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SM vs. CH -465

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by R72K5, Jan 1, 2003.

  1. R72K5

    R72K5 Banned

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    howcome ppl call the 465 an SM when GM Corp lists them as CH ?
    the only 4 speed that was SM model was the 420 last in 67, then was the 68-72 CH465, i cant say for sure what GM called the 465 in 73-up, havent checked on that yet, i cant find any difference in GM specs sheets listings from 4x2 to 4x4 regarding the 465, all GM listings describe them as the chevrolet CH465

    the three speeds were different though, they are SM318 unsynchronized base model through 69

    then after that the SM326 fully synchronized was in all models and also was the SM330 for the 4x4 trucks


    thanks
     
  2. TX Mudder

    TX Mudder 1/2 ton status

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    I dunno.
    Some manuals call it the Sm, some call it the CH, and some just call it the 117 MM.
    I don't think there is any difference, just like some people call the 14bolt a 10.5" and some call it a Corporate 14 bolt. Both are right and I've seen it called both in manuals.
    -- Mike
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't have my '82 parts manual handy to look, but what the heck would CH stand for?

    SM makes sense, Saginaw-Muncie, and I'm 99% sure the 465 was made by Muncie. It may have been a merger of the two companies later on or something if the CH is referenced early by GM, since the "muscle" car 4 speeds were known simply as "muncie's" from all I've ever heard, while the Saginaw was always called just that, and was always the lesser strength 4 speed. Perhaps CH was simply Chevrolet, but that wouldn't make a whole lot of sense to go from Chevrolet to Muncie later on, unless of course GM contracted out to Muncie to make the 465 for them after a few years.

    FWIW, Muncie is now part of New Venture Gear, which of course is indicated by the "NV" trannies and transfercases now. (Believe New Process was another swallowed up by the formation of New venture gear)

    Couldn't find anything online to help out in the CH/SM465 department though!
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    You're correct, NP was swallowed by New Venture.

    Never heard of a CH 465, only an SM 465.
     
  5. R72K5

    R72K5 Banned

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    thats what chevy was calling them though, check out the specs sheets from GM in at least the 68-72 years and see its CH

    and then find older than 68 specs sheets and look up the 420 and see that its SM

    i cant remember how they are listed in the GM truck service manuals, ill have to look in the 71 one and see

    i would assume CH is Chevrolet

    and why would three speed SM models made by saginaw be SM ? all the 70-up iron case trannies with the 7 bolt side covers were saginaw not muncie.


    http://www.dtcomponents.com/gmchdt.htm

    http://www.federal-mogul.com/bca/engine_bearings_xfer_and_man_tran_kit.html

    http://www.drivetrain.com/transmanuallisting.html
     
  6. tarussell

    tarussell 1/2 ton status

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    The "465" is definetely made by Muncie.
    To the best of my knowledge this is the reason for the two prefix's for the 465 tranny's.
    The 1968 through 1979 ( or around that year ) the tranny was refered to as a SM465. It is known as the first edition.
    The second edition is refered to as the CH465 and also as the 117mm design. The 117mm is the distance between the mainshaft center line and the counter shaft center line. There is also a difference in some of the bearings for this model .
    If you go to a tranny parts house they will always ( or should ) ask for 1rst or 2nd design .
    Either which one they are both refered to by GM as option code "M20".
    The SM465 & CH465 are the same animal with some small differences in the bearing dept.
    Anyway that is why the manuals state SM and CH ; it all depends on what year it is.
    HTH ,Tom
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, to throw another wrench in the works, why are there two different rebuild kits shown only for 68-87 and 88-91?

    http://www.drivetrain.com/muncieSM465.html

    Don't take this wrong, this is not intended as a flame, because for all I know, that web page could be wrong. Perhaps what they list is the year split you are thinking of? *I* don't have a 1987 and 1988 parts manual to compare part numbers with, so I can't know for sure. I've got an 85/86 manual, if anyone wants to volunteer to compare their '88+ part numbers with me, I'll be more than happy to try and sort it out.

    Fairly certain the rebuild section in my '82 service manual references it as a 117MM 4 speed.

    I'm beginning to doubt that SM even means Saginaw-Muncie, I don't see anything linking those two companies together. As a matter of fact, it appears Saginaw is now part of Delphi.

    Perhaps SM means synchro-mesh? SM and CH obviously got started somewhere, but I can't find out where. The 420 is also prefixed with the SM from all I see, and that application was like 1947-69. According to the original post, CH is 100% for sure the GM designation of the early 465's, so if that is the case, I doubt they went CH, then to SM, then back to CH, although its entirely possible. I'll try to remember to look in my '82 service manual transmission section to see if it says SM or CH anywhere, but I believe they are all referenced in MM's.
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Who cares what it's called? We love the strength, hate that it pops out of 3rd gear, and love the granny for its crawling abilities...oh yeah, and hate that split between 3rd and 4th.

    But we still love our 4 speed!
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    I dunno, who really cares what "010" and "020" denote on the SBC's?

    It's probably a pet peeve of his, and if nothing else, has taught me a few more things about GM and their suppliers!

    I for one, am 100% for using the correct terminology. You'd probably correct someone that referred to your truck as a C10, no?
     
  10. imiceman44

    imiceman44 1 ton status

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    Don't quote me on this but I believe that SM nomination came from SYNCHRONIZED MODEL 465.
    CH465 was internal in GM.
    SO the SM nomination is more like a nickname description if you want.
    From the research fourwheeler did a couple of years ago, Muncie was the manufacturer of the 465 IIRC.
    I will try and dig up some old issues and get some more info on the matter.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    That makes more sense than anything we've heard/seen/made up yet /forums/images/graemlins/smile.gif

    SM could very easily have been Muncie's name for it, (since it went to Ford, Dodge, and GM) and GM just called it something else, probably consistent with their part naming policies at the time. Anyone happen to know if any other GM trannies also had the "CH" at the time?

    It is amazing how hard it is to prove/disprove this sort of thing isn't it? Makes it even more difficult as GM used M20 as the RPO for the 465 (at least in the late 70's-up) while M20 was the Muncie wide-ratio car 4 speed in the 60's(and early 70s?).
     
  12. tarussell

    tarussell 1/2 ton status

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    I agree that that seems to be the best explination. I guess we may never really know the rime or reason to the prefix's but Muncie using SM and GM using CH seems very logical.
    It's discussions like this that bring out more ( hopefully correct ) info .
    Either way , I think that we all agree that (once the third gear snap ring is replaced w/ a solid spacer) they are a FINE tranny and will last for years and years.

    On the Muncie car tranny's , I thought the wide ratio 4-speed was the RPO code M21 and M22 was the rock-crusher.
    I may very well be wrong but I thought the M20 was the truck "465" only ???
     
  13. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    I can't add much to this thread, but it makes great reading. Anyway, I have only seen the muscle car 4-speeds refered to as M21 or M22. IIRC the M21 was the wide ratio and the M22 was the close ratio "rockcrusher"
     
  14. BCB2

    BCB2 Registered Member

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    010 and 020- Block has 10% Tin and 20% nickel content.
    010 or 020 - Block has 10% or 20% nickel content.
    no numbers- negligible amounts of either alloy.
    010/020 Blocks are best from a material standpoint, but this doesn't make them best because they may not have the thickest cylinder walls. As far as the original topic, I have heard the SM to be Standard Manual as well as variations mentioned above, but dont have a clear answer on that.
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    010 and 020- Block has 10% Tin and 20% nickel content.
    010 or 020 - Block has 10% or 20% nickel content.
    no numbers- negligible amounts of either alloy.
    010/020 Blocks are best from a material standpoint, but this doesn't make them best because they may not have the thickest cylinder walls.

    [/ QUOTE ]

    Show me either metallurgical test results of these blocks, or actual GM data that proves this.

    Doesn't exist so far as anyones come up with, and so far its just a theory thats been propagated at race tracks in books, and here on the internet, with no basis in fact as far as I'm concerned.

    I'm serious about proving this myth/theory one way or another, but not nearly enough people have sent me block samples to have tested, which I *will* have done if people are interested and can get me small pieces of engine blocks.

    But, I digress. Off the subject of this post, anyone that likes can PM me directly on this. Don't mean to sound confrontational, but I can't stand hearing that over and over again, when its all hearsay.
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    Just had to drag this back up. Actually, I just remembered to look in the manual.

    Per my 1982 GM service manual, it *is* a CH465! Listed as "117mm" transmission, but at the front of the chapter, in only one place, where all three of the manual transmissions available are discussed, "CH465" is mentioned.

    "The 117mm, Model CH 465 truck transmission uses a constant mesh first gear that engages with the second speed synchronizer sleeve..." (pg 7B-2)

    Now I just gotta remember to call it that /forums/images/graemlins/smile.gif
     

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