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Thread: Diff oil?

  1. #1
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    Diff oil?

    I'm trying to figure out what oil to use. I do bashing and racing (on road and off) 50/50. Thanks for the help.

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  2. #2
    RC Turnbuckle Jr. El Sob's Avatar
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    The best response I can give to you is to get several different weights of oil and try it out. I am a basher and love 100,000 weight in the rear differential. It acts like a Posi-Traction rear end! I have better launches and I can get into the throttle earlier coming out of a curve. I have the stock 30,000 in the front.
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  3. #3
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    Quote Originally Posted by El Sob View Post
    The best response I can give to you is to get several different weights of oil and try it out.
    That's the best advice.

    What one guy likes... another guy may not. If there was 1 perfect oil that could do it all, Traxxas would just sell one kind.

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    I am trying 50k front and 30k rear. So far it works great, but I've only tested it on the street. Hopefully in some loose dirt this weekend.

    I've tried a posi-type setup in my 2WD, but on that track it pushed bad in corners. For bashing it was great fun.

    I still need to order some 100K to try in the rear diff.

    I've read plenty of posts on this subject and these seems most common.
    F:30K R:50K
    F:30K R:75K
    F:30K R:100K (seems to be a favorite for bashing)
    F:50K R:50K (mixed bash and street)
    F:50K R:30K (better for mixed bash and track)
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  5. #5
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    I'm running 100K/100K but I only bash and it's winter time here with plenty of snow. The 100K gives no slip traction on the ice, etc. I'm sure I'll switch over to thinner stuff once spring hits.

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    I was under the impression that generally you want to run a lighter weight fluid in the rear than the front. Currently I'm running the stock 30k front and greases rear. I bought some 60k and 100k and plan on trying 100k front and 60k rear.

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    RC Turnbuckle Jr. El Sob's Avatar
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    Quote Originally Posted by BLachance75 View Post
    I was under the impression that generally you want to run a lighter weight fluid in the rear than the front. Currently I'm running the stock 30k front and greases rear. I bought some 60k and 100k and plan on trying 100k front and 60k rear.
    I have tried that and it didn't fit my driving style. I like for my rear end to get the most traction. I prefer rear wheel drive automobiles when I drive 1:1 cars also.
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    Quote Originally Posted by El Sob View Post
    I prefer rear wheel drive automobiles when I drive 1:1 cars also.
    Same here. I have a Dodge Ram, a Mustang and a Lincoln Town Car. No "pullers" in this house. LOL

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    Quote Originally Posted by BLachance75 View Post
    I was under the impression that generally you want to run a lighter weight fluid in the rear than the front. Currently I'm running the stock 30k front and greases rear. I bought some 60k and 100k and plan on trying 100k front and 60k rear.
    I'm under the same impression. The front helps pull it around corners better and reduces understeer from too much rear bite.

    Everyone has their own driving style though.

    I might try 50K/50K next.

    I prefer rear wheel drive over front only. Front only does help with corning though and all wheel drive being the best handling.

    With 1:1 I've experience way too much understeer which is common in American vehicles. It's supposed to be safer they say.


    Quote Originally Posted by matts175 View Post
    Same here. I have a Dodge Ram, a Mustang and a Lincoln Town Car. No "pullers" in this house. LOL
    What year Ram? I owned a 2000, 2003 and currently own a 2011. Cummins.. 12.67 in the quarter mile. Love it!
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    Quote Originally Posted by BLachance75 View Post
    I was under the impression that generally you want to run a lighter weight fluid in the rear than the front. Currently I'm running the stock 30k front and greases rear. I bought some 60k and 100k and plan on trying 100k front and 60k rear.
    A lot of bashers like the thick stuff and more rear traction bias because it makes the vehicle more stable and predictable, especially off-road, since it won't go squirly from diffing out easily. Now in a race environment it's a totally different story, you want that pull because most tracks will have lots of corners you need to take at a certain line. Most race rigs run very light oils, like 10k/10k/5k, to optimize handling and technical driving

  11. #11
    RC Turnbuckle Jr. El Sob's Avatar
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    Quote Originally Posted by matts175 View Post
    Same here. I have a Dodge Ram, a Mustang and a Lincoln Town Car. No "pullers" in this house. LOL
    At the moment I just have a 1999 Chevrolet Blazer. 4.6L V6 with a little something, something done to the motor Flow Master Dual exhaust, lowered six inches in the rear and five in the front! Does wicked brake stands and hit a corner and leave at least 100 feet of rubber. I am hoping to get another pre 1975 Chevrolet C 10 soon

    Last edited by El Sob; 01-22-2015 at 04:58 PM.
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    RC Qualifier Panamon Creel's Avatar
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    Quote Originally Posted by BLachance75 View Post
    I was under the impression that generally you want to run a lighter weight fluid in the rear than the front. Currently I'm running the stock 30k front and greases rear. I bought some 60k and 100k and plan on trying 100k front and 60k rear.
    well lets think about this, the thicker the oil the more you "lock" the right and the left wheel making it harder for them to run at different speeds. All nice and good as long as you go straight but in the corners the wheels have to run at different speeds and one will start to slip on the ground if the locking force is too high for the surface you're running on. For the front that means that you'll get the tendency to understeer if the oil is thick and for the rear you'll get the tendency to oversteer. Personally I prefer oversteer over understeer when cornering

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    Thanks for the advice. I'm getting my new Front Diff box tomorrow, as i cracked the first one going head on into a curb at 60mph. Not pretty. Going to put 30k in front which was stock

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    Quote Originally Posted by Panamon Creel View Post
    well lets think about this, the thicker the oil the more you "lock" the right and the left wheel making it harder for them to run at different speeds. All nice and good as long as you go straight but in the corners the wheels have to run at different speeds and one will start to slip on the ground if the locking force is too high for the surface you're running on. For the front that means that you'll get the tendency to understeer if the oil is thick and for the rear you'll get the tendency to oversteer. Personally I prefer oversteer over understeer when cornering
    Having the rear locked or close to it causes the front end to push out, i.e. understeer. Unless you plan on sliding the rear end around the corner.

    I had my 2wd near locked.. it was a horrible track setup. Great for bashing.
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  15. #15
    RC Turnbuckle Jr. El Sob's Avatar
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    With 100,000 weight it is not even close to being locked. The tires still spin independently. If you get hard on the throttle they almost lock up. I am able to exit corners controlled and faster with 100,000 than the stock grease. I have had the same results on pavement and dirt.
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    Which brand of oil do you guy prefer?
    I got the locker from a friend of mine. If don't like it, I'll try 100,000. It was free so I figure I'll give it a shot

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    Im running stock 30k in front and 50k rear its been pretty good for me, been thinking of trying 50/100 for winter time fun though. Sooo many choices for oil. I personally use losi or team associated, traxxas makes diff oil as well, there are quite a few different makers of oil, some use different like labels for the wt of the oil though so feel free to experiment around. Im not sure if there is an industry standard as to how they measure the wt though, so traxxas 50k could be like team associated 75k, as I said im not sure on this.

  18. #18
    RC Qualifier Panamon Creel's Avatar
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    Quote Originally Posted by El Sob View Post
    With 100,000 weight it is not even close to being locked. The tires still spin independently. If you get hard on the throttle they almost lock up. I am able to exit corners controlled and faster with 100,000 than the stock grease. I have had the same results on pavement and dirt.
    True it's never completely locked even with the heaviest oil, you'd have to mechanically block it for a complete lock. However the higher the oil weight the higher the resistance between the two wheels on that diff to turn at different speeds, too high of a resistance for the surface and you'll lose traction in the corner.

    Quote Originally Posted by BigART71 View Post
    Having the rear locked or close to it causes the front end to push out, i.e. understeer. Unless you plan on sliding the rear end around the corner.

    I had my 2wd near locked.. it was a horrible track setup. Great for bashing.
    Again my wording was a bit wrong with stating "locked", should have wrote higher friction, resistance, whatever. Sure locking the rear completely will also have a negative effect on cornering since the rear wheels also want to go straight however it will kick the rear end out and have more tendency to oversteer but that will depend on the surface, tires and other setups as well. I can guarantee you that my real life 1:1 Wranglers turned far better with just the rear locker engaged than with just the front locker engaged .

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    Quote Originally Posted by Panamon Creel View Post
    True it's never completely locked even with the heaviest oil, you'd have to mechanically block it for a complete lock. However the higher the oil weight the higher the resistance between the two wheels on that diff to turn at different speeds, too high of a resistance for the surface and you'll lose traction in the corner.



    Again my wording was a bit wrong with stating "locked", should have wrote higher friction, resistance, whatever. Sure locking the rear completely will also have a negative effect on cornering since the rear wheels also want to go straight however it will kick the rear end out and have more tendency to oversteer but that will depend on the surface, tires and other setups as well. I can guarantee you that my real life 1:1 Wranglers turned far better with just the rear locker engaged than with just the front locker engaged .
    I know what you're saying. I've ran lockers front and rear in my 1:1 75' Blazer. My buddies 77' bronco has a detroit locker in the rear. He has to be careful when the roads are slick. My Dad's old 68' Ford F250 had posi and that rear end was all over the road if you tried any throttle around a corner while raining.

    In the RC world.. on the track.. that rear end getting closer to locked was so horrible because it wouldn't allow that differential rotation between inside and outside tire on a good track. I had to go back to something more reasonable. Trying to drift an RC when you're trying to race it isn't a great setup. LOL
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    RC Champion thesmogman's Avatar
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    Just for a comparison I have found that I like for a clay wet track I run 7k front 5k center and 2k rear.
    For my on road/ testing I have 70k front 50k center and 10k rear.

    I just bought another set of diff's so I can go back and forth without messing with changing oils out.
    And a tip, I mark the diff oil I have in it with a Sharpie (silver color) on the diffs.

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    What do you mean Center? Like i said im new to the Rc world. Where is the center diff? I know of the front and rear.

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    Quote Originally Posted by rodneyddalton1 View Post
    What do you mean Center? Like i said im new to the Rc world. Where is the center diff? I know of the front and rear.
    The center diff is an option part. It replaces the slipper clutch. I would suggest a center diff for racing too.

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    I got to test out my 100k front and 60k rear setup. For me it goes way better than the stock 30k front and greased rear. The rear end has a lot more bit and the steering seems better too. I also feel it is a lot more stable going in a straight line than before.

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    I tried 2 packs with 50K front and 30K rear.

    The rear diffed out once on me. I think I'm going to try 50K F/R now.

    I'm having an issue with steering though. Sometimes it pulls left a little, I correct it with trim. Than later it pulls right, correct it with trim too. A little later it pulls left again. I've had this issue on my 2wd as well. I doubt it's the servo. I don't want to derail this thread, so if anyone has a quick tip or can point me in the right direction that would be great. If it has to do with diffs... than that could work to stay in this thread.
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  25. #25
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    I've looked at a number of posts on this subject and see 30k as being the factory weight for the front diff but haven't been able to find what the factory is running in the rear diff.

    I love the way my truck handles so I'd like to stick with the factory weights when I freshen them up, if someone could tell me what the factory uses in the rear I'd appreciate it.

  26. #26
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    Quote Originally Posted by TruSound View Post
    I've looked at a number of posts on this subject and see 30k as being the factory weight for the front diff but haven't been able to find what the factory is running in the rear diff.

    I love the way my truck handles so I'd like to stick with the factory weights when I freshen them up, if someone could tell me what the factory uses in the rear I'd appreciate it.
    The rear is filled with grease. Don't know what kind it doesn't say
    https://traxxas.com/sites/default/fi...-OM-EN-R00.pdf
    Pg 28 of the manual

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    Thanks Er...what equivalent weight silicone oil would I use, pretty heavy I would think, I'd like to keep the performance and handling characteristics as close to out of the box as possible...it just works well for me at this point.

    I'm a noob so any and all of your knowledge is beneficial and appreciated, thanks

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    Quote Originally Posted by TruSound View Post
    Thanks Er...what equivalent weight silicone oil would I use, pretty heavy I would think, I'd like to keep the performance and handling characteristics as close to out of the box as possible...it just works well for me at this point.

    I'm a noob so any and all of your knowledge is beneficial and appreciated, thanks
    Man Idk what would be equal to stock. I would say something thick as well. If start with 50wt changing diff oil is like changing shock oil. Pretty much have to find what's best for your truck and style of driving. I run 60/100 in mine and 50/100 in both my sons. And 30/100 in my wife's, her's hooks up nice and tracks straight on wheelies. She's the only ine running mt wheels and tires. The other 3 runs 1/8 on road wheels and tires

  29. #29
    RC Champion RazorRC22's Avatar
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    Quote Originally Posted by TruSound View Post
    I've looked at a number of posts on this subject and see 30k as being the factory weight for the front diff but haven't been able to find what the factory is running in the rear diff.

    I love the way my truck handles so I'd like to stick with the factory weights when I freshen them up, if someone could tell me what the factory uses in the rear I'd appreciate it.
    Spin front and rear and tell us which end seems thicker/thinner? I don't have the stock rear diff anymore, but my replacement feels pretty thick and I'm guessing it's heavier than the front. Like maybe 50k or 60k.

    When you relube the rear diff, get a new housing and seals. Grease does NOT mix with oil, and you'll want to get as much as you can out of the rear diff before you rebuild it. The housing is like $6 and way worth to just throw it away rather than try to clean all the grease out.
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    Quote Originally Posted by El Sob View Post
    I have tried that and it didn't fit my driving style. I like for my rear end to get the most traction. I prefer rear wheel drive automobiles when I drive 1:1 cars also.
    Hmm, all i want is to replace my rear bulkhead, and stop breaking my U-joints. I already tried oiling them, not helping in the least, have to replace at least 1 driveshaft per 10, 15 runs. can i get some help on this please?

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    This is a great thread, as I'm just now at the point in my rebuild that I'm in the market for diff oil.

    I'm somewhere in the middle of bashing and racing, as I have my own back yard track, which is more or less exactly like what you would find at a hobby race track, with this being said I can spend time tuning in my set-up.

    I come from a 1:1 racing back ground, and a lot of that can be translated into the 1:10 world.

    I like a car that is primarily neutral, but on the short end of being loose when you squeeze the throttle so as to be able to rotate it around a corner, this is a good trait as there is a section on my track (Rattle Snake) that is quite tight, and being able to "Step it Out" rotate the car with the throttle can help here.

    I was looking at going with a 50k oil in the rear, and a 10k in the front, I believe this wold give it a pseudo 70/30 split favoring the grip in the rear and being able to rotate the car with the throttle when needed and giving it more over steer rather than under steer.

    I like the idea of having a couple of extra diff's to be able to swap out, but I'm primarily looking for a good starting point to work with.

    Tires I'm using are the J Concepts Choppers, shocks are the GTR with the white spring with black stripe and 30w oil, on a hard packed clay, some of it is black clay when wet is very high grip, and the other areas are a tan clay with sand mixed, very good grip when wet, but has a great amount of control when using lots of throttle to rotate the car.

    Out playing in the dirt

  32. #32
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    I went 30k front and 80k rear. But only because the hobby shop didn't have 100k

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