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Thread: Turbo 350/NP208 to SM465/NP205 Swap

  1. #1
    Arctic Blaze Knows their $hit whitels1's Avatar
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    Turbo 350/NP208 to SM465/NP205 Swap

    I've been working on this for a while, If you guys think I missed anything or have any questions let me know. I'm also going to work on another how to for a NP205 rebuild.

    Before I forget everything about the swap I might as well keep it fresh. With fluids etc I spent around 2k on the whole swap. I used a manual clutch bellhousing, manual clutch pedal assy, with a Howe hydraulic throwout bearing to eliminate the need for linkage. I have been driving it off and on for over a month and love way it drives since the swap. I've towed travel trailers, gone wheeling, and 100 mile trips on the highway at 65.

    Truck Specs which may be relevant before the swap
    81 K5
    Quadrajet equipped 350
    TH350/NP208
    3" body lift
    3.73 gears.

    Here is what I spent and where I got the parts needed for my swap.
    $225 trans / bell housing / pedals / transfer case - Craigslist
    $210 seals / gaskets for the 205 and the SM465 - CarQuest
    $65 NP 205 input shaft bearing. - CarQuest
    $250 trans to t-case adapter - Offroad designs
    $81 trans to t-case 10 spline sleeve - Offroad Designs
    $20 Stock 205 shifter - Local trans shop (Mine was missing)
    $220 11-7/8 Clutch & Flywheel - CarQuest
    $55 Howe throwout bearing remote bleeder kit 8287 - Summitracing
    $149 Howe hydraulic throwout bearing 82870 - Summitracing
    $84 Tilton 7/8in universal master cylinder 875U - Summitracing
    $510 Drivelines Adam's Driveshaft (Local driveline shop)

    Parts needed to pull off my swap
    When I did have to contact the parts store for the clutch, flywheel, gaskets etc, I called Car Quest and told them it was for a 74 K20.

    SM465 with - short 10 spline output shaft.



    NP205 with - figure 8 bolt pattern and 10 spline input shaft.



    SM465 - NP205 10 spline adapter and 10 spline coupler / sleeve.





    SM456 & NP205 gasket assy's ( The important gaskets are the ones for the adapter and they may be available separately)

    Manual clutch bell housing.



    Manual Clutch pedal assy.



    11-7/8 Clutch & Flywheel (Ordered as a stock clutch & flywheel for a 74 K20)



    Howe hydraulic throwout bearing
    Tilton Clutch Master cylinder
    Hydraulic line from Master to Bearing (Included in the Howe bleeder kit)
    New rear driveline, shortened front driveline
    Shfter fork hole boot, to keep debris out.

    Transmission Inspection

    Now that all that's out of the way, I took the top and covers off the SM465 for inspection and gasket replacement, cleaned the magnet and checked for any problems.

    *To remove the top shift half way to reverse, then tilt the top back while lifting*

    This is what you will see with the top cover off, make sure no gears are missing any teeth or chipped and that the synchros look ok. I'm no trans expert but you should visibly see any major problems in the gear box.




    The magnet is easily accessed with the side covers off and will most likely look like this.





    It will be common for your low(granny) gear and reverse to look like this





    Next I removed the input shaft cone and replaced the input shaft seal inside.









    Don't forget to replace the gasket on the cover directly below the input shaft cone, use silicone on both sides of the gasket and around the fasteners.



    Next clean the surface areas, install new gaskets and reinstall all covers.

    Before you start this swap, I would recommend you have access to an engine hoist to make it easier to remove the door and lower the trans through the inside of the cab, for ease and safety.

    Let's start the swap


    • Initial prep work
      Chock the wheels
      Disconnect the negative battery terminal
      Remove the driver door and seat if your ambitious remove the passenger door and seat to make things easier
      Remove the NP208 shifter assy and disconnect the linkage
      Remove the carpet and anything keeping you from accessing the hump cover
      Remove the hump cover
      Remove the steering wheel if you didn't take off the pass seat and door
      Drain the transmission and transfer case
      Unbolt and remove the front and rear driveline
      Remove the speedo cable
      Unhook the vacuum lines / any wiring from the transmission or transfer case
      Disconnect the TV cable from the carb/throttle body
      Remove the trans dipstick tube
      Disconnect the transmission cooler lines
      Remove the rod connecting the transfer case to the bellhousing


    ---At this point there should be nothing attached to the transmission or transfer case except the engine and crossmember---

    • Removing the Trans / Transfer case
      Remove the flex plate cover
      Remove the 3 bolts connecting the torque converter to the flex plate
      Remove the bolts holding the transmission to the engine
      --At this point the only thing holding your trans and transfer case is the cross member--
      Take your engine hoist and put it through the passenger side, use a couple of ratchet straps around the trans / transfer case to even out the load and keep them level during the descent.
      As carefully as possible without getting under the trans / transfer case remove the 4 bolts holding the cross member to the frame the weight of the assy should be supported by the engine hoist.
      Gently lower the assy down preferably on something that rolls, in my case I used my shop creeper protected by a towel
      Remove the trans cooler lines and cooler if equiped
      Plug the vacuum line that was disconnected
      If you wish you can remove the TC lock up controller, located next to the brake booster


    • Removing the auto pedal assy
      Outside
      Disconnect the steering linkage rag joint
      Loosen the Two bolts on the outside of the firewall where the steering column comes through
      Remove the 4 lower brake booster bolts
      Inside
      Remove the automatic shift lever by removing the roll pin
      Remove any lower dash covers
      Remove the complete cluster bezel
      Disconnect the booster linkage from the brake pedal
      Disconnect the brake switch and the torque converter lock up switch if needed
      Remove the 6 bolts holding the steering column to the firewall
      Remove the two nuts under the dash holding the steering column / pedal assy up (The steering column will fall)
      Gently remove the pedal assy


    • Preparing the manual pedal assy
      I'm going to talk about my set up.
      This step by far took the longest to complete, I had to pull the pedals in and out several times, so no beer till after!
      My truck originally came with cruise ctrl and the hole in the firewall for it was aligned just about perfect with the pedal assy and almost the same size I needed for the master.
      I wallowed out the hole in the firewall to fit the master, the master is positioned sideways due to the way the firewall was stamped, I then drilled the mounting holes and got it secured.





      Drilled out the spring hanger on the clutch pedal and removed it, I tried to use that hole but it was not lining up correctly.
      I drilled another hole down and behind that hole for my master linkage.





      The threads on my master linage are (5/16 - 24) I needed a coupler, some all thread and a rod end heim joint with stud.
      Installed a pedal stop with a small piece of angle iron attached to the pedal and a some all thread coming through the top of the pedal assy.
      I marked on the linkage to show the maximum throw and then set my home made pedal stop to be just before that point.


    • Re-securing the steering column and Installing the manual clutch pedal assy
      Disconnect the 3 wires from the neutral safety switch located at the bottom of the steering column.
      The large wires need to be wired in a manner that your ignition signal gets to the starter (Clutch pedal switch, etc).
      The small wire is for your b/u lights and will connect to one of the terminals on the b/u switch on the SM465, with a 12v accessory wire connected to the other terminal.
      Reconnect the new pedal assy and steering column the same way they were disconnected.
      Connect clutch master linkage.
      Connect the brake booster linkage, brake switch bracket and brake switch.
      Clean up and check any wiring that may have been damaged or bumped while swapping the pedal assys.





      Reinstall any removed dash bezel parts.


    Clutch, throw out & transmission install
    • If you haven't already remove the flex plate.
      Install the supplied pilot bearing / bushing from your clutch kit.
      Install your flywheel with new fasteners & thread locker, torque to 60 ft-lbs and clean clutch mating surface with brake clean.



      Insert the clutch alignment tool through the clutch disc and into the pilot bearing to hold it in place.
      Prepare you pressure plate for installation, by cleaning the clutch mating surface with brake clean.
      Align the pressure plate, with new fasteners and thread locker torque all bolts to 35 ft-lbs, remove the alignment tool.



      Install your bell housing.



      Install the howe throw out bearing alignment pin into the front of the transmission.
      Measure the bearing clearance for shimming, shim as needed, mine did not require any shims.
      Set your transmission on a transmission jack and get ready for install. Alternatively get your transmission ready and positioned under the truck, attach to your cherry picker to lift into place.
      Route the bleeder / master hydraulic lines through the clutch fork hole in the bell housing, connect to your throw out bearing and have it in the proper position.
      Insert the transmission onto the throw out bearing, through the clutch and into the pilot bearing.
      Secure the transmission to the bell housing.


    Master cylinder set up
    • Install the reservoir onto the clutch master cylinder. (I would suggest finding a suitable location for a remote reservoir, or possibly shimming out the master to clear the wiper motor, I opted to remove my wiper motor as it never rains here and it's not my daily driver)
      Connect your hydraulic line coming from the throw out bearing. (The line that came with the howe remote bleeder kit did not mount directly up to my Tilton masters AN-3 line adapter, I had to get some fitting from my local hardware store )
      Fill your reservoir.
      Bleed the master cylinder and slave.
      Check the ops of your throw out / master while turning the transmission from inside the cab.


    Transfer case install
    • With a floor jack / transmission jack support your transmission.
      Replace the oil seal in your trans / transfer case adapter.
      Using the proper gasket, install the transfer case adapter with thread locker and 10 spline sleeve.





      Fasten the cross member to the adapter and jack into place, mark the frame and drill your holes.
      Fasten the cross member to the frame.
      Using your transmission jack install the transfer case and secure all fasteners with thread locker.



      Install your front and rear drive shaft.
      Reconnect your speedo cable.
      Attach your transfer case shifter to the adapter and connect all linkage.


    Finishing up
    • Mark and cut the hump cover for your shifters. Not shown in the photo I also had to modify the cover for my transfer case shifter, but I'm not using the stock linkage so yours may differ. I also opted to run my reverse light wires through the hump cover





      Install the shift boots and your hump cover.



      Fill the transmission and transfer case with gear oil. (Roughly 7 quarts for both)



      Reinstall your carpet, seats, doors etc.
      Recheck everything again.
      Hook up your battery and fire her up for the first time.
      Double check everything again and go out and break it!
    Last edited by whitels1; 10-27-2011 at 01:30 PM.

    | R.I.P Arctic Blaze |

    | 84 K10 | 5.3/SM465/NP205 | 10 bolt / 14 bolt SF | 2-1/2 suspension | 35" BFG M/T |

  2. #2
    awesome!!! thanks im looking to do mine this weekend so this will deffinetly help. what weight gear oil did you use?

  3. #3
    Arctic Blaze Knows their $hit whitels1's Avatar
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    Quote Originally Posted by slacker67 View Post
    awesome!!! thanks im looking to do mine this weekend so this will deffinetly help. what weight gear oil did you use?
    75w - 90w

    | R.I.P Arctic Blaze |

    | 84 K10 | 5.3/SM465/NP205 | 10 bolt / 14 bolt SF | 2-1/2 suspension | 35" BFG M/T |

  4. #4
    (Brent) Senior member NightKrwlr's Avatar
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    very good write up
    When the clutch drops... the bullsh*t stops

    Current:
    2005 EC/LB 2500HD Duramax- 4" fabtech lift, 5" flo pro, EFI live, EGR block, PCV reroute, LBZ turbo mouthpiece, future mods-suncoast stage 5 trans

    Past:
    1988 K5 the Night Krawler
    1990 K5
    1976 Jimmy, 7" susp 3" body, 40" ground hawgs
    1995 2500, SFA HPD44, 14bff, 350/nv4500/np241

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