How do i tell if a synchronizer is good or bad?

Posted by edmundturner, May 19, 2005
Drivetrain Tech - 4G63 transmission, clutch, flywheel, driveshaft, gears, differentials, transfer case, shifter, etc.

  1. edmundturner

    edmundturner Proven Member

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    Hey everyone.
    I am in a predicament. I recently bought an EVO2 AWD tranny and dropped it in my 6 bolt. The gearbox was disassembled and clean prior to the installation. I had a grinding problem putting it into 4th gear. Due to the lack of replacement parts, i sourced for a used 'input shaft' with all the gears intact. Dropped the gearbox and installed it in. 4th gear was great, but i still had grinding issues going into 3rd gear. ARRGHGHHGHG!.

    Dropped the gearbox again, this time removed the 4th gear and double cone synchronizer from the existing input shaft and replace it into the first input shaft i originally got. Should be good right? WRONG. I still have grinding issues going into 4th!. Does anyone have an idea where i am going wrong? Could it be a selector fork issue?

    All the synchronizers show signs of use but not chipping or cracking. How do i tell if a synchronizer is good or bad without reassembling the whole gearbox and dropping it back into the car?

    edmund
     
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  2. 1fast97gsx

    1fast97gsx Proven Member

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    just replace all the syncros ... they are like $20 each?
     
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  3. edmundturner

    edmundturner Proven Member

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    unfortunately, i cant get replacements from the country which i am in now. I am looking to source for someone who is willing to sell and ship them to me over the internet.

    im screwed.


    edmund
     
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  4. 1fast97gsx

    1fast97gsx Proven Member

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    Why not paypal the money to someone on the forums and give them like an extra $40 to cover shipping and their time?

    Basically you just look at the syncros for any breakage or roundness. The little teeth should be triangular and fairly sharp. If they are dull and rounded off the syncro must be replaced. Either way I'd replace them for sure while it's apart. Maybe your fork is worn? A worn 3/4 hub and sleeve can also cause these problems.
     
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  5. edmundturner

    edmundturner Proven Member

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    thankfully paypal does recognize the credit cards that have been issued to me. Now i just got to try to find someone whos willing to help me out.
    I did check the hub and sleeve, and both sets i have look identically worn but without breakage etc.
    -Are you referring to the selector fork which sits behind the throw out bearing or the shift rail (-some people refer to this).
    -I just want to make sure i get the correct replacement parts.
    -How do i tell if the fork needs to be replaced?

    edmund
     
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  6. 1fast97gsx

    1fast97gsx Proven Member

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    the fork behind the throw out bearing is in no way a selector fork ... that is known as the clutch fork. The shift forks are the forks inside the trans held onto the shift rails by pins. The forks may begin to wear over time, leaving a lot of play between the fork and sleeve. Just because your hub and sleeves "look" equally worn doesn't mean they are both ok. Have you ever rebuilt a trans? Do you know what exactly to look for?
     
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  7. edmundturner

    edmundturner Proven Member

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    Unfortunately not!. This is my first attempt in rebuilding a tranny. I am only armed with only the manuals from the DSM cd. I have intermediate knowledge and experience with rebuilding stock heads, blocks, changing water pumps, belts, etc. There is a lot to be learnt from manuals. :p

    Dont let me mislead you,its not that i am a stingy bast**d. I am NOT trying to save a penny by avoiding having the tranny rebuilt professionally. It is just that there isnt anyone competent here (in my current location,) who can. I have sent the tranny to 2 DSM specialist (or so they claim) and they both are puzzled. In total, the tranny has been pulled out and disassembled 5 TIMES! .
    Labor cost alone is equivalent to the cost of the gearbox!

    Their advice, is to get a new tranny from the junkyard. My budget is not too happy with their recommendations.
    What I meant by that both sleeves and hubs have the same used signs, is that I actually took apart my friends W5M33 gearbox (which shifts perfectly well) to compare it with my tranny internals. I checked the synchronizer ring, hub, clutch gears, but not the forks attached to the shift rails.

    Last week I reassembled and installed my friends tranny back into his motor. Now I don’t have an identical shift rail –fork for comparison. I just referred to the manual and it does not tell how to identify a fork which is out of spec. If you wouldn’t mind, how do I tell if the fork is good?

    I appreacite any help/tips/suggestions i can get.
    Tranny blues….

    edmund
    .
     
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