To any driving enthusiasts,
I was driving my Dodge Caravan to the coast on winding, but not hilly roads.
The speed limit was 55 mph.
Every once in a while I would come upon a slow driver ahead of me, and would softly put on my brakes.
When it was on a curve I would feel pulsating or shaking of the brakes.
When it was on a straight road, no pulsating.
My guess is, braking on a curve or turn is harder on the brakes.
From the laws of physics, can anyone describe exactly what the effect of turning has
on the brakes while braking?
I believe it probably has something to do with the weight transfer, but I can't say for sure.
Thanks for any input here!
(I did have my brakes checked at Les Schwab and the rotors were very thin.)
QUOTE (saferoader+Oct 20 2009, 07:34 PM)
To any driving enthusiasts,
I was driving my Dodge Caravan to the coast on winding, but not hilly roads.
The speed limit was 55 mph.
Every once in a while I would come upon a slow driver ahead of me, and would softly put on my brakes.
When it was on a curve I would feel pulsating or shaking of the brakes.
When it was on a straight road, no pulsating.
My guess is, braking on a curve or turn is harder on the brakes.
From the laws of physics, can anyone describe exactly what the effect of turning has
on the brakes while braking?
I believe it probably has something to do with the weight transfer, but I can't say for sure.
Thanks for any input here!
(I did have my brakes checked at Les Schwab and the rotors were very thin.)
weight shifts to the front wheels when braking. My guess would also be that when you're turning the wheel axel is putting lateral force on the axle. After all, the tire is gripping the road as you turn to prevent you from flying out of the curve! I believe this would put some torque on the rotors, which could twist them inside the caliper. If the rotors are warped at all, which they probably are if they're thin, then this might be more noticeable when braking while going around a curve. This is all speculation. You could make a better guess by looking at the caliper/rotor configuration, pushing on the car and looking at how the rotor moves inside the caliper.
If I were you, I would replace the rotors, check the pads, and check the system. If you're not confident with doing it yourself, consult an expert or park the car until you do.
I was driving my Dodge Caravan to the coast on winding, but not hilly roads.
The speed limit was 55 mph.
Every once in a while I would come upon a slow driver ahead of me, and would softly put on my brakes.
When it was on a curve I would feel pulsating or shaking of the brakes.
When it was on a straight road, no pulsating.
My guess is, braking on a curve or turn is harder on the brakes.
From the laws of physics, can anyone describe exactly what the effect of turning has
on the brakes while braking?
I believe it probably has something to do with the weight transfer, but I can't say for sure.
Thanks for any input here!
(I did have my brakes checked at Les Schwab and the rotors were very thin.)
weight shifts to the front wheels when braking. My guess would also be that when you're turning the wheel axel is putting lateral force on the axle. After all, the tire is gripping the road as you turn to prevent you from flying out of the curve! I believe this would put some torque on the rotors, which could twist them inside the caliper. If the rotors are warped at all, which they probably are if they're thin, then this might be more noticeable when braking while going around a curve. This is all speculation. You could make a better guess by looking at the caliper/rotor configuration, pushing on the car and looking at how the rotor moves inside the caliper.
If I were you, I would replace the rotors, check the pads, and check the system. If you're not confident with doing it yourself, consult an expert or park the car until you do.
Do you by any chance have ABS?
QUOTE (buttershug+Oct 21 2009, 02:28 AM)
Do you by any chance have ABS?
Judging by the fact that he's posting on this forum, there's a better chance that he just has BS.
Judging by the fact that he's posting on this forum, there's a better chance that he just has BS.
Thanks light in the tunnel and buttershug.
I did have the rotors replaced, however the brake technician said it wasn't unsafe to drive with the brakes shaking, I didn't believe him.
When we bought the Caravan it was used, I have never had an owners manual but have always thought it had ABS, but I was told if you have ABS there will be a light on the dash saying "ABS" I don't have that light. However, I read that Dodge Caravans from '99 on have ABS.
So How would I tell? I guess I could go back to Les Schwab and ask them.
I did have the rotors replaced, however the brake technician said it wasn't unsafe to drive with the brakes shaking, I didn't believe him.
When we bought the Caravan it was used, I have never had an owners manual but have always thought it had ABS, but I was told if you have ABS there will be a light on the dash saying "ABS" I don't have that light. However, I read that Dodge Caravans from '99 on have ABS.
So How would I tell? I guess I could go back to Les Schwab and ask them.
QUOTE (saferoader+Oct 21 2009, 03:05 AM)
Thanks light in the tunnel and buttershug.
I did have the rotors replaced, however the brake technician said it wasn't unsafe to drive with the brakes shaking, I didn't believe him.
When we bought the Caravan it was used, I have never had an owners manual but have always thought it had ABS, but I was told if you have ABS there will be a light on the dash saying "ABS" I don't have that light. However, I read that Dodge Caravans from '99 on have ABS.
So How would I tell? I guess I could go back to Les Schwab and ask them.
If you can safely drive in an empty wet parking lot on a rainy day, you can try braking very hard. If you lose traction and spin out, you don't have abs. If you have abs, you should feel the brakes pulsating in the pedal and come to a stop without sliding. Be very careful if you try this because you will lose total control over your vehicle and I can't promise you that it won't roll over. This is an exaggerated risk from my point of view, but I wouldn't want to give anyone the impression that there are no risks involved with spinning a car out in a wet parking lot.
I did have the rotors replaced, however the brake technician said it wasn't unsafe to drive with the brakes shaking, I didn't believe him.
When we bought the Caravan it was used, I have never had an owners manual but have always thought it had ABS, but I was told if you have ABS there will be a light on the dash saying "ABS" I don't have that light. However, I read that Dodge Caravans from '99 on have ABS.
So How would I tell? I guess I could go back to Les Schwab and ask them.
If you can safely drive in an empty wet parking lot on a rainy day, you can try braking very hard. If you lose traction and spin out, you don't have abs. If you have abs, you should feel the brakes pulsating in the pedal and come to a stop without sliding. Be very careful if you try this because you will lose total control over your vehicle and I can't promise you that it won't roll over. This is an exaggerated risk from my point of view, but I wouldn't want to give anyone the impression that there are no risks involved with spinning a car out in a wet parking lot.
QUOTE (light in the tunnel+Oct 20 2009, 07:57 PM)
Judging by the fact that she's posting on this forum, there's a better chance that she just has BS.
Thanks for the tip LITT!
I will try that out when it rains, or I might have my daughter try it out, since she is 15, has her permit and is learning to drive!
I will try that out when it rains, or I might have my daughter try it out, since she is 15, has her permit and is learning to drive!
I would check the wheel bearings. Jack the vehicle up and wiggle the wheels without undoing the nuts. If you can feel excessive play then it's time for some new wheels bearings. Another thing I can think of that might cause this is a dodgy suspension swing-arm, but I don't think that's as likely.
Also, unless you've already done this, check your wheel nuts with a torque wrench and tighten them in the correct order.
QUOTE (prometheus+Oct 21 2009, 02:46 AM)
I would check the wheel bearings. Jack the vehicle up and wiggle the wheels without undoing the nuts. If you can feel excessive play then it's time for some new wheels bearings. Another thing I can think of that might cause this is a dodgy suspension swing-arm, but I don't think that's as likely.
Wheel bearing failure seldom results in a wiggle but a distinctive hum on the turn. Perhaps what you are thinking of is the "struts" which, in concert with worn sway bars, will wiggle. Bad struts also show signs of oil leakage from their seals.
Wheel bearing failure seldom results in a wiggle but a distinctive hum on the turn. Perhaps what you are thinking of is the "struts" which, in concert with worn sway bars, will wiggle. Bad struts also show signs of oil leakage from their seals.
Check your front tires for a tread separation or bubble. Very bad news at highway speed...
Bad front-end alignment will allow you to track straight sometimes, but out-of camber errors are more noticeable in a turn, and will wear the tires unevenly.
Bad front-end alignment will allow you to track straight sometimes, but out-of camber errors are more noticeable in a turn, and will wear the tires unevenly.
QUOTE (NoCleverName+Oct 21 2009, 08:42 AM)
Wheel bearing failure seldom results in a wiggle but a distinctive hum on the turn.
That depends on the condition of the bearing retainer. If it's been damaged, it could cause a wiggle, depending on how it's damaged. I've seen this before, though it was only once, and it was on a high performance oval track car.
I should point out that this is not a particularly likely cause. Tire damage or bad struts or a wheel (or wheels) out of camber are more likely.
That depends on the condition of the bearing retainer. If it's been damaged, it could cause a wiggle, depending on how it's damaged. I've seen this before, though it was only once, and it was on a high performance oval track car.
I should point out that this is not a particularly likely cause. Tire damage or bad struts or a wheel (or wheels) out of camber are more likely.
Thanks for all the input, I would guess if the wheel bearings were bad, Les Scwab would have told me me when they checked the brakes and replaced the rotors.
So far since the rotors were replaced I haven't felt that shaking, although I haven't been going out to the coast since then either.
The reason for the question on the effect turning has on brakes is because I am writing a page on driving on curves and winding roads, so I want to be able to explain to my readers a bit about braking in a curve (which normally you should not do. Brake before, coast through and gas out)
So I want a good explanation WHY that is so.
Thanks,
SR
So far since the rotors were replaced I haven't felt that shaking, although I haven't been going out to the coast since then either.
The reason for the question on the effect turning has on brakes is because I am writing a page on driving on curves and winding roads, so I want to be able to explain to my readers a bit about braking in a curve (which normally you should not do. Brake before, coast through and gas out)
So I want a good explanation WHY that is so.
Thanks,
SR
Hi, you may have better chance's of diagnosing the fault if you post the questions in car enthusiast forums. There's plenty of them, dealing with every make and model available. I'm sure someone has already had a similar problem as yourself.
Perhaps try here,
http://dodgeforum.com/forum/index.php and
http://dodgeforum.com/forum/dodge-caravan-23/
Perhaps try here,
http://dodgeforum.com/forum/index.php and
http://dodgeforum.com/forum/dodge-caravan-23/
Well, I'm no mechanic, but if you wanted an explanation: when traveling a curve or circle you are always changing direction.
I don't know if this helps.
I don't know if this helps.
QUOTE (Matador+Oct 22 2009, 12:35 AM)
Hi, you may have better chance's of diagnosing the fault if you post the questions in car enthusiast forums. There's plenty of them, dealing with every make and model available. I'm sure someone has already had a similar problem as yourself.
Perhaps try here,
thanks matador, I am a member of an automotive forum, while they can give answers as to what causes the problems on vehicles, I have found, the auto enthusiasts don't really explain the "physics" of driving. Forinstance:
you must use gas out of a curve or a turn (usually) to come out smooth and to keep up momentum. I know pushing the gas pedal puts more weight and traction on the back tires. So exactly WHY is more weight and traction in the back important to keep momentum and speed up?
Just as braking puts more weight to the front. How does all this help the balance and stopping of a vehicle? (especially on curves)
And is it the opposite if you have rear wheel drive? How is the traction and weight balance different then? Or with all wheel drive?
While I know some of the physics of driving, to explain how it all works together is where I have problems.
(maybe a racing forum would answer these questions better)
Thanks,
SR
Perhaps try here,
thanks matador, I am a member of an automotive forum, while they can give answers as to what causes the problems on vehicles, I have found, the auto enthusiasts don't really explain the "physics" of driving. Forinstance:
you must use gas out of a curve or a turn (usually) to come out smooth and to keep up momentum. I know pushing the gas pedal puts more weight and traction on the back tires. So exactly WHY is more weight and traction in the back important to keep momentum and speed up?
Just as braking puts more weight to the front. How does all this help the balance and stopping of a vehicle? (especially on curves)
And is it the opposite if you have rear wheel drive? How is the traction and weight balance different then? Or with all wheel drive?
While I know some of the physics of driving, to explain how it all works together is where I have problems.
(maybe a racing forum would answer these questions better)
Thanks,
SR
A tire has only so much friction available. Only so much force it can put out. You can use this to brake really hard, turn really hard, or even do a combination of the two...but then neither the braking nor the turning will be as hard as if you separate them.
It's called a friction circle. Race car drives do their best to always be as close to the edge of this circle as possible.
User posted image: User posted image
Weight at the back increases traction at the back. This increases the size of the friction circle at the back tires, and lets you press harder on the gas, turn the steering wheel more, or do a combination of the two (such as when exiting a corner)...assuming you have rear wheel drive. If you have front-wheel drive, then this weight transfer when accelerating will hurt you. All wheel drive-it doesn't really matter then.
Weight at the back increases traction at the back. This increases the size of the friction circle at the back tires, and lets you press harder on the gas, turn the steering wheel more, or do a combination of the two (such as when exiting a corner)...assuming you have rear wheel drive. If you have front-wheel drive, then this weight transfer when accelerating will hurt you. All wheel drive-it doesn't really matter then.
Just as braking puts more weight to the front. How does all this help the balance and stopping of a vehicle? (especially on curves)
More weight to the front gives you more friction at the front, which lets you press the brakes even harder before you lock them up, or lets you turn harder while braking (such as when entering a corner).
It's called a friction circle. Race car drives do their best to always be as close to the edge of this circle as possible.
User posted image: User posted image
QUOTE
you must use gas out of a curve or a turn (usually) to come out smooth and to keep up momentum. I know pushing the gas pedal puts more weight and traction on the back tires. So exactly WHY is more weight and traction in the back important to keep momentum and speed up?
Weight at the back increases traction at the back. This increases the size of the friction circle at the back tires, and lets you press harder on the gas, turn the steering wheel more, or do a combination of the two (such as when exiting a corner)...assuming you have rear wheel drive. If you have front-wheel drive, then this weight transfer when accelerating will hurt you. All wheel drive-it doesn't really matter then.
QUOTE (->
| QUOTE |
| you must use gas out of a curve or a turn (usually) to come out smooth and to keep up momentum. I know pushing the gas pedal puts more weight and traction on the back tires. So exactly WHY is more weight and traction in the back important to keep momentum and speed up? |
Weight at the back increases traction at the back. This increases the size of the friction circle at the back tires, and lets you press harder on the gas, turn the steering wheel more, or do a combination of the two (such as when exiting a corner)...assuming you have rear wheel drive. If you have front-wheel drive, then this weight transfer when accelerating will hurt you. All wheel drive-it doesn't really matter then.
Just as braking puts more weight to the front. How does all this help the balance and stopping of a vehicle? (especially on curves)
More weight to the front gives you more friction at the front, which lets you press the brakes even harder before you lock them up, or lets you turn harder while braking (such as when entering a corner).
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