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Thread: M5R2 5 speed transmission rebuild: assistance required

  1. #1
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    Jun 2002
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    Illinois
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    M5R2 5 speed transmission rebuild: assistance required

    Over the time I have owned my car, my M5R2 has been subject to wear slowly degrading the blocker rings and possibly other parts, leading to a grind in second gear.

    Essentially this grind occurs only in second, whenever it is selected after a downshift, and when upshifting from first unless shifting very slowly at low rpms.

    Do to cost and possible future upgrades which may eliminate the m5r2 from my SC, I would like to rebuild this transmission myself if possible. Therefore, from logic and my current knowledge, it seems the things I must know to perform this will include:

    1. A method for diagnosing which parts may be worn to the point of causing misoperation, and the names of these parts.

    2. The best source(s) to acquire the necessary replacement parts, from both a quality and price standpoint.

    3. The tools, especially unusual tools, which will be required for the process of removing, rebuilding, and reinstalling the transmission. Also sources for any unusual tools or possible substitutions would be useful.

    4. The instructions/processes, torque specs, and other various information which will be necessary for a person who has no previous background in this reguard to perform a proper quality rebuild without significant unexpected obstacles, including removal and reinstallation of transmission.

    5. The location of any current documented information which would be relevant to this task.

    6. The length of time this task normally takes, and any other significant information I have not accounted for.

    From what I have kept track of over time, it seems to me that I probably have a worn second gear blocker ring, and the synchronizer assembly itself is ok. I think this due to the fact that only second gear has the problem, and it occured gradually from improper shifting (not me ). It also looks like current prices for parts to rebuild the basics are running around 400 dollars, does this seem ballpark? Finally, it doesn't look like the process is overly complicated. From what I can tell, there may be significantly less work involved than in changing motor/trans mounts, hence this is something that could be performed in a day.

    Thanks a lot for any help you can offer me!

  2. #2
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    Mine was doing the same thing. It can be done in a day if you know what parts you need before hand. {LONG DAY} It sounds like you need new blockers and if you haven`t rebuilt your shifter, now is a good time.
    Getting the bearings out the ends of the shafts are the hard parts but you will figure it out. I have a set of new brass blockers {CHEAP} let me know. The brass rings in the pick are what you need to replace.
    Attached Images Attached Images  

  3. #3
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    Apr 2004
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    I just got mine disassembled, I'm going to rebuild it after I get the parts I need. I will try to do a tutorial on assembling it but it may be a couple weeks before I'm done. Here are some pictures of it coming apart www.fivaxis.com/set4

  4. #4
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    Excellent, thanks for the info so far. I figured it could take a day or two, shouldn't matter too much.

    I have been questioning for some time whether to use fiber or copper blockers.

    I understand copper can be more durable, but at the same time I have heard reports that it will almost always grind, especially when cold, even when not speed shifting (something I don't do). OTOH, I have also heard that they only grind for a while when new and stop after 'breaking in', then only when speed or power shifting.

    As for fiber, I have heard it will essentially last forever when shifted properly. However, I would like to occasionaly let others drive my car and am concerned about reports that it wears quickly when misshifted or otherwise abused.

    Essentially, this leaves me undecided about copper or fiber.

    What exactly do the rebuild kits, such as that from Southern gear, include?

    Keep the info coming everyone, thanks again!

  5. #5
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    bump......

  6. #6
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    I'm getting started on my tutorial http://www.fivaxis.com/m5r2rebuild/

    I ordered the parts today so they should be in sometime next week. I just ordered the parts I needed which came to around $270 shipped.

  7. #7
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    fivaxis; thanks for your assistance, I'm sure your tutorial will be a valuable resource for many owners!

    scbird1; I would probably be interested in your brass blockers if I could simply get the issues reguarding brass Vs fiber cleared up.

    Would using these brass blockers be worse in our transmission for shifting vs something which uses them stock like a Ranger?

  8. #8
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    Im not sure as to what the issues are but the guy from liberty transmission said that these were the best blockers for our cars. He told me to use regular motor oil like 5w30 but I used GM`s syncromesh in my last trans and it works great. I think the biggest problem is that some have used auto trans fluid with these and they grind but the 5th and reverse are just brass blockers and seem to never ware out. $55.00 shipped and there yours.

  9. #9
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    speaking of fluid..

    I have observed a wide selection of different transmission fluids available which seem suitable for our M5R2. These include conventionaly mercon III & V from various brands, synthetic mercon III & V from brands like Mobil 1, blends, and also various brands of syncromesh such as Penzoil syncromesh. I was under the impression that Mercon and especially Syncromesh were trademark names, but apparently not. If I were to use syncromesh, are there both synthetic and conventional types? And which brands make this kind beyond penzoil and GM?

  10. #10
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    I would love to rebuild my M5R2...

    I may not be able to offer significant technical assistance to this post, but I have come to the conclusion that if you are willing to take a chance, I think that the M5R2 might make a great transmission if you rebuild it properly and take care of it properly.

    I think XR7 Dave was talking about it and it convinced me. But it seems that your best bet is to stick with the fiber syncros. I heard a rumor about some "upgraded" fiber syncros or possibly Carbon Fiber ones which would be stronger and have a higher friction co-efficent.

    But nonetheless, I was looking at the photos that Fivaxis posted and I got thinking about an experienced machine shop carefully drilling additional "lightening" holes in each gear and possibly rifle drilling the carrier shafts. The amount of weight reduction may be minimal, but it just might make the transmission a touch edgier than stock and would allow the fiber syncros to last a bit longer.....

    Apparently their was a rumor that I heard about a gentleman who had this done to a maserati transmission and it worked well.

    Top it off with the B+M shifter and use a quality clutch with a new slave (might as well while the whole thing is off) and you've got something to brag about.

    As far as transfluid is concerned, there may be the possibility that the Brass Syncros grind when only certain kinds of trans fluids are used. But I would probably use redline synthetic transfluid myself due to it's superior lubrication properties and it's abiltity to free up a bit more HP....

  11. #11
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    I have drove plenty of these cars with a stick and all I can say is syncromesh is the bomb Im going to dump the fluid on the other car as well and change to syncromesh.

  12. #12
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    Synchromesh is a fluid design that was developed by General Motors for use in the Tremec transmissions. Since that time it's become a popular fluid and is used in many Chrysler transmissions as well. A specification for it's properties has been issued and now other lubrication companies sell such fluids that they label Synchromesh that meet this GM spec.

  13. #13
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    Ok as usual choices are limited for transmission fluid at the various stores. Among the best I think I have found are Mobil1 syn Dextron/Mercon and Penzoil syncromesh.

    Which of these would be the better choice, and are all brands of syncromesh a synthetic fluid?

  14. #14
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    I went to the Chevy dealer for mine $9.50 a qt.

  15. #15
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    Dissasembly ?

    Quote Originally Posted by fivaxis
    I'm getting started on my tutorial http://www.fivaxis.com/m5r2rebuild/

    I ordered the parts today so they should be in sometime next week. I just ordered the parts I needed which came to around $270 shipped.
    I checked out your site, very informative. Could you also include some dissasembly tips?

    What special tools were required for dissasembly? Or what creative techniques were required to remove some of the pressed bearings without custom tools, etc?

    My tranny needs 1,2,and 3 synchros. I've had it out twice for clutch related work but I thought the tranny dissasembly Required special tools.

    Any dissasembly advice is apprecieated.

    thanks
    Bob

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