going to put the five speed transmission that came with the L-20-B engine that came out of the 1980 720 junkyard truck into Ratsun.  But that transmission is longer than the stock 521 transmission, so I need to make a shorter transmission mount.  One piece of steel is already cut, and fit into the transmission mount.

Steel1.JPG

 

A piece will be cut out of this angle to attach to the transmission cross member.

Steel2.JPG

Edited by DanielC

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Daniel, if you make a piece of 90 degree metal that bolts to the cross member using all 4 mount holes, you can then cut that mount you have off at the correct length and tack it to the piece mounted to your cross member at the proper height, once it fits then pull it out and weld it up.

The ones I have made in the past use the 720 transmission mount as it is more common, if you came to my house I would give you the mount you need.

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Maybe this will help.  Aproximately 2" shorter.

 

TransMountMod.jpg

 

Like Wayno suggested keep all four dross member mounting bolts.

Edited by Charlie69

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My plan is to drill and fit a piece cut out of the angle steel to the cross member, with four bolts.  Then weld a piece of the rectangle tube to it.  Next step, cut a notch in the piece that is fitted into the transmission mount, that will slide forward or aft on the rectangle tube already welded to the angle bolted to the cross member.

Then swap the transmission in the truck, and bolt the transmission mount to the transmission, and the square tube to the bottom of the transmission mount.

Bolt the angle piece, with the rectangle tube to the cross member. and the square tube will sit on the rectangle tube in the right spot.  Tack weld the two pieces together.

Unbolt the tacked pieces from the transmission mount, and cross member, and finish welding them together.

 

Pictures will become available as the parts get made.

 

I may have gotten a 720 transmission mount when I was removing the parts from the junkyard truck.

 

 

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It would probably be better to use the 720 transmission mount if your gonna fab that bracket.... those u shaped rubber mounts are hard to find if at all....

You can still get the 720 mount new, and it's what they list on parts websites for the 521, which is clearly wrong....

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I have two stock 521 transmission mounts on my bench now.   Ratsun has another stock 521 transmission mount, with the stock four speed transmission currently in it. 

I think I have one 720 mount, I might use it.  I need to get the 720 transmission mount out of the box it is stored in, and see how difficult it is to use it.

 

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In the last few 5 speed and automatic swaps I have done I have used the later model transmount as they are cheap to buy new.

 

Later_Datsun_Nissan_Trans_Mount.jpg

 

 

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4 hours ago, DanielC said:

I have two stock 521 transmission mounts on my bench now.   Ratsun has another stock 521 transmission mount, with the stock four speed transmission currently in it. 

I think I have one 720 mount, I might use it.  I need to get the 720 transmission mount out of the box it is stored in, and see how difficult it is to use it.

 

I figured you had a few old ones.... 

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A funny thing happened to my 521 yesterday.  I live on a hill, and of four roads I can take away from my house, three pretty much go down, except one that goes up, before it goes down.  The one that goes up before it goes down has a 16% grade on the down hill part.

I went up and down the steep hill, bought some groceries, came back up the hill, bought more groceries, and visited my bank, and came home.  Then I went down the other side of the hill, to Ace Hardware, to buy a fan, it is hot here in Oregon.  

On the way down that not so steep hill, my brake pedal went all the way to the floor.  Near the bottom of the hill, i turned around, and drove Ratsun back home, checked the fluid in the master cylinder, it was still full. 

I drove my other running vehicle to Ace Hardware, and got a fan so I could work in the garage.

I ordered a new Centric master cylinder yesterday from a good auto parts store if you live in Portland, OR, Clackamas Auto parts.

 

Last night, I did a little work on making a bracket to hold a rubber transmission mount for a five speed in a 521.  This is just the  first attempt of the piece of steel that will bolt to the cross member on a 521 frame.

TransBracket1.JPG

 

I have two five speeds, condition unknown, that I can put in my 521 trucks.  I went and looked at them, and both of the transmissions have a 720 type of transmission mount on them.  I may take peoples advise, and build a 521 transmission mount bracket using the 720 rubber mount.

Edited by DanielC

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7 hours ago, DanielC said:

A funny thing happened to my 521 yesterday.  I live on a hill, and of four roads I can take away from my house, three pretty much go down, except one that goes up, before it goes down.  The one that goes up before it goes down has a 16% grade on the down hill part.

I went up and down the steep hill, bought some groceries, came back up the hill, bought more groceries, and visited my bank, and came home.  Then I went down the other side of the hill, to Ace Hardware, to buy a fan, it is hot here in Oregon.

On the way down that not so steep hill, my brake pedal went all the way to the floor.  Near the bottom of the hill, i turned around, and drove Ratsun back home, checked the fluid in the master cylinder, it was still full.

I drove my other running vehicle to Ace Hardware, and got a fan so I could work in the garage.

I ordered a new Centric master cylinder yesterday from a good auto parts store if you live in Portland, OR, Clackamas Auto parts.

 

Last night, I did a little work on making a bracket to hold a rubber transmission mount for a five speed in a 521.  This is just the  first attempt of the piece of steel that will bolt to the cross member on a 521 frame.

TransBracket1.JPG

 

I have two five speeds, condition unknown, that I can put in my 521 trucks.  I went and looked at them, and both of the transmissions have a 720 type of transmission mount on them.  I may take peoples advise, and build a 521 transmission mount bracket using the 720 rubber mount.

As I said Daniel, if you come over here I will give you the mount you need, we also could talk about front disc brakes if that is the route you are going to go.

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Wayno, Thanks a lot for the offer.  I have Mike K's front disk brake brackets, and some hubs, but not the disks, yet.

 

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As mentioned above, a slight detour from working on transmission brackets.  Brake master cylinder replacement.

 

The master cylinder push rod is held to the brake pedal by a pin through the clevis, the pin is held by a "hair pin", and there is a spring that pulls the brake pedal up.  Disconnect the spring, remove the "hair pin", and remove the pin through the clevis.

PinandSpring.JPG

Sorry, no pictures.

Remove the brake line from the master cylinder with a flare nut wrench, 7/16 if your 521 is stock.  This may be difficult to remove.  I have found that sometimes clamping a pair of vice grips on the outside of the flare nut wrench jaws removed some flex in the jaws, and enables you to loosen the flare nut with less damage to the flare nut.

Remove the two nuts holding the master cylinder to the firewall.  These nuts are 5/16-28 SAE.

There might be shims between the master cylinder, and the firewall, watch for them.

 

Anyway, remove the nuts, and washers, and the master cylinder can be pulled out of the firewall, and out of the truck.   The brake line will be in the way, gently hold it out of the way.  If you bend it a lot, it will be more difficult to start it back into the new master cylinder.

 

The push rod and clevis were longer on the new master cylinder.  I switched the push rod and clevis from the old master cylinder to the new one.

 

Then I bolted the new master cylinder to the firewall of the truck, and hooked the brake pedal back up to it.  You want the push rod length adjusted so that it is not putting any pressure on the master cylinder, just barely.  if the push rod holds the master cylinder pushed in even a little, brake fluid cannot return to the master cylinder, and may cause the brakes to drag, or even get tighter each time you step on the brakes.

 

You may have heard that you need to bench bleed a new master cylinder.  you do, but I do it after the master cylinder is installed on the truck like this.  In this picture, I had just added brake fluid to the empty master cylinder, and bubbles were slowly coming up into the reservoir.   I pumped the brake pedal three times, slowly.  If you have not figured it out yet, the curved short brake line just returns fluid to the master cylinder reservoir.  You do not want the fluid going back into the cylinder forcefully, that will push air bubbles to the bottom of the reservoir, and possibly back into the cylinder.

MasterBleed1.JPG

 

This is after I pumped the brake pedal three times.  Notice how much lower the brake fluid is.

MasterBleed2.JPG

 

Then I removed the short brake line loop, and reattached the trucks brake line to the master cylinder.

MasterBleed5.JPG

 

After reattaching the truck's brake line to the master cylinder,  I needed to bleed some air out of the brake line.  The little cup and hose has a rubber end that seals over the brake bleeder fitting.  I crack open the bleeder fitting, and put the rubber end of the hose over the fitting.  Then I make sure the master cylinder reservoir is full, and step on the brake pedal.   The wheel cylinder  fitting is only open enough that it takes about a second or two for the brake pedal to go all the way to the floor.  Then I hold the brake pedal down for about five to ten seconds.  521 wheel cylinders have only one port in them.  Any air in the wheel cylinder has to be expelled out to the bleeder by the brake shoe springs collapsing the shoes, and wheel cylinder piston.  you cannot use a pressure bleeder on a 521 because the brake system pressure is not relieved, and any air in the wheel cylinder just stays in there.

MasterBleed3.JPG

 

Close view of the brake bleeder cup.  There is a hose inside the cup that goes to the bottom of the cup, and that seals out any air from getting back in the hose.

MasterBleed4.JPG

I got lucky, and only had to bleed one wheel cylinder to get the brake pedal high and not soft because of air in the system.  for reference, the brake pedal being stepped on hard enough to lock the brakes is above the gas pedal.

Edited by DanielC

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