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  1. #1
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    Question Sealed Differential

    i am running thick diff fluid in my stock slash gearbox and i hate how overtime it leaks out. so i have been looking at the flm sealed diff, but i am a bit worried about the price also i have read that it will change the ride of my truck, just wondering waht you guys think.
    Slash 2wd Vxl, ERBE; Crash N Learn

  2. #2
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    or why dont dont u seal the diff you have hella easy and better. yup instead of losing spead going up on one wheel youll have kinda a posi rear end

  3. #3
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    New gears, red anodized on new FLM units, O-rings at top of gear and each half where output axle goes through. This is filled with 100k lube. Too bad it is hidden inside the trans LOL
    FLM (Fast Lane Machine) diff is pretty trick and pretty tight tolerances. I have one installed on an Anza-Slash build but have not run it yet. I put 100k diff lube in it to hopefully stop the power from unloading to the inside wheel. The 'seal your own' diffs are a bit iffy from what I see.
    You can spend the $45 at SpecPointConcepts and just buy a new set of planetary gears for cheap and some 100k diff lube and be done with it or..........Hot Racing offers a solid spool to install if you want to chance the impact it will have on trans and axles. My thought is if you don't do extreme bashing that the solid spool on a dirt track might do very well. If you are looking for a little 'give' then the FLM diff is your only other choice.

    I am surprised there are no other big players that offer a better diff for the Slash. The open one from the factory helps save trans and axle/driveshafts parts but does a much less than ideal job delivering bite to both tires in cornering situations and a loss of forward bite and travel will contribute to roll overs.

    As far as changing the ride of your truck I think it will be a positive change and increase your cornering speeds and forward bite and acceleration. If you are going to launch off huge jumps I see not adavantage in it at all.
    Last edited by kwitty; 05-02-2012 at 10:25 PM.

  4. #4
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    Thanks Kwitty, after reading this i definetly want one... only thing is i have read lots of revews on the internet about how finicky they are and how hard they are to install, i'm pretty good with diffs, at least fullsized car ones, but the revews are scaring me.
    Slash 2wd Vxl, ERBE; Crash N Learn

  5. #5
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    I just took the stock diff apart and packed it with silicone brake slider grease ( from automotive shop ) . Keeps the diff locked up on loose dirt/ one wheel airborne and allows slip with high traction . Stays in the diff and hasn't leaked out - if it does it don't hurt anything .

  6. #6
    RC Turnbuckle Jr. rag6's Avatar
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    I hope pro line will sell the diffs from their gearbox separately. Hopefully it will be as durable and leakproof as the flm.

  7. #7
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    Quote Originally Posted by wmckay96 View Post
    Thanks Kwitty, after reading this i definetly want one... only thing is i have read lots of revews on the internet about how finicky they are and how hard they are to install, i'm pretty good with diffs, at least fullsized car ones, but the revews are scaring me.
    I was a little unhappy with the seating of the O-rings in the outer cases, called FLM and they sent new ones. There have been some upgrades and this red anodized body is supposed to be the newest version. They don't give any included instructions of which they should. They gave me three flat shim washers which made me wonder???? Well one was an extra LOL. You place one over each O-ring to protect it from the axle gear that sets on top of it. You need to make sure the O ring is correctly seated because if not it push up the axle gear and bind it on the lower planetary gears next to it!
    Assemble in a few dry runs and you will understand, you won't have any problem figuring it out. You won't need to fill past the drive gear large seated O ring either, when you place the other half with the other axle gear it will displace the oil up through the four mounting bolt holes so I found it best to just use two bolts to correctly position it then set it on top and let it settle in slowly and push that thick diff oil up the other two holes as needed.

    Hope that makes sense and if not PM me if you think I can be of more help

  8. #8
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    Quote Originally Posted by rag6 View Post
    I hope pro line will sell the diffs from their gearbox separately. Hopefully it will be as durable and leakproof as the flm.
    That sounds encouraging! There should be more than one choice, I still think there is a better system to be had for us on these that is adjustable from the outside somehow or a mini-locker system.

  9. #9
    RC Turnbuckle Jr. rag6's Avatar
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    Kwitty, must the dif be packed full(no air)? My 1/8 buggy diffs did not require to be more than 3/4 full to work effectively

  10. #10
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    Quote Originally Posted by rag6 View Post
    Kwitty, must the dif be packed full(no air)? My 1/8 buggy diffs did not require to be more than 3/4 full to work effectively
    My thought on this is fully submersing all gears in the lube provides equal action and no air voids that may be inconsistent at times and no actual slinging off of the lube that creates the resistance for the ability to engage longer before unloading to one wheel.
    Are the buggy diffs planetary or ring gear type??

  11. #11
    RC Turnbuckle Jr. rag6's Avatar
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    They are not the planetary type. I am gonna have to ask around. It was my understanding that with these thicker oils, that the diffs did not need to be completely full. It does not matter what type of gear diff it is. The oil sticks to the teeth, and works the same in both types.

  12. #12
    RC Turnbuckle Jr. O.G.'s Avatar
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    I hav an FLM diff on order and it should be here any day. I can't wait to drop it in my racing slash.

    Sent from the cockpit of my Jeep Wrangler
    My Black & Blue Rally is faster than your color...

  13. #13
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    Swami's has a sealed diff that is all metal and looks heavier duty than the FLM but is about $25 more expen$ive.

    Sent from the cockpit of my Jeep Wrangler
    My Black & Blue Rally is faster than your color...

  14. #14
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    Quote Originally Posted by rag6 View Post
    They are not the planetary type. I am gonna have to ask around. It was my understanding that with these thicker oils, that the diffs did not need to be completely full. It does not matter what type of gear diff it is. The oil sticks to the teeth, and works the same in both types.
    I guess as long as the gears stay in a bath of the lube it would be fine but not as full of a benefit. If not for the sealed ability of the FLM then it wouldn't be any different than the. Traxxas unit. I can't imagine enough diff action as a benefit from only the bind up created by about two teeth meshing with the lube as the friction agent. Submersing the gears would only add greatly to the resistance created on all surfaces effected by being in the diff fluid which would account for an increase in the ability to slow down blow out to the wheel that becomes unloaded..

    Problem is this is really a poor way in the first place to accomplish a bind or locking action to solve the problem. I don't know of any automotive differentials that even begin to use the 'lube' as the device that creates the locking action we are looking for.
    GM used an advanced G-rotor pump that hydraulically created a very advanced trac system but others as we know are clutch engaged (posi) or gear engaged (locking) type or totally solid as in a spool.

    So, we needed to design a diff that is frictional plate adjustable and we just need a hollow axel that we can slide an adjusting tool into to tune the amount of friction we want it still baffles me that the best we have to work with is simply by fluid or it's tackiness ability to bind gear mesh, very crude and the wrong way to go about resolving the issue..

    Maybe a unit with a central gear with an adjustable clutch on each axel independent, you could bias the bite to the tires getting the weight transfer like in your circle track racing maybe even a internal drive gear with external clutching at the output shafts..
    Last edited by kwitty; 05-06-2012 at 08:20 PM.

  15. #15
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    Quote Originally Posted by O.G. View Post
    Swami's has a sealed diff that is all metal and looks heavier duty than the FLM but is about $25 more expen$ive.


    Sent from the cockpit of my Jeep Wrangler
    I can't seem to find the one you mention ? Help!

  16. #16
    RC Turnbuckle Jr. O.G.'s Avatar
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    Go to swamirc website and you'll find it. Last I checked it was about $70 for an all-metal differential. I believe the FLM has an external plastic gear.

    Sent from the cockpit of my Jeep Wrangler
    My Black & Blue Rally is faster than your color...

  17. #17
    RC Turnbuckle Jr. O.G.'s Avatar
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    Now that I'm home, I can post a link to the swami-rc website. The diff is 74.95 + shipping.

    http://www.swami-rc.com/ordering/

    I really, really like their wheelie-bars.
    My Black & Blue Rally is faster than your color...

  18. #18
    RC Turnbuckle Jr. rag6's Avatar
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    The flm diff has all metal construction. No plastic.

  19. #19
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    thanks for the imput every body... i have ordered and flm diff. while i was at my Lhs wes told me about the new proline transmission and diff, it sounds pretty exciting! i might have to buy another slash so that i can compare the two!
    Slash 2wd Vxl, ERBE; Crash N Learn

  20. #20
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    Quote Originally Posted by wmckay96 View Post
    thanks for the imput every body... i have ordered and flm diff. while i was at my Lhs wes told me about the new proline transmission and diff, it sounds pretty exciting! i might have to buy another slash so that i can compare the two!
    I'm still waiting on my FLM diff to arrive. Can't wait to get it into my Truck!!
    My Black & Blue Rally is faster than your color...

  21. #21
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    Im Back!!!! hey everybody sorry to revive an old dead thread (no pun inteded) but my FLM diff FINALLY arrived yesterday it has been like 2 months!! i havent driven my slash latley because i was waiting for the diff to arrive so i decided to rebuild it all. anyways im back into the transsmision and setting up my diff do the stock traxxas internals work in the FLM diff? what weight fluid are you guys using?
    Slash 2wd Vxl, ERBE; Crash N Learn

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