sd22 in a 1948 Willys Truck.

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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ehtrain
Posts: 141
Joined: 9 years ago
Location: regina, sk

#166

Post by ehtrain »

have you looked in http://nissandiesel.dyndns.org/viewtopic.php?t=3323

i have my d21 body VIN - JN6JD12S9HW000291 (2nd one down on weblink) it has the rotary IP nissan may be able to get the part. or a zexel dealer should be able to get the part? i know there are lots of things using rotary IP. VW, toyota, nissan, cummins to name a few

also if your looking for rebuild parts i believe everything but the crank is the same as the sd25. it's just shorter stroke if i remember correctly. If im also not mistaken the sd23 got the sd25 cylinder head later on as an update, something about the valve head diameters being different on the first gen. big valves = more air = better efficiency

how about turbo? ive been ebay shopping for a small tb25 turbo similar characteristics to the td27t would be a greater performer.... maybe even a tad large for the 2.3L. This is the one I'm looking at http://www.ebay.com/itm/Nissan-RB20-RB2 ... 5b&vxp=mtr

also you say 5.38 gears in the axles? are you running the lower ratio gearbox the diesels came with? i cant remember what I read several pages back now lol. I have the sd25 and with turbo and no fuel touched. I also have the lower range gear box. I currently run 31x10.5 and 4.37 gears. the truck performs reasonable with turbo, without it struggled. turbo with 235/75r15 (29.5in) had tons of jam. according to my math when I switch to a 5.13 ratio I will have close to the same power on paper with a larger 35x12.5r15 as the smaller 29in tire, however I don't know my goat math well enough to figure out the extra tire weight in to it. something to think about.... turbo!!! 5psi and those 33's would be nothing haha


also i see that you have no transfer case mated to manual transmission. what transfer case are you using? I'm guessing its a divorced unit from something?
elminero67
Posts: 143
Joined: 11 years ago

#167

Post by elminero67 »

I had been following your thread with interest, hope you continue!

I'm still running the 5.38s with the divorced 720 transfer case (2.4 to 1 low iirc) and the transmission with lower 1st gear. I have bought a new set of axles and may change to a 4.10 or 4.56 (with a second transfer case), but am a little concerned that I will lose drive-ability. With the 5.38s and 33x9.50 tires, 60 mph is as fast as I like to push the diesel for sustained highway driving. I don't know what the actual rpm's are, just going by feel.

I don't know if you will be happy with a tire as big as a 35x12.50 with your SD25: that wide of a tire is very heavy. BTW, your Pathfinder/Terrano already weighs about 1000 lbs more than my Willys truck. It will depend on what your expectations are, some people need 250 hp to feel comfortable, others can cruise one of those dreadful 68hp, 5500 lb VW Vanagans down the interstate...
ehtrain
Posts: 141
Joined: 9 years ago
Location: regina, sk

#168

Post by ehtrain »

interesting I didn't realize the t-case was divorced in the 720.... maybe I should find one for my other project...

well as for gear ratio as long as the gearing is matched to the tire size my speedo wont even be off. so you have to compare apples to apples. if 120hp sd25t is enough to keep tires going smaller. the only thing its gaining is weight and tire width. I'm not like the jeep people trying to stick the biggest tire i can on some 3.73 ratio, in which case your mega underpowered like my 2.4 gas was. clutch drops to get the tires spinning vs dump clutch and it doesnt care. Id prefer a 35x10.5 but they are not common and very expensive. The winner for diesel is the low end torque doesnt give two %$*&s about that added tire weight to get it moving. I also gave my self extra 5% gear to hopefully make up for the power. your 5.38 would have actually been better. my biggest concern is the shitty fs5w71 tranny... im worried that might end up being a regular rebuild item... which sucks but the solid axle swap will fix some things for me. with turbo and 235 tires that truck would wrap the speedo faster then my gas ever wished it could. thats hell of enough jam for me in a little pickup
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asavage
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Re: sd22 in a 1948 Willys Truck.

#169

Post by asavage »

I think that if you run with the later, larger front bearings and good synthetic gear lube, and never drop the clutch in reverse, the FS5W71b holds up OK. It just doesn't have a lot of margin for abuse.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
elminero67
Posts: 143
Joined: 11 years ago

Re: sd22 in a 1948 Willys Truck.

#170

Post by elminero67 »

Agreed on the transmission, I try to baby mine as much as possible after reading a few threads on them.
If you ever get serious about using the Datsun/Nissan divorced case, let me know. Like the transmission, there are at least two variations. You can also bolt two together and end up with a ridiculously low crawl ratio for a fraction of what the "Extreme 4x4" crowd pays for their crawler transfer cases, if that is your cup of tea.
ehtrain
Posts: 141
Joined: 9 years ago
Location: regina, sk

Re: sd22 in a 1948 Willys Truck.

#171

Post by ehtrain »

I generally do baby the gear box also. I blew up more then a few in my race car. I'm thinking I need a working spare either way haha.

I was curious about the t-case because it makes it easy to put any 2wd motor plateform in front of it like a rb25det or ka24et. There are kits that turn toyota mated cases into divorced units. Suzuki samurai also has divorced, but its reduced 4h gear as well as 4L meaning 4H is not 1:1. The 720 stuff is rare around here tho so it will take some hunting to just look at one. Ideally I was wanting to build an offroad buggy or "truggy" as some would call it. Parts that I can get from the junk yard that can perform is more up my alley then paying big $$$ for custom stuff. The toyota unit has a winner like atlas in a way that you can single or double mount the cases with no driveshaft in between them. That makes it pretty compact and lots of gear selection if one t-case uses a different gear range. the 2.2:1 I think it is in the d21 is already low. But to reduce gear box loads and make it easier on everything else a 3 or 4:1 would be nicer even if its only a single t-case.

to bad the fs5w71 is such a weak gear box there are so many engines that use it. in the cars around 350-400hp they start blowing up pretty regularly. the diesel isn't making the 350-400hp. but after Im done fiddling with my engine its going on the dyno because im sure its going to have the torque up in the 250-300 mark
waynosworld
Posts: 525
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Location: Vancouver Washington USA

Re: sd22 in a 1948 Willys Truck.

#172

Post by waynosworld »

They are over/under transfer cases.
Image
I know the voices are not real,
but they have some really good ideas.
elminero67
Posts: 143
Joined: 11 years ago

Re: sd22 in a 1948 Willys Truck.

#173

Post by elminero67 »

Unlike the Nissan FS5W71b transmission, the transfer cases are pretty much bombproof. I had a friend that had a stroked and built 383 with a NP435 and dual Nissan cases and 37" tires. He drove it like he stole it, was breaking axles, motor mounts and u-joints, but the little Nissan cases held up.
Interesting that the 720 4x4s are scarce in Canada, they are common here in the US-I've had several and have never paid more than $100 for one. In fact all of these 720 parts can be had cheap in the states as early 80s 4x4s are plentiful. If you keep an eye out in the North Dakota craigslist, one should pop up. The one caution I have is that the divorced cases exert a lot of force-you really need to weld up a strong set of mounts.
You can also get the real short Nissan transmission to transfer case driveshaft in 1981-1984ish, and it will slide in most Nissan transmissions, making that part of a 2wd to 4wd conversion easy.
I will eventually be using a late 1980s d21 attached transmission transfer case combo with the 720 divorced case. This will give me 15 forward gears and a low range around 90 to 1. A little excessive, but I do like having the ability to run a rough trail now and then, and being able to drive without touching the clutch is important. I had a 1982 720 4x4 and liked it, except the lack of low gears and those horrible Z-motor carburetors that made it worse by idling at 1500rpm.
ehtrain
Posts: 141
Joined: 9 years ago
Location: regina, sk

Re: sd22 in a 1948 Willys Truck.

#174

Post by ehtrain »

VERY INTERESTING!!!

I will have to source one of those gear boxes. That is EXACTLY what I was looking for. a direct over under, I don't even care if 4h isn't 1:1. Finding a front diff might be abit of an added challenge but good to know. as far as I was aware the tx-10 thats matted to the 4cyl and 6cyl 4x4 d21 was a pretty tough t-case. People run them behind the 300zx twin turbo swapped 4x4's, I havn't searched the t-case extensively, but h233b rear axle will handle 40+ inch tires bone stock. I would hope the t-case is up to the job.... mind you it is chain drive.

are these gear drive?

also yes the 720 is pretty rare around here. I've only ever seen a couple 4x4s, most are 2wd. same with the 610... i might have seen 1 outside a junk yard. the white 720 pickup i cut that sd25 from had no floor pan on drivers side and box floor is pretty much gone. it's flinstone's mobile hahaha

up here nissan/datsun/toyota/suzuki are known as "water soluble " lmao
elminero67
Posts: 143
Joined: 11 years ago

Re: sd22 in a 1948 Willys Truck.

#175

Post by elminero67 »

Yep-gear driven. 1:1 high range and something like 2.26 to one low. The only downside I can say is that they do add a noticeable amount of drag.

Here is one in the Portland Craigslist for $100: http://portland.craigslist.org/clk/pts/4446593650.html
elminero67
Posts: 143
Joined: 11 years ago

Re: sd22 in a 1948 Willys Truck.

#176

Post by elminero67 »

I realized that I haven't done any updates on this many, many months.

But there is nothing to report, mechanically!

In the last couple of years I've put thousands of miles on the setup, and it has proven to be as reliable and maintenance-free as I had hoped. This includes a 1500 mile trip on backroads and trails (as little pavement as possible) across Oregon and Nevada on the old Applegate trail:

Image

I'm still planning on swapping in 4cylinder 86+ tranny and transfer case at some point. The turbo is on the backburner because it has enough power to cruise the highway at 60ish, which is probably a little faster than a 1948 Willys was designed to go...
waynosworld
Posts: 525
Joined: 8 years ago
Location: Vancouver Washington USA

Re: sd22 in a 1948 Willys Truck.

#177

Post by waynosworld »

Well it's good to hear from you again.
So you have it going again I hope, you learned a lot I bet.
I know the voices are not real,
but they have some really good ideas.
plenzen
Posts: 869
Joined: 13 years ago
Location: Cochrane Alberta Canada

Re: sd22 in a 1948 Willys Truck.

#178

Post by plenzen »

Thanks for checking in.

Would like to see some of the photos of your "rural route" journey .
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
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