Simultaneous blown stock kraton tires

[Toddys]

While running over the weekend on 6s, both of my front tires blew at the same time. I have 20 K front 100K Center and 50k rear diff oil. The good news is hobbico is sending me a set of backflips under warranty. I'd like to avoid this occurring again so I plan to put 200k in the center diff and leave the other oils as they are. Does anybody else have any recommendations Beyond this? I don't understand why Proline or some other company has not come out with belted off-road tires that will avoid ballooning.

 

[Jerry-rigged]

For 6s running, pretty much the only solution is taping or fishing line. One of the reasons I run 4s.

 

[TooTall]

While running over the weekend on 6s, both of my front tires blew at the same time. I have 20 K front 100K Center and 50k rear diff oil. The good news is hobbico is sending me a set of backflips under warranty. I'd like to avoid this occurring again so I plan to put 200k in the center diff and leave the other oils as they are. Does anybody else have any recommendations Beyond this? I don't understand why Proline or some other company has not come out with belted off-road tires that will avoid ballooning.

Do you have 20K in front and 50k in rear like you say?

If so, that is probably why they blew.

You want lighter fluid in rear so it will get power applied easier, thus putting more power to rear wheels.

If you have lighter fluid in front, they will get more power and spin higher rpm as they will have less power under acceleration and break loose easily.

I don't think there is any difference in the actual diffs, so you can probably just pull them and swap them front to rear and see if it is better, the diff fluid weights you said you have in were the standard recommendation for a long time.

Lately, more are going to super heavy centers, like 500K or even 1 millionK.

TT

 

[bicketybam]

The fluid in the differentials will control the power delivery from one half of the diff to the other. In the front and rear, that means the left and right tires. Lighter fluid up front actually helps turning because in order to effectively turn one wheel needs to spin faster than the other. The center diff is what controls power front and rear as the diff is turned sideways in relation to the two others. Heavy fluid will help keep both halves (front and back) spinning at the same pace.

People will go heavier in the front so when they turn under acceleration, the wheel opposite the turn doesn’t turn even faster and ballon up as the diff tries to get it more traction. I believe the tires blew because of the lighter center diff oil as opposed to the lighter front oil.

 

[TooTall]

These are normal diffs, not limited slip.

The easiest to spin wheel or in case of center diff the easiest to turn front or rear diff will get more power.

Add that to the fact that naturally when accelerating the weight transfers to the rear, and the fronts will spin extremely fast when under high acceleration when their is lighter fluid in the front.

The heavy fluid in the center tries to equalize the power deliver more one way or the other, but outside of a locked diff one set of wheels will get more power from the center diff.

You watch some videos on YouTube and you see even the guys running 1000K still have balloon issues.

I agree with @bicketybam that some racers run heavier in front on certain tracks to aid in handling, but for general bashing (which I assumed was the case here) heavier in the front should reduce front tire spin.

100K up until recently was always considered heavy in the center, these high power 6s rigs are what brought about the use of 500K or 1000K.

TT

 

[bicketybam]

These are normal diffs, not limited slip.

The easiest to spin wheel or in case of center diff the easiest to turn front or rear diff will get more power.

Add that to the fact that naturally when accelerating the weight transfers to the rear, and the fronts will spin extremely fast when under high acceleration when their is lighter fluid in the front.

The heavy fluid in the center tries to equalize the power deliver more one way or the other, but outside of a locked diff one set of wheels will get more power from the center diff.

You watch some videos on YouTube and you see even the guys running 1000K still have balloon issues.

I agree with @bicketybam that some racers run heavier in front on certain tracks to aid in handling, but for general bashing (which I assumed was the case here) heavier in the front should reduce front tire spin.

100K up until recently was always considered heavy in the center, these high power 6s rigs are what brought about the use of 500K or 1000K.

TT

I get all of that except how a lighter fluid up front will make both wheels turn faster. Or faster to the point of tearing up the tires. I thought the center diff was responsible for how fast the front tires will rotate together. When I got my Kraton I ran 200 in the center and like 30 rear and 50 front. 6s on stock tires. They ballooned but didn’t explode.

What would happen if you ran say 10k in the center, 50k in the rear and 1000k in the front (other than having a very hard time turning)? Wouldn’t the front tire still balloon upon acceleration?

 

[Spar69!]

You're right @bicketybam the thicker the fluid in the center the more it acts as a "locker" so you get equal power to the f/r diffs. So by putting thicker weight in f/r diffs you're controlling the side to side action... the thicker the oil, the less slip you have ....I run 60k/1M/60k in all my ARRMA's on 6S and the only ballooning issue I have is when I run my MX38 Trenchers. If you put 1M weight in front and 10k in your center you'll have a heck of a time turning but all your power will still unload on the front.

 

[TooTall]

I get all of that except how a lighter fluid up front will make both wheels turn faster. Or faster to the point of tearing up the tires. I thought the center diff was responsible for how fast the front tires will rotate together. When I got my Kraton I ran 200 in the center and like 30 rear and 50 front. 6s on stock tires. They ballooned but didn’t explode.

What would happen if you ran say 10k in the center, 50k in the rear and 1000k in the front (other than having a very hard time turning)? Wouldn’t the front tire still balloon upon acceleration?

You're right @bicketybam the thicker the fluid in the center the more it acts as a "locker" so you get equal power to the f/r diffs. So by putting thicker weight in f/r diffs you're controlling the side to side action... the thicker the oil, the less slip you have ....I run 60k/1M/60k in all my ARRMA's on 6S and the only ballooning issue I have is when I run my MX38 Trenchers. If you put 1M weight in front and 10k in your center you'll have a heck of a time turning but all your power will still unload on the front.

Im not saying that a light center doesn't have an effect as it does of course, or else why would we all change it, but 100K center isn't that "light".

What i am saying is that by having thicker in rear, it transfers more power to front, thus potentially causes wheels to spin faster.

Diff fluid isn't going to slow down the motors rpm that much, so when @Spar69! says he has 1M center and 60K in both he is truly trying to balance the power front to rear by nearly locking the center, and by having the same weight both front to rear he is essentially letting diff load, traction, etc control which ones spin.

Something has to turn with each revolution of the motor, there is no slipper so regardless of diff weights something always has to turn, remember these diffs are like old cars, the wheel with the least resistance will spin. Also, diff fluid has no affect on straight line top speed when all things are equal. In identical traction between front and rear situations, moving in straight line, the whole diff is spinning, the spiders are stationary.

So by the OP having lower weight in the front, he will get more torgue applied to front diff (since it has less resistance) from the non-locked center diff thus he will get more wheel spin.

Just like when a car wheelies under power, both the front's balloon like crazy as the front wheels are off the ground and have equal traction so both wheels spin together, and the front spins faster than rear due to less traction.

So it really comes down to tuning your diffs to your driving style, the harder you accelerate, the more weight transfers to rear, thus the front has less traction and spins. To truly minimize ballooning, every person would need to experiment with the tuning to get the difference in diff fluid weight between front and rear to offset the amount of weight transfer to rear, but still maintain turn ability.

Like @Spar69! if both front and rear are equal weights, and you accelerate under control by rolling on the throttle front ballooning should be minimal. But if he would give it full throttle his fronts will spin also.

It is all relative to how and where you are driving.

TT

 

[bicketybam]

What i am saying is that by having thicker in rear, it transfers more power to front, thus potentially causes wheels to spin faster.

TT

Let’s agree to disagree on this point as I believe this isn’t true. The center diff is what controls the transfer of power between the rear and the front. The front diff controls the transfer of power between the front left and front right wheels.

https://www.myrcbox.com/articles/tech-article-diff-tuning-guide-for-buggy-and-truggy/

 

[TooTall]

Let’s agree to disagree on this point as I believe this isn’t true. The center diff is what controls the transfer of power between the rear and the front. The front diff controls the transfer of power between the front left and front right wheels.

https://www.myrcbox.com/articles/tech-article-diff-tuning-guide-for-buggy-and-truggy/

Exactly, the center diff controls front to rear, it is just a front or rear diff turned sideways, so therefore the end with the least resistance (the front due to lower weight diff fluid) will get more power transferred to it.

From your quoted article:

........

..........

They recommend heavier in front than rear as the starting point.


Answer this, with heavier diff fluid in the rear, pick up the car and hit the throttle, which ends wheels will spin faster??

TT

PS The answer is the front.

 

[Jerry-rigged]

Answer this, with heavier diff fluid in the rear, pick up the car and hit the throttle, which ends wheels will spin faster??

TT

PS The answer is the front.

Wrong. (on a few different levels)

First - if all the wheel are off the ground, the all have the same level of resistance, so they will all spin the same, regardless of diff fluids.

BUT -

Thick in the rear won't have an effect on the front - only the center will effect the power split between the front and rear. Thicker fluid in the rear diff WILL NOT effect power to the front. In you wheelie example - high traction in the rear, fronts in the air - the rear is not effecting the front at all. Go thick with the center, and more power will go to the rear. Go light in the center, and you can't get enough power to the rear wheels to wheelie.

 

[bicketybam]

Exactly, the center diff controls front to rear, it is just a front or rear diff turned sideways, so therefore the end with the least resistance (the front due to lower weight diff fluid) will get more power transferred to it.
.

Again, disagree. The front has the least resistance because under acceleration the weight is transferred to the rear tires, thus giving them more traction. It has nothing to do with the difference in oil weight between the front and the rear. With the wheels off the ground and thus equal traction to all 4 tires, the center diff should send the same amount of power to both the front and the rear. The front and the rear left and right tires also have equal traction and their is no differential effect which is what the oil controls.

As to why you would run heavier in the front, this guy sums it up:

When you corner hard under throttle, the inside front tire has the least amount of weight, and is the most prone to spin, sometimes spinning in the air, losing power and torque to the outside front tire> The outside front tire needs enough torque to pull the truck around the corner, and sweep away dust, it also adds a little understeer. In the rear, if the fluid is too thick, both wheels spin, and it can oversteer suddenly, lighter oil in the rear keeps both from spinning until you add a lot more throttle, so if only the inside wheel is spinning, the outside wheel has more lateral traction, and is slower to oversteer. The rear also tends to have the suspension compressed more than the front, and any rough patches can make it unstable if the diff is too tight, thinner fluid makes it track straighter and react less to rough tracks.

At the end of the day, the 20k (or whatever it was) difference between the front and the rear is not what caused his front tires to blow out. It was the center diff oil being too light, causing the center diff to unload to the front. I respect your knowledge and you have helped me in the past. But I don’t agree with your assessment here. No hard feeling ?

 

[TooTall]

Wrong. (on a few different levels)

First - if all the wheel are off the ground, the all have the same level of resistance, so they will all spin the same, regardless of diff fluids.

BUT -

Thick in the rear won't have an effect on the front - only the center will effect the power split between the front and rear. Thicker fluid in the rear diff WILL NOT effect power to the front. In you wheelie example - high traction in the rear, fronts in the air - the rear is not effecting the front at all. Go thick with the center, and more power will go to the rear. Go light in the center, and you can't get enough power to the rear wheels to wheelie.

Jerry, yes this was a bad example, I forgot that if all wheels off the ground that the spider gears in all the diffs would not be moving, it would be essential the same thing as locking all three diffs.

TT

 

[TooTall]

Again, disagree. The front has the least resistance because under acceleration the weight is transferred to the rear tires, thus giving them more traction. It has nothing to do with the difference in oil weight between the front and the rear. With the wheels off the ground and thus equal traction to all 4 tires, the center diff should send the same amount of power to both the front and the rear. The front and the rear left and right tires also have equal traction and their is no differential effect which is what the oil controls.

Yes as I responded to Jerry, bad example.

@bicketybam @Jerry-rigged

I bow to the masters!!

So really, the unfortunate situation is if you grab full throttle their is nothing that will stop ballooning other than different tire, strapping,etc as once you unload that diff and shift weight traction to rear, the front will get more power.

Learn something new every day, I'll chalk this up to mine!!

TT

 

[bicketybam]

When I switched from 100k to 500k in my Typhon it cut down on the ballooning of the 2.8 badlands I run. They still balloon but not much more than the rears under high speed.

 

[Toddys]

Quite the discussion. I should point out that I misrepresented my front and rear fluids in the original post. I use 50k in the front and 20k rear. I'm planning to increase the center from 100k to 200k. Lastly, I am purchasing Src terrain crushers to avoid ballooning.