Charlie69s 71 521 soon to be a quad cab Wayno convinced me

[Charlie69]

Well I bought a 1971 521 today.  She is a little rough but will soon my quad cab build just fine. Pictures next week after I pick it up.

Edited June 15, 2019 by Charlie69

[wayno]

This is the 720 section Charlie.

 

Are you going to make your 66 Datsun 520 into a 4 door?

[Charlie69]

Had the thread moved to the 521 section thank you Wayno and Redeye!

 

No my 66 will stay a standard cab with updated creature comfort and some mild custom changes.

 

I am in the process of buying another 66 that some one tried to install a Ford small block V8 in.  It is already cut up so it lends its self to be coming a quad cab. I get this 66 I will have 4 cabs and twelve doors  and 6 fenders for the quad cab build.

[wayno]

So your going to make a 1971 Datsun double cab(4 door?), very ambitious, are the rear doors going to be suicide or normal?

I would suggest either finding a wagon roof with the correct curve on the sides or have one made, any other way requires a lot of bondo to make it look proper, although that worked for me on my 520/521 kingcabs.

I thought about doing this at one time, what I thought about doing was putting together two cabs back to back, then cutting the front of the back cab off near the windshield at the top removing that rear firewall, then pasting/blending another rear cab piece into position on the back, then I would have made 2 square doors out of 4 doors with a large window operated electrically, hinge mounts would have to be made inside the door to make this work with normal opening doors.

I also thought about hinging the rear doors on the back(suicide doors), and then welding them to the front post of the front door, once all the sheet metal work was done then I planned to cut that post at the top and bottom to free the rear door, I would then have closed the top and bottom and then figured out how to hold that rear door closed top and bottom so the door jamb would keep the front door closed using the rear door with the post connected to it, this way when both doors were open there would be no post, I had not really figured out everything but that was my outline.

In the end I didn't need a double cab(4 doors), kingcabs are fine with me, I will never do another one again, it was fun making them though, gave me something to do to stay out of trouble.

[Charlie69]

That is what I am planning to do Wayno.  Put the 71 cab in front for the engine compartment length and the 66 cab in the rear.  I want about 4" to 6" between the doors and the rear door, I will use the stock hinges.  I also want 4" to 6"  between the rear door and the back of the cab.  The rear door will be full size with the front of the window (actually the back of the window) will be squared off to make a nice large window.

 

I also have the  66 & 67 520 chassis, the 85 720 king cab chassis, and the 90 hard body chassis so I should be able to get enough length for a full length bed.

 

Did I mention this will be a VG30, 4 speed automatic, and dually rear end.  I will build the cab first then build the frame to match.

 

 

Edited May 25, 2019 by Charlie69

[Charlie69]

I will be stretching the 520 hood and fenders to match the 521 fender and hood length.  I will be running the 67 dual headlight grill and the 67 tail lights with the backup lights in them.

 

I want the back area of the cab large enough for Gracy my Great Dane to be able to sit and lay comfortably.

 

This will be accomplished with my brother Garret and Shawn doing the fab/customization.  I am the visionary and grunt. LOL

 

When I actually start this build I will start a new thread "Charlie69s 66 Datsun Quad Cab  Dually".

[gene knight]

a lot of work but i bet it will be awesome and 1 of a kind  when done

Edited May 8, 2019 by gene knight

[wayno]

It will be a one off like both my kingcabs.

That is going to be one long cab, and a big job, good luck with the build.

Any rear window other than stock is going to take fabricating, they way the back corners curve limits the size if the rear window.

 

[Charlie69]

Thank you Wayno.  Good point about the curved back cab corners limiting the size of the windows.

 

Wayno my thinking is to build the cab first then build the frame to match the cab please any sugestions will help.

[wayno]

The back half of the cab is going to be tricky, I would skip the 4 to 6 inches between the front and rear doors, I would cut the backs of the cabs off straight up and down about a 1/2" from the uprights and just paste them together with a one inch post between the upper window frames, and the doors will share one gap(no outer sheet metal piece between them), this also minimizes the blind spot a giant post there would create.

The rear outer sheet metal of the back doors will need to be modified also, you will want that line to be straight up and down so the rear cab section will be easier to deal with as your going to have to hide them rear hinges, I had not really thought too much about that, I originally thought I would make one door out of 2 sets of doors for each side, 2 back half's mated together to make 1 square door, but I would have had to make the hinge connections inside the doors to hold them on, it's a lot easier to do it the way you mentioned and deal with the sheet metal and window frame I think.

It's going to take a lot of thinking to do what you have planned and have it look right/proper, I did my kingcabs the way I did them because I wanted them to look like the factory did them, I didn't want people thinking that was scary or the police stopping me because it looked goofy, I also didn't want a blind spot over my right shoulder so that is why I have rear windows.

Keep in mind that you want to do this in such a way as to minimize having to create posts and other such stuff from scratch on the inside and outside, I suspect connecting the backs of the two cabs together can be fairly easy without having to create anything, just cut them perfectly straight up and down inside and out, put them together and weld(tack) them together, I would ad a 1" strip to the inside of one half of the cab(half inch in) from to to bottom on the inside of the cab and at least the top half of the outside post, then when slid together they align themselves, the strip will then give you a way to spot weld them together, it's hard to explain but you drill holes in the cab sheet metal, then when slid together you can see the inside strip thru the holes that were drilled, you then weld the hole shut to that strip on the inside, that is a spot weld, they will only be 1/4 inch holes but the cabs have to fit together perfect so the metal strip is touching the outer sheet metal, I am sure it would be easier just to tack weld the 2 cabs together on the outside, but it will not be as strong.

It's a big job your planning that will take quite a while to do right, it can be done in a year or it can take 4 years depending on how much fabrication your going to do(making things from scratch), doing it from scratch which takes time(ask Lockleaf).

[Charlie69]

One benifit I have on the fabrication is I draw a picture of what I need add dimensions to it give it to my brother and within a week or or even sooner I have the parts in my hands ready to weld together.  He has a complete metal fab shop at his disposal.

 

I do feel that the time frame you give Is a spot on time frame.

 

One of the reasons I want the 4" to 6" "B" pillar is for 3 point seat bealts and to  also be able to move the front set back about 2".  I am sure that I will have many questions on this build as it progresses. 

 

We use the welding up holes tecnique when doing fish plates on frames.

 

I am looking at this build as a fun learning experience.  If I get tired or burnt out on it I will take a break and then start back on it when it is time. 

 

I will finish my 66 520 before much get done on this one.

[wayno]

That is very handy having pieces made, the roof will be a lot easier for you than it has been for me, I found a 411 wagon roof worked good on my 320 kingcab, that is not how I did the 520/521.

Getting everything straight is a big deal, a 14 inch extension was hard, I kept fighting getting the rockers straight and having the rain gutters straight also(length and height), 4 feet is going to frustrate you as 14 inches frustrated me.

Keep in mind that even tack welds 4 inches apart warp metal, each little tack weld adds to all the other tack welds, it's like skipping a rock on a glass smooth pond, ripples everywhere.

[Charlie69]

Wayno as I go through this build I will post pictures and ask for your suggestions are how you would approach certain problems that arise during the build.

 

I plan on having 3 pieces  2" x 4" x .188" steel that we will cut and weld together in to a level and square work surface.  It will have adjustble height legs in order to level the top on the concrete slab we will be working on. The with of the rails on this table will be the same as the 520/521 chassis.

 

We will place the 2 cabs on the work table back to back and move them back and forth until the spacing between the cabs looks good to me.  At this point we will make brackets And bolt each cab down before any cutting starts.  By doing this I hope that this will help minimize the warpage from the wleding.  The cabs will have cross bracing tacked in to help hold the cabs from warping when cutting.

 

The setup for this will take some time and money.

[Stoffregen Motorsports]

Charlie, your brother probably already has a system to keep the frame/chassis flat and level while everything is cut apart, but I figured I'd share one of my methods.

 

Using 1" Acme thread, I built four "jackstands" that are very sturdy and easily adjustable. On the top, I have a removable foot, but for most frame work, the u-shaped piece works great. Once you get the truck leveled out, mark the jackstand location on the concrete floor, so if you have to move them for any reason, you know exactly where they were before. Building or modifying a chassis has many similarities with building a house. It needs to be flat, level, and square. To help ensure this, I use digital levels, bubble levels, plumb bobs, even a laser level/transit like you would see on a construction site. Lasers are great for marking straight lines on curved panels, like rooflines or inner fender wells.

 

Anyway, here are the jackstand pics. Note - I just recently built two more lighter duty stands to use under the motor and trans. They are adjustable too, but use 3/4" all-thread.

 

 

 

[BrothersGarage]

^Damn that's slick Matt. 

Also: Saw this posted to Facebook and i thought the rear door setup may be of some interest to you for the guys 'future' plans for his truck:

[Stoffregen Motorsports]

There's a guy on here that built a bagged crew cab 521 with a Ford small block (I think). I think he did a horrible job. Totally unsafe and hack work. Sure, call me an ass, but I wouldn't drive my kid around in anything like he built.

 

But yes, a crew cab dually 521 would be very cool.

 

For what it's worth, I am trying to figure out how to build a bed for my 1970 Chevy C30 dually. One that looks like it could be original, but as we all know, Chevy didn't offer beds on their duallies until 1973. Open to suggestions.

 

 

[wayno]

I used concrete blocks and a couple 4X4s on my 521 kingcab, same idea just low tech.

 

I seen that 521 crew cab at Blue Lake last year, it's still on the road, I didn't look real close at it, don't want to pick the job apart like I don't want anyone picking mine apart, I thought it had a Chevy drive train but it doesn't matter, all I know is interesting to see the transmission come apart on video, I am happy no one was hurt when it happened.

 

There are lots of folks on here to give you advise Charlie, remember what the factory 521 crew cab looks like, here is a photo of one.

[Charlie69]

Thank you Guys for the words and pictures of encouragement.

 

The reason I want to build a frame/body table is I plan to build the cab first then the frame.  The frame looks like it might be 3 maybe 4 pieces fishplated together.  After I get the frame built I might have my brother bend me up some one piece frame rails and then build a 1 piece custom frame.  My brother loves to do this kind of stuff it all depends on if his back will let him.

Edited May 23, 2019 by Charlie69

[Stoffregen Motorsports]

Good idea. Build the body first and then let the chassis come together from there.

 

I think the roof panel may be the most challenging part of the job. Perfect time to buy an English wheel!!!

[Stoffregen Motorsports]

One thing I just noticed is the wheelbase. The wheel opening on a standard cab looks to be further back than on the double cab. Are you going to try and keep the wheel opening in the same place and just shorten the front of the bed? Or are you going to increase the rear overhang?

[Charlie69]

On 5/23/2019 at 10:12 AM, Stoffregen Motorsports said:

Good idea. Build the body first and then let the chassis come together from there.

 

I think the roof panel may be the most challenging part of the job. Perfect time to buy an English wheel!!!

From what I understand the older suburban roof is over size so you mark center and measure all directions and cut it to fit.

 

On 5/23/2019 at 10:14 AM, Stoffregen Motorsports said:

One thing I just noticed is the wheelbase. The wheel opening on a standard cab looks to be further back than on the double cab. Are you going to try and keep the wheel opening in the same place and just shorten the front of the bed? Or are you going to increase the rear overhang?

I will adjust the frame to center rear wheels in the wheel opening in the bed sides.  I would like to run the full size bed.

Edited June 15, 2019 by Charlie69

[wayno]

You will have to re-design the e-brake system, I only extended my 1980 Datsun 720 truck 16", and before I was done I had to completely make my own system, lengthening the rear cables didn't work for me even though that is basically what they did on the mobile homes.

 

I had issues with the roof sides when I used the 411 roof on my 320 kingcab, the roof piece needs to match the existing roof curve on all sides, I used a pry bar to help the 411 roof into position, by the time it was connected it looked wavy on the sides and it was not caused by the tack welding, in between the tack welds the metal was slightly raised, so above the tack welds was wavy.

 

[Charlie69]

I use the 720 front and rear ebrake cables.  I will have to lengthen the front cable for this build as to accomodate the added length of the frame.

[wayno]

But that is not where you lengthen the 720 chassis Charlie, it gets extended in back of the cross member that has the e-brake assembly, in front of that cross member is where the chassis narrows.

I suppose one might try modifying the chassis in front of that cross member but I suspect your going to have to remove that cross member to do that and then weld the cross member back in, but then your not really extending it in front of that cross member, your extending it at the cross member where the frame starts to narrow, you could just extend it in back of that cross member where the frame is straight and move the cross member to the proper spot or put another cross member in the proper spot and leave the original one where it is at, that is likely what I would do.

 

 

[Charlie69]

I found out the king pins are real bad on the 71 521 so I am off to look at another parts truck tomorrow.  If the King pins are bad on that truck I will just find another 720 to buy.

 

Originally I wanted to use a 521 front section of the chassis, long enough to incorporate the rear cab mounts plus 12 inches. Then take a middle section from the 67 520 chassis that incoporates the middle and the back cab mounts. Turn this one back to back with the front frame section leaving about 3 to 4 inches in between cab mounts.  This is to ensure I have enough room to mount the upper 3 point seat belt mount sercurly.  Then from a third frame (520) cut the bed section off 4 inches in front of the rear cab mount.  By doing this I hope to use the factory 520 leaf sping mounts.   This basically shows how the cabs will be placed back to back.

 

 

Edited June 5, 2019 by Charlie69