NP440 4-Speed Transmission

[R3VO 3VOM]

I did a forum search on this transmission and got no results so I thought I'd document the swap and comment on driving impressions.

 

The transmission in question is a New Process 440, or NP440. Its an overdrive 4 speed derived from the Mopar version called the A833. The A833 in early years was similar to a Muncie 4-speed in terms of functionality (external shift, bellhousing pattern, etc.) maintaining a 1:1 final drive. However, in later years it became an overdrive 4-speed with the final drive reduced to .73:1. The 440 was a GM version of the A833 with GM 10 spline input and 27 spline output shafts. It came in all manual '81-'86 GM trucks. To my current knowledge, all came with factory Hurst shifters. They came in two bellhousing bolt patterns. The first (early years; '81~'83) being the traditional GM manual style like a Muncie/T5; bellhousings from the Muncie/T5 will swap with a little modification. The second however is unique to the NP440; these are the later model versions (pictured below). If you are looking at one of these make sure you get the bellhousing!

 

What's interesting to note is that the traditional 4th gear spot inside the transmission is still a 1:1 ratio, but third gear spot is the .73:1 listed final drive. What NP did is swap the third gear ratio and make old third gear fourth gear and old fourth gear third gear. Make sense? This was done via switching the shift linkages on the outside of the transmission to change the order of the shifts.

 

Being a truck transmission the ratios aren't quite ideal for a car, with first gear being a steep 3.09:1. However, they are nearly the exact same ratios as a 700R4 of comparable years. I've read the only annoying part of these ratios is the first to second shift is a huge drop. 

 

I picked mine up last Friday for $400 complete with everything. Bellhousing, Hurst shifter, clutch, flywheel, pressure plate, linkages, lower cover plate and shift fork. My reason for buying being I want to go back to manual. T5's are very expensive (in my area) in the GM pattern and the Ford ones aren't much better. They are cheap when the syncros are worn out. T56's are way out of my budget. Muncie/Borg Warner 4-speeds don't gain me anything as my car currently has a TH350 with the 1:1 final drive. The NP440 with its .73:1 final drive will drop my cruising RPM, according to my calculations based on stock R200 gearing and tire size, approximately 1000rpm which should increase my gas mileage, among other things, tremendously. 

 

Currently have the Wilwood master cylinder and new slave cylinder on order. Will update once I get it all installed.

Edited July 20, 2015 by R3VO 3VOM

[Michael]

That sounds like a promising swap!  I've long been asserting that for a high-torque engine in a lightweight car, the last thing that we need is a transmission with a large number of gears.  A 4-speed with large drop between each successive ratio would be ideal.  Are the gear ratios 3.09, 1.67, 1.00 and .73 ?  Is it a cast-iron case, or aluminum?  Weight?  Any guesses on torque-capacity?

 

Currently I'm running a Doug Nash 5-speed, where 5th gear is actually 1:1.  It's the exact antithesis of what I've been advocating about wide-ratio vs. close-ratio.  But I wonder... could 4th gear be replaced with overdrive, retaining 5th gear as 1:1?

[R3VO 3VOM]

Are the gear ratios 3.09, 1.67, 1.00 and .73 ?  Is it a cast-iron case, or aluminum?  Weight?  Any guesses on torque-capacity?

Yes, those are the correct ratios.

The early Mopar units had a cast iron case. This was later switched to aluminum sometime in the 70's. All the ones made for GM trucks are this later aluminum case.

I don't have a weight figure as of now. I can tell you it's wayyy lighter than the TH350 that's in the car now! I'll weigh it and report back once I get it ready to put up in the car.

Torque capacity..... Well the A833 version was put factory behind the 426 Hemi if that's any indication of internal strength (Now, this was with an 18 spline input shaft as opposed to GM's 10 spline). But it's been proven in the muscle car world above 600ftlb in stock form. They do make stronger internals for the A833 which can be popped in the case of the NP440 (as they are basically the same transmission). 

 

Currently I'm running a Doug Nash 5-speed, where 5th gear is actually 1:1.  It's the exact antithesis of what I've been advocating about wide-ratio vs. close-ratio.  But I wonder... could 4th gear be replaced with overdrive, retaining 5th gear as 1:1?

This I could not say as I'm no transmission expert. But in theory however it is doable. That's exactly what New Process did with the late A833/NP440. Swapped out third with a new ratio, swapped the shift levers on the outside between third and fourth and bam, new transmission. 

 

I can't stand a 1:1 final drive. Spinning 3k rpm down the highway isn't my idea of a good time. Maybe for a drag car but for a street car that see's the track sometimes it sucks. 

Edited July 24, 2015 by R3VO 3VOM

[R3VO 3VOM]

Just ordered all the parts to install the NP440 into my Z. They should be in this Friday.

 

After much debate I decided to go with a hydraulic clutch release bearing as the stock bellhousing does not have a provision for mounting a hydraulic slave cylinder. Stock Chevy vehicles used a Z-bar mechanical linkage for clutch actuation.

 

It seems there are fixes out there and custom made brackets on internet forums to do so. But with all the fabrication work I'm doing on my "project" Z, school and work, the last thing I want to do is fabricate something else. Novak does make a conversion kit for Chevy bellhousings but its $208.00. With careful shopping I managed to get all my parts, new, for $190 (including a remote bleeder assembly for the throw out bearing as I have 0 clue how you're supposed to bleed those things otherwise!). Not a huge savings but anything helps.

 

Transmission is assembled but some of the linkages are out of adjustment so I will need to look into those. Also will need to have a ring cut for the bellhousing. It seems I have a mismatch of equipment with my setup. The front retainer is a smaller diameter than the bellhousing mating hole. The larger hole indicates it's a truck housing as it should be. But the small retainer points to someone swapping it along the way with a car one. 

[R3VO 3VOM]

One part down a few more to go. This is the item you need if you plan to run a truck bellhousing with a car transmission (the NP440 isn't a car transmission but mine has the car bearing carrier which I suspect has been swapped before me). Why would you want to run a truck bellhousing? It easily allows you to run the 11" clutch (versus the 10.4") without the costly 621 bellhousing. Although it's now being remanufactured, it's around $250. A truck belhousing can be had for cheap (free to $50) and this ring at $30 and you have yourself an 11" clutch bellhousing for cheap.

[Mike Mileski]

R3VO 3VOM, did you know that Chevy made a truck bellhousing with an external slave cylinder mount? (see attached picture) If you were interested in going this route, here is a complete listing of everything needed, including the choke ring, which I believe you already have.

 

bellhousing       15530202

slave cyl.           15615868

T.O. bearing     15613306

fork                   15592270

pivot ball           15592268

flywheel cover   15521936

fork boot            15590132

 

McLeod choke ring    673-8701-4

 

 

Mike Mileski

Tucson, AZ

[R3VO 3VOM]

R3VO 3VOM, did you know that Chevy made a truck bellhousing with an external slave cylinder mount? 

 

bellhousing       15530202

 

Mike Mileski

Tucson, AZ

Mike, I saw pictures of those bellhousings when I was doing my research. I never could find the part number though.

Only issue I have is the cheapest one recently sold that I found was $220 plus shipping. More than I paid for my entire kit including larger bore master cylinder. Even more than the Novak conversion kit. Only way it would pay would be finding one local for cheap. And finding one local, I couldn't even imagine trying to (it took me almost a year to find an NP440 that wasn't the 4WD variation and complete).

 

I'm also interested to know if the huge extension on the side of the housing for the slave cylinder would clear the S30 transmission tunnel. My tunnel has been "clearanced" with a hammer. But I fear there wouldn't be the room under the car for that bellhousing. Another reason I went the route I did.

[Mike Mileski]

I'm pretty sure that bellhousing came in 1985 - 1991 Chevy and GMC manual transmission trucks, so there's lots of them out there.

 

Mike Mileski

Tucson, AZ

[R3VO 3VOM]

Got the transmission fully assembled tonight. Had to mod the adapter ring ever so slightly to clear the heads of the bolts on the front bearing retainer.

Adjusted all the shift levers as I got it in pieces. Bellhousing was off as well as the shifter and linkages.

 

After adjusting them and making sure that all the gears work, I have to say this is one of the coolest shifters I've messed with. Its spring loaded to be over at 3-4 spot. 1-2 is an easy pull to the left. So quick 1-2 then when you go to 3-4 the spring helps pop it over as you make the quick change. Very cool.

Reverse is a spring loaded lock out so you really have to pull left to get it to go into reverse. I guess to keep you from going into reverse by mistake.

 

Here it is. This is my first side loader transmission so I find it very cool to see all the shift mechanisms external to the case.

 

Edit: Realized afterwards that the 3-4 shift linkage is installed upside down. I put it on like a muncie. However we must remember what's posted in the original post. 3-4 is flip flopped and the shift linkage switched. So the shift pattern according to position inside the case is technically 1-2-4-3. So I had to flip the front lever arm 180.

Edited September 4, 2015 by R3VO 3VOM

[R3VO 3VOM]

Well did some measurements tonight and found why so few people run muncie style transmissions. The overall length of the transmission is around 2-3 inches shorter than a T5. This means that the shifter is 2-3 inches forward from where the T5 shifter is and thus no longer through the factory shifter hole. To solve this issue I made a new shifter bracket out of some steel I had laying around and moved the shifter back 3 inches to accommodate for the shorter length. Now I just need to lengthen the shift rods and it will be back to working condition. (Yes I know there is not a 3rd bolt in the bracket. Just put two in there to make sure reverse still worked. 3rd will be put in upon final mounting)

 

Edited September 7, 2015 by R3VO 3VOM

[Michael]

Unfortunately I missed the bellhousing discussions!  The point was to suggest the Lakewood blowproof bellhousing, which presumably fits the NP440, as it also fits my Doug Nash 5-speed. 

 

About the shorter length from bellhousing case to shifter....  For an externally-shifted transmission this can be adjusted, but it's it going to be challenging to weld-in linkage-extensions, and to adjust the linkages?  Would it have been easier to cut the shifter hole in the Datsun transmission tunnel?  In my case, the firewall is set back, so even with the shorter transmission, the shifter pokes out well aft of the stock location in the transmission tunnel.  It was also necessary to widen the tunnel on the driver's side, to accommodate the shift-linkages.

 

Between the gear-ratio spacing, the compact size, the torque capacity and the smoothing shifting, this sounds like an incredibly appealing and overlooked option for the higher-torque V8 swaps!  Make this thread a FAQ???

[R3VO 3VOM]

About the shorter length from bellhousing case to shifter....  For an externally-shifted transmission this can be adjusted, but it's it going to be challenging to weld-in linkage-extensions, and to adjust the linkages?  Would it have been easier to cut the shifter hole in the Datsun transmission tunnel?  In my case, the firewall is set back, so even with the shorter transmission, the shifter pokes out well aft of the stock location in the transmission tunnel.  It was also necessary to widen the tunnel on the driver's side, to accommodate the shift-linkages.

I really dont want to cut another hole if I don't have to. I'd like it to come up through the factory hole. I don't want to do what roadkill did fitting their NV3500 S10 trans and hack up the dash and heater controls.

I took a rough measurement with the engine and trans bolted up and it's looking like it will come up perfectly through the factory hole. Only issue will be drivers side clearance for the shift box and the 3-4 linkage. How did you widen the tunnel? Was it necessary to cut and make a box patch or could you massage it out with a hammer? It's looking like it will be very very close.

 

But to accommodate for the moved shifter mechanism I just extended the shift linkages using the stock rods and welded in extensions. All shifts as smoothly as before I cut them. I was even able to tuck the 3-4 rod closer to the trans ever so slightly. But what I found upon further investigation is my shifter isn't the factory Hurst shifter that came with these transmissions but rather a Hurst Competition Plus unit. The levers have been modified once which is why they didn't sit close to the trans. So I fixed that when I lengthened them.

Edited September 21, 2015 by R3VO 3VOM

[R3VO 3VOM]

WELL I took today and got the transmission in. It's tight but I didn't have to cut any of the tunnel. After catching the car on fire once I really am hesitant to welding on anything close to the interior. I did have to smack one spot for the shifter box but otherwise there is plenty of space. It's a lot more narrow than the TH350 that came out of the car. I did have to modify one shift linkage to tuck it closer to the transmission (remember, mine have been modified once before me and again when I lengthened them for my new shift bracket) but otherwise the linkages cleared the transmission tunnel and even cleared the TH350 JTR crossmember.

Here is the transmission in the car.

 

Clearance on the side of the transmission tunnel between the shifter box and the shift linkages. The stock mounts have already been removed per the JTR manual.

 

Interior picture. Shifter comes up almost center of the factory hole. 3 inches back and once inch down seems to be a good spot; although another 1/2 inch back wouldn't hurt. It should be noted that my car is a factory auto car so it has an extra plate welded in for the auto shifter. You can see outlined in black sharpie the factory manual shifter opening. As of the time of the picture I hadn't removed the factory auto shift plate making it as wide as the factory manual opening.

 

Here is the clutch master I am running per the hydraulic throw out bearing recommendations. Didn't have to slot any of the holes. Bolted right on. Nice fit.

 

Now just waiting on the driveshaft to be shortened and I'll be ready to fill it with fluid and drive. Hopefully it doesn't have any issues. I really don't want to pull it back out again. 

 

[R3VO 3VOM]

Well the transmission is in. I can't say that it was an easy road to travel but I finished it. Made the first drive yesterday. Few small kinks to work out but none of them are with the transmission. 

 

I changed to a traditional clutch fork and external slave cylinder setup because even after calling the manufacture I still could not get all of the air to bleed out of the hydraulic throw out bearing. It wouldn't move to release the clutch. And after reading a lot of reviews on all various brands of hydraulic throw out bearing I decided that if it didn't work I would be going with a traditional external slave; all of them seem to leak after a set amount of time and it's an amount of time that is way less than the unit should last. Got the point it didn't work so I went that route. The main issue here was that the bellhousing I was using is either for a truck or C3 corvette (couldn't find definitive answers either way). So I had to notch the firewall for clearance. Wasn't anything difficult; the most difficult part was building the box to enclose the notch and not catching the car on fire welding the box in.

 

After driving it I will say overdrive is awesome. Cruising at 2000 rpm isn't the best but I'll take it over the 3300 I was spinning before. The clutch is the heaviest single plate I have ever driven. But that isn't "transmission" related. The trans shifts very smooth. I will say however that, even though the ratios are the exact same as a 700r4, 1st is basically useless. I never realized how fast the auto would shift out of first but you shift at more or less 5mph because you're winding out first gear. 

 

So in the end, I would personally do the swap again. These cars, in my opinion, need to be manual. Auto is nice but as I don't drive this car everyday I want to enjoy the experience. And the picked up mpg and drop in cruising rpm is really nice.

 

What to take away from this thread? I would NOT recommend this swap if you have little fab skills. It's a good amount of work. The shifter bracket must be custom made and the shift arms extended and tucked close to the transmission. If you must attempt this swap I highly recommend the C4 corvette 4+3 bellhousing like JTR recommends for the T5 swap. It has the fork coming out around lower than my bellhousing and the slave cylinder is tucked very close. All this allows you to not have to notch your firewall like I did. The other camaro T5 housing that puts the trans at a 15 degree angle I would not recommend because then you'll have to make a custom shifter and may run into issues with the shifter box hitting the transmission tunnel; especially if you have a 240Z with the narrower tunnel. 

 

[R3VO 3VOM]

Bit of an update. Transmission drives awesome. Love being able to shift gears. The Hurst shifter is amazing. The .73 overdrive is great cruising down the highway. Dropped the engine RPM a lot. Not as good as the .64 T5 ratio but I'll take it over the 1:1. I've said it before and I will say it again: first gear is basically useless. I start in second half the time because it's not even worth being in first and shifting to second within 3 feet of starting off.

 

It did develop a slight leak out of the 1-2 shift shaft after a few drives so pulled the car back in and pulled the cover to fix it. You can pull the cover off the transmission leaving it in the car which is nice. I can't tell if the reverse shaft is leaking as well, as the fluid from the 1-2 may have run down and gotten on the reverse. I'm thinking of changing it but in order to do it properly you have to disassemble the entire transmission which is something I'd rather not do. So I may try to get creative. It will come out the front of the case but removing the o-ring retainer might be a bit of a challenger without messing it up.

I'm trying to source some new o-ring retainers so I can attempt to pull the one for the reverse shaft out of the front. However these transmissions aren't exactly common so it's proving to be "fun". I may just machine some out of aluminum or something to get a better fit. The stock retainers seem to be a plastic of some sort. Maybe machine down some new delrin plastic. Would make my life easy if I could just find some though. Nobody seems to sell them when they sell used covers so people must be getting them from somewhere.

 

 

On a side note: If you're ever looking to do this swap and need to know what fluid it takes. 80W-90 or 75W-90 or 80W (cold climate) gear oil. I was worried I had the wrong stuff in it because reading internet forums some people said ATF while others said 10W-40 motor oil or other weight motor oil. No. The factory Chevy service manual for the trucks this transmission came from recommend those above weights of gear oil. So I'm going with what the factory manual says versus internet forums. That is, once I get it reassembled. 

 

[floydschultz4@gmail.com]

Ive been looking for this set up for my nova,if you find another complete set up can you let me know?The fluid is atf.

[Krenshaw]

So much uninformed speculation on this post it boggles my brain, fist right out of the gate, this was not the “ only” manual truck transmission installed in 80s GM trucks in fact it is kinda rare, the most common manual in 80s GM trucks was the muncie sm 465

 with the granny low, 4 wd versions of the np440 were all cast iron cases , despite similar with the A833 used in the monster hemi motors of the mopar days the 80s version is rated below the 300 lb/ft range I didn’t see what rear gear ratio poster was running but with a 3.09/1 1st gear ratio getting to 15-20 mph before shifting has been my experience with this stick shifted slush box” slay slush box as this transmission indeed came from the factory with ATF as the fluid