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  1. #1
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    3.3 Reverse Conversion

    Hey guys,

    So I have been reading up on adding reverse to the 3.3. I realize how some feel about this and did not come to this site to get flamed. I'm not trying to build a drag truck that does the quarter mile in 6 seconds, I would like reverse for convenience... that's it. With that being said I have been reading up on doing the conversion with kit 4995x and most recommend adding OptiDrive to prevent engaging reverse while still moving. Back in the day at one of the off road shops I worked at had a T-Maxx (back before I cared to get into RC) that we would screw around with after work. I remember it having reverse (and no extra modules) and it wouldn't switch until it came to a stop. Come to find out through this info filled forum that those transmissions used something internal to prevent reverse from engaging until it stopped moving forward. I have yet to find any write ups on doing a conversion with the 3.3 and the old style "fail safe". Is there a way to get the 4995 kit into the 3.3 trans and also add the mechanical prevention from the older T-Maxx trans so I don't have to use the OptiDrive?

  2. #2
    Marshal Double G's Avatar
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    There was no mechanical prevention, it was a sensor in the transmission that would sense movement and the Opti-Drive module would process that and not allow the reverse servo to move. Many people remove the OD and just be careful not to switch into reverse.

    That all said, if you are looking for a Fast and Furious rocket, a FOC transmission is much stronger and will give you less rotating mass for the engine to spin.
    The Super Derecho

  3. #3
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    So OptiDrive has been used in EVERY T-Maxx that has had reverse?

  4. #4
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    Quote Originally Posted by strocket View Post
    So OptiDrive has been used in EVERY T-Maxx that has had reverse?
    Not on every one, the older one's never had opti-drive (thank goodness, I hate it)
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

  5. #5
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    I didn't think so. So is there a way to utilize that same style with the 3.3 tranny?

  6. #6
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    I don't know much about the new 3.3's all of mine are older. If it has the opti-drive in the new 3.3 I'd just remove it and then it will be the same as the older one's. If you look at the exploded views on the tranny's you will see a shift fork which the servo slides it back and forth to engage. The opti-drive is just like Double G said a sensor to keep it from moving into reverse when throttled up going forward.
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

  7. #7
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    Come to think of it I believe the new 3.3 does not have reverse.
    OOP'S i need to read better, I see you want to add reverse.
    Last edited by JerrysMaxx; 10-23-2015 at 08:22 PM.
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

  8. #8
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    Well the new 3.3s that don't have reverse out of the box wouldn't have OptiDrive. So I want to use the new 3.3 trans that is forward only, add the 4995 kit, but be able to use the old school way of preventing reverse to engage unless the truck is stopped INSTEAD of the the OptiDrive... Know what I mean? LOL I know it seems confusing.

  9. #9
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    I just looked at the 4995 and it definitely looks like the older ones. The only difference I see is the use a micro servo in place of the older bigger servo's. Nothing else different. I'd say it's exactly what you want.
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

  10. #10
    RC Turnbuckle Jr. Snook Man's Avatar
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    The old style reverse system (black transmission) is not compatible with the 3.3 style (grey transmission). Gear ratios, transmission housings, etc are different and just dont play well together.
    No slipper/tall gearing/power = broken parts.

  11. #11
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    Quote Originally Posted by Snook Man View Post
    The old style reverse system (black transmission) is not compatible with the 3.3 style (grey transmission). Gear ratios, transmission housings, etc are different and just dont play well together.
    Yes but the part number he is referencing to is listed in the new 3.3 Maxx accessories. PN# 4995x
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

  12. #12
    RC Turnbuckle Jr. Snook Man's Avatar
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    Yes, I understand that.

    I'm pretty sure the OP is wanting to use the 3.3 reverse kit without electronic optidrive and use the old style mechanical system that prevented shifting from forward to reverse and vise/versa until the truck came to a stop.

    While very similar in the way reverse operates in both the black and grey tranmissions they are still very different.

    the 3.3 style has a plastic drive dog that slides on splines of the output shaft forward and back to engage either
    the forward or reverse gearmand is moved by the actuation of the servo, conectiing linkages and fork. The drive dog has protruding nubs on both sides that will engage/lock into the forward or reverse gear. Opti drive is an electronic optical system
    that sences movement of the primary shaft and locks out the 3rd channel/reverse switch until it no longer sences movement
    allowing for the 3rd channel to then operate the reverse servo, move the drive dog to the other gear and switch gears.

    The old style 4910 (black) tranmissions use a steel inner clutch bell that slides on a flat spotted shaft.
    The clutch bell has pins inside the inner wall lips. The reverse and forward output gears have pawls built into them
    (much like the 2nd gear clutch setup) when the gear rotates the pawl swings open and grabs a pin to turn
    the output shaft, The pawl when open also rides inside the lip of the clutch bell which prevents the accidental switch
    between forward/reverse because the servo can not pull the clutch bell lip past the open pawl.

    For what its worth, back in the day when I did run reverse in the black transmission a lot of us did the no buck mod.
    We would remove the pawls from the F&R gears and add screw pins to the gears that engaged the clutch bell instead of the pawls.
    This would allow the accidental switching from forward to reverse while the truck was moving. Not once in quite a few years of
    running that way did I ever accidentally hit the reverse switch. I did however do it on purpose a few times for scientific reasons...
    No slipper/tall gearing/power = broken parts.

  13. #13
    RC Turnbuckle Jr. JerrysMaxx's Avatar
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    Thanks for the clarification on how the 3.3 works Snook. I have never opened one of the new one's up. All mine are older and my friends hobby shop where I help out part time never had one available for me to work on.
    I never heard about the no buck mod before sounds interesting although reverse was never my thing
    T/SportMax/Slayer Pro/Bandit
    Stampede/Rustler

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