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  1. #1
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    Big bore set up slash 2wd

    So if I keep these big bores I bought..............what springs and oil should I start with in front and rear?

    Itís got LCG chassis, most rpm parts, castle SW3 4600kv

    Would like to run on the clay track do a little jumpin on the hard clay without smack and all that lol.

  2. #2
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    The stock springs are pretty soft, so I usually recommend trying a different set of springs. Oil wise the Big Bores do well with 40-50 weight in them.
    Manager at LHS ~7 Years. I've seen some stuff lol

  3. #3
    RC Champion Mr Wolf's Avatar
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    I've run the Big Bores on my Protrac LCG race Slash for about 7 years.

    After much experimentation I ended up running with Losi Black 2" springs with 35wt AE oil up front and Losi Blue 2" springs with 30wt AE oil with at the rear. If the track is very rutted then I would use a slightly softer springs but keep the same oil. This is using the stock 2-hole shock pistons.

    Your choice of springs and oil will radically affect how the truck handles. The firmer the springs and the thinner the oil the quicker the reactions of the truck will be. It will also be more difficult to drive, especially on rough terrain.

    Remember that the true purpose of shock oil is simply to dampen the action of the springs, not prevent the chassis from bottoming out. A fine handling LCG truck will always be able to slap the chassis to the ground following a big jump.
    Pretty please, with sugar on top, clean the RC car

  4. #4
    RC Champion zedorda's Avatar
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    I admit I am not a great suspension expert but from my understanding. Raising the spring rate without changing the fluid wt just makes the suspension more bouncy but raising the wt of the fluid without changing the springs would increase damping. Because aren't the spring rates supposed to match the weight of the vehicle and the fluid wt is what you change to match the track conditions?

    I am asking because I am trying to wrap my brain around suspension dynamics and wonder if I have it wrong.

  5. #5
    Marshal Double G's Avatar
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    Makes sense to me.
    The Super Derecho

  6. #6
    RC Champion Mr Wolf's Avatar
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    As a rule, all other things being equal, a higher spring rate requires more damping. This can be achieved through thicker oil or fewer (or smaller holes) in the shock pistons.

    Creating an effective racing set-up is obviously personal to a driver, his truck and a given track. It involves getting the trade-off right between stability and agility. Compromises are made so it's important to understand the respective roles of springs and oil and the trade-offs in play.

    The resistance of the springs limit body roll and therefore weight transfer. Weight transfer positively affects grip levels but negatively impacts lateral agility i.e. how quickly a car can transfer its grip from side to side as it changes direction. Firmer springs therefore reduce the amount weight transfer and traction but improve the speed at which a truck can change direction. Firmer springs can also reduce stability on poor surfaces as they give a bumpier ride which can make the truck more difficult to control.

    Oil dampens (i.e slows) the action of the shock as it provides resistance to the piston moving inside the shock cylinder. Thicker oil provides more resistance and slows the speed of weight transfer. Using shock oil that's too thin will cause the truck to bounce too freely on its springs which will negatively impact stability. Using shock oil that's too thick will cause the suspension movement to become slow/lifeless and inhibits agility.

    I consider myself only an average club level racer but I know a good racers' preferred shock balance is more towards agility than stability i.e they use the firmest springs possible that provide just enough stability for maximum agility and pair these with the thinnest oil that provide just enough damping to be effective. If you study the set-up sheets of National level racers, you'll find they all use relatively thin oil for this reason.

    Anyway, the above is a small part of what is a ridiculously complex topic - performance car suspension. Many other factors come into play such as toe-in/out, ride height F/R, tire compound/tread/foam, wheel camber, wheel camber gain rate and droop.
    Pretty please, with sugar on top, clean the RC car

  7. #7
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    Quote Originally Posted by Mr Wolf View Post
    I've run the Big Bores on my Protrac LCG race Slash for about 7 years.

    After much experimentation I ended up running with Losi Black 2" springs with 35wt AE oil up front and Losi Blue 2" springs with 30wt AE oil with at the rear. If the track is very rutted then I would use a slightly softer springs but keep the same oil. This is using the stock 2-hole shock pistons.

    Your choice of springs and oil will radically affect how the truck handles. The firmer the springs and the thinner the oil the quicker the reactions of the truck will be. It will also be more difficult to drive, especially on rough terrain.

    Remember that the true purpose of shock oil is simply to dampen the action of the springs, not prevent the chassis from bottoming out. A fine handling LCG truck will always be able to slap the chassis to the ground following a big jump.
    so when ppl say the traxxas big bore is no good for racing, are they full of it?

  8. #8
    RC Champion zedorda's Avatar
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    Quote Originally Posted by JDS123 View Post
    so when ppl say the traxxas big bore is no good for racing, are they full of it?
    I wouldn't say big bores are not good for racing. They are lower on the performance scale compared to the other options tho. Since they have lower oil capacity than Ultras but do suffer far less failures than Ultras. With metal caps and TiN coated shafts I would say the Ultras are then better in every way to Big Bores for racing. Big Bores imo are meant for bashers with less focus on performance and more on durability for a good price.

  9. #9
    RC Champion zedorda's Avatar
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    Quote Originally Posted by Mr Wolf View Post
    As a rule, all other things being equal, a higher spring rate requires more damping. This can be achieved through thicker oil or fewer (or smaller holes) in the shock pistons.

    Creating an effective racing set-up is obviously personal to a driver, his truck and a given track. It involves getting the trade-off right between stability and agility. Compromises are made so it's important to understand the respective roles of springs and oil and the trade-offs in play.

    The resistance of the springs limit body roll and therefore weight transfer. Weight transfer positively affects grip levels but negatively impacts lateral agility i.e. how quickly a car can transfer its grip from side to side as it changes direction. Firmer springs therefore reduce the amount weight transfer and traction but improve the speed at which a truck can change direction. Firmer springs can also reduce stability on poor surfaces as they give a bumpier ride which can make the truck more difficult to control.

    Oil dampens (i.e slows) the action of the shock as it provides resistance to the piston moving inside the shock cylinder. Thicker oil provides more resistance and slows the speed of weight transfer. Using shock oil that's too thin will cause the truck to bounce too freely on its springs which will negatively impact stability. Using shock oil that's too thick will cause the suspension movement to become slow/lifeless and inhibits agility.

    I consider myself only an average club level racer but I know a good racers' preferred shock balance is more towards agility than stability i.e they use the firmest springs possible that provide just enough stability for maximum agility and pair these with the thinnest oil that provide just enough damping to be effective. If you study the set-up sheets of National level racers, you'll find they all use relatively thin oil for this reason.

    Anyway, the above is a small part of what is a ridiculously complex topic - performance car suspension. Many other factors come into play such as toe-in/out, ride height F/R, tire compound/tread/foam, wheel camber, wheel camber gain rate and droop.
    Of everything in RC suspension has alway been abit of a mystery to me. Thanks for such a clear explanation.

  10. #10
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    Quote Originally Posted by zedorda View Post
    Of everything in RC suspension has alway been abit of a mystery to me. Thanks for such a clear explanation.

    Lol yeah I will pry reread this many times myself lol

  11. #11
    RC Champion Mr Wolf's Avatar
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    Quote Originally Posted by zedorda View Post
    I wouldn't say big bores are not good for racing. They are lower on the performance scale compared to the other options tho. Since they have lower oil capacity than Ultras but do suffer far less failures than Ultras. With metal caps and TiN coated shafts I would say the Ultras are then better in every way to Big Bores for racing. Big Bores imo are meant for bashers with less focus on performance and more on durability for a good price.
    I disagree. I would say the Big Bores are a truly excellent shock for racing, provided the truck is no heavier than the weight of a 2WD Slash.

    Before I raced my LCG Slash with the BBs, I raced it with upgraded Ultras (i.e. fitted with the hardened TiN coated shafts and aluminium caps) for a few years. In fact I still run these on my modified race spec Rustler but I don't race that truck anymore.

    The durability of both these shocks on the track is excellent and, for racing purposes at least, comparable to one another. The Big Bores do however offer three (non-durability) advantages over the upgraded Ultras.

    The insides of the BB's aluminium shock bodies are coated with Teflon (a hard non-stick material) which provides two benefits over the plastic Ultra bodies. Firstly, it's smoother and has less friction. Secondly, unlike the Ultra's plastic cylinder material it doesn't rub-off so it keeps the shock oil clean. Have you ever noticed the grey colour of the oil when you tip it out of an Ultra shock? This oil pollution inhibits the smooth flow of oil through the piston holes. The third benefit for racing is that the BB's fractionally smaller spring retainers fit the Losi springs much better, my preferred tuned racing springs (something which every racer needs). Frankly, the upgraded Ultras offer 80% of the BB's performance but they are far more onerous due to the higher frequency of oil changes.

    Your comment about BBs having lower oil capacity implies that their bore is smaller than the Ultras. This is a myth that I've tried to dispel several times over the years but it keeps returning to this forum, usually from people that haven't owned big bore shocks. Their bores (i.e. internal diameter of the shock cylinder) are identical. I know because I have measured them both myself with digital calipers. BB's external cylinder diameter is smaller on account of the aluminium bodies being thinner than the plastic bodies.

    Many people switch to GTRs but I do not think they are a better race shock for a 2WD Slash. The GTRs are no doubt more durable than the BBs as they have thicker shafts and were designed for a heavier truck - the Slash 4x4. I've chosen not to switch to GTRs for racing for four reasons. 1) Their extra durability offers no advantage on a track. 2) They have threaded collars which constantly need checking with calipers or a spacer to see if they've drifted out of place - at least that's what I have to do on my Touring Car's threaded collared shocks. 3) they're heavier 4) Their extra damping from a larger bore isn't required on a truck this light - I'm only on 30wt/35wt oil as it is. For bashing though, the GTRs are top drawer shock.
    Last edited by Mr Wolf; 12-05-2019 at 05:16 AM.
    Pretty please, with sugar on top, clean the RC car

  12. #12
    RC Champion zedorda's Avatar
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    True I have not owned and am going off of hearsay about them. Not that I heard the diameter was smaller but that the pistons are thicker and there was more internal hardware to them ie more c-clips to the bottom seal. As for the PTFE coating well I think that is more to regain the loss with using machined aluminum over plastic. The cost to machine aluminum to the mirror finish you can get from cast plastic is more than just finishing it with a PTFE coating and getting nearly the same result. The grey color in shock oil is mostly from dirt coming it on the shaft and dirt imbedded in the o-ring seal wearing against the shaft(if not TiN coated) plus some wear from the piston which is softer than the shock body.

    But I sure will correct myself and not repeat that Big bores have less fluid capacity since I believe you are a more reliable source than the hearsay I was parroting.

  13. #13
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    Quote Originally Posted by zedorda View Post
    True I have not owned and am going off of hearsay about them. Not that I heard the diameter was smaller but that the pistons are thicker and there was more internal hardware to them ie more c-clips to the bottom seal. As for the PTFE coating well I think that is more to regain the loss with using machined aluminum over plastic. The cost to machine aluminum to the mirror finish you can get from cast plastic is more than just finishing it with a PTFE coating and getting nearly the same result. The grey color in shock oil is mostly from dirt coming it on the shaft and dirt imbedded in the o-ring seal wearing against the shaft(if not TiN coated) plus some wear from the piston which is softer than the shock body.

    But I sure will correct myself and not repeat that Big bores have less fluid capacity since I believe you are a more reliable source than the hearsay I was parroting.
    just wanted to say both you guys are are good cats. Chill attitudes with knowledge yet humble enough to have regular conversation vs keyboard snobbery lol.

    Thanks for all your time and info.

  14. #14
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    Quote Originally Posted by Mr Wolf View Post
    I've run the Big Bores on my Protrac LCG race Slash for about 7 years.

    After much experimentation I ended up running with Losi Black 2" springs with 35wt AE oil up front and Losi Blue 2" springs with 30wt AE oil with at the rear. If the track is very rutted then I would use a slightly softer springs but keep the same oil. This is using the stock 2-hole shock pistons.

    Your choice of springs and oil will radically affect how the truck handles. The firmer the springs and the thinner the oil the quicker the reactions of the truck will be. It will also be more difficult to drive, especially on rough terrain.

    Remember that the true purpose of shock oil is simply to dampen the action of the springs, not prevent the chassis from bottoming out. A fine handling LCG truck will always be able to slap the chassis to the ground following a big jump.

    Wait you said 2 inch springs in front and back? Is that what fits my 2wd? I thought it was 2 in front and 2.5 in back.........

  15. #15
    RC Champion Mr Wolf's Avatar
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    Quote Originally Posted by JDS123 View Post
    Wait you said 2 inch springs in front and back? Is that what fits my 2wd? I thought it was 2 in front and 2.5 in back.........
    Sorry that was a typo, you want the Losi 2.5" buggy springs in the rear.

    Here's a list of the springs. I've never tried using softer than Green at the front or Orange at the rear.

    FRONT BUGGY SPRINGS
    Losi Part #
    LOSA5128 2" Spring 2.5 Rate (Red)
    LOSA5129 2" Spring 2.9 Rate (Orange)
    LOSA5130 2" Spring 3.2 Rate (Silver)
    LOSA5132 2" Spring 3.5 Rate (Green)
    LOSA5134 2" Spring 3.8 Rate (Blue)
    LOSA5135 2" Spring 4.1 Rate (Black)

    REAR BUGGY & TRUCK (front and rear) SPRINGS
    Losi Part #
    LOSA5144 2.75" Spring 1.4 Rate (Gold)
    LOSA5146 2.75" Spring 1.6 Rate (Gray)
    LOSA5147 2.75" Spring 1.8 Rate (White)
    LOSA5148 2.75" Spring 2.0 Rate (Yellow)
    LOSA5150 2.5" Spring 2.3 Rate (Pink)
    LOSA5152 2.5" Spring 2.6 Rate (Red)
    LOSA5154 2.5" Spring 2.9 Rate (Orange)
    LOSA5156 2.5" Spring 3.4 Rate (Silver)
    LOSA5158 2.5" Spring 3.7 Rate (Green)
    LOSA5160 2.5" Spring 4.1 Rate (Blue)
    Pretty please, with sugar on top, clean the RC car

  16. #16
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    Quote Originally Posted by Mr Wolf View Post
    Sorry that was a typo, you want the Losi 2.5" buggy springs in the rear.

    Here's a list of the springs. I've never tried using softer than Green at the front or Orange at the rear.

    FRONT BUGGY SPRINGS
    Losi Part #
    LOSA5128 2" Spring 2.5 Rate (Red)
    LOSA5129 2" Spring 2.9 Rate (Orange)
    LOSA5130 2" Spring 3.2 Rate (Silver)
    LOSA5132 2" Spring 3.5 Rate (Green)
    LOSA5134 2" Spring 3.8 Rate (Blue)
    LOSA5135 2" Spring 4.1 Rate (Black)

    REAR BUGGY & TRUCK (front and rear) SPRINGS
    Losi Part #
    LOSA5144 2.75" Spring 1.4 Rate (Gold)
    LOSA5146 2.75" Spring 1.6 Rate (Gray)
    LOSA5147 2.75" Spring 1.8 Rate (White)
    LOSA5148 2.75" Spring 2.0 Rate (Yellow)
    LOSA5150 2.5" Spring 2.3 Rate (Pink)
    LOSA5152 2.5" Spring 2.6 Rate (Red)
    LOSA5154 2.5" Spring 2.9 Rate (Orange)
    LOSA5156 2.5" Spring 3.4 Rate (Silver)
    LOSA5158 2.5" Spring 3.7 Rate (Green)
    LOSA5160 2.5" Spring 4.1 Rate (Blue)
    Ok so losi 2.5 in rear and 2.0 in front right?

  17. #17
    RC Champion Mr Wolf's Avatar
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    Quote Originally Posted by JDS123 View Post
    Ok so losi 2.5 in rear and 2.0 in front right?
    Yes, that’s right.
    Pretty please, with sugar on top, clean the RC car

  18. #18
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    Quote Originally Posted by Mr Wolf View Post
    Yes, that’s right.
    Thanks bro

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