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Thread: Transmission Swap

  1. #16
    Senior Member turbokinetic's Avatar
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    Quote Originally Posted by philbert View Post
    Thanks guys, this is a world of information and I'm attempting to digest it.

    Jr., you're saying I might be able to plug and play a '96-97 trans, but the only issue may be in the speedometer being off? Is there any way to verify that? Worst case the internal harness would need to be swapped? Not to sound like a complete moron (I'm in actuality only a partial moron), how difficult is that? What about the issue that Turbokinetic brought up about the PCM not recognizing the "wrong" transmission properly?
    The PCM tells the transmission what gear to operate in. The PCM compares the engine speed and wheel speed and calculates the actual gear ratio the transmission is creating. The PCM compares the actual ratio measured by the sensors, to the EXPECTED ratio for the commanded gear. If the ACTUAL gear is not the COMMANDED gear, the PCM will flag a fault that the transmission is not operating properly. If you change the gearing (chain or final drive) the PCM's "expected" gear ratios will not match up with the transmission's performance. Therefore you will get a fault even though there is nothing actually wrong.

    The chip can be reprogrammed to make customized combinations if you have the correct parameters for the transmission you plan to use.

    David



  2. #17
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    Quote Originally Posted by philbert View Post
    Thanks guys, this is a world of information and I'm attempting to digest it.

    Jr., you're saying I might be able to plug and play a '96-97 trans, but the only issue may be in the speedometer being off?

    Yes the speedo will be off by a couple MPH higher up on the scale.. An example would be at 10 Mph you may only be 0.1 off... And at 60 you may be 2.0 off.. Not 100% correct for numbers but there will be a slight variation at speed..

    Is there any way to verify that?

    No need to verify, I promise you if you use a 96-97 4T60E you will be a hair off


    Worst case the internal harness would need to be swapped? Not to sound like a complete moron (I'm in actuality only a partial moron), how difficult is that?

    Its not that difficult at all, you will need a side pan gasket kit for the trans you are going to use, and then you will remove that harness and install the one from your van, I do not think this will be needed tho as the 94-97 Bonneville, Buick LeSabre, Olds 88, and 94-95 U bodies have the transmissions wired 100% the same..



    What about the issue that Turbokinetic brought up about the PCM not recognizing the "wrong" transmission properly?

    If you had a newer car this would be a problem as the PCM's got quite a bit smarter... The 94-95 PCM is a little bit on the dumber side and is simply looking at Slip numbers when lock up is commanded, if you stick with a 3.06 ratio you will be fine... An example would be you could go to a 2.97 gear ratio and not have any real issues, other than a shift thats slightly earlier due to the taller gears, but the PCM would not have any issues with this... If you went to a 3.33 ratio then the PCM will see an issue as it will think you have slip when you really don't and may at that point set a code..
    Keep asking questions, I want you to know everything you can know before you walk into this..

  3. #18

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    Thanks again guys...

    I should have been more exact in my wording about "any way to verify"...I didn't mean to verify the speedo will be off, that I understood would be reality. I meant "is there a way to verify I can plug and play the 96-97 trans and only have the speedo being off by a few mph?"

    I also assumed the PCM would not necessarily recognize the tranny properly, if the gear ratios are different. It may shift a bit late or a bit early, right? I'm not sure if I'm getting conflicting advice now....will I be ok with the '96-97 trans without having the chip reprogrammed or not? If I am going to have an issue with the PCM, could I just swap the chip from the donor?

  4. #19
    Senior Member turbokinetic's Avatar
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    Quote Originally Posted by philbert View Post
    Thanks again guys...

    I should have been more exact in my wording about "any way to verify"...I didn't mean to verify the speedo will be off, that I understood would be reality. I meant "is there a way to verify I can plug and play the 96-97 trans and only have the speedo being off by a few mph?"

    I also assumed the PCM would not necessarily recognize the tranny properly, if the gear ratios are different. It may shift a bit late or a bit early, right? I'm not sure if I'm getting conflicting advice now....will I be ok with the '96-97 trans without having the chip reprogrammed or not? If I am going to have an issue with the PCM, could I just swap the chip from the donor?
    The speedometer will not be affected. The transmission output speed sensor (that is what signals the speedometer) is reading off the final drive carrier. That turns at the axle speed, regardless of ratio.

    See below. In the lower left corner of the picture there is a light silver "toothed wheel" that the speed sensor reads from. That is part of the housing that turns with the axle. The small end of the final drive (bearing race) that points straight into the lower left corner of the picture is where the CV axle goes into the transmission.



    David

  5. #20
    Senior Member turbokinetic's Avatar
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    The problem you may have is, if the PCM detects an error, it considers the that it has lost control of the transmission. For safety, the transmission may be held in third gear to prevent further damage.

    The van's chip is special for the van application. The safest thing to do would be to copy and paste the transmission constants from the chip from the donor car into your van chip. That would minimize the chance of side effects.

    If you can give me the BCC code off your chip, I can look at it and tell you if I can change the program without actually seeing the van.

    Take care!
    David

  6. #21

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    We're not going to have a food fight, are we? One says the speedo will be off a tad, one says it won't! *S*

    I think I got it then from the explanation. The speed sensor is really nothing more than an electrical pick up that takes a reading from the "toothed wheel". If it's taking the reading from axle speed, it matters not a whit, because, well, it's just reading the axle speed electronically. Quite unlike the "old days" of matching gears to the speedo.

    So....if the internal wiring is the same and the speedo is not a problem, and I assume the original axles will fit these other transmissions/the cradles mounts are the same/the bolting is the same, am I then left with the only issue being the shift points, i.e. the PCM programming? If that's true, then will I be ok with the original PCM or will I have to have it reprogrammed or can I just swap chips with the donor? I can't imagine fuel mapping of the chips will be that dissimilar...

  7. #22
    Senior Member turbokinetic's Avatar
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    If you get a trans from a 96 or newer, that donor vehicle will not have a chip that can be used in your PCM because the 96 and newer were FLASH programmable. If it has one, get the chip from the donor car, and try both. Whichever works best - use it!

    If you get the BCC code and post that, I can tell you for sure what can be done to the chip.

  8. #23

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    On the outside cover of the chip it says this:

    BLSD
    1620
    8027

    The PCM itself is this:

    Serv No 16183247 BLSD
    86BLSDM75171GSYE *

  9. #24
    Senior Member turbokinetic's Avatar
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    Quote Originally Posted by philbert View Post
    On the outside cover of the chip it says this:

    BLSD
    1620
    8027

    The PCM itself is this:

    Serv No 16183247 BLSD
    86BLSDM75171GSYE *
    Alright! I just looked on the GM-ECM site and didn't see the program from that chip posted there. I sent a message and some of the members will probably have the stock program they will e-mail to me. With that I can view the settings and see what can be done. If the transmission failure detection function can be turned OFF, then you would have everything just like before but the shifting points would be a little different.

    David

  10. #25

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    And if there is no transmission failure detection function?

  11. #26
    Senior Member turbokinetic's Avatar
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    Quote Originally Posted by philbert View Post
    And if there is no transmission failure detection function?
    If you turn off the errors for invalid gear ratios, everything will run fine. If the transmission develops a problem, you will not get a Check Engine light and will not have a code about it.

    My car has a swapped-in trans and transmission ECU without any diagnostics enabled. It doesn't affect it any.

    David

  12. #27
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    I hope I am not confusing you...

    What I am getting at is the 94-95 3.06 for the vans and the C & H bodies all used a 31 tooth reluctor, for these cars and vans the only purpose for the reluctor is for the Vehicle Speed Sensor, so there will be 31 pulses per full revolution of the wheel

    The 96-97 will have a 30 tooth reluctor, this is the reason why you will be a tad off as your chip will be doing its math at 31 pulses not 30... The reality is that this will not be a problem other than your speedo reading a couple MPH low at interstate speeds.. I had no issues running a 30 tooth reluctor on my 95 Trans Sport, and I went to a heavier gear ratio 2.97 as opposed to the stock 3.06.. I drove 1 year with no issues, not even a single Trans related code..

    If you could have a chip burned that corrected for the VSS Reluctor you would be 100% correct as opposed to 99%, but for your application its not needed..


    On a side note, when I went to my Series III 3800 in my van I decided to go to the 3.33 gear ratio, I used a stock 3.06 Bonneville chip and never threw any transmission codes... Only thing we did was we had to turn off the security in the chips program as the car used the passkey system with fuel enable.. This was the only thing we did...

    Its the newer cars( 96 + ) that will have a hissy fit with a differing gear ratio, When we went to the 97 PCM in my van we had to get the Pulses and pulse counts correct for the PCM to be happy as I used the 3.33 ratio as opposed to the Bin Files 3.06... The older generation of GM PCM's aren't too picky.. You should be able to swap with no worries..

    This is the first Transmissions we installed in the van after we did the rebuild on it... This was a Buick Rivera Supercharged Trans, and had the 2.93 Gear ratio... we ran this one for several months and later found a leak that turned out to be a hairline fracture in the case.. 2.93 Ratio with a 30 count Reluctor...


    This is the vans original trans, I choose to rebuild it after we found the crack on the first one.. On this one I used the 3.33 Diff and changed the drive an driven gears to make it an Overall 2.97 ratio, I ran this trans with 0 issues as well..


    Both of those transmissions were under the control of the BLSD Chip with the original motor.... Never had any issues..
    Last edited by Jr's3800; 08-16-2010 at 07:45 PM.

  13. #28

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    ok guys...in your highly exalted opinion....what transmissions can I then use...completely plug and play.

  14. #29
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    I can Promise you that a 3.06 FW2 from a Bonneville, LeSabre, Olds 88/LSS and or any of the U Body 3800 vans 94-95.... These will be 100% Plug & Play with no speedo errors..

    the 96-97 Bonneville, LeSabre, Olds 88 with the 3.06 FW2 are all also useable, but you will have the slight variation with the speedo due to the reluctor count making it in my eyes 99% perfect for your application...

    If you can find any of these transmissions with low miles and for a good price I would run the best one you can get... The 96-97 will not require you to change out the internal harness, but no matter what trans you get, while you have it on the ground I would recommend changing out the side pan gasket just to kill off any possible future leaks..

    Also when and if you find a good trans, I do recommend a Trans cooler for it, the number one failure for these is due to overheating.... Some of the U bodies had Dual Heat Exchangers in the radiator for the trans, would you happen to know if yours does?

    We installed the 97 trans in my buddies 93 LeSabre, only change was the side pan gasket and the internal harness to make it compatible with his 93... Its been 1 year and 15,000 miles with no issues at all..

    Just curious... Where are you located? If you were near the Space coast we could lend you a hand..
    Last edited by Jr's3800; 08-16-2010 at 08:11 PM.

  15. #30

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    Not sure how to tell if I have a dual heat exchanger in the radiator.

    This trans has been on the way out for a while. It developed the "shudder" like you're driving over those bumps in the road and then finally one day it just would not shift out of first. Reverse slipped horribly. But for 235,000 or so miles, it's lived a good full life and I'm not complaining. Not like anyone would listen anyway....

    So, just to be crystal clear....any '94-95 3.06 Bonneville, LeSabre, or Olds 88/LSS will be a no problem, just drop it in, and I'll be on my merry way donor? Same for the '96-97 with maybe a slight speedo error or shift points that aren't going to be weird?

    I'm in Minnesota. Land of misquitoes, taxes, lutefisk, and strange politicians.

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