NP440/MY6 Swap Info

Discussion in 'Transmission & Driveline Topics' started by K1ng0011, Jun 23, 2017.

  1. K1ng0011

    K1ng0011 Veteran Member

    Mar 22, 2014
    United States
    *Will upload pictures later*

    There is a lot of info here. I have completed my swap of a NP440 into my 1972 Camaro. When I got it it had an automatic turbo 400 transmission in it.
    I wanted to have overdrive for a nice crusing car for road trips to states with speed limits 70-80mph and daily driving. I also wanted to have a manual transmission in my car. Since I have learned to drive a manual I realized how fun they are to drive. Unfortunatley all of the manual transmissions with an OD gear are either expensive or weak. All of the chevy 4 speeds 4th gear is 1.00 and the first gear is usually low like 2.50 or 2.20.
    Most people solve the lower first gear in the transmission issue by putting a higer geared rear end like a 3.73 into the car which costs more and also makes it so the 4th gear has high RPM on the highway. I decided to do the opisite. I found a transmission with a high first gear to make up for my 2.73 rear end. With the TH400 it was nice on the highway but it was slow on the takeoff.
    When I was looking for transmission candidates to swap in I found out about the little known NP440 or MY6 transmission. This is a 4 speed transmission. This has a 3.09 first gear and 4th gear is .73. This is the best of both worlds for what I was looking for.
    The problem with this transmission is that it is rare. Not a lot of people even know it exists. It is hard to come by. Especially one that is complete. I got lucky and found a older gentlemen who had rebuild manual transmissions for the last twenty years who was retiring and selling his remaining stock. He had a brand new rebuilt 2WD NP440 that I got a deal on because no one knows what they are and he could not sell it.
    I bought another 4WD NP440 for spare parts and the bellhousing. The NP440 is basically the Chrysler A833 OD of the transmission that chevy used from about 1980-87 in trucks and vans. Chevy just used custom, input shaft, output shaft, bell housing, main case, shifter/rods. The gears inside the transmission are the same as the A833 which is my understaning. The NP440 has almost the exact same gearing as the 700R4. When I bought the transmission I got to see a side by side of a muncie vs the NP440.
    The muncie is quite a bit smaller than the NP440 in the main case area. It does fit our cars but barely. Before I ever bought the NP440 I made sure I understood the affect of changing gear ratios. I have put a link to a website with a Windows program below for calculating gear ratios. It was within 200rpm of being acurrate when I got the transmission installed so I was pretty happy about that. At about 80mph in 4th gear I am at about 2200RPM.

    My Tire Size: 225/70 x R14
    Rear End Gear: 2.73 Open
    TH400 Gear Ratios: 1st 2.48, 2nd 1.48, 3rd 1.00
    NP440 Gears Ratios: 1st 3.09, 2nd 1.67, 3rd 1.00, 4th .73, Reverse 3.00
    700R4 Gear Ratios: 1st 3.06, 2nd 1.62, 3rd 1.00, 4th .70, Reverse 2.29
    Overall First Gear w/TH400: 6.77
    Overall First Gear Ratio w/NP440: 8.43
    Bearing Retainer Collar Size: 1.375 in
    Input Shaft Splines: 10
    Input Shaft Diameter: 1 1/8 in
    Output Shaft Splines 2WD: 27
    Output Shaft Splines 4WD: 32
    Shifter/Shift Plate: Used 4WD Shift Plate/shifter (Cut and Bent Shifter Rod)
    NP440 Neutral Position: 1st/2nd * | * 3rd/OD * | * Reverse * \ *
    Flywheel/Clutch Size: 11 inch/168 tooth
    Inspection Plate: generic Chevy one that I cut and drilled holes to fit
    Starter: standard automatic diagnol bolt pattern 168 tooth starter
    Drive Shaft Length: Stock Th350 Length
    Fluid: Dextron/Mec 2
    Gear Calculator:

    Installation Problems
    * Hydraulic Throughout Bearing - The Bearing is to close to clutch fingers. You have to grind down the front bearing retainer where the hydrualic throught bearing sits to provide proper 1/8 in clearence.
    * Shifter - Have to cut the shifter short and bend it with a touch to get it to fit right. Its a truck shifter so its way too tall.
    * Clutch Hoses Hydraulic Throughout Bearing - You will need two 45 degree fittings off of the throughout bearing to get the hoses out the clutch fork hole. Otherwise the hoses will be pointing at the bell housing and you wont get them through the clutch fork hole.
    * Installation - This transmission is heavy even all aluminum. I had to put the bellhousing under the car first. Balance the transmission on the jack and roll it under. Once under I put on the hydraulic throughout bearing and bolted the main case to the bell housing. After that I started to jack it up. The jack handle was in the tunnel where the drive shaft was. I jacked it up and bolted it in place being really careful. Do not try and feed the hoses through the clutch fork hole after the trasmission is installed and bolted up. It wont work ask me how I know.
    * Shift Rods - After buying two of these NP440s I had several shift rods. I used a MAP gas torch to heat the rods and bend them. This took a LOT of test fitting to get it right. One of the most time consuming things of this whole swap.

    Part List
    Hydraulic Throughout Bearing: $199 RAM 78125HD

    168 Tooth Flywheel: $105 Pioneer IO-FW100

    11 In. Clutch, Pressure Plate, Pilot Bearing: $115 Zoom MU5505-1

    Hydraulic Clutch Conversion Kit: $275 McLeod 1434005

    Manual Pedal Set: $72 Auto Metal Direct W-328

    NP440 Transmission: $800

    Factory Th350/4 Speed Crossmember 70-74: $100

    * 2WD Truck - Will mount to factory TH350/4 speed Crossmember
    * 2WD Van - Will mount to 1970-74 Factory Th400 Crossmember
    * 4WD - Output shaft is 32 spline. Has to mount to 208 transfer case. Have to change entire main shaft to use 2wd tailshaft on this.
    * Note: 2WD Tailshafts same except transmission mount location

    Main Cases
    * Aluminum: Came on 2wd NP440
    * Cast Iron: Came on 4wd NP440
    * Crysler/Chevy Hybrid Bolt Pattern: REQUIRES a special bell housing with a hybrid chevy/crysler 4 speed bolt pattern
    * Chevy Bellhousing Bolt Pattern: Has standard chevy bolt pattern but the front bearing retainer is larger so a stock 621 chevy 4 speed bellhousing will need to be modified. Or get the correct NP440 bellhousing.
    * Note: Main cases are Swappable

    * Hybrid - Will mount the hybrid chrysler/chevy style main cases
    * Standard - Has the standard chevy 4 speed mounting pattern for the main case but the bearing retainer is larger.
    * Hybrid/Standard - Drilled for both the hybrid and standard chevy 4 speed main case bolting pattern. This is the best all NP440 main cases will bolt to this bellhousing.
    * Note: Can come as Hyraulic Slave or as manually operated clutch forks

    Shift Plate
    * 2WD Shift Plate - The plate places the shifter to far forward for our cars it would probably hit our dash if you tried to install this shifter/plate. You do not want this one.
    * 4WD Shift Plate - This puts the shifter in the area around where the factory 4 speed would be. The plate needs to be ground down a little bit to clear the speedometer hump on 2WD tailshafts.

    * 4WD Small Shifter Body - Fits well has different shift gates than the large body.
    * 4WD Large Shifter Body - May work have not tested but the clearence will be close to the trans tunnel if it does.
    * Note: Both shift rods will need to be shortend and bent they are WAY too tall. These were ment to be in trucks. Stock 4 speed console will not work without a 90 degree bend like the stock shift rods.

    Transmission Shifter Arms
    * 1st/2nd Gear: has to be pointed UP
    * 3rd/OD Gear: Has to be pointed down
    * Reverse: Arm can be pointed up or down. Will make reverse be up or down when shifting into it. Mine is to the left and down. My arm is pointing down.
  2. K1ng0011

    K1ng0011 Veteran Member

    Mar 22, 2014
    United States
    Lots of helpful pictures if someone other than me ever does this swap.

    2wd vs 4wd shifter mounting plate np440.jpg
    4WD Shift Plate on Left. 2WD Shift Plate on Right. (You want the 4WD plate)

    Hybrid Main Case Bolt Pattern on Left. Normal Chevy 4 speed bolt pattern on right.

    2WD 27 Spline tail-shaft on Left. 4WD 32 Spline tail-shaft on right.
    Bell housing drilled for standard Chevy 4 speed bolt pattern and the Chevy/Chrysler hybrid. Not all bell housings for the NP440 are drilled for both. (mine was)
    Floor cut out for shifter. 4wd shifter and plate.
    Not pretty but shifter fits under factor 4 speed hump. I bolted it down to make it easier to get to the shifter.
    Factory NP440 hurst shifter and dakota digital speedometer sensor. No the reverse rod does not touch the sensor even though it looks like it. np440 c10 and van tailshaft.jpg
    2WD Tailshafts only differences is where the rubber transmission mount is located and where it bolts to the cross member. One on the left will fit a TH350 cross member. One on the right will fit a TH400 1970-74 cross member.
    Small 4WD shifter on left. Large 4WD shifter on right both factory hurst shifters.
  3. black_aerocoupe

    black_aerocoupe Veteran Member

  4. spooge031

    spooge031 New Member

    Jul 16, 2017
    I just did the same swap but in a firebird, ran into the same issues and solved some by using heim joints and 3/8 rod to make shift rods i did have to custom bend up the reverse one though but the 1-2 and 3-4 are straight linkage is TIGHT, i found a used hurst shifter on ebay and rebuilt it and installed the correct offset lever for the "F" body, i also had a shift mount from summit that was a bit short so i "extended" it and made a new one from 1/4" plate that way it came out right around the factory hole, the big issue was with the bellhousing i'm running a pontiac engine so i needed a BOP housing, i opened the center bore and redrilled 1 ear and the housing (filled with aluminum weld) to allow the "mopar" half to mate properly, i used a spacer from speedway motors to get some space and hydraulic TOB from speedway as well i still don't gave the gab BUT the instructions said properly set up there should be no gap on their bearing we shall see ;-P, but overall it was an EASY swap the shift lever i will use might be from a 1st gen camaro/firebird it looks to have a better bend found all the specs on hurst's website, now i just have to fill with juice and get the old gal runnin again
    2017-07-09 19.03.10.jpg
    Last edited: Aug 18, 2017
  5. GAA

    GAA New Member

    Aug 18, 2017
    Thanks for this post. I have a 4x4 version of this transmission and would like to put it into a 2wd. Would a 33 spline yoke work with a 2wd housing and not need to change main shaft?
  6. GAA

    GAA New Member

    Aug 18, 2017
    32 spline... sorry
  7. K1ng0011

    K1ng0011 Veteran Member

    Mar 22, 2014
    United States
    The 4wd version of this transmission comes with a 32 spline output shaft like the TH400 transmission. The 2wd transmissions come with a 27 spline output shaft like the TH350. You cannot use a 2wd tail housing on a 4wd transmission without changing the whole output shaft on the transmission. They are different lengths. This kind of makes it more difficult to piece together one of these. I will say though now that I have been driving it around a few months I got to say that I like this transmission. Using it with my eaton true trac and 2.73 rear end works about perfect. 80mph in 4th at around 2200 rpm on the highway is nice. Glad someone is using the info on this thread though. Also I think the main case/bellhousing spacer that spooge031 suggested along with an extended pilot bearing is a good idea. Probably a lot easier than than what I did with grinding down the main throwout bearing seat on the bearing retainer.
  8. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    Now that you have it on the road, how does it drive with those super wide ratios between gears? In the trucks, that tranny seemed very wide between gears which is OK in a truck, but probably not as nice in a performance car.
    It should be great on the highway with the overdrive gear.
  9. K1ng0011

    K1ng0011 Veteran Member

    Mar 22, 2014
    United States
    I make it to about 20MPH then shift into second I shift at about 2500 ish rpm or so. Unless I am doing some spirited driving then I will shift at about 4500 rpm or so. There is an RPM drop from 1st to second but it does not really bother me that much. Keep in mind I have a 2.73 out back. If I had a 3.73 or something like that I would probably be shifting much earlier and I think first would be useless. I think a 3.08 is the highest I would go personally. If you were running your car on a track or want all out performance I can see how the RPM drop could be an issue but for normal street driving it works for me. Basically I use 1st-3rd gear up until around 60MPH. At about 60MPH I am cruising at about 2200RPM plenty of get up and go to pass someone since I my power probably drops at around 5000 rpm or so. 4th gear is strictly for cursing down the highway at about 80MPH I am at about 2200RPM again. Perfect for interstate cruising at 75+MPH. Below I have posted some example rear end end gears along with the first gears in some of the muncies and the NP440. So you can get an idea of an overall first gear ratio of a NP440 vs the mucnies and what you would need to do to get a similar setup without overdrive. From what I have read 8.5-9.5 or so seems to be what people recommend for a street cars. I dont think a lot of people think about the gear ratios in the transmission and the role that they can play in getting your car set up for what your going to use it for, street, drag, etc. Also you can see below manuals can come with a variety of gear ratios so selecting the right rear end for your transmission is pretty important. That is one of the reasons I went with this particular transmission is it suits what I am using it for.

    NP440 w/2.73: 3.09x2.73 = 8.4
    NP440 w/3.08: 3.09x3.08 = 9.5
    NP440 w/3.73: 3.09x3.73 = 11.5

    M22 w/3.73: 2.20x3.73 = 8.2
    M22 w/4.33: 2.20x4.33 = 9.00

    M20 w/3.42: 2.56x3.42 = 8.7
    M20 w/3.73: 2.56x3.73 = 9.5

    NP440 Gears Ratios: 1st 3.09, 2nd 1.67, 3rd 1.00, 4th .73, Reverse 3.00

    1963 - 1965 M20 None 2.56 / 1.91 / 1.48 / 1.00 2.64
    1966 - 1975 M20 Two 2.52 / 1.88 / 1.46 / 1.00 2.59
    1964 - 1975 M21 One 2.20 / 1.64 / 1.28 / 1.00 2.26
    1967 - 1972(2) M22 None 2.20 / 1.64 / 1.28 / 1.00 2.26

    Saginaw 4-speed 1st 2nd 3rd 4th
    No lines 2.84 2.01 1.35 1.00
    1 Line 2.54 1.80 1.44 1.00
    2 Lines 3.11 2.20 1.47 1.00
    3 Lines 3.50 2.47 1.65 1.00

    Borg-Warner Super T-10 P-code 2.43 1.76 1.47 1.00
    Borg-Warner Super T-10 S-code 2.43 1.61 1.23 1.00
    Borg-Warner Super T-10 U-code 3.44 2.28 1.46 1.00
    Borg-Warner Super T-10 V-code 2.23 1.77 1.35 1.00
    Borg-Warner Super T-10 W-code 2.64 1.75 1.34 1.00
    Borg-Warner Super T-10 X-code 2.64 1.61 1.23 1.00
    Borg-Warner Super T-10 Y-code 2.88 1.74 1.33 1.00
    Borg-Warner Super T-10 Z-code 3.42 2.28 1.46 1.00
    Borg-Warner Super T-10 AA-code 3.29 1.72 1.00 1.00
    Borg-Warner Super T10 BB-code 4.17 2.28 1.46 1.00
    Borg-Warner Super T-10 CC-code 2.88 1.91 1.33 1.00

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