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 > Blowout control technique

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Toolslinger

Portland, Oregon

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Posted: 04/07/10 07:53pm Link  |  Print  |  Notify Moderator

There is another resource available to protect yourself in the event of a front tire blowout. It's called Tyron Flat Tyre protection. It's used on police vehicles and armored vehicles as well as trucks and RV's. I have them on my MH. See: Tyron (you know, click here)

I bought mine with the MH. They were almost $1400 installed, but excellent insurance. I suspect you can get them cheaper if you don't go to an RV dealer like I did.


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Cloud Dancer

San Antonio and Livingston TX USA

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Posted: 04/08/10 07:58am Link  |  Print  |  Notify Moderator

Conclusion:

We've determined the EXACT scenario that causes a motorhome to suddenly veer to the side and go OFF the pavement whenever a front tire blows out.
The driver hits the brake, the engine goes OFF cruise control, the steering wheel is yanked from the driver's hands, and the MH steer tires turn all the way to the side of the failed tire.


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PackerBacker

Montreal (Qc) Adirondacks (NY) Myrtle Beach (SC)

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Posted: 04/08/10 09:05am Link  |  Print  |  Notify Moderator

Cloud Dancer wrote:

wny_pat wrote:

Crazy as it sounds, like everyone is telling you, do not hit the brake, Down on the accelerator, that relieves the weight off the steer axle so it is easier to hold straight. Do not go off the pavement until you are going slow enough, about 15 or 20 mph, that you can control it.


Are you implying that by depressing the accelerator all the way it will actually result in lifting the front end?
I don't want to be argumentative, therefore I'll just voice my opinion. I do NOT believe it,......unless you have an engine in your MH that's not known to me.

Let me offer my thoughts from an old racer's perspective. It likely won't lift the front end as such, but it will transfer some weight off the front wheels which will help reduce the unwanted yaw/oversteer.

I like to think of it as not letting the vehicle get ahead of you. Many drivers have a tendency of responding to the vehicle where the vehicle wants to oversteer or understeer and they react to those conditions instead of having the vehicle respond to their control directives and avoid oversteering or understeering. There's a fine line there but it does exist.

The problem for many drivers is being able to react relative to how fast things can happen. In racing, you blow a front right while in a corner and bang, you're in the wall. If it happens on a straight, you've got a fighting chance. My guess is no one will really know until it happens to them.

* This post was edited 04/08/10 09:14am by PackerBacker *


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Cloud Dancer

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Posted: 04/08/10 09:34am Link  |  Print  |  Notify Moderator

PackerBacker wrote:

Cloud Dancer wrote:

wny_pat wrote:

Crazy as it sounds, like everyone is telling you, do not hit the brake, Down on the accelerator, that relieves the weight off the steer axle so it is easier to hold straight. Do not go off the pavement until you are going slow enough, about 15 or 20 mph, that you can control it.


Are you implying that by depressing the accelerator all the way it will actually result in lifting the front end?
I don't want to be argumentative, therefore I'll just voice my opinion. I do NOT believe it,......unless you have an engine in your MH that's not known to me.

Let me offer my thoughts from an old racer's perspective. It likely won't lift the front end as such, but it will transfer some weight off the front wheels which will help reduce the unwanted yaw/oversteer.

I like to think of it as not letting the vehicle get ahead of you. Many drivers have a tendency of responding to the vehicle where the vehicle wants to oversteer or understeer and they react to those conditions instead of having the vehicle respond to their control directives and avoid oversteering or understeering. There's a fine line there but it does exist.



Oversteer and understeer is a characteristic of the chassis, and NOT something that a driver does.
The amount of front-end LIFT that the engine can perform is INSIGNIFICANT (as it relates to this subject), WHEREAS the amount of FORWARD weight transfer as a result of "standing on the brake" is HUGE.

There's only two(2) occurrences that INITIATE a deadly yaw into the side of a failed tire:
First, it's the friction/drag of the flat tire itself.
Secondly, it's the ADDTIONAL drag of the 'same-side'/bad-news side of the REAR drive dual tires.

Explanation of why there would be more traction on the rear dual tires, the ones which are on the same side as the failed tire:

Whenever a front tire goes flat(loses all air), THAT corner of the vehicle goes DOWN, and the REAR DIAGONAL corner goes up. THIS is what forces the OTHER rear corner and the other front corner TIRES to carry more of their normal load(weight of the vehicle)!

NOT yet explained:
THIS additional traction of the WRONG-side REAR dual tires, is WHAT makes it SO devastating IF you "hit" the BRAKES.

THEREFORE, perhaps NOW you can see why it's SO important to NOT hit the brakes, AND to HIT the throttle, AND to NOT let go of the steering wheel!

AND NOW, perhaps you(everyone) can see the huge importance of "hitting the throttle". The added traction(mentioned above) of the DRIVE tires on the same side of the failed front tire, is EXACTLY what can be used to PROPEL you AWAY front "the ditch". BUT, this can only happen if you immediately "stand on the throttle". Because if you are in cruise control, and you instinctively/intentially hit the brakes the engine immediately spools down.

SO, train-train-train yourself to immediately get on the throttle whenever you experience a blow out. You do NOT necessarily need to accelerate, just make sure you feed power to the drive tires.
I trust that you will intuitively "hang on to the steering wheel", and the added traction on the other steer tire will help you in steering away from the side of the failed tire.
If you are not experienced in these matters, just talk the intructions to yourself as you drive down the highway.

* This post was edited 04/08/10 10:05am by Cloud Dancer *

stugpanzer

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Posted: 04/08/10 09:41am Link  |  Print  |  Notify Moderator

I too have been concerned about this subject. I always drive with both hands on the steering wheel, and I never go over 60mph but I really don't know how I would react during a front blow-out. I am pricing the Steer Safe product and the Tyron Blow-out Straps. I am leaning towards the Steer Safe product which for just over $400 is a reasonable amount to pay for peace of mind! I am waiting for pricing on the Tyron product for my coach. I am even considering going with both!

* This post was edited 04/08/10 09:48am by stugpanzer *


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PackerBacker

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Posted: 04/08/10 10:10am Link  |  Print  |  Notify Moderator

Cloud Dancer wrote:

...........................

Oversteer and understeer is a characteristic of the chassis, and NOT something that a driver does.
The amount of front-end LIFT that the engine can perform is INSIGNIFICANT (as it relates to this subject), WHEREAS the amount of FORWARD weight transfer as a result of "standing on the brake" is HUGE.

There's only two(2) occurrences that INITIATE a deadly yaw into the side of a failed tire:
First, it's the friction/drag of the flat tire itself.
Secondly, it's the ADDTIONAL drag of the 'same-side'/bad-news side of the REAR drive dual tires.

Explanation of why there would be more traction on the rear dual tires, the ones which are on the same side as the failed tire:

Whenever a front tire goes flat(loses all air), THAT corner of the vehicle goes DOWN, and the REAR DIAGONAL corner goes up. THIS is what forces the OTHER rear corner and the other front corner TIRES to carry more of their normal load(weight of the vehicle)!

NOT yet explained:
THIS additional traction of the WRONG-side REAR dual tires, is WHAT makes it SO devastating IF you "hit" the BRAKES.

THEREFORE, perhaps NOW you can see why it's SO important to NOT hit the brakes, AND to HIT the throttle, AND to NOT let go of the steering wheel!

Willie, I fully agree.

The point I was trying to make was that many drivers will simply respond to what they feel is happening. The front right tire goes down and the vehicle lurches to the right. The driver pulls the steering to the left to correct and likely hits the brakes then waits to see what the vehicle will do next instead of pro-actively making the vehicle respond to what he wants it to do right from the original lurching. Trying to maintain a good vehicle balance.

This is what I was trying to infer about not letting the vehicle get ahead of you (maybe I'm just not expressing it correctly). This should be at all times, not just when a significant event happens. It could be on slippery roads or windy conditions etc...

... Eric

malibufam

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Posted: 04/08/10 11:19am Link  |  Print  |  Notify Moderator

Great information!!! Thanks.


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Steve S.

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Posted: 04/08/10 03:35pm Link  |  Print  |  Notify Moderator

Daveinet wrote:

If its a front tire, NEVER HIT THE BRAKE. It will yank the wheel out from your hand.


While I absolutely 100% agree the best thing to do is to not slam on the brakes and instead give the vehicle more throttle, I don't agree that if you ever were to hit the brake that the wheel would instantly yank our from your hand.

I've driven through a good 1/2 a dozen front tire blowouts over the years (although none in a motor home) plus experimented with blown front tires and my experience is that the pull towards the side with the blown tire is proportional to the amount of braking you apply. If you hit the brakes lightly it is relatively easy to keep the steering turned to counter the pull. If you increase the braking force smoothly and keep the steering "tweaked" to keep the vehicle steering where you want it to go you can slow down safely and a lot faster than if you just roll on the blown tire.

I believe this is what the Michelin video really is trying to say. They don't say to never touch the brakes at all.

So, with a heavy motor vehicle with a relatively low power to weight ratio (such as a motor home), if we blow a front tire we need to:

1. Immediately give it a fair bit of throttle to help minimize the pull in the direction of the blown tire. Quickly and without panicking get the vehicle under control with the steering turned to compensate for the blown tire.
2. Ease off on the throttle while adjusting the steering to keep the vehicle going where you want it to go.
3. Start slowly and smoothly applying the brakes while continuing to adjust the steering to keep going where you want to go.
4. If the pull feels too much, ease off on the brakes a bit.
5. When the speed is quite slow, pull off the road.

The heaviest vehicle I blew a front tire on was probably around 10000 lbs and it had MANUAL steering (no power assist). It was an old 1950's flat bed truck loaded with hay with an unloaded top speed of about 50 mph. I found with it I needed to turn the steering roughly 1/4 of a turn away from the front blow tire when coasting. I had to hit the brakes since cars were braking in front of me and I was going down a hill. As I applied them I needed to turn the steering wheel another 1/3 to 1/2 EXTRA away from the blown tire (so a total of up to 3/4 of a turn away from the blown tire). I was able to brake quite hard and avoid crashing into the cars ahead without any trouble. Usually vehicles with power steering require less rotation of the steering wheel (to steer in general), but I would bet that a motor home still requires a fair bit of steering to compensate.

There are MANY situations where you have no option other than to use the brakes so you need to be aware of what to expect and understand that you CAN still brake.

Imagine what would happen if you were heading down a Rocky Mountain pass when a front tire blew and you refused to ever touch the brakes. Similarly imagine what would happen if all of the cars in front of you hit their brakes and you refused to because you have a blown front tire.

Also it does not really matter what method is used to decelerate (down shifting/exhaust brake, parking brake, or regular service brakes), any form of braking will increase the pull towards the blown tire and will require additional steering correction to keep going straight. The strongest pull will be from the service brakes but even this is still manageable, especially with power steering.

Another point to keep in mind is as long as you are able to steer enough to counter the additional pull, you can actually brake very hard if you do it smoothly. In fact at the limit of traction where you lock up the tires due to braking too hard, the vehicle can actually pull away from the blown tire because the blown tire ultimately has less traction than the remaining good tires.

I actually performed this experiment in a lighter, ~4000 lb vehicle, but it makes sense that the same physics apply to a motor home also. By the time I got my "new to me" 1976 Aspen Wagon "pre-crashed" parts car home to the farm I had driven 1/2 way or at least 20 miles on a blown front tire (it was still on the rim the whole time too). As an experiment I braked harder and harder, while compensating with the steering. At some (very hard) braking point the car started to steer away from the blown tire instead of towards it. It was a smooth transition from pulling towards the blown tire to less and less pull, to then starting to pull away from the blown tire. By the time it started to pull less, the blown tire's rim was locked up and no longer turning and the good front tire had more grip. I tried this several times and this experiment showed that the pull was consistent and always related smoothly to the amount of braking effort. The pull direction always switched once braking very hard also.

Since that experiment was done early in my driving "life", I have blown many different front tires since then and have never had any trouble controlling the vehicle. A couple of front blowouts were on curves but they were not sharp for the speed traveling. One was at roughly 80 mph on a slight curve with the outside front tire being the one that blew. That one was the most nerve racking and it destroyed my right front fender and the rim (that was also the last blowout I experienced).

I would really like to hear from someone who has blown a front tire on a 40 foot motor home such as my Dynasty and I would like to know how much steering was required to coast and how much was required when using the brakes to slow down. My guess is it will take about 1/4 of a turn of the steering wheel to coast and something like 1/2 a turn when braking moderately but this is only a guess.


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adondo

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Posted: 04/08/10 03:58pm Link  |  Print  |  Notify Moderator

Quote:

I would really like to hear from someone who has blown a front tire on a 40 foot motor home such as my Dynasty and I would like to know how much steering was required to coast and how much was required when using the brakes to slow down. My guess is it will take about 1/4 of a turn of the steering wheel to coast and something like 1/2 a turn when braking moderately but this is only a guess.


As I mentioned before, it happened on the Safari on a Yosemite trip. So, there’s your 40 foot coach with a front blowout.

Although I have a Howard Power Center Steering system, it wasn’t much use after the shedding tire ripped all its air lines apart. I did have to compensate somewhat, but I don’t remember a quarter turn on the wheel.

There’s a lot of talk about hitting the gas pedal too, and I didn’t do that either, and the coach handled just fine. My biggest concern at the time wasn’t keeping from wrecking, it was looking back at all the cars swerving around our trail of debris. I thought there was going to be a major pile up behind us.

I also had to cross two lanes to get off the freeway as we were in the center lane of a ten lane freeway. (5 per side)

Keep your head, and don’t panic at the noise of the exploding tire and/or slapping tread in your wheelwell. Just hold it steady and get off the road.

As for brakes, you can use them if needed, just don’t slam them on hard.

The worst one I ever had was when I was doing 3 digit speeds in a 1980’s Ford LTD. That was a front tire too, and it exploded without warning. (don’t they all?) I didn’t wreck that time either despite cruising at 115 MPH or so.

Probably a lot of my experience comes from driving race Jeeps off road. Hitting soft patches of dirt when flying along at 100 MPH prepares you for anything. I’ve lost count of how many times I’ve rolled in race Jeeps. Most things that come at you on pavement are tame compared.


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Daveinet

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Posted: 04/08/10 04:17pm Link  |  Print  |  Notify Moderator

Steve S. wrote:

Daveinet wrote:

If its a front tire, NEVER HIT THE BRAKE. It will yank the wheel out from your hand.


While I absolutely 100% agree the best thing to do is to not slam on the brakes and instead give the vehicle more throttle, I don't agree that if you ever were to hit the brake that the wheel would instantly yank our from your hand.


My brother had a front blowout in my RWD car. When the car had coasted to about 20 mph, he very gently began to EASE on the brake. The wheel was yanked from his had and he almost hit the guard rail. It is really dependent on what is left of the tire as to what can happen when the brakes are applied. If the bead is broken, the tire can peel off and get caught. Applying the brakes can break the bead if its not already broken.
You also have no idea why the tire blew in the first place. A bad bearing or stuck caliper could be the root cause. Hitting the brakes introduces one more variable into the process of keeping control. As long as you are basically under control, and things are still turning, I'd be inclined to coast until I'm down to a few mph. In a rear wheel drive motorhome, I would probably downshift and use engine braking to reduce speed, but never the brakes unless I was about to hit something.


Dave

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