L4N71B SWAP INTO A 620

[ghammer]

So...you want to swap a L4N71B into your 620.....here's some pics of my install. Your opinion and install may vary. Good luck, it's a tight sob under there! It's not running yet as i'm doing lots of other things to it at this time also. But, will be on the road soon.

 

First things first, obviously remove old trans(had to be said), completely remove one of the torsion bars. Makes it much easier to muscle in the heavier 4 speed. Remove the trans tunnel cover. You will have to cut off the mount pads to the rear of the speedo on tailshaft housing. They will contact the torsion bar bolt mounts. After multiple tries of attempting to place the much larger 4 speed auto into place, you HAVE to unbolt the engine from the mounts and move it forward. Slip the trans into place, then bolt the engine back to mounts. Now you can throw a couple bolts to hold trans and engine together. I used a socket under rear of tail housing to hold trans up at proper height. Now the fun part...fabricate a new crossmember assembly! You cannot use the stock maxima trans mount. NO ROOM! I cut up the stock mount that bolts to rear of trans and made a new cradle to mount a trans mount to. I was only able to use the top bolt on each side, as you cannot get to lower bolts. I then made a new crossmember to support that assembly. I modified the vacuum and trans lines from the donor maxima. As my truck is an automatic, I used my original shifter. I had to bend the arm below the floor as it hit the trans. I had to shorten the shift rod also, since the trans shift arm is further back on the trans. In a nutshell that is it. LOL! Good luck to anyone that forges down this road. This pic is of it's initial placement before any fab.

[ghammer]

This shows the rear mount I mentioned that needs to be trimmed off.

This shows how close it is to torsion bar crossmember.

This is the cradle I made. I cut the original mounting tabs from the original mount and created from there. The trans mount bolts to this.

This shows how tight everything is between the pan edge and torsion bar crossmember, when the cradle and trans mount are installed.

This is what I came up with for a crossmember that left access to the trans pan for service.

This shows just how close everything is when installed. I actually had to grind back the lower edge of the torsion bar crossmember where corners of trans crossmember are.

 

[ggzilla]

Was all that work worth it?

[ghammer]

Here's what you'll need from a '83-'84 Maxima donor car for this swap:

1. Transmission/convertor with wiring harness.

2. Flexplate with crank spacer(if you're not starting with an auto truck already, then you already have one on the back of your crankshaft).

3. Grab the dipstick, vacuum, and trans cooler lines.

4. The trans mounts that bolts to the back of the tailhousing, if you're going to make a mount like I did. The crossmember is useless to you since it will go unused...one less thing the self service yards will charge you for.

5. The shifter handle out of a '88 maxima, adapt it to your stock shifter, so you can turn off the overdrive. Since Nissan doesn't allow for a manual downshift out of overdrive. You actually have to put power to the overdrive solenoid to downshift to third(I still have to get this as my local PNP got rid of the car they had before I could get back out and get it).   :frantics:

 

Don't bother getting the front driveline. I did and found out at the driveline shop the front u-joints are non-servicable and had to buy a new slip yoke. It cost the same amount as I paid PNP for the front driveline. Doh!  Other than that, it's all up to you and some fabrication skills.

[ghammer]

I sure hope it will be in the end. It is going to be my commuter and prefer not to have to be shifting a manual trans......that would get in the way of my texting and drinking while driving! Just kidding everyone. I have a decent commute to and from work, just want to put it in drive and go, turn on the radio and a/c, and cruise down the road. 

[darrel]

It will be worth it if you drive on the highway a lot.

 

The handle doesn't have to come from an '88 maxima, it's just what I used.

 

Don't forget about the linkage for the shifter at the trans. You might be able to shorten the original and run a die over the end.

[zerow]

Good Job ghammer! Another trailblazer! Verify that the end of the transmission and differential angles will allow for minimal vibration at highway speeds. My driveshaft is out of phase, so I have some vertical adjustment to do at the end of the transmission.

[ghammer]

Good Job ghammer! Another trailblazer! Verify that the end of the transmission and differential angles will allow for minimal vibration at highway speeds. My driveshaft is out of phase, so I have some vertical adjustment to do at the end of the transmission.

My rearend angle is only 2 degrees off from my trans output shaft angle. I'll get some 2 degree shims and correct the rearend angle. Simple fix.

 

It will be worth it if you drive on the highway a lot.

 

The handle doesn't have to come from an '88 maxima, it's just what I used.

 

Don't forget about the linkage for the shifter at the trans. You might be able to shorten the original and run a die over the end.

I shortened my stock shift linkage. I cut it in the middle, took about 2" out if it, and welded it back together.

 

Hey darrel, I haven't really looked at any other cars at the wrecking yard.....do a lot of other nissan cars have shift handles with the on/off switch on them?

Thanks, ghammer

[ggzilla]

Yes, most overdrive automatics have them up into the 90s.

[darrel]

Like ggzilla said, up into the 90's. Get enough of the wiring so you get the connector. It is a three wire. The third wire is for the light. I didn't hook that one up. You just need two for the OD to work. I wired mine to the lighter. I forget where I wired it the first time, but it kept blowing the fuse.

[ghammer]

I've got a couple of quick questions about the wiring. I've got things torn apart still and can't put power to anything yet, but I need to figure out a couple of things. My truck is a 78 auto with a/c. I'm in the process of matching up wiring from the '84 trans to the '78 body harness. When checking the original 3 speed auto harness, I found everything is wired independently.....nothing sharing any common wires in the trans harness. The '84 trans shares some common grounds between a few things. My question, did the truck originally run 12v power down through the neutral safety switch and backup light switch? Or did they just run ground through the switches to trigger relays? And also with the new '84 overdrive i'm quessing they just use the switches for transferring ground to trigger relays, since there were several things sharing common grounds? Thanks in advance!

[datzenmike]

The 620 reeverse lights are power from the dash switch through the trans switch and back to the reverse lights to ground.

[ggzilla]

Yes, the 620 Nuetral Saftety Switch switches 12V for the reverse lamps.

 

 

> with the new '84 overdrive i'm quessing they just use the switches for transferring ground to trigger relays, since there were several things sharing common grounds?

 

Unknown. I'd check out the wiring harness.

[ghammer]

Here's a couple pics of the shift handle I used. It was out of a '95 Altima....kinda classes the joint up a bit...well makes the shifter look newer at least..lol!

 

Of course I didn't make it easy on myself. This shift handle was a smaller diameter than the original from the truck. So, I cut the stalk off of the stock truck shifter, went back out to PNP, cut the same portion off the donor car and tig'd it together. The donor actually will slip right into the base of the truck to make things a little easier. I also cut the actual push rod and spliced the top part of the donor to the original one. Since I used the base of the original, this way I could utilize the stock lower retention pieces. Worked out nice in the end.

 

[ghammer]

I can't wait to start driving this thing. When I finally got it going a couple of weeks ago, I tested it up on jackstands.....and boy it really dropped the RPMs when it shifted into overdrive. I think this is going to work out real nice cruising down the freeway! I'm hoping to be on the road in a couple of weeks.

[heretic]

more :)

[ghammer]

Finally after all this time......got to drive the truck. Wow, the overdrive trans is nice!!!! I'll post some pics with the shifter installed in truck. Be back soon! :thumbup:

[darrel]

thought you and your tranny got a room together and drove off into the sunset.

[datzenmike]

[DeviousPsycho620]

 

Hey man... You know this kind of shot belongs in insomniacs. Bahahaha Just playin' :)

[ghammer]

This thing has snowballed into so much more than what I planned in the beginning.....as all projects do. As a former shop owner, I know this all too well. And I'm not too happy with myself for letting it happen. You know when you get so far down a road and you just can't turn back....you have to keep going.....that is what happened on this. I initially bought it and planned on spending about $2500-$2800 on it total. I'm now in the $4500 range! And still not done. I still need to buy an a/c compressor and condensor to get that going. After the maiden voyage last night i'm very pleased with the way drives and hoping to get many years of economical driving out of it as a commuter. It's going to get aligned later this morning, then it's time to start putting some miles on it!    :D

[tdaaj]

Odmanjohnson, another Ratsun member pulled this swap off about 10 years ago in a 77 620. Put it be hind an Lz24 hybrid motor. Made a world of difference.

[ghammer]

Alrighty, here's a couple of pics of shifter handle installed.

[ghammer]

Here's a teaser shot. It's done now just need to take a finished shot. Enjoy!

[heretic]

that console looks AWESOME ghammer. I have to admit when you had the shifter on the bench I wasn't sold that it was going to look right in the cab, HOLY SHIT was I wrong.

 

I'm stoked to hear it's meeting your initial expectations an overdrive auto has been on my radar for awhile now.

 

BITCH'n looking truck.