Brake Slam

[Last Ride Bronco]

Anybody had a slamming on the brakes experience yet? If so, tell about it here.

My experience: 2 door WT, Interstate, 70 mph. Car in front of me suddenly decides to slow down quickly. I did not slam on brakes fully but aggressively slowed down. Felt a little squirrelly and had the feeling of moving side to side a little. It definitely reminds you that you are driving an off road vehicle. Otherwise, it stopped just fine.

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[93_SVT_3503]

I test drove a dealer demo Wildtrak and noticed the same feeling under hard braking. That feeling is from the soft tread compound in the tires, and the fact the tread lugs aren't intertwined like some all-terrains. I noticed that you can 'feel' a lot more of the road as you are driving with the softer tires as well. One reason I was looking into moving up a load range size when I get mine, even though it will lose a little bit of ride quality.

Notice the tread gaps, there isn't much for stability in any direction for the lugs.

The BFGs are a little better because of the tread pattern giving the lugs less mobility during braking.

 

[Last Ride Bronco]

I test drove a dealer demo Wildtrak and noticed the same feeling under hard braking. That feeling is from the soft tread compound in the tires, and the fact the tread lugs aren't intertwined like some all-terrains. I noticed that you can 'feel' a lot more of the road as you are driving with the softer tires as well. One reason I was looking into moving up a load range size when I get mine, even though it will lose a little bit of ride quality.

Notice the tread gaps, there isn't much for stability in any direction for the lugs.

The BFGs are a little better because of the tread pattern giving the lugs less mobility during braking.

Thanks, I’ll check that out!

 

[HotdogThud]

One of the first things I plan to do to mine when it comes in, is upgrade a few of the key parts of the brake system, specifically, pads and SS lines. The fact that brakes are always 'just good enough' should be a crime. Brakes on a car should be the most impressive feature that a car has.

 

[martyb]

It is more likely due to the large sidewalls. This is the reason performance cars have big wheels and narrow sidewalls.

 

[Techun]

One of the first things I plan to do to mine when it comes in, is upgrade a few of the key parts of the brake system, specifically, pads and SS lines. The fact that brakes are always 'just good enough' should be a crime. Brakes on a car should be the most impressive feature that a car has.

Do you expect shorter stopping distances in a panic stop with those?

 

[HotdogThud]

Do you expect shorter stopping distances in a panic stop with those?

definitely. there's obviously a lot of factors that go into braking, such as tires, weight, even air pressure in the tires, etc. but getting good bite on the pads, and having lines that don't flex under hard pressure really does make a huge difference. Have done it to all of my performance cars over the years, and from a safety perspective, I really see no reason not to do it on every car from here on out.

 

[Bronco1971]

It's called brake squirm and the more you insulate the chassis hard points from the road, the more likely it is to become a factor.

When driving a tall off road vehicle it's important at highway speeds to maintain a following distance much greater than almost everyone does these days. Most drivers allow for .2-.5 seconds of following distance, which means that you barely have enough time to react and move your foot to the brake (not break). In order to avoid a vehicle ahead that is emergency stopping, without also doing so yourself, is 1.5-2 seconds. That's 140-170 feet at 60 MPH. I roll my eyes and back off when I see people in traffic at 80mph following at 20 feet. It's no wonder we have pile ups on the freeways.

Next thing, unless there is something wrong with the vehicle, differential tire pressures, bad shocks, sacked out springs, bad bushings, etc., brake squirm should be controllable. People tend to object fixate when situations get intense. That usually means focusing on a close object as your point of reference for the world. Keep your eyes up and maintain position relative to the long view. Your hands will follow your eyes. It only takes very subtle motions to control brake squirm, don't over drive. Lastly, it's hard, but stay relaxed. There's nothing wrong with practicing hard braking in a parking lot to get a feel for how the car will act. There's a reason race car drivers practice so much.

 

[Bronco1971]

definitely. there's obviously a lot of factors that go into braking, such as tires, weight, even air pressure in the tires, etc. but getting good bite on the pads, and having lines that don't flex under hard pressure really does make a huge difference. Have done it to all of my performance cars over the years, and from a safety perspective, I really see no reason not to do it on every car from here on out.

I had the opportunity to be in a Wiltrak 2 door during a full on panic stop. There is an immense amount of brake dive, not quite making the rear unstable, but not far from it. Panic braking at 60 pulling a trailer of any mass would be terrifying. Honestly, if I were to change anything it may be looking into the anti-dive geometry, though that's a massive can of worms.

The only reason the fronts didn't lock is because the antilock system engaged. So, from my experience there is ample braking in this vehicle. Though I'm with you on the pads and lines, because durability, braided lines are much tougher.

 

[Techun]

I had the opportunity to be in a Wiltrak 2 door during a full on panic stop. There is an immense amount of brake dive, not quite making the rear unstable, but not far from it. Panic braking at 60 pulling a trailer of any mass would be terrifying. Honestly, if I were to change anything it may be looking into the anti-dive geometry, though that's a massive can of worms.

The only reason the fronts didn't lock is because the antilock system engaged. So, from my experience there is ample braking in this vehicle. Though I'm with you on the pads and lines, because durability, braided lines are much tougher.

Yeah is have some doubts that pads and lines will improve stopping distances, but I have yet to do a panic stop to see what happens.

My ASSUMPTION is that you should be able to engage abs at any speed.

 

[Spray]

The rear track bar is also contributing to this. As the front end dives the rear is lifting, this causes the rear axle to shift slightly to the drivers side. This gets worse as the Bronco is lifted. On lifted Broncos the best way to mitigate this is to raise the track bar mount to keep it as horizontal as possible. The first gen Bronco has a track bar on the front end and a three inch suspension lift absolutely throws the front to rear wheel alignment way out of whack. Track bar riser and drop pitman arm are needed to fix it. Otherwise every time you hit the breaks hard the truck wants to turn as the nose dives. The only Broncos that didn’t do this were the twin front I beam models.

 

[Bronco1971]

The first gen Bronco has a track bar on the front end and a three inch suspension lift absolutely throws the front to rear wheel alignment way out of whack.

Along with changing the angle of the radius arm altering the side view swings arm and the instant centers. Even lifted, the new Bronco is going to be night and day better than and early.

 

[Spray]

Along with changing the angle of the radius arm altering the side view swings arm and the instant centers. Even lifted, the new Bronco is going to be night and day better than and early.

I didn’t want to go that far down the rabbit hole! I used 7 degree offset radius arm bushings and adjustable upper ball joints to fix that problem On our ‘73 rebuild.

 

[Bronco1971]

I didn’t want to go that far down the rabbit hole! I used 7 degree offset radius arm bushings and adjustable upper ball joints to fix that problem On our ‘73 rebuild.

Gotta beat that dead horse,... right?

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