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320 Balljoint conversion


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I just sold my Datsun L320 and part of the deal was to install a 720 frame clip on the 320 before the buyer took it away. I have a clip from a 720 that I will be installing during the next couple of weeks and I will be posting with pics as I go along.

 

The conversion is pretty straight forward. I didn't want to do as others have done and use the stock 320 control arms, because the 720 geometry is better. So I will be chopping the frame around the motor mount area, narrow the 720 clip to accept the stock 320 torsion rod width, and end up with a WMS width of about 2.75" wider than stock. This will put the tires just under the fenders and most people won't know the difference. I am also converting from the single master cylinder to the dual circuit master, but I won't be using the booster.

 

One major difference is where the steering box mounts. On the 320 it's connected to the steering column via a tube and it's mounted on the inside of the frame. The 720 box is mounted on the outside of the frame and will use a u-jointed shaft instead.

 

The stock wheels will clear the calipers and rotors so we will be using those instead of going aftermarket. I think the stock wheels with hubcaps and whitewalls look better anyways. It's not a race car...

 

Here's the truck "before"

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I also beleave stock wheels and caps look good. Are you cutting the stock column shorter in the engine compartment and adding the U joints in the middle? I put the 720 steering gear on the outside of my 521 frame as far forward as I could get it and put a stock idler arm where the stock steering box was(521 idler arms will bolt to either side), then I had a custom (custom parts suck) center link made that had a tierod connection as far to the passinger side as it could be put, presto, power steering. The reason I brought this up is that the steering gear column connection on the 720 was fairly close to the same place as the stock column connection for the 521, but I did have to cut sheet metal for the gear itself as it is on the outside of the frame.

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I also beleave stock wheels and caps look good. Are you cutting the stock column shorter in the engine compartment and adding the U joints in the middle? I put the 720 steering gear on the outside of my 521 frame as far forward as I could get it and put a stock idler arm where the stock steering box was(521 idler arms will bolt to either side), then I had a custom (custom parts suck) center link made that had a tierod connection as far to the passinger side as it could be put, presto, power steering. The reason I brought this up is that the steering gear column connection on the 720 was fairly close to the same place as the stock column connection for the 521, but I did have to cut sheet metal for the gear itself as it is on the outside of the frame.

 

Yeah, I'm going to have to cut the stock shaft and support it near the firewall. Maybe I'll just machine a bushing that slips into the stock column tube.

 

I don't want to have to cut the sheetmetal, but there's no way around it. And I will try to modify the center link instead of making a custom one. When I do make custom parts like that, I like to use over the counter parts, and I hate using heim joints. I don't care how much you spend on them, they last a year and then they start getting sloppy from all the road grit that gets in them. And the greasable ones are weak.

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Greetings! Matt is modifying his truck for me, the new owner):

 

I have always liked these old trucks, but they have always needed better brakes, in my opinion. When Matt is done modifying the front frame by splicing in the slightly narrowed 720 front crossmember, I think the truck will handle better, stop better and track much more sure-footed down the road ... And the cool thing is very few people will be able to look at this and know he changed anything!

 

 

Now I just have to find someone who sells new or reproduction 320 vent window rubber:) Anybody find a source for these yet?

 

Regards to all.

 

 

 

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  • 3 weeks later...

I have been busy getting all the work done and in the midst of it I got a new computer with new photo software that I haven't been able to figure out yet. I'll get some pics up soon.

 

The truck is nearly complete and I am really looking forward to driving it. I'm glad I had a good plan in mind before I cut because it has all, well mostly, worked out so far. The 720 frame was cut in half down the middle and narrowed to fit with the stock 320 torsion bars. The 720 control arms and 320 control arms use different end links, but the spline is the same, so the 320 torsion bars fit right into the 720 end links.

 

I did have starter clearance issues, but that was easily remedied with a cutoff wheel, some plate steel and a welder. I'm the only one I know of running a A12 in a 320 so I don't know that this would apply to anyone else.

 

The motor's back in and I'm finishing up on the assembly so expect to see pics in a couple days.

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  • 3 weeks later...

Well the job is complete and I am really happy with how the truck drives. No more clunking from worn out kingpins. And the brakes are phenomenal. Maybe a little on the stiff side, but the 720 came with a power brake booster and there's no way I was going to fit one in the engine bay of the 320.

 

I'll compile my pics and post a blow-by-blow for you guys.

 

IMG_5486.jpg

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cool I can't wait to see the tech write up with oics on how to do this.

 

Me also, i have a 320 project coming up this winter, i want to hear what he all had to do, one might think all you have to do is cut 3 or 4 inches out of the middle and weld it all back together and call it good, but it seldom works out that way.

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Matt has finished the new custom gauge panel, the front end conversion and a ton of other work. He's been having some computer problems posting pics, and I am located 4 hours away from his shop. He is waiting for his buddy to rewire my old truck. I plan to go pick it up next weekend if all goes well. I can tell you, the conversion looks very sweet sitting up on the lift, but I did not get to drive it when I was up there visiting. Matt made some modifications that allow for much more custom alignment settings. I'll defer to him to explain this when he posts his writeup, I don't want to muck up his thread. When I get a hosting service I'll post a few pics myself. Eric

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  • 2 weeks later...

Sweet build! I was a bit sad to see that it was a pre '84 frame clip....same brakes as the 620.

 

Now that you have ball joints, if you ever want even better brakes(less fading) you can easily upgrade to later 720 or Hardbody vented rotors/calipers by swapping the spindles. Unbolt the balljoins and tierod ends and swap the entire assemblies.

 

The A series in a 320 has been done before, but I've only seen a couple....the oil filter/motor mount conflict stopped most swaps....hhmm....actually, only one completed swap...the second was a hack job on a rig I bought for parts. Great upgrade in my opinion!! Looks really close to stock and you do really nice work! Thanks for posting!

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Sweet build! I was a bit sad to see that it was a pre '84 frame clip....same brakes as the 620.

 

Now that you have ball joints, if you ever want even better brakes(less fading) you can easily upgrade to later 720 or Hardbody vented rotors/calipers by swapping the spindles. Unbolt the balljoins and tierod ends and swap the entire assemblies.

 

The A series in a 320 has been done before, but I've only seen a couple....the oil filter/motor mount conflict stopped most swaps....hhmm....actually, only one completed swap...the second was a hack job on a rig I bought for parts. Great upgrade in my opinion!! Looks really close to stock and you do really nice work! Thanks for posting!

 

Thanks!

 

The truck only weighs 2000 lbs so I don't see the solid rotors being a problem.

 

I remember when I did the motor install, the stock filter did hit, so I swapped it for a Toyota filter which is a smaller diameter. It was close before, but now with the new steering system the idler arm mounts on the outside of the frame for even more clearance.

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Thanks!

 

The truck only weighs 2000 lbs so I don't see the solid rotors being a problem.

 

I remember when I did the motor install, the stock filter did hit, so I swapped it for a Toyota filter which is a smaller diameter. It was close before, but now with the new steering system the idler arm mounts on the outside of the frame for even more clearance.

 

I did an A15 swap with dual SU type and dogleg 5 spd. into a 65 L320, the oil filter did hit on the idler arm, as the 320 idler is so big, I used a remote oil filter for a little while. Then I figured out that the much smaller 521 idler arm would fit and work properly in the L320, so I swapped it out and had a little more than an eighth inch clearance for the stock A block oil filter. It was a great little truck till the kid came around the corner and hit me head on and ruined it, it was a rust bucket, but for $250, it was great.

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I did an A15 swap with dual SU type and dogleg 5 spd. into a 65 L320, the oil filter did hit on the idler arm, as the 320 idler is so big, I used a remote oil filter for a little while. Then I figured out that the much smaller 521 idler arm would fit and work properly in the L320, so I swapped it out and had a little more than an eighth inch clearance for the stock A block oil filter. It was a great little truck till the kid came around the corner and hit me head on and ruined it, it was a rust bucket, but for $250, it was great.

 

It sucks when something cool gets trashed. Just about every Datsun I've ever sold has ended up in the scrap pile and it breaks my heart. I hope Eric (ol' 320) takes care of my 320.

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I'll tell you guys one thing, the brakes on this thing feel super. I really enjoyed the long drive home. Called my ins agent. Collision coverage "with everything ..." was only $47 dollars for six months coverage:)

 

Hopefully Matt will post more pics soon. This frame looks "factory" and the workmanship on the chassis is incredible.

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So, I've put about 600 miles on this truck with the "new" front end. Love the brakes. They have just a touch of free play to the pedal, and then it is rock hard and done within another inch of travel. Just enough give to modulate the brake feel, and then it is nice and firm. Very satisfying to have really good brakes that stop on a dime. I don't know if this is all due to the new Brembo rotors, pads and all new steel lines, rubber brake lines and the upgraded dual circuit M/C, or what, but this is easily the best improvement that has been made on this truck.

 

By converting to a 720 ball-joint front clip, with the newer, unmodified geometry (no reconfigured A-arms and such, just new stock stuff) the truck has zero squeaks, creaks or rattles. Steers like it has power steering with the newer 720 box. THis truck has new "old school" bias ply whitewalls on it, and it would be silly to toss those when they are almost like new, but I am sure with radials this truck would ride and steer even better.

 

The 720 suspension is really nice when a speed bump sneaks up on you. The 320 just floats over the parking lot bumps. The truck has re-bushed rear leaf spring hackles as well, and new shocks all the way around. Matt lowered the front end slightly - about 2.5 inches lower than the stock 320 ride height - and it seems to set nicely there with great ride quality.

 

I'm hoping Matt will post a series of pics on here as to how he did this. The result is exactly what I was hoping for when we made our deal for me to purchase the vehicle with this framework completed. Eric

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