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Thread: Need some help ID'ing Transmission

  1. #1
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    Need some help ID'ing Transmission

    Hey, so I am sure these questions pop up all the time, but please bear with me. I have been searching for a while, and can't come up with a conclusive answer.

    Here is the trans. I don't know which year/model E21 it came out of. The bellhousing looks identical to an E30 G260 I have laying around. The dimensions are actually about the same also. Is it a 5 spd. out of a 323i? The only significant numbers I can find are on the tail (pictured)

    Just need a solid answer on what it is, and what it might be worth.

    Thank you very much,

    Steven












  2. #2
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    that's a 240, used in the e30 m42

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  4. #4
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    The 260 is a common swap for M42 guys, it has the same bolt pattern but it's slightly longer than the 240. And if you check the part number stamped on the 260, the first three will be 260.

    edit: i did a little more searching and it looks like the 240 was also used on the E21 and the E30 M10. It was a one year deal for the E21 in 1983. I can't tell if the old 240 is identical to the M42 240.

    edit again: If it's the E21 transmission it will have a mechanical speedo drive. If not, it's from an E30. If the M42 240 is the same transmission that would make the E21 tranny the perfect swap for an M42 E21!
    Last edited by bflan2001; 01-19-2012 at 03:42 AM.

  5. #5
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    I am not talking about the G260, I just had it in the picture for comparison. The G260 sitting there (the clean one) came out of a '91 325i that I personally removed. I am trying to decipher the other trans (greasy one) as it came to me in a large batch of un-marked parts.

    The numbers on the rear read "240.0.0266.90"

  6. #6
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    I was saying if you look at the 260, the first three numbers will be '260', just like on the 240 the first three are '240'. The page below has some info on the different models, though they don't list the M42 as using the 240, I'm sure it does (I just don't know if it's the same bell housing).

    http://www.metricmechanic.com/catalo...tion-chart.php

  7. #7
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    Quote Originally Posted by bflan2001 View Post
    The 260 is a common swap for M42 guys, it has the same bolt pattern but it's slightly longer than the 240. And if you check the part number stamped on the 260, the first three will be 260.

    edit: i did a little more searching and it looks like the 240 was also used on the E21 and the E30 M10. It was a one year deal for the E21 in 1983. I can't tell if the old 240 is identical to the M42 240.

    edit again: If it's the E21 transmission it will have a mechanical speedo drive. If not, it's from an E30. If the M42 240 is the same transmission that would make the E21 tranny the perfect swap for an M42 E21!

    This is why I have been having trouble figuring it out. What does the mechanical speedo drive look like? And where is it located? Thanks for helping me figure this out.

  8. #8
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    It would just be a hole and a small set screw on the rear section of the transmission. Something for a cable to plug into. I don't see one in the pictures. I think the best way to tell is to verify whether or not the bell housing bolt patterns are the same. If it's the same pattern as the 260, then it's from an M42. If it's different, it's for an M10.

    If it turns out there is a mechanical speedo drive on it, that would make it either from an E21 M20 (if the bell housing pattern matches the 260), or from an E21 M10.

  9. #9
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    it's a G240 from a 83 E21. it will not bolt up to a M42, only the M10. it does have a speedo drive.

    the way you can tell is the shifter. the M42's G240 uses the beam type shifter like shown on the G260, but the M10's G240 uses the sheetmetal shifter with 2 mounting bolts. also the M42 has 2 rear trans mounts, the M10 has only one.

    i payed $50 for one. the E21 guys don't want them because. * you have to source a 83 driveshaft, * the G245 is a stronger box. the reason i bought one is to swap the tail section onto my M42's box so that i have a speedo drive.

    Quote Originally Posted by StevenHenriksen View Post
    Last edited by Tom D; 01-19-2012 at 06:15 AM.
    Tom D

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  10. #10
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    IF that is a 240, without the intermediate section between the rear cover and the main housing I'd suspect it is the 4 spd, which would put it '80 or prior for the E21. Still have to compare the 323 vs. the 320 (M20 to M10 bell housings) and I don't have both in front of me. If the 260 came from a 325i (M20 type) then I'd wager it's a old 323 M20 4 speed transmission.
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  11. #11
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    the G240 5 speed does not have a intermediate section.

    the G260 E21 would use the sheetmetal shifter.

    so what is pictured is a E21 G240 and a E30 G260.
    Tom D

    77 e21 - m42
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  12. #12
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    The "G240" etc tells you what gears are inside the box. It doesn't tell you what engine it fits. In the same way, there's a G245 for M10's and a G245 for M20's. This leads to assumptions such as Bflan made above that it's the same transmission and it is not. NO 92mm bore spacing engine (M42, M20, M50/52, S52/54) with interchange transmissions with any 100mm bore spacing engine (M10, M30, S14, S38).

    Your transmission is worth something to 83 owners, since it's harder to find these than the G245. Some 2002 owers use them for swaps too, but the 245 is more popular with them.

  13. #13
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    Ok, thanks for all the info guys. This trans looks to have the same bell housing pattern as the G260 off the M20. How different is the M10 pattern? I would assume it would be blatantly obvious which engine it fits. That seems to be the last piece of the puzzle

  14. #14
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    No, it's not obvious. M10 and M20 bellhousings are exactly the same shape, but slightly different size.

  15. #15
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    Ah I see. Ok, then this is a G240 5 speed out of an '83 M10 E21. Sound correct?

    On a related note, is there any sort of page that shows the lengths of the different driveshafts? I have a pile of un-marked shafts, would like to figure them out

  16. #16
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    i understand there are different 240s, that why i was referring to them as 'm10 240s' and 'm42 240s'

    so tom, did the mechanical drive swap work out for you? i just started looking into this last night, i'd love to have a mechanical drive on my m42 240 but the consensus on 2002faq seems to be that it can't be done.

  17. #17
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    Quote Originally Posted by StevenHenriksen View Post
    On a related note, is there any sort of page that shows the lengths of the different driveshafts? I have a pile of un-marked shafts, would like to figure them out
    Realoem has the lengths for some of the larger cars, but not E21's as I recall. Not sure exactly what the specified length is though, driveshaft places usually measure from the welds, not the overall length.

  18. #18
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    Thanks for everyone's help with this. Transmission is for sale, PM for details

  19. #19
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    I appreciate you doing the legwork on this man. I had kinda come to the same conclusion. Lots of conflicting info out there. Anyone that is looking at any of the stuff this guy has for sale should rest assured that he is a great seller. Was on the phone/texting with me late into the night to help me figure out if this is the tranny I needed for my car. Great seller.

  20. #20
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    Quote Originally Posted by StevenHenriksen View Post
    Ok, thanks for all the info guys. This trans looks to have the same bell housing pattern as the G260 off the M20. How different is the M10 pattern? I would assume it would be blatantly obvious which engine it fits. That seems to be the last piece of the puzzle
    Looks like you have already figured this out, but there is an easy way to determine M10 vs M20 and that is the distance between the upper two bolt holes below the cylinder head. M20 has a much wider spacing than M10.

  21. #21
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    Quote Originally Posted by 83320i View Post
    I appreciate you doing the legwork on this man. I had kinda come to the same conclusion. Lots of conflicting info out there. Anyone that is looking at any of the stuff this guy has for sale should rest assured that he is a great seller. Was on the phone/texting with me late into the night to help me figure out if this is the tranny I needed for my car. Great seller.
    Thanks man, that is nice of you to say

    Quote Originally Posted by LJ851 View Post
    Looks like you have already figured this out, but there is an easy way to determine M10 vs M20 and that is the distance between the upper two bolt holes below the cylinder head. M20 has a much wider spacing than M10.

    Ok, thanks for the tip!

  22. #22
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    I know I am pulling an older thread, but Tom, were you able to make the G240 parts work with your M42 swap/5 speed and get a speedo? If so, do you have a build thread?
    Thanks...I am still trying to figure out something for my same setup...

    Tim

  23. #23
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    hey Tim, i have not had the time as of yet, but from my research the only thing different between the E21's and the E30's G240 is the front case, so other then breaking down the transmissions, which can be a bitch, and any shimming of the shafts, it should be doable.

    the downside of doing this and the reason i'm not in a hurry, is that with the E21's tail section you will also have to use the sheetmetal shifter plate and a single mount for the trans. i'm rather fond of the I-beam shift carrier mated to the E21's shifter. it shifts like butter.
    Last edited by Tom D; 03-25-2012 at 11:13 PM.
    Tom D

    77 e21 - m42
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  24. #24
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    Just found this thread - I have a 240 that was behind the 2lt M60 in our track car - it is a lot smaller then the E30 265. But ours has the rear double tranny mount "tail section" of the case on it? Is this a Factory thing or did a PO do this, any idea's?

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