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th350 to sm465

Discussion in 'The Garage' started by 74poj, Jan 27, 2006.

  1. 74poj

    74poj Registered Member

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    so my buddy eric (72 sac) and i went to the junkyard today and found a 79 k20 burb. pulled the 10b and 14bff for install on my 74poj. well, the k20 also had a sm465 and np205. the 74poj, aka piece of junk, runs a rebuilt turbo 350 with less than 100 miles and a 203. after almost 2 years of ownership the poj is gonna be a daily driver within the next 2 weeks, got a new block with all the goodies on the way. current dd for the last 5 years is a straight stock 95 pk with heavy duty 5 speed, so i'm used to the shifting. and i love the creeper gear. i've wheeled plenty with a clutch in jeeps i used to own, so i know what i'd be getting into in that aspect. so here's the questions. how bullet proof are the 465/205? neither one seemed to shift great in the k20 on blocks, they did lock into gear though. think there might have been something missing in the linkage, clutch pedal stayed on the floor when pushed. i've read the article in the tech forum on the 350/465 swap. so, who's done it? how hard is it? what pitfalls should we look for? we're shade tree mechanics, one decent-me, one very good-eric. if they turn out to be junk can two shade tree mechanics rebuild them? junkyard wants $75 for the 205, $85 for the 465, and i've got a buyer lined up for the rebuilt 350. the're complete from the bellhousing to the shifters. i want the 4 speed bad, but not sure if it's worth the trouble.
     
  2. u2slow

    u2slow 1/2 ton status

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    Not hard to rebuild the 465. You do need a press though. I helped somebody with one once. I didn't know what I was doing, and he knew less than I did. :haha:

    Most of these old trans and tcases work fine. Clean them up, maybe a seal or two. The only bearing I might do - without a complete rebuild - is the input bearing on the trans.

    I will be putting a 456/np205 combo in my 2wd auto Suburban. It's just a matter of when :rolleyes:
     
  3. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    I did the exact swap on my rig quite a few years ago.. You'll need the clutch pedal assembly from the 465 truck. Ya have to remove the steering column to bolt it in. You'll need the z-bar and all the linkage from the burb. You'll need to either fab a bracket to bolt to the frame for the z-bar to mount too, or figure out a way to get the bracket off the frame on that burb and bolt it to your frame. You'll have to cut a hole in the floor for the clutch rod to go through. You'll need a longer rear drive shaft and a shorter front. You'll need the clutch, flywheel and return springs of course.

    If you're fairly proficent and have all the tools you need, it can be done in a long weekend. If not, figure on two+ weekends. It's pretty straight forward, just time consuming.:wink1:
     
  4. goldwing2000

    goldwing2000 Guest

    Another option is finding a newer truck with a hydraulic clutch or making one with Wilwood cylinders (or similar). That manual linkage is a pain in the ass.
     
  5. noahrob

    noahrob 1/2 ton status Author

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    I just finished converting from a TH400/205 to a SM465/205 and actually went out and tested it out for the first time today (real test, not jsut driving to the store and back). I would be happy to tell you exactly what I did, what pats I needed etc...just PM me.

    For the record, I am stoked and am so glad I did the swap!
     
  6. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I just did a 2wd TH400 -> SM465/205 swap

    Took me an afternoon to get everything but the floor hump stuff sorted out. My cab was a low hump 2wd cab, which basically meant it didn't have the hump for the transfercase under the seat, nor did it have an unboltable hump to install the high hump.

    I've got everything good to go, cept I'll need to drop my t-case to replace the shift rails / fluid, and find a cab hump for my truck.

    I used a hydro clutch, and the interior was mostly gutted already, all of which definitely helped to make things go quicker!

    After I get her running properly, and everything is working properly -- Then in my typical fashion I'll have to tear her apart again for an NV4500 swap :P
     
  7. K5-newf

    K5-newf 1/2 ton status

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    id go for it and im sure a local tranny shop would charge to much to rebuild it. good luck


    Jason


    "Keep on truckin"
     
  8. koldsimer

    koldsimer 1/2 ton status GMOTM Winner

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    sounds like a good deal on the combo... I say go for it! I did the swap a year ago and have loved every minute of it. I went hydro clutch so the hardest part for me was getting the pedals in and building the proper bracket so the master cylinder had a good straight push on it. As fas as the question of durability, i dont think a 465/205 combo can be beat for toughness in a light truck. The weakest link in it is the 10 spline coupler and that thing doesn't look too easy to break!
     
  9. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I'd be surprised if the 465 really did need a rebuild...

    Chances are it needs new shift forks, shifter o-rings, and shifter retaining roll pins, lol

    And as far as it being tough to get into gears while the truck is not running -- All of them do that. My freshly rebuilt one does. You gotta remember that the gears are not syncronized when the transmission isn't being spun, so you are basically forcing the shift collar to mesh. Now, if two teeth from both the shift collar and the gear are back to back, there is no way you'll get into that gear.

    Try putting the transmission into several different gears before trying to put it into one that won't go in. I find that I usually need to pop mine into second gear before it'll go into reverse or low.
     

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