Considering swapping to Sm465

[Benelli]

I currently have a 1979 Chevy K10, (Stats in sig)

And, well I'm considering swapping it to a 4 speed. I already have the Sm465 and Np208 in my garage. I was wondering about drivelines, and to the guys that have done it before how challenging and how long it took them?

Did you notice an increase in fuel mileage? Any difference in power? Are there any build threads I can look at?

thanks

[GmtGmt]

manual transmission will always get better milage then slush boxes

[bmchevy1979]

Talk to DirtyLarry over in the 4x4 section he did the swap he might be able to give you a few pointers on it he is now swapping in a nv4500

[Benelli]

actually, mods could you please move this to 4x4 section? I think they would be a little more knowledgable.

Thanks for the suggestion Bmchevy

[76stepsidechevy]

I always prefer a manual and I have a 465 in my truck and honestly its like driving a dump truck. Im on the look out for something with overdrive.

[gchemist]

If had to drive a manual, NV4500 is the way to go! Pricey but worth it.

[Zoomad75]

As for actually using the truck off road, the 465 is more flexible for it than an auto slushbox. Granny gear is worth it's weight in gold for descending downhill without using the brakes. Granny gear shines when crawling it up stuff too.

Downfall to the 465 is as others have said it's like shifting a dump truck. Lack of overdrive kills highway mileage. While in general terms manual trannies get better mileage than auto's, if you are driving a squarebody 4x4 you are counting MPG's in single digits with a small or big block. The difference between the two in this case is small and they both suck.

I helped DirtyLarry with the swap from auto to 465 way back when in Detroit. I remember freezing my tail off performing the swap in a open carport with nothing more than 2 floor jacks. Driveline lengths will change. Swapping itself is straight forward, but to do it right you need more than the trans and t-case. You need all the clutch/bellhousing parts, clutch linkage & mounts, clutch and brake pedal assembly, floor turtle shell and if you really want it to look factory, a manual trans steering column.

Larry was smart as he had a complete 4speed truck to pull all the parts from, swap his auto stuff back over to and then sell the truck that donated the 4speed parts. Plus we could see exactly where it all went. He did a lot of prep work before we actually installed the trans, actually putting in the trans and t-case took a weekend. Getting the trans into position was quite funny. Larry lifted the trans with a floor jack as my huge by wide ass was standing inside the cab lifting up at the shifter. Getting the 205 case into position was just as comical. We had it balanced on 2 floor jacks with chunks of wood and we were using our legs on the jacks to lift as we both guided it into it's mounting place. By the time he finished the swap it looked factory. (you might have noticed that in his projects as a theme).

I wouldn't go off road without a manual trans. It's a personal preference but no auto can match the creepability coming down a steep mountain pass shelf road.

[bmchevy1979]

Actually I am planning on this swap as well I have a complete parts truck I am getting ready to buy it has a sm465 and 3/4ton axles so that gives me a chance to upgrade

[tucsonjwt]

So far, I have owned 350/350 auto, 454/400 auto, and 454/SM465 granny old squares. All were C20 3/4 ton long bed trucks. Of all of these combos, the 454/400 was the best performing and best gas mileage (I drove that truck for 18 years until excessive rust made it too dangerous to drive.)
A 3/4 ton truck kills gas mileage because of the extra 1000 lbs. you are hauling around empty, but a built up engine 1/2 ton and 4 WD also hurt gas mileage.
No matter what combo you have on an old square, I don't think you can expect much better than 10-12 mpg city, with a couple more mpg highway.
My current 454/SM465 gets 10 city/13 highway with a gear vendor added to the drive train (mileage can drop to 8-9 city when hauling a full load in my dump box and a lot of idling.) The gear vendor is only good for about 2 mpg improvement in mileage, maybe more if you are on a long highway trip and use cruise control.
You will not be speed shifting a granny 4 speed, and as was previously mentioned, it shifts like a dump truck - which is good for me since I have a dump conversion box If you off road your 4WD, then I am told the granny 4spd is the way to go.
Bottom line, the TH400 is the best daily driving transmission for an old square, in my opinion, unless you upgrade to more modern transmissions and a whole modern engine/drivetrain - then you might as well buy a modern truck.

[Benelli]

I only get 8 or 9 highway in my square.

I guess I was hoping for a little bigger numbers, lol. I'm not sure I'll still attempt it, for a while but I think I'll still give it thought. I wonder if it'll give any better power to the ground than the slush-box. I tow some things around that are fairly heavy.

At where this point, I might just try and find a nice square already with the manual, that has a good body and just drop in the engine. The body on mine is a little rusty.

Thanks guys.

[dubb492]

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[ironroad9c1]

I love my 465. It makes the truck feel like a real truck, Not one of these new wanna be cars with a bed on the back. A real truck is supose to ride like a pogo stick, and be a workout to drive.

[Shyguy]

Yep, I like the feel of a real truck myself. My '71 has the 465 and my '67 has the 420. I really enjoy driving them both because of the engine set up in each. The '71 has 454 and the '67 has a 250 L6.

[spudz]

I have a sm465 in my 79 1ton behind a 454. Its tough, and strong...... BUT dont expect to speed shift. If you have to find a gear quick your out of luck.

[csb#356]

Go with the 4 speed for sure. You'll have to have the front shaft shortened and the rear lengthened. but and driveline shop should do both for around $150. You'll definately get more power to the wheels. And you'll like it offroad to.

[Benelli]

Would my highway RPM's drop any? 3.40 gears, if someone knows a good gear calc give me the link please.

[csb#356]

If your turbo 350 has a lockup converter your highway rpms will go UP with the 465 because both transmissions have the same 1:1 ratio in third gear and the lockup converter in the automatic would bring the revs down about 500 rpms

[Benelli]

Thanks. I don't believe it has a lock up, runs about 2500 or so at 65.

[MTCK]

Actually, without a lockup TC now you will see slightly lower rpm's with a manual. If you did have a lockup they would be the same. The non lockup allows the crank to spin slightly faster than the input shaft on the trans... Lockup acts the same as a clutch that is all the way out. I've had TH350, TH400, 700R4 and an SM465 now. If you are looking for mileage that 97 chev in your signature looks like the ticket. SM465 is tough as nails, shifts like crap and has huge ratio changes between gears - definitely gives the classic 'truck' feel when driving. If you want a lower first gear and an overdrive with lockup, I'd look at a 700r4.

[Benelli]

I just already had the tranny and I was jsut wondering about it - I have had a lack of projects all winter and I've been looking for something to work on.

My 97 gets great mileage, but it's not a v8.

Thanks everyone for your help again.

[mustardjimmy71]

mtck hit it on the head. 700r4 or 200r4 with lock up. Huge aftermarket support. 700r4 has a low 1st gear but is longer than t350 so you will need to get your drive shaft cut down. 200r4 is the same length as t350 im not sure about the gears or if they were ever used in 4wd aplications and still plenty strong. they came in 80s regals mote's cutlas and malibu, even grand nationals. more common than u might think

[propanemudtruck]

It really sounds like you've got your mind made up, but one thing I haven't seen mentioned is if you had two comparable transmissions (gear ratios per gear) the torque converter would create more "power" torque off the line because of it's design. Think of two fans, one is powered by the engine and the other is transmitting power through the tranny. That's basically a TC but the design allows the trans fluid to spin the driven faster than the engine if conditions are right and you would see more torque at the wheels. Granted the 465 has the granny gear, I bet that outweighs the TC design and you'll be able to pull your neighbor's house down!

[Masstowingllc]

I am selling a mint sm465 4 wheel drive came out of a low mileage garaged 1972 k5 blazer it's in mint condition.. Only reason I am selling it is I need a 2 wheel drive sm465 same style so I would trade for a 2 wd mint condition sm465 plus some money on top
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