Page 1 of 3 123 LastLast
Results 1 to 40 of 109
  1. #1
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198

    How to tune your Slash 4x4 for racing on the track

    I'm kinda bored, so I figured I'd start a new thread on tuning your Slash 4x4 for racing. I don't claim to be some pro-driver or awesome racer or something, but I have a reasonable amount of experience in getting RC cars to drive pretty well and this is the part of the hobby I enjoy the most, so I figured I'd start it.

    Words of warning: it's quite possible I'm going to say something that offends people (don't use aluminum A-arms), so I apologize, but I am giving my opinion and I will always explain to the best of my ability why I think that way. I'm also sure to be wrong on something, but we can't always be correct and hopefully I will provide more good in this thread than bad. This is also going to focus on racing at a racetrack (dirt, indoor clay, carpet, whatever). It's not mean for speed runs, crawling, jumping 30 feet in the air, etc. However, if you just drive at your local BMX track or homemade makeshift track, this should also apply.

    This is going to be a multi-part series of posts, and if people have specific questions, I'll be happy to answer them as best I can. A lot of it will be obvious, but I'm going to start with the easiest/simplest stuff first and move on to more esoteric topics if people are interested. The Slash 4x4 is a pretty good platform, because it has a nice blend of adjustments, without having TOO MANY that you can get lost trying to navigate.

    So...

    #1 Get your truck in order!

    Check all your bearings, set your end points, make sure none of your hingepins are bent, your shocks have oil in them, you shocks shafts aren't bent, etc. etc. Remove the shocks and make sure your arms move up and down freely by gravity alone. Clean out your halfshafts. Remove a camber link and spin a halfshaft/axle/wheel in the wheel bearings and make sure they move freely. Those bearings go bad really easily, so replace them often. Disconnect your servo draglink and make sure the bellcranks move smoothly left/right. Remove your motor or pinion and roll the truck on a flat surface and make sure nothing is binding/dragging. Hold down the center driveshaft and turn one wheel and make sure the other wheel turns smoothly (your diff is working properly). If something is not moving smoothly, it will be impossible to tune your car and you'll be chasing your tail trying to figure out why.
    youtube.com/c/RazorRCvideos

  2. #2
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    #2 Put whatever parts you want on, now!

    Tuning is an iterative affair, meaning you will go through it, get it working well, make a change (new motor, center diff, etc.) and then have to start all over. Lather, rinse, repeat. If you're going to get an LCG chassis, put that on now! If you're going to use a lightweight battery, put that on now! If you're always adding new heavy aluminum parts, changing tires, moving your ESC around, etc., you are changing the weight balance, weight basis, roll, etc., and you'll often have to start over.

    So get that stuff, put it on now, and then we can go about actually tuning the truck. Else you will get it working pretty good, change it, and then have to start messing with springs, roll centers, etc. again.
    youtube.com/c/RazorRCvideos

  3. #3
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    #3 Set the basics: toe, camber, ride height

    OK, your truck is in decent order, you have the parts you want on it, it's time to actually do something.

    Set your ride height so that arms are level. Better yet, get yourself a ride height gauge and set the ride height front and rear. For the LCG chassis with normal race tires, somewhere around 27-28mm is a good place to start, but whatever you do, set it and stick with it. Each day you drive your car, check it before you run out and make sure your ride height is the same as before. 1mm makes a big difference believe it or not. To set it, pick up the truck with body off and electronics on, drop it from about a foot off a flat surface, and then measure the height under each diff.

    Set your camber to -1 degrees. You will need a camber gauge for this. You can use various degrees of camber, but -1 is a good safe number that will work in 95% of cases, so just go with it. Again, drop the car from a foot, measure, and then roll the car back and forth and check again. Tires are not totally round, so different spots on the tire will measure differently. Just make sure the average of the different spots is about -1 degrees (1 degree pointing inward on the top).

    Set your toe-in to 0 degrees. This means your front tires should point straight ahead. You never want the front tires pointing inward. Pointing outward (toe-out) can sometimes be beneficial in some spots, but zero degrees is a good, safe number that will work in 95% of cases. I usually just eyeball toe, there are various ways to measure it, but eyeballing seems to work fine for me.

    Set your rear toe-in to 2.5 degrees. This means using the stock black plastic rear hubs, and not the Traxxas aluminum carriers. The aluminum ones only do 4 degrees or 1 degree which is way out of whack unless you're doing speed runs or you're running on the loosest, lowest traction track in the world. 2.5 degrees is pretty close to ideal in 95% of cases, so use that! If you have a Platinum or Ultimate, it came with aluminum ones, but should have also come with the original plastic parts in the box. Put those back on.

    After all this, make sure your truck still drives straight (set your steering trim) and it's not a bad idea to re-check your EPA/dual-rate on your radio.
    youtube.com/c/RazorRCvideos

  4. #4
    RC Qualifier
    Join Date
    Jun 2017
    Posts
    361
    I am pretty sure that this will be one of best threads here


    Sent from my iPhone using Tapatalk

  5. #5
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    #4 Tires

    If you're going to get the Proline Protrac suspension kit, do it now before you buy tires. You don't want to buy a bunch of wheels and tires, and then go to Protrac later and render them all useless. I did not use the Protrac suspension on my 4x4, but I run it on my Slash 2WD. The nice thing about it is that it allows you to use Losi wheels, which are the most common wheel offset size amongst all brands of short course. I don't know how much of a difference Protrac makes to the 4x4, just something to keep in mind if you were planning to do that later.

    If you ask anyone that does any type of motorsports racing (F1, NASCAR, motorcycle, MX, etc.), they will all agree that tires are the most important thing, and it's no different in RC. You NEED to be on the right tires for your Slash, so it's critical you address this first before messing with shocks, springs, etc. Go to your local track, see what the fast guys are using, and get the same tires. For indoor clay, you want to run clay compound and sauce them with tire sauce. For outdoor dirt, you will want to use soft or super-soft compound. For carpet/astroturf, get carpet tires, etc.

    For wheels, ROAR specifies it has to be realistic-looking with spokes, so you can't use dish wheels. Get some wheels from Proline, Jconcepts or DE Racing. Traxxas-brand wheels have a weird internal taper to them and use proprietary foams, so I recommend going aftermarket. I also like bright wheels, because they are easier to see on the track and you will notice things (like your servo saver is giving) that you wouldn't with black wheels.

    Closed cell foams work best indoors because they are stiffer and support the vehicle better on the higher traction surface. On really loose bumpy outdoor tracks, open cell would probably work better because they are softer and will shape themselves to the ground better. Most tires will come with the appropriate foams for the terrain you run them on, so you should be fine there.

    OK, you got your tires mounted onto wheels now. I also balance them with a wheel balancer and lead tape, which you can definitely notice on a 4x4 vehicle with big wheels and tires. Just hold it on in the air, give it full throttle/full brake a few times, and you'll notice how much smoother it runs. Not totally necessary, but something to consider.
    youtube.com/c/RazorRCvideos

  6. #6
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Taking the time for a little more backdrop:

    I did a whole series on upgrading/tuning the Slash 2WD from bone stock to a race-capable machine. It focuses more on upgrades, but there is a lot of tuning information in there to explain the "whys" in addition the "whats". You can find the playlist here:

    https://www.youtube.com/playlist?lis...wC4RDjWaLdpqCz

    Some of it will apply to the Slash 4x4, not so much in terms of upgrades, but in terms of vehicle theory about the Slash platform in general. I'm also going to go more high-level in this thread (just do this and not that) so that each post isn't like 20 paragraphs, but if people want to know more about a specific topic, let me know and I'll do my best to explain in more detail.

    Or if this thread bores you or you want me to stop, let me know too! Obviously I'm not doing this for my own edification!
    youtube.com/c/RazorRCvideos

  7. #7
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    #5 Shocks

    Ok, it's time for everyone's favorite topic, shocks! The stock springs on the Slash 4x4 are too soft for any sort of racing, and meant more for all-purpose bashing. You're going to be going FAST and you need something that will hold up. Let's talk about the Traxxas shocks that are available and what to do with them:

    Ultrashocks: these are the plastic shocks that come on the lower-end models. Not my favorite shocks, because they always leaked on me, the shafts are prone to bending, and the plastic caps pop off. Get aluminum shock caps at a minimum. If you're going to use these, start with black Losi 2" springs up front and blue Losi 2.5" springs in the rear. The Slash is a heavy vehicle, and these shocks (and 10mm shocks in general) were originally designed for lightweight buggies and stadium trucks. They are barely adequate for short course. Shock weight, I would start with Associated 35wt oil in the front and 30wt in the rear.

    Big bore shocks: Never ran these, don't really see a reason to buy them. They're the same as Ultrashocks AFAIK, just in aluminum.

    GTR shocks: This is what I ran on my 4x4. I ran a rear shock tower with rear GTR shocks in the front. This gives the front suspension more droop (downward travel) because stock Traxxas shocks are a little short in front, having been originally designed for buggy/stadium truck. The rear shocks in the front also allow you to use TEN-SCTE front springs all around, I ran SCTE black front/blue rear on high traction, and blue front/green rear on low traction. If you run Traxxas GTR springs, run blue front and rear (the stiffest springs). Start with 30wt Associated oil in the front and rear.

    If you're SERIOUS about racing, I'd look into TLR shocks. That's what I run on my Slash 2WD, and the performance is amazing, and more importantly, you have a much wider range of springs and pistons to work with. 12mm bore shocks are the standard in 1/10 scale racing, and even the newer TEN-SCTE trucks come with 12mm shocks (not the 13mm bore of the original).

    Also a note on shock oil: there is no standard on viscosity from the various brands, so stick with one brand. I generally use Team Associated oil, because it's the most commonly available race oil available and comes in every viscosity. TLR oil needs to be about 2.5wt heavier as compared to Associated oil (i.e. 30wt Associated = 32.5wt TLR).

    Shock springs are always going to stiffer in the front, and usually a heavier wt oil as well. The Slash 4x4 is the only vehicle I found that seemed to run better with equal or slightly heavier wt in the rear, but it will depend on your track and shocks.

    Now mount the shocks onto your truck into the middle hole up top and the stock location on the bottom. Check that your droop seems reasonable (rear wheels should extend down a little more than the front, maybe a half inch). And then... do the drop test!





    Pick your truck up about 18 inches off the ground, and drop it level so that all of the wheels hit the ground at the same time. Use your phone camera on slo-mo and record it. What you want to see is that the whole truck evenly compresses when it lands, and then rebounds smoothly and evenly. If the chassis slaps, your springs are too light or your shock oil is too light. If one end moves down or up faster than the other side, you will need to slow down that side (or speed up the other).

    This particular video is what I was running for very high traction indoor clay. If you're running on a lower traction, bumpier surface I'd aim for a little faster rebound, meaning I'd go with a slightly lighter shock oil.

    This test will get you in the ballpark of what you're looking for in terms of shock performance.
    Last edited by RazorRC22; 05-08-2018 at 05:00 PM.
    youtube.com/c/RazorRCvideos

  8. #8
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    SUBSCRIBED! I might have to disassemble my slash 4x4 MaX-D monster truck and put some racing tires and a short course body back on it and take it to the track for some fun! WOO-HOO..

    Sent from my VS985 4G using Tapatalk

  9. #9
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    Say good bye!

    Sent from my VS985 4G using Tapatalk

  10. #10
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    There's one thing that I never liked about the stock slash 4 x 4 with GTR shocks, the front shocks were just too dang short. I'm anxious now to try my truck in short course version at the track being that I have rear shock Towers on the front

    Sent from my VS985 4G using Tapatalk

  11. #11
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    That's enough typing for now. Gonna take a little break for awhile.
    youtube.com/c/RazorRCvideos

  12. #12
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Hmm, I guess this topic is too esoteric for the usual Slash 4x4 crowd? If there are only like 3-4 people interested in this, I guess I'll shelve the thread, as it's kind of a lot of effort.
    youtube.com/c/RazorRCvideos

  13. #13
    RC Racer
    Join Date
    Apr 2018
    Location
    Downriver,Michigan
    Posts
    147
    Please reconsider your plans. I enjoy the thread and your format. Its perfect timing also, I will be watching my son unbox his Slash in about a week. I appreciate all the work!

  14. #14
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    When I was racing my slash 4 x 4, I actually had pretty good results being an average driver finishing in the middle to the top of the B-main. I did indeed beat some Losi and Tekno trucks during those times. When the drivers found out that they got beat by a slash they were Furious! I just chuckled to myself, but then everyone wanted to see what was under the hood so to speak. Shortly thereafter, I shelved the Slash to drive my tlr 22 SCT 2.0 2wd truck in the 4 X4 class. I'm actually a better 2wd driver as I was turning laps as fast if not faster with the tlr truck than I was with a slash 4x4. My problem was that I was driving the slash 4x4 like a 2wd truck as that's what I was used to. Had I actually driven the slash like it should have been driven, I probably would have finished higher on the leaderboard and perhaps even made it to the a-main.

    Not that the slash was a slouch by any stretch of the imagination. I did have the pro Trac suspension on it which really did make the truck drive and handle better especially in the rough parts of the track and I could take Corners a lot harder and faster than I could with the stock suspension. The main reason for the pro Trac on the Slash was to be able to share Wheels with the 2wd if need be. I put the pro Trac on my slash 2wd for the same reason.

    I actually let a buddy of mine who is a sponsored Tekno driver take my slash 4 x 4 for a spin around the track. He couldn't believe that he was driving a slash. He said it didn't feel like a slash at all but more like a Losi or Tekno. He said it felt like a racing machine not a stock slash. His words not mine.

    Now that I have the carbon rear shock Towers on the front and rear, I'm going to put my slash back together as a Short Course Truck and take it back to the track to see what it can do.

    Razor, I would love your feedback and input on this and implore you to continue this journey with the Slash 4x4.



    Sent from my VS985 4G using Tapatalk
    Last edited by MaXDee; 05-09-2018 at 06:45 PM.

  15. #15
    RC Turnbuckle Jr. Squeegie's Avatar
    Join Date
    Jun 2014
    Location
    Southern California
    Posts
    7,567
    I do not race, but for those that do, I am sure your thread would be an invaluable source of knowledge.

    Please keep this thread going.
    Creativity is intelligence having fun. -Einstein

  16. #16
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    I don't know why it wasn't obvious to me earlier that the actual % of Slash 4x4 owners that are interested in racing their truck, willing to take the time/effort to learn how to tune it, and then actually apply it and not give up after 2 races and buy another brand is like, really low. Maybe 1%?

    Most people just want to stick a Mamba Super Max Pro Castle Sidewinder 6000kV motor in their truck and call it a day. And then get a steel spur gear, MIP driveshafts, 17mm hexes, RPM arms, aluminum shock towers and then wonder why their diffs explode every other run. I guess.

    Kind of a shame, because something like the Platinum Slash 4x4 is actually a pretty good race truck right out of the box with like a couple of upgrades. If you look at my setup sheet in the Steve Slayden thread, there are hardly any upgrades in it and I could keep up with 1/8 scale E-buggies at my local track. The 2WD Slash pretty much sucks as a race vehicle unless you sink $500 into it, but a stock Platinum Slash 4x4 is really good.

    So I guess the conclusion is that if you want to race, just throw my setup on there, see if you like it and call it a day. That's about 90% of the results for about 1% of the effort. If you have specific questions, I'll answer them.

    So here's my 3-step guide if you want to race a Slash. Get your Platinum, and:

    1. Put in a real servo and get rid of the servo saver.
    2. Put rear GTR shocks and shock tower on the front.
    3. Put on my setup below. Not just some of it, you have to put on all of it. A cake isn't going to taste very good if you only use half of the ingredients.

    That's it!

    youtube.com/c/RazorRCvideos

  17. #17
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    Razor, I'm going to try your set up. I drive on med/high bite clay outdoors. Did you not have a sway bar on the front?

    Sent from my VS985 4G using Tapatalk

  18. #18
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Quote Originally Posted by MaXDee View Post
    Razor, I'm going to try your set up. I drive on med/high bite clay outdoors. Did you not have a sway bar on the front?

    Sent from my VS985 4G using Tapatalk
    No front sway bars. I tried it and it just took away corner entry steering, and I don’t think it’s necessary.
    youtube.com/c/RazorRCvideos

  19. #19
    RC Racer
    Join Date
    Apr 2018
    Location
    Downriver,Michigan
    Posts
    147
    Shocks,center diff and sway bars, are what makes a Platinum a Platinum?
    Last edited by Workingstiff; 05-10-2018 at 10:20 AM.

  20. #20
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    Quote Originally Posted by RazorRC22 View Post
    No front sway bars. I tried it and it just took away corner entry steering, and I donít think itís necessary.
    This answers my corner steering dilemma that I had. I was always running silver sway bars front and rear

    Sent from my VS985 4G using Tapatalk

  21. #21
    RC Qualifier
    Join Date
    Apr 2015
    Posts
    779
    DANG! With a few tweaks here and there, I'm sure I could probably make it into the a-main!

    Sent from my VS985 4G using Tapatalk

  22. #22
    RC Qualifier
    Join Date
    Jan 2018
    Location
    North Texas
    Posts
    398
    Quote Originally Posted by RazorRC22 View Post
    No front sway bars. I tried it and it just took away corner entry steering, and I don’t think it’s necessary.
    Really? I guess that makes sense. My track is kind of loose so I have front and rear sway bars to kick the rear out a little in corners.
    Guess who's back.
    Back again.

  23. #23
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Rear swaybar will help reduce rear roll (and traction) and allow it to swing out/kick out in the corners to allow the truck to rotate more. It will also help stabilize the truck in high-speed sweepers and not fold over as much. I ran silver in the rear.

    Front swaybar would basically do the same thing to the front (not roll as much, slide more), but that just makes the truck push/understeer in the corners, especially on corner entry, so you just end up losing steering.

    Only place I could see you might want front swaybars is if you were on a really fast track with high speed corners just because so much weight is transferring to the outside.

    This is all assuming you have the proper springs -- if you're running too soft springs on your truck, swaybars will help mask that problem, but the real fix is to get stiffer springs.
    youtube.com/c/RazorRCvideos

  24. #24
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Quote Originally Posted by Workingstiff View Post
    Shocks,center diff and sway bars, are what makes a Platinum a Platinum?
    It's got all aluminum front steering blocks/spindles, rear aluminum hubs, Velineon electronics, no radio/receiver and an unpainted body.

    BTW, there's some subtle things in my setup -- I ran 1.5mm pistons front and rear, which come on the front GTR shocks. Normally the rear GTR shocks come with 1.6mm pistons. This adds more pack, which helps the truck land without bottoming out as much, or if you have a track with really short, steep ramps, it helps prevent it from chassis slapping off the face of the jump (which causes the dreaded nose-dive).
    youtube.com/c/RazorRCvideos

  25. #25
    RC Racer
    Join Date
    Apr 2018
    Location
    Downriver,Michigan
    Posts
    147
    This seems like a really awesome intro to shock setup 101!

  26. #26
    RC Racer
    Join Date
    Apr 2018
    Location
    Downriver,Michigan
    Posts
    147
    WTH!, how did I miss that entire shock post,sheesh.....GREAT thread!

  27. #27
    RC Competitor
    Join Date
    Aug 2013
    Location
    Orlando
    Posts
    88
    Great thread. And if you guys do a quick search you will see that last year I was looking for this info. I pm’d Razor a few times, used some of his recommendations and went on my own. I was able to make great strides with my Platinum and did/still do very well with it. Is it my Tekno? No. But it can hang pretty well. I will say that using the GTR REARS in front along with the corresponding tower made a huge improvement. I will also say that many on here say that because of the diff designs that you must use a thicker than normal fluid. I thought so too until I tested a bunch. I landed at 30/30/7 for a fairly loose low grip track and it works well for me.

    Thanks for the effort Razor. I say keep the thread going as there are plenty out there who still find the info useful. I’d be happy to chime in with some of my findings as well if prompted.

    Tony

  28. #28
    RC poster
    Join Date
    Apr 2018
    Posts
    1
    Thank you for the info. I really enjoy reading well put together information and would enjoy more if you would write more. Thanks again.

  29. #29
    RC Competitor
    Join Date
    Mar 2018
    Location
    NorCal
    Posts
    72
    Great thread, while I may never race this truck seriously, I really appreciate the setup tips to make this rc handle better.

  30. #30
    RC Competitor
    Join Date
    Mar 2018
    Location
    NorCal
    Posts
    72
    RazorRC22, question on the rear shock tower moved to the front. Did you Dremel it out to make the tower fit the correct direction, or mount the tower backwards and relocate the arms to the back of the tower so as not to interfere with the shocks? Can you attach a picture of two?

  31. #31
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Quote Originally Posted by Trajan View Post
    RazorRC22, question on the rear shock tower moved to the front. Did you Dremel it out to make the tower fit the correct direction, or mount the tower backwards and relocate the arms to the back of the tower so as not to interfere with the shocks? Can you attach a picture of two?
    It's mounted backwards, here's a blog post on it with some pictures. You can still run the shocks on the front of the arms.

    http://razorrcblog.blogspot.com/2016...-on-front.html
    youtube.com/c/RazorRCvideos

  32. #32
    RC Competitor
    Join Date
    Mar 2018
    Location
    NorCal
    Posts
    72
    [QUOTE=RazorRC22;6451645]It's mounted backwards, here's a blog post on it with some pictures. You can still run the shocks on the front of the arms.

    http://razorrcblog.blogspot.com/2016...-on-front.html[/QUOTE
    Thanks. Have you had any issues with camber link at the slight rearward angle?

  33. #33
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Quote Originally Posted by Trajan View Post
    Thanks. Have you had any issues with camber link at the slight rearward angle?
    No, they work fine.
    youtube.com/c/RazorRCvideos

  34. #34
    RC poster
    Join Date
    Oct 2017
    Posts
    3
    Hellou from Finland!

    Like to share my setup also which is made for SSC8 LCG chassis Slash 4x4 but works also with stock LCG chassis.

    I have GTR front and rear shocks and normal aluminium shock towers front and rear. I have fine tuned this setup now half year and its very good base setup for all surfaces and tracks. My truck has HW Xerun 4300kv motor and XR8SCT ESC + Sanwa MT44 controller + Highest DLP750 servo.

    Many drivers here have liked this setup which goal was to make Slash 4x4 fastest Short course truck on race track.







    Last edited by VulvoS40T4; 05-22-2018 at 01:19 PM.

  35. #35
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Ok, I’m sitting around waiting for a smog check, here’s a post from my blog a few years ago.

    #6 Center differentials

    One of the most misunderstood tuning options for the Slash 4x4 is the center differential. I’ve read a lot of posts on center differentials, and the majority say: use a slipper clutch for bashing, and a center differential for racing.

    I would agree with that statement, but why is that? To understand why, you have to first understand what the two devices do and the differences between them.


    Slipper Clutch

    In a Slash 4x4, power is normally distributed equally front to rear, left to right.

    50% of the power goes to the front, 50% to the rear. And at each end there is another differential that allows the left and right wheels to turn at different rates. When going straight, the left and right wheels will turn at the same speeds. When turning, the outside wheel needs to turn faster than the inside wheel. I think most people understand that.

    What the slipper clutch does is allow the whole drivetrain (all the power in the system) to slip when necessary. The tighter you make the slipper clutch, the harder it is to make the drivetrain slip. The looser, the easier. When does it slip? When the motor is trying to turn at too much of a different rate than the wheels. When you take those giant 20 foot jumps and land with the car going 20 mph and the motor pinned at 40mph, the slipper will slip instead of grenading your drivetrain. This is a good thing and prevents parts from breaking.

    You can also do some tuning for low traction conditions: when you mash the throttle and the motor tries to turn at a ridiculous speed, a looser slipper will slip rather than instantaneously try to apply full power and spin the wheels. This is often used in 2WD cars to provide a primitive form of traction control.


    Center Differential

    Now the center differential is more complicated, and nearly everything I read about it on Slash forums is wrong. At its most basic, the center differential allows the front and rear wheels to rotate at different rates, much like the front/rear differentials allow the left and right wheels to rotate at different rates.

    Why is this helpful? This link has the best description I’ve seen, and I never see anyone explain this simple concept, even though it’s extremely important:

    http://4x4abc.com/4WD101/abc4.html

    Most people say “You need a center diff to handle better. You need one for racing. It drives better”. Well OK, but why? What does “handle better” even mean? In what way does it “drive better”?

    In a turn, the front wheels and rear wheels need to rotate at different speeds because each wheel is not following the same line in a turn! The outside front wheel has to travel the furthest, and the inside rear wheel the shortest. So to keep each wheel spinning at its correct rate, the front output shaft from the center diff needs to turn faster than the rear output shaft.

    This is what the center diff does – it allows the front wheels to turn faster than the rears. Or: in a turn, more power goes to the front and less to the rears. If you lock down the center diff (super thick fluid, or use a locked down slipper), the front and rears have locked down output shafts and cannot spin at different rates.

    A slipper clutch can’t produce the same effect – power is always equal front and rear, it only allows the whole system to slip, not individually front and rear.

    This is why 4-wheel drive cars “handle better” with a center differential. The wheels can follow their natural line more easily. As a result, the car doesn’t push as much and will follow the line you’re pointing the front wheels at.


    Center diff: wheelie control

    Another effect of a center differential occurs when only two wheels are on the ground. With a tight slipper, you can easily wheelie with a powerful motor, because the front will lift (rear will squat). The rear wheels will still get their normal % of power no matter what you do and will continue to drive the car forward (or upwards!).

    With a center diff, as the front wheels rise and start to lose traction, it automatically starts transferring power to the end with less traction. The rear wheels are stuck to the ground, but the fronts are in the air and able to spin more easily. Since they can spin more easily, they do, and power will transfer to the wheelying front wheels and away from the rear. This reduces overall motor power applied to the rear. You can tune the anti-wheelying effect of the center diff by using thinner/thicker fluid.

    While big wheelies look cool, they usually aren’t the fastest way to accelerate. By not wheelying, you may be able to accelerate faster! Advanced race motorcycles usually have anti-wheelie control to accelerate the bike faster, and the same concept can be applied to RC cars. It’s also easier to steer when the front wheels are on the ground…


    Center diff: disadvantages

    So we’ve talked about all of the great things about a center diff, what are the downsides? Well, first, the device is much more complicated and prone to failure than a simple slipper clutch. It’s also more work to maintain and tune and get right, since you have to remove it, drain it and refill fluid. With a slipper, you just take a wrench, adjust it, and you’re on your way again in 10 seconds or less.

    Another effect I found is that there are sometimes track features where you still want maximum power applied to the (rear) wheels when you only have 2 of the wheels on the ground (2 in the air).

    At my local track, the current layout has a set of 3 small doubles that we call the rhythm section. You basically have very small windows in which to jump the car, land it, and then immediately jump again. And you have to do this 3 times in a row.

    With the very small area in which to jump, land, and then jump again, it’s very difficult to land all 4 wheels at the same time perfectly. If you don’t, however, when you hit the throttle to go off the next jump, power will be bled away from your (rear) drive wheels to the wheels in the air. The overall effect is that you don’t get very good drive, and it’s difficult to generate enough momentum to make the next double.

    With a slipper, this effect is negligible. With a tight slipper, even if only the front wheels or the rear wheels land, you can still get very good forward drive (just like you can when wheelying) to accelerate the car and make the next jump. I actually convinced my friend Alex to put a slipper clutch in his race Slash 4x4, just to make this section easier to do, and he found the results profoundly better.

    In a 2WD car, the rhythm section is also fairly easy because you always get full power applied to the drive wheels to help you accelerate for the next double. Even expert 4x4 short course drivers (using a center diff) have a difficult time making the series of jumps, while it’s fairly simple in a 2WD short course truck (my TLR 22 SCT, for example).

    The final disadvantage of a center diff is that it does not protect the drivetrain as well as a slipper clutch. When you land all 4 wheels at the wrong speed (relative to the motor RPM), there is nothing to slip and bleed power off. The best it can do is bleed power off to a wheel that has less traction, but this isn’t always possible. Overall the drivetrain will take more of a beating.
    Last edited by RazorRC22; 05-30-2018 at 12:09 PM.
    youtube.com/c/RazorRCvideos

  36. #36
    RC Qualifier
    Join Date
    Nov 2017
    Location
    Planet Earth...I think?
    Posts
    541
    The 4x4 lcg platinum setup sheets were helpful. Could you do one for outdoor off-road racing on an 8th scale clay track? (It’s very green. It was just made a little under a month ago. I’ll be racing a lcg sl4sh soon! It’s just the moneyyy. hopefully I can save up enough to race soon! I’ll have race footage on my YouTube channel when I start. (EvHexRC 1)
    Last edited by EvHexRC; 05-30-2018 at 12:23 PM.
    $+RC+more$+friends+more$=FUN!
    YouTube: EvHexRC1

  37. #37
    RC poster
    Join Date
    May 2018
    Posts
    3
    subscribed, this seems like a very interesting thread

  38. #38
    RC Racer
    Join Date
    Apr 2018
    Location
    Downriver,Michigan
    Posts
    147
    Nice job, very interesting and informative.

  39. #39
    RC Competitor
    Join Date
    Mar 2017
    Posts
    51
    Razor thanks for putting this together. I used your advice that you provided in my setup thread and I was able get my slash under control on a local indoor track. It is way more enjoyable now that I can actually make the corners without rolling over.

  40. #40
    RC Champion RazorRC22's Avatar
    Join Date
    Sep 2015
    Posts
    2,198
    Quote Originally Posted by Aliensrgr8 View Post
    Razor thanks for putting this together. I used your advice that you provided in my setup thread and I was able get my slash under control on a local indoor track. It is way more enjoyable now that I can actually make the corners without rolling over.
    Awesome, glad to hear it!
    youtube.com/c/RazorRCvideos

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •