ahp 4 speed in 81 ct cases.

Discussion in 'Modifications' started by mark from florida, May 5, 2020.

  1. mark from florida

    mark from florida Active Member

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    went out to get new tranny in and seem to be having shift issues? tranny is new ahp..installed into cases with provided thrush washers in place.bolted cases together and stood motor upright. while spinning drive gear shifted trans by moving shifter arm.works smooth one time and not the other? don't want to get it all together and have issues. lookin for suggestions.has kicker in place with return spring. shift cog mounted to trans and arm placed under washer to work with pins.bolt tight thru shifter lever side of case.small roller arm and spring installed.
     
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  3. racerx

    racerx Administrator
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    Okay, first, you do need the center case gasket in place, for lateral clearance. Check endplay of both shaft assemblies. There should be ~0.005" - 0.010". If there's (virtually) none or, if there's more than the thickness of a thrust washer, it's time to figure out why and correct it. The case screws can be lightly snugged, they don't have to be torqued, until final assembly. None of these transmissions like to bench shift, even OEM. Keeping the primary driven gear spinning will give you a better idea of what to expect, while the engine is running.

    I also like to verify shift action, using the shift drum fixing bolt, instead of the shift linkage...as its own, separate, test. With the mainshaft stationary, you can expect some balky gear changes and that will vary by gear. Being able to jiggle the shift drum, using a socket, you should be able to shift gears anyway, don't force anything. Comparing shift action stationary and with the mainshaft rotating, you should notice a big difference. If you cannot get reasonably smooth gear changes, via the shift drum fixing bolt, something is incorrectly assembled.

    The tranny assembly needs to be at least lightly oiled. Do keep in mind that the new trans needs some break-in mileage...and, it's not OEM Honda, so it may not shift quite the same as OEM, break-in could make more of a difference.
     
  4. mark from florida

    mark from florida Active Member

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    Thanks racer x.yes maybe I am expecting buttery smooth shifts while just sittin. like I said, sometimes I can shift it fine by just turning the drum with my finger tips.while testing last night I did not have the center gasket in place.where is the best place to measure end play? or would that be kind of a guesstimate moving shafts once cases are back together. you are not the first person to tell me these things don't like to be bench tested. just cant seem to get it through my thick head.just don't want to assemble whole thing and have to tear it apart again.
     
  5. racerx

    racerx Administrator
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    I've never seen any specs for transmission endplay. The estimated specs I provided are based on decades of observation. Excessive endplay will really f**k with shifting. Insufficient endplay could cause problems with the tranny bearings, if thermal expansion caused binding.

    What I'd suggest is testing endplay by feel...first w/o the case gasket, then with the gasket in place. There should be almost none detectable, sans gasket...and an amount that is close to gasket thickness with a gasket installed. A little less than gasket thickness is fine, significantly more than that would need to be addressed. Unless there's something wrong with your cases, I doubt you're going to find excessive endplay.

    As for buttery-smooth shift quality, IDK that you can reasonably expect that from an inexpensive aftermarket transmission. On the bench, it's unlikely from any gearbox. These transmissions need rotation to operate as intended.
     
  6. darrel gunderson

    darrel gunderson Active Member

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    Is this engine going to have an auto clutch or manual ? Is the shift pattern 1dn 3 up ?
     
  7. mark from florida

    mark from florida Active Member

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    engine will have a manual clutch and shift pattern will be 1 down 3 up.
     
  8. mark from florida

    mark from florida Active Member

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    finally got cases back together. end play looks about right. thanks.
     
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