3/4 ton back half build

[chopped65]

This is my first build thread. The truck is a 1965 C-20 that I am retaining all the 8 lug. The front end has been converted to disk already with Brothers drop spindle disk brake kit. I already have my wheels and tires. I bought the tires first to build the truck around which are the Mickey Thomson S/R's 31x18.5x20. The wheels are Helo Maxx 8 20x10 and were sent to a custom wheel guy in Azusa, CA to be widened to 20x15 and had the tires mounted on the wheels. My axle in the truck now is the Eaton HO52 and I bought a Dana 60 off of craigslist with 4.10 gears and a locker in it. Dans Driveline in Las Vegas, NV is going to narrow the axle housing, change out some bearings inside and measure everything for Moser to build the axles. 7 years ago I bought an aluminum under bed fuel cell from Brothers so I am eliminating all the rear frame and building everything new. I will be building a box around the fuel cell and that will be the rear section of the frame.

What I've done so far as I am starting this after I started. I built a cart on wheels for the bed which is in the pictures. Before removing the bed I removed all the electrical, fuel lines and pump, drive shaft, exhaust and fuel cell. Then removed the 8' bed with one other person. WHAT A PAIN IN THE A** THAT WAS! for only 2 people. I removed the panhard bar mount and the bed mounts from the frame. I boxed the frame using 6" flat stock 1/8" steel. I boxed from the trailing arm crossmember (back of cab) to about 26" in front of axle centerline. Did this with two pieces as the angle of the frame went up in the center of that point. Ground all welds smooth to make nice and pretty. Next which I should have done first but it didn't effect anything was that I leveled the complete truck in the garage which was difficult with the crooked garage floor. See pictures for my shimming on the jackstands. The rear right jack stand had to be shimmed. Created a new mid crossmember with 2x4 .120 wall tubing 30" in front of axle centerline. The 30" is measured to the rear of the crossmember closest to the axle. The new crossmember is "pressed" in to the frame, it is a precise fit. The tubing has been ground at an angle to make the weld solid. I still need to weld this in, almost out of gas so probably don't have enough to finish welding this in. Next steps are welding the crossmember in, building braces for the crossmember and welding those in. I am ordering my center frame piece from Nate at Porterbuilt which will go from my mid crossmember to the front of the frame box that is around my fuel cell. See drawing. The center frame piece will have a large step notch as this will eventually lay frame and with the 31" tall tires it puts the axle sitting pretty high to clear. While Nate is building that I will be building the frame surround for the fuel cell. I was just going to make the frame go straight back from the mid crossmember but since I spent so much 7 years ago on the fuel cell, I will kick the frame back out to fit around the tank.

Where I am at right now is: what kind of brace do I build for the mid crossmember. Do I make it a K Member and make larger 12" braces at a 45 degree angle (guestimate measure and angle), or do I make gussets?

[chopped65]

the first picture has the 30" mark which is right in front of the rear bed mount. the second picture is the axle centerline. the third picture, in front of the light colored patch is the line for the 17.5" mark behind the centerline. from that line to the rear of the frame will be all new steel tubing to the exact dimension of the fuel cell. the fuel cell + the 2x4 tubing in front and rear came to the exact measurement of the factory frame that was left behind that line. the 17.5" measurement came from radius of the tires + 2". the last two pictures are the flat stock welded in

[chopped65]

this is the boxed section all ground smooth

[chopped65]

this is the new mid crossmember before being welded in. I don't believe I will be grinding these welds smooth. Its possible to do the weld to a 45 degree angle ground but not sure if I will, depends on how pretty of welds I can lay.

Any thoughts on grinding these welds?

Also how should I make the braces?

[vin63]

Originally Posted by chopped65

this is the new mid crossmember before being welded in. I don't believe I will be grinding these welds smooth. Its possible to do the weld to a 45 degree angle ground but not sure if I will, depends on how pretty of welds I can lay.

Any thoughts on grinding these welds?

Also how should I make the braces?

Here is a photo of my boxing plate in the same area as yours. I am not a fan of grinding welds. I mainly TIG weld my stuff, but if you are MIG welding, make sure you have enough amperage. What type of shielding gas are you using? As far as the braces, are you planning on installing a four-link suspension, or something similar, with this new crossmember as the forward mount for the suspension? My apologies...I'm not quite sure what you're asking.

[chopped65]

Sadly I am Mig welding all this. I love Tig welding but cannot afford one right now. I am using a Miller 135 maxed out at 10 and my wire speed about mid way. Every piece I have tested on has great penetration. With a Tig, the welds are always beautiful but with Mig at this amperage and wire speed I'm at about 60% of time it's beautiful the rest is so-so. The gas I'm using is 75-25. I am going to be putting a 4 link in and mounting it to that cross member. Not sure yet if I"m going to do a parallel or triangulated though. But yes, I am not a fan of grinding welds on heavy metal but didn't have a choice with my 60% rate. Thanks

[vin63]

At only 135 amps, I would make a couple of passes, at least, welding in that crossmember, particularly if you will be using it as a suspension mount point. I would also gusset it as you mentioned. I tend to use tubular gussets, but that also depends on the available space. If you have any leftover length of that crossmember, you can cut a couple of 45 degree pieces and weld them in at the corners of the butt welds.

[chopped65]

I plan to use the same 2x4 tubing but turning it on its side. What do you think?

[vin63]

Using the leftover lengths for gussets will work. I would use them upright, but if you're accommodating exhaust tubing, or other items that need the space underneath, turning them on their sides should be fine. Looks like a great project.

[chopped65]

The reason being for on their sides is so that it is only 2" tall. If I do it upright, 4" tall, then if you look at the crossmember going straight back, it's taller than the current frame so it won't fit. I have to put the pieces on their side in order to make full contact with the frame. My exhaust will be on the outside of the frame. I will be building, if I cannot find good ones, fenderwell headers that will kick the exhaust outside of the frame. I am choosing to go that route because as I want to lay the truck down, I will not have anywhere to have the exhaust pass over to the outside of the frame unless I route the exhaust through the frame. Through the frame might be interesting but have never seen that done before. I need to check with clearance issues to run the fenderwell headers. I already plan on removing the inner fenders creating new ones so that's not the issue. The issues will be suspension and tire clearance. Has anyone installed fenderwell headers on these trucks, if so please show pictures. The area of the frame behind the mid cross member I installed will hold the tank and compressor for the bags and possibly the battery. I plan to raise the bed floor since I do not like where the bed kicks up in the center to clear the step notched frame and axle.

[chopped65]

Did some more work today. Wish I had more time than a few hours each night during the week. Welded the cross member in. Last week it was just pressed in. I made the gusset for one side and tacked it in place. At first I was going to weld the cross member afterward so that the gusset would fit tightly in the corner then decided to chop off the corner of the gusset to go around the weld and welded the cross member in. Tomorrow I will make the gusset for the other side and finish welding both in. I made the gusset with the same 2x4 that the cross member is. Starting Wednesday I should be making the box for the fuel cell and should have it all finished up this week. I need to send my axle off to get narrowed which is gonna cost me just over $500 to have them rip the gears out, narrow the housing, replace all the bearings and seals, put it all back together and measure for custom axles from moser. Is that a good price or should I try to find something better? Still trying to figure out what kind of 4 link to go with, triangulated or parallel. If I go with parallel I might put a Watts Link in.

[chopped65]

Removed the rear suspension today. Didn't realize that all my jack stands were behind my motor so my motor and axle were doing a balancing act. When I unbolted the coils from the frame, the truck fell way forward (see pics). After that moved front jack stands under the front cross member, re-leveled the complete truck and completely removed the rear axle and suspension. The gussets are completely welded in now except for about 4 inches, I ran out of wire again. I cut all the frame pieces to build the fuel cell frame section. Thought I was going to have to raise the rear frame more than the front for the gas tank to have clearance but I'm mounting the tank on top of the frame now and it will hang below 1.5" at the lowest point and I will still have 2.5" clearance if I am laying frame.

[chopped65]

Shaved the Dana 60 down removing the leaf spring brackets and shock brackets. Sent axle to Dan's Driveline in Las Vegas. They are changing out my yoke, narrowing the axle housing 9", setting the gears and sealing it up. Should have the axle back in about a week and a half

[chopped65]

finished off the rear section of the frame. It fits the fuel cell perfectly. The hose outlet hangs just perfectly below the rails, as if I planned that. I still need to drill the holes to bolt the fuel cell to the rails, then I'm going to weld the nut brackets to the inside of the fuel rail. Not sure if I should mount the nut brackets inside the rail or drill all the way through the rail and mount the nut brackets on the bottom. It would suck if a nut got stripped and I couldn't fix it because its inside a sealed rail. I still need to cap the rails but will wait until I figure this out.

[chopped65]

Removed the rear frame section. Used my engine hoist, bolted a couple of chains to corners of the frame to keep it steady when I cut it off. Last picture is the new frame section set in place. Still need to cap the old frame rails off. Will get this done this weekend hopefully.

[chopped65]

This is for Nathan with Porterbuilt. This is the rear cab mount for the 3/4 ton trucks. I plan to remove this style and install the 1/2 ton version which I believe is exactly like the front.

[chopped65]

Rear frame section is complete. I drilled and tapped the holes to mount the fuel cell. I boxed all open frame sections on all ends, 4 on the rear fuel cell surround and the two on the end of the original frame. Prior to closing in the old frame I welded from the inside of the boxed section to the old frame. Wanted to add as much strength as possible to that area.
For now, I am done just waiting on parts. The notch is on its way and the 4 link will be ordered tomorrow on its way with the notch. Both are from Porterbuilt. The axle is also being completed as we speak. I believe the axle will be completed the end of next week.

[jonzcustomshop]

1/2 ton rear and front mounts. front is same 3/4 and 1/2.
rear is different, and different from the front.

[chopped65]

what years are they the same from? Suicide doors sells the rear cab mount 1/2 ton for a 67. Will this fit?

http://www.*****************/-63-87-f...hassis-mount-3

[61_FL_Apache]

Subscribed.

Nice job so far!!

[chopped65]

Thanks. Just ordered all parts from Porterbuilt should arrive in a couple weeks right when the axle will be completed. Hoping mid Dec. everything is done in the rear then time to start on the front.

[chopped65]

I GOT CHRISTMAS PRESENTS!!!!!!!!

Got my first shipment from porterbuilt which included: bags, shocks, shock bar and mounting brackets, 4 link pars and joints and step notch.

First thing I did was just set the notch in place to see how it looked.

[chopped65]

I did not go the conventional way of welding in straight frame rails, weld in the step notch and cut out the center. I found that to be a waste of tubing. Actually I was about 5" short on the amount of tubing required. So, I did it my own way which so far worked out great. I made the front frame piece and rear frame piece and welded them to the notch creating the center section needed. Everything has been leveled out perfectly and tacked together. I began welding the bottom pieces so that I don't have to weld upside down but ran out of gas again. Tomorrow, buying new bottle of gas, new 14" cut off wheel and new die grinder disks. After welding up the center frame pieces, I will be tacking in to complete the frame and weld everything up.

[chopped65]

Forgot, thank you Porterbuilt. What an excellent product Nate makes, could not believe how perfect of a fit it was and the measurements were spot on. As soon as the rear end is complete I cant wait to get a dropmember and tubular control arms.

[jonzcustomshop]

Originally Posted by chopped65

what years are they the same from? Suicide doors sells the rear cab mount 1/2 ton for a 67. Will this fit?

http://www.*****************/-63-87-f...hassis-mount-3

those repros don't look like an exact fit or repro for 60-66, but do look like they will work.

if you want to be sure get some from any 63-66 1/2 ton truck.