Vg3xt swap in 1981 Datsun 720

[Quickshift]

I need some help answering some questions performing this swap in my 1981 2wd 720.

I like the z-naps z22 that came in the truck. Problem is, she's well over 200,000 miles at this point. And the horsepower definitely leaves a bit to be desired.

I own 4 z31's at this point and i'm fairly familiar with the vg series of sohc engines. got a few spares and parts laying about too. So why not stuff one in the truck?

Honestly, it's this or rb20det swap and I don't really feel like cutting apart the firewall to fit the engine.

 

Questions I have come up with so far:

1. Referring to transmissions, the truck is currently a 5-speed. The 71b specifically. I plan to use the 71c trans from a non-turbo 300zx. Will the driveshaft for a 71b fit the 71c trans? or do i need to get one made?

2. Engine crossmember. I plan on using the vg crossmember from a d21 or pathfinder. Will this bolt up to the 720 frame? (Obviously I will have to modify it to run the stock turbo location for a z31)

3. Fuel tank. Not really swap related, but I read that the 720 should have a 16 gallon fuel tank. 8 gallons fill it from empty and I have never put more than 11 in it at the pump, even when I ran it out of fuel. Is this normal? or is something in the gas tank?

4. Regarding the inner fenders. I like slammed cars/trucks and I've already lowered mine about 3 inches from where it sat when I bought it. I have seen bagged builds that remove these inner fenders completely. I plan on using a coilover set-up all the way around (with a triangulated 4-link in the rear) Is there a write-up or something that details how to do this properly?

[datzenmike]

1. Referring to transmissions, the truck is currently a 5-speed. The 71b specifically. I plan to use the 71c trans from a non-turbo 300zx. Will the driveshaft for a 71b fit the 71c trans? or do i need to get one made?

 

If the 71C was from a 4 cylinder, I'd yes no problem, but it's from a VG and (I think) it will be a larger spline diameter. Either way the driveshaft length will not be the same.

 

 

2. Engine crossmember. I plan on using the vg crossmember from a d21 or pathfinder. Will this bolt up to the 720 frame? (Obviously I will have to modify it to run the stock turbo location for a z31)

 

The D21 or any truck for that matter do not have a crossmember for the engine to attach to. The truck has a frame and the engine mounts directly to the two frame rails on either side

 

3. Fuel tank. Not really swap related, but I read that the 720 should have a 16 gallon fuel tank. 8 gallons fill it from empty and I have never put more than 11 in it at the pump, even when I ran it out of fuel. Is this normal? or is something in the gas tank?

 

In '81, only the

Long Bed and the Cab Chassis got the 16.9 US gallon tank.

Reg cab and King Cab 4x4s got the 15.8 US gallon tank

Long Bed 4x4 got a 19.8 US gallon tank

All 2wd Reg Cab and King Cab trucks got a 13.2 US gallon tank

 

4. Regarding the inner fenders. I like slammed cars/trucks and I've already lowered mine about 3 inches from where it sat when I bought it. I have seen bagged builds that remove these inner fenders completely. I plan on using a coilover set-up all the way around (with a triangulated 4-link in the rear) Is there a write-up or something that details how to do this properly?

 

I don't know. Try typing bagged 720 into the search engine.... upper right of every page.

[Quickshift]

Thanks for the quick reply datzenmike.

Now I know:

A. Get a custom driveshaft made.

B. Engine mounts are going to be stupid simple.

C. Gas tank is smaller than I thought.

 

I'm going to need to edit this with pictures at some point.

[datzenmike]

http://community.ratsun.net/topic/691-how-to-post-pictures-and-keep-online-photo-albums/

[Quickshift]

This is the only picture i've got that isn't from instagram so far.

[Quickshift]

Friend of mine, Alex Via, has performed a vg33 swap into an s13, to use for drifting. Turns out the FS5R71C from the 300ZX Z31 N/A models is similar to the FS5R71C found in the 240sx with ka and sr's. it's also similar to trans used on rb's. http://z31performance.com/showthread.php?13560-71C-trans-Z31-and-240SX-full-gear-clusters-can-interchange

How similar are the truck transmissions to 240sx 5-speeds?

 

I should just be able to switch bellhousings from the z31 transmission to the transmission currently in the truck. "I used a z31 71c and a stock s13 drive shaft. Could use a z31 bellhousing on any 71a/b/c if you need a specific trans length. The hardbody uses a much shorter trans and the rb20 is a weird middle length. Z31/240sx's are the same (long) length" -Alex Via

[datzenmike]

The S12 had a VG30 engine around 87? The trans output spline from it was larger I believe than all the 4 cylinder ones. Also the 280zx turbo automatic had a larger spling than the n/a autos. I know that's not proof just a hunch that the VG may be different.

 

The 71B comes in 26" and 31.5" lengths. None of the 71C are that, usually longer in the S13/14. The D21 2wd 5 speeds may be around 30"???? I don't have one.

 

A 71C front case from a VG will bolt to a 71B trans but you will need to replace the 56mm counter bearing with a 62mm one. Also the 1st/2nd shift rod hole in the front case will be slightly large. It will work but may be sloppy?.

[Quickshift]

Sounds like it would be a good idea to take them both apart and take pictures.

[datzenmike]

Well swapping the front case eliminates finding another trans and drive shaft mods.

[Quickshift]

 I'm looking to do a triangulated 4-link and coilovers on all corners. my question on this subject is what size square tubing will I need for the 4-link arms? suggested diameter and wall thickness would be immensely helpful.

As for sway bars, my truck currently has none. Body roll in corners is ridiculous. I would like to use a sway bar at least in the front to use softer springs but still eliminate body roll. Is there a stock or aftermarket bar I can use? I'm not sure how a sway bar will cooperate with the 4-link rear, but I would like to run one in the rear as well.

On the subject of drop spindles. Since my truck is an 81 my understanding is that while d21 2inch drop spindles will work, I need to use d21 lower control arms, correct? Do I need anything else? I plan to acquire new v6 front disc brakes to help with stopping power.

On H190 rear ends, are there any stock LSD options for this? or am I better off just using an r233 rear end? Do I need a new brake master to run the rear disks? Or is my stock brake master sufficient?

[NissanNut]

All my trans I have done clutch jobs on have been the same 24 spline. 88wd21 vg30i, 93d21 vg30e, 85 720 z24, 96 r50 vg33e, 74 l18, 79 280zxL28, 98 d22 ka24. Been using the same alignment tool I bought in th 80s.

 

Now the vg3x output is 24 spine on 4cyl and 30 spline on v6 on all trucks and wagons. At least on all the 4wd models.

[Lockleaf]

Quickshift, go check out the last two copies of the magazine project car tuner (they are a year or two old now). They custom build a four link rear end with coils and swap in a 240sx front crossmember with its full suspension into a datsun 620. It won't be a huge difference to do the same to a 720. If you aren't familiar with the magazine, they do only tech articles, they do great work, and it's clear step by step detail. Should tell you 80% or more of everything you need to know to coilover your truck

[Quickshift]

slight update. timing chain has stretched to the point where it wont run anymore. tore most of it down and discovered that the crank pulley will not come off. impact wont do it, left the truck in gear and tried to do it by hand, just moves the truck. wedged a prybar in the camshaft pulley sprocket, worried about cracking the head, because i put an awful lot of pressure on the breaker bar. so, time for an engine swap.

 

Going to get all of the odds and ends into the shop to put it together within the next couple weeks. 

Parts list is as follows:

vg33e out of a 2002? Frontier 4x4 (bitch to pull in the rain)

ported OWO heads off of said vg33e (nothing goes back together without head porting now. free power.)

stock t3 turbo/turbo manifolds/injectors/ecu/wiring harness from a 1986 Nissan 300zx turbo

new radiator

custom motor mounts

either a 71c from a non-turbo 300zx or the t-5 from the aforementioned 1986 300zx turbo

going to do the driveshaft myself (use the 720 rear half, cut and weld on the 300zx u-joint)

custom built exhaust turbo-back (might front mount the turbo if it doesn't fit in the stock 300zx location on the drivers side under the manifold)

no intercooler for now, but i have a few to choose from later

 

 

My only real concern is the rear end. the H190. how much torque can it hold? In 300zx's the vg33e-t is proven capable of 250hp/399tq at 10lbs of boost all stock. no head porting, stock cams. I plan on drifting this truck so i'd like to be able to push it when I need to. the vg33 alone puts out more than double the horse power the z22 makes. I plan on running a h233 out of a d22 pathfinder, I just don't have one yet.

[Lockleaf]

I'm assuming by D22 you mean the 96+ pathfinder? If so, the chassis code is actually R50.

 

There are basically three versions of the hb233 axle.

 

Pre '90 - 9 studs holding the 3rd member and 10mm bolts on the ring gear, 31 spline axles.

 

'90 to '99 - 11 studs, 12mm ring gear bolts, 31 spline axles. This one is found in both wd21 and r50 pathfinders.

 

'00 to '04 - 11 studs, 12 mm ring gear bolts, 33 spline axles

 

The last version is the strongest. The pathfinder came with disc brakes only during a few years in the early 90s, all the rest are drum. But from what I understand, those brakes can be swapped on to any of the axles without much trouble.

 

Most of them come with lsd, but if you're going to abuse it, then that will be much better off with a rebuild.

[petercscherer]

tore most of it down and discovered that the crank pulley will not come off. impact wont do it, left the truck in gear and tried to do it by hand, just moves the truck. wedged a prybar in the camshaft pulley sprocket, worried about cracking the head, because i put an awful lot of pressure on the breaker bar. so, time for an engine swap.

 

Yeah... You need a pulley-puller to remove the front crank-pulley. I picked mine up for $14.99 at Harbor Freight and it popped right off. Otherwise, good luck on the swap, I might be doing my own in a few months.

~Peter

[Quickshift]

no, i mean, the crank pulley bolt won't come off.

[petercscherer]

Well, that's a new one for me. Only solution there is heating it up and using an air-wrench to zip it off. :/

~Peter

[datzenmike]

Stick a suitable socket and Johnson bar on it and brace against the passenger side frame. Bump the starter. Use the heavy socket and lightly tap the rear of the pulley. 20-30 taps and it will slide forward and off. I've removed at least a dozen pulleys by simply stomping sideways on the Johnson bar even on engines laying on the ground. The inertia of the crank and flywheel is enough resistance to do it if done quickly and hard. Have never used an air gun for this.

 

The H-190 is good for just under 300 ft lbs of torque and as the point of drifting is tire smoke the tires act like a fuse. They break loose at way below 300 ft lbs. Weld the diff up.. it's drifting and over steer is the name of the game.

[Quickshift]

air impact wont take it off either. shouldn't be too bad of a swap. as long as I don't get crazy with turbo stuff, and have the mounts and driveshaft made before hand, the truck should go together in 2 days max.

[datzenmike]

  the truck should go together in 2 days max.

 

 

:lol: :lol: sorry let me laugh harder... :lol: :lol: :lol: :lol: :lol: :lol: :lol:

[Quickshift]

did my first vg33 swap in my z in one afternoon, start to finish, outside. Started snowing on me halfway through. this time i have a shop.