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3-speed trans supposed to whine?

Discussion in '40- & 55-Series Tech' started by rusmannx, Jun 1, 2003.

  1. rusmannx

    rusmannx

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    i was told that all 40 trans whine, but my buddie's 4-speed is so quite...

    could it need a bearing rebuild kit, or do all 3's just whine?
     
  2. CruisinGA

    CruisinGA

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    Mine whines pretty bad, but its a combo of rear diff and tranny. Its wearing out. Rebuild would probably help, I'm swappin in a 4spd. Theres not a 3 spd out there thats less than 30 years old, most have at least 100k on them.
     
  3. rusmannx

    rusmannx

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    can 4-speed mate to existing t-case? 72 40
     
  4. CruisinGA

    CruisinGA

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    change input shaft on tcase I believe... different spline count.
    I should be in there checking out the same thing sometime soon, will let ya know.
     
  5. Pin_Head

    Pin_Head

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    If it whines in 3rd gear, it is most likely the transfer case. The idler shaft and its bearings tend to wear.
     
  6. rusmannx

    rusmannx

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    i've already had the t-case rebuilt so i'm sure it's not that.

    it sounds like it's coming from the trans, and it only loud at high speeds.

    are there such things as quite 3's? i thought it could be the gears if the bearings aren't shot. i just don't want to pull and rebuild it to find out all 3speeds are loud.
     
  7. Chef

    Chef

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    The three speed transfer will work on a four speed with an adaptive gear and bearing. The four speed output shaft is fatter(new bearing required) and 16 spline instead of 10(thus the new gear). A 47-67 gm sm420 four speed will bolt to the three speed bellhouse...a spaceghost plate adapter gets your transfer onto the 420, classic cruiser or wardens make nosecone adapters for you throwout and pilot bearing. Either way is a nice upgrade. Stock toyota three speed: 2.5 to 1 first. Toyota 4 speed: 3.5 to 1 first. Toyota h41 four speed: 4.9 to 1 first...sm420: 7 to 1 first...
     
  8. IDave

    IDave

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    Speaking of throwout bearings, how often do you guys see these cause a whine? I seem to have a similar high-pitched rub/whine after rebuilding both tranny and transfer case. Comes and goes with putting the clutch out and in, and changes with engine speed. Also, seems to be affected by hitting bumps in the road.
     
  9. mcfj40

    mcfj40

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    I have the same problem on my 73. I only notice it in 3rd gear over 45mph. I have only been able to get up to 60mph, because the noise gets too loud. I am probably going to pull my tranny out in a few weeks and take a look at everything and see what is going on. Let me know if you find out something before I do, and I will do the same for you.

    Thanks :eek:
     
  10. 72cruiser

    72cruiser

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    yeah, i hear ya on the whinin.

    my 3 spd just started to do it about 500 miles ago (i put 1000 on her in the last 2 wks. wow.)

    it only happens to me above 40 in 2nd and anywhere from 65 to 75 in 3rd. it's not constant, but it is real annoying.

    have y'all noticed that the radiator fan comes on right before it starts to whine? maybe it's just been conincidence for me. no idea if anything correlates between the two.

    i thought it might have something to do with the clutch, but i don't know. pushin in the clutch or lettin off the gas for a while makes it stop for me.

    oh well. a lot of information, and as usual, no help.

    jonathan
     
  11. rusmannx

    rusmannx

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    maybe it's time for the 420. so the trans bolts right to the engine, but a conversion plate is required to bolt on the t-case?

    is that a 4-speed? i don't know anything about this transmission.
     
  12. CruisinGA

    CruisinGA

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    Go to tech, read all the writeups there. Heres the quick n dirty:
    SM420-GM 4 spd 1/2 to 2 1/2 ton trucks/vans. '47 to '67. Later years are better because they don't spray oil on the clutch at steep descents. The big plus is the 7.05 : 1 first gear, first gear is not syncronized, and will in all but extenuating circumstances not used on road, think of it as a toy 3 spd with a syncroed first gear and a granny gear only for crawling. So its road manners are marginally better than the 3 spd because of the syncroed first.
    Requires toy 3spd bellhousing to bolt to either F or 2F
    (SO far only part of conversion I'm not clear on is the clutch setup)
    Adapter used to bolt to transfer. Simplest, most inexpensive and hence best is probably SG's plate adapter. &nbsp:Doesn't necessarily need driveshaft length change-I'm not sure on this and it doesn't matter for me cause I need new/retubed shafts anyway cause the front is dented bad.
    Thats the basic info. I was orignally planning on a toy 4 spd conversion, but then heard about this one, realized its not much more difficult, almost cheaper, and gets a first gear thats twice as low. I could throw 3.70's in the diffs and have a solid 75 mph highway speed and still have a better granny than I have now, with the ability to run as large of tires as I could want too with a 4" lift. Its a beautiful transmission perfectly suited to my needs.
    Now you need to decide if its the one for you.
     
  13. rusmannx

    rusmannx

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    how much would any of you extimate the cost of doing the 420 conv? including all adapting stuff and the actual trans... assuming i do the entire thing myself.
     
  14. KMAN

    KMAN

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    I used to run a SM420 with 3 speed case and I always though the ancient tranny was making the noise. I swapped the 3 speed for a split case and 90% of the whine is gone, mostly v8 and tire noise now.
     
  15. MarkFJ40

    MarkFJ40

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    My truck sounds like 30 screaming babies at 60mph.
    I had a 3-speed and stock case and now I have a SM420. Still howls. I am pretty sure all 3-spd t-cases do.
     
  16. CruisinGA

    CruisinGA

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    $125 for SG adapter
    ~$100 for tranny itself
    $130 for rebuild kit (seals, bearings, 3rd 4th syncros)
    Set aside another oh lets say $100 for misc. parts, hardware and tools.
    Oh yeah either buy an AA twin stick T-case shifter (what I will do) or build your own. (not an option for me cause I can't weld)
     
  17. rusmannx

    rusmannx

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    why do i need this?
     
  18. CruisinGA

    CruisinGA

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    Because the SM420 w/ adapter is a different length than the stock setup, so your transfer case shift linkage will no longer work. The AA one is length adjustable, making it the easy choice for us welder-less cruiserheads.
     
  19. rusmannx

    rusmannx

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    when are you going to put yours in? are you going to make a write up for the rest of us?

    i'm in the process of hunting down a 420. i've got a friend with more spare engines and transmissions sitting around then he knows what to do with. i'm hoping he can get one for me. he's also connected with everyone motorhead in the county, so hopefully things will work out.
     
  20. CruisinGA

    CruisinGA

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    I am starting to collect parts now.  Hopefully meeting SG in Tellico later this month to buy the adapter in person, and making calls to junkyards to see if they have any '60 to '67 GM 1/2 to 2.5 ton trucks sittin around. :G
    As soon as I get the tranny I will rebuild it, and then make sure I have all the parts, then take out the seats, gas tank, gas tank cover, and tranny hump and tow it out to a friends 8,000 sq ft shop, where I will spend a day actually bolting the tranny in and all.  ETC is end of July.
    I might do another writeup, I don't really see a point considering how complete Pin_Head's is. Normally when I start on a project I'm in too big a hurry and focusing too hard on the project to take time to take pictures and such. :dunno: