320 frame swap

[Thane]

I want to do a frame swap on my 320. I have found 1984 720 extra cab pickup, so besides shorting the frame, body mounts and bunch of other what not's involded for this swap.

 

So my main question is the WMS close to the same width? Sorry for the newbie question, just to make sure if this going to right choice of truck for the swap.

[merlin]

first question is why do you want to do this? Brake upgrades, mods, etc have been done for the 320, and the 720 engines wont fit without serious hacking.

[Thane]

The main thing is the newer supension and the 320 is missing some supenions parts. Plus the cab/fire wall has been hacked up by someone before.

[wayno]

This is what was done to OL'320s 65 datsun 320.

 

http://community.rat...int-conversion/

 

His truck has an A12 block, "A" blocks will fit with a minimun of issues.

Read the thread above, the 720 frame had to be narrowed about 4 inches, that's a lot of work, only the front part of the 720 clip was used, and the steering linkage is a custom fabrication.

 

What parts are you missing from your front suspension?

You can use parts from the 520/21 series trucks, depending on what you are missing.

As merlin mentioned, Mike K. has a kit that allows the use of the 85/86 datsun 720 front brakes(vented rotors/calipers) to bolt on to your 320 spindles.

[Stoffregen Motorsports]

The reason I wanted to do the whole front suspension was to get the modern front suspension. Balljoints are far more comfortable a ride than kingpins, especially after they start to wear. Also, the 720 front suspension geometry was vastly improved for camber gain while turning and for ride comfort. I also wanted the disc brakes.

 

I know there is a kit for the 320 to mount disc brakes, but if you can do the work, I would clip it. You will be happy with the results. If you can't do the work...call me, I've done it.

 

[Stoffregen Motorsports]

Two other benefits worth mentioning are steering related. First, the steering box and the idler arm mount on the outside of the frame allowing more room between the frame rails for more engine room (like clearing a filter). The second reason is the steering shaft converts to a open shaft allowing for easier removal of the steering box, and also more room for things like a header or whatever.

 

[Thane]

I agree with you 100%.

 

Do you remember how much did you narrow the frame?

 

If it is 4 inches, I have been thinking about trying to just setting the body on it to see how its going to look. Cause that's only 2" wider per side.

Maybe find some rims that have very little offset. Like the chrome wheels from Nissan hard bodies.

 

I'm still in the process of getting all the info that I can right now.

[wayno]

I agree with you 100%.

 

Do you remember how much did you narrow the frame?

 

If it is 4 inches, I have been thinking about trying to just setting the body on it to see how its going to look. Cause that's only 2" wider per side.

Maybe find some rims that have very little offset. Like the chrome wheels from Nissan hard bodies.

 

I'm still in the process of getting all the info that I can right now.

 

I thought it was narrowed 4 inches, but I could be wrong, as I can't find what made me think that.

You need to determine how much it would need to be narrowed, if your able to do it with just wheels, please share how you did it with us ratsun folk.

[Stoffregen Motorsports]

I agree with you 100%.

 

Do you remember how much did you narrow the frame?

 

If it is 4 inches, I have been thinking about trying to just setting the body on it to see how its going to look. Cause that's only 2" wider per side.

Maybe find some rims that have very little offset. Like the chrome wheels from Nissan hard bodies.

 

I'm still in the process of getting all the info that I can right now.

 

I think it was 2 7/8" that I narrowed it.

 

The stock 720 WMS width is about 6" wider than the 320 so by cutting 3" (2 7/8") out of it, you arre still gaining 3" of width. In other words, if you put it down on the stock width 720 chassis, your stock 320 wheels and tires would stick out of the fender almost three inches.

 

I know I never said exactly how much, but if you refer to post #37 in the link http://community.ratsun.net/topic/34698-320-balljoint-conversion/page__st__20 it should help.

 

Also look at this pic and you'll see how close they are.

[Stoffregen Motorsports]

The most important measurement is the width of the stock 320 torsion rods. Take that measurement and subtract it from the width of the 720 torsion rods and that is how much you need to narrow it.

 

I did it this way so as to keep the 320 trorsion rod crossmember, saving me from a lot more work.

[wayno]

I see, so you cut the 720 frame to match the 320 torsion bar spread, and you used the 320 torsion bars on the 720 LCAs, as they just plugged right in, correct.

I thought it was cool what you did to Erics truck, the only thing I try to do is aviod custom parts, but there are just some things that you can't help when doing something like that modifacation.

I have everything I need for my next 320KC project, but am still torn between keeping the stock frame and lengthening it, and using the Z'd LCAs mike made, and his kit for disc brakes, or to narrow a 720 frame from one end to the other.

[Stoffregen Motorsports]

I see, so you cut the 720 frame to match the 320 torsion bar spread, and you used the 320 torsion bars on the 720 LCAs, as they just plugged right in, correct.

I thought it was cool what you did to Erics truck, the only thing I try to do is aviod custom parts, but there are just some things that you can't help when doing something like that modifacation.

I have everything I need for my next 320KC project, but am still torn between keeping the stock frame and lengthening it, and using the Z'd LCAs mike made, and his kit for disc brakes, or to narrow a 720 frame from one end to the other.

Thanks Wayno.

 

Yes, they plugged right in. The only custom parts in the conversion were the steering shaft and column, which you would never have to replace, and the center steering link, which was only narrowed and could be replaced by a similarily mod'd unit in the future. It will last for quite a long time so no real need to worry. You could also make a custom center link with replaceable joints.

 

I say however you do it will be better than stock. And cutting a frame down the middle is probably easier, but the same amount of work.