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When and what kind of solder to use when rebuilding manual transmission?

Posted by XC92, Oct 25, 2020

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  1. XC92

    XC92 Proven Member

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    Queens, New York
    I'm about to drop the trans on my '92 Talon TSi AWD manual, to replace the shot clutch and hopefully fix an issue with the trans where it pops out of 1st gear under load (but not with the clutch pedal pressed).

    I won't be able to know what's causing this let alone fix it until I take the trans case off and probably remove both gear stacks and see what's going on, but hopefully it's one of the more typical causes, like loose staked nuts or a bad shift fork (and for all I know it's a loose shift or select lever).

    I understand that at certain points doing trans work, you have to place several small pieces of solder on various races and bearings, close the case, torque it to spec, then reopen it to measure the width of the partially crushed solder with a caliper, to tell what spacer widths you need to use.

    What I'm wondering is, if I don't have to take the stacks apart and the issue is something simpler, like the nuts, fork or levers, do I still have to do this, especially if there's no shaft play?

    If so, what kind of solder? I understand that it has to be 1.6mm or 0.62" in width. I only have thinner kind for electronics work I've done, so I'd have to get some.

    Does it matter if it's solid, hollow, rosin or acid core, or leaded or lead-free?

    Is there any other, unrelated work one might have to do on the car that would require one or the other kind of solder, either electrical work or repairing an exhaust hole (I assume the latter would require acid-based solder), so I could get that kind for potential future double duty (assuming it'll work for this task)?

    ...Ok, while I'm at it, 3 other semi-related questions.

    One, I understand that when I put it back together, I have to apply RTV as there are no actual gaskets. Which kind do I use?

    Two, I also understand that I'll need to apply grease at certain points. What kind? Right now I have several, silicon-based for brake caliper glide pins, general-purpose grease from a mini-cartridge for ball joints, and some really old white lithium grease I once used on my old road bike, when I repacked the bearings. Can I use any of these, or do I need another kind, e.g. moly?

    Three, where should I use threadlock, and what kind? And do I need to use antiseize anywhere?
     
    Last edited: Oct 25, 2020

    298  1

    1992 Eagle Talon TSi
    awd · manual · 1G DSM
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  2. TK's9d2TSi

    TK's9d2TSi Supporting Member

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    Start from post 129 for what solder to use.

    https://www.dsmtuners.com/threads/transmission-rebuild-time.527066/page-6

    I would guess you can reuse the shims if you’re not taking the stacks apart but from my rookie experience of taking apart two transmissions, the case and one shim will most likely have some wear so it wouldn’t be a bad idea to check since you have it apart.

    Any quality rtv will work. I used permatex grey no leaks.

    I don’t recall using anti seize, thread lock or grease at all. Just lube everything during assembly.
     

    522  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    552  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

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    1992 Eagle Talon TSi AWD
    12.2 @ 120 · 1G DSM
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  3. XC92

    XC92 Proven Member

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    Queens, New York
    Still confused since there were references to lead-free, rosin and acid-based solder. There isn't a consensus on which to use? I'd think that the main if not only concern is that the solder doesn't partially decompress once you remove the cover, and perhaps the ambient and case temperature. I'm guessing that the colder they are the less decompression, but ideally there would be none at all temps.

    Also does the FSM state exactly when and where to use solder, or are there "implied" situations where you'd have to be an experienced trans expert to know?
     

    298  1

    1992 Eagle Talon TSi
    awd · manual · 1G DSM
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  4. twicks69

    twicks69 Supporting Vendor

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    Use permatex ultra grey or ultra black RTV. The regular stuff decomposes in the transmission and clogs oil passageways.

    For solder, use a softer rosin core solder. You will be using 0.062" for input, intermediate and front diff. 3/32" for center diff and output pinion shaft.

    1st gear pop out expect wiped out intermediate shaft bearings, 1/2 hub and slider, synchros, 1/2 fork and possibly the gear itself as well.
     

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  5. TK's9d2TSi

    TK's9d2TSi Supporting Member

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    Tim is the man and you can get parts from him as well. He is THE transmission man.
     

    522  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    552  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 3K  5

    1992 Eagle Talon TSi AWD
    12.2 @ 120 · 1G DSM
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  6. XC92

    XC92 Proven Member

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    Joined Jul 22, 2020
    Queens, New York
    Thanks, very helpful. A part of me even looks forward to fixing all that because it might be fun plus it probably needs a good overhaul anyway at this point.

    Thing is, I have to get the car out of its current spot within the next 10 days or so, because it's in a neighbor's driveway and they're going to need that space soon, and street parking is the only viable option for me at this point, which in NYC means the car has to be insured, registered and inspected.

    No way can I fix the trans issue and put everything back on that quickly AND do it right. Not a chance.

    But this should be enough time to replace the clutch, put the trans and everything else back on, and get the car to where it can be driven and made legal again and parked on the street.

    So if I do punt on the trans issue for now, should it at least be safe to drive it to an inspection station a few miles away, so I can get it legal again? I doubt that it would fail inspection because of the 1st gear issue.

    I'd then park it on the street and work on it there, where there are no time constraints (other than that it's getting cold here and working on a trans outdoors is not likely to be very fun).

    Pushing my luck even further, if I decided to put the trans repair off till the spring, when it gets warm again, would driving the car do the trans any further harm than what it likely already has? Before the clutch gave out the car drove fine in all but 1st gear, and even it worked if I held the shifter in until it was time to upshift.
     
    Last edited: Oct 25, 2020

    298  1

    1992 Eagle Talon TSi
    awd · manual · 1G DSM
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