Kia Sephia Weak Brakes ~ Solved the Mystery! - Kia Forum

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Old 09-26-2012, 11:17 AM Thread Starter
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Lightbulb Kia Sephia Weak Brakes ~ Solved the Mystery!

There is a Fact: The Second Gen (1998~2001) Kia Sephia (Like my Wife's Model) has Weak Brakes and Suffers from Premature front Brake Wear. I Noticed the Weak Brakes since we obtained the Car.

I investigated further on the Subject on Internet and I Found that the Problem was so generalized that it ended in the Court, with Lawsuits against Kia, in some cities of USA.

I'm Lawyer, so I spent Hours and Hours Reading Documentation on-line, Such Like the Following:

(Each one is a clickable a Link to a Website)

"Judge Certifies Class Action Suit for Kia Sephia Owners"

"KIA SEPHIA BRAKE PROBLEMS AND CLASS ACTION"

"New Jersey's Court Desicions in the Subject"


Could you Believe that there are some Websites entirely dedicated to that issue?

"Facebook Page for the Sephia's Defective Brakes"

http://kiasephiadefectivebrakes.com/

Well, some of the Lawsuits says: (Source: Kia Sephia Brake Defects Promote Class Action Lawsuits in PA and NJ)

Quote:
Consumers Suffer Brake Defects in 1998, 1999, 2000 Kia Sephias; Class Action Suits Filed in Pennsylvania and New Jersey, More than 166,000 Automobiles Could Be Affected
So, the Problem is a Fact that I Needed to Solve ASAP, but after Weeks Reading many Documents, seems like no one found the Answer of "Why" that Happens and "How" to fix that problem; they only talk about the weakness of the Brakes and the Front Rotors' Warp plus premature wear.

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Old 09-26-2012, 11:17 AM Thread Starter
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But after some Brake Jobs, I Disassembled all the parts involved and double checked each part, then carefully inspected everything... also I went three times to Talk with the Local Kia Dealer's Master Mechanic, to gather info related to that issue and how they and / or Kia Motors fixed that.

So, after many research, I Found the Culprit and the Solution.


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Old 09-26-2012, 11:18 AM Thread Starter
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You must consider that there are Two Problems with the Sephia's Brakes:
  1. Weak Brake Power.
  2. Front Rotor Warp and Premature Wear on Pads.

The Weak Brake Power has Two Causes

After I Disassembled almost everything on my Wife's Sephia, I Noticed that the Proportioning Valves, which are Located in the Firewall, behind the engine, has some sort of Design Flaw: Vertical Grooves.

Those Vertical grooves made the Proportioning Valves to Leak Brake Fluid while letting Air to get sucked into the System; you can see the Leaky vertical grooves on the Sephia's Brass proportioning valves, in the Following Photo:





Those were the Original (stock) Proportioning Valves, made of Brass... The Local Kia Dealer had the Replacement for those, but made from a different metal, which looks like Polished Stainless Steel with chromed tops, and Does NOT have the faulty Vertical Grooves, as you can see in the Following Photo:





This is their Part Number:




Think about this: Any Brake system that Loose Brake Fluid and gets air inside the pressurized lines, will have a Weak performance; isn't it?

The Leaky Proportioning Valves with Vertical Grooves will make the Brake System Weak, no matter how many times you Bleed the System, they'll let go fluid while suck air; So, I changed the original Proportioning Valves that had Vertical Grooves, with the ones with Newer design without the vertical grooves and new metal alloy instead of brass; the ones you saw in the Photos.

So, the faulty Proportioning Valves was the First Cause for Weak Brake Power.
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Old 09-26-2012, 11:19 AM Thread Starter
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The Second Cause for Weak Brake Power is the Cause of the Second Problem itself: Warped Rotors and Premature Pad Wear.

The Cause for Premature Front pad Wear and Warped Rotors, was Not on the front Brakes themselves,
(Calipers, Front Wheel Cylinders, Pads, etc... ) No. I Found the Problem that lead to the Front Brakes to have such Premature Wear, and believe me or not, the Culprit is on the Rear Brakes! ... ... Let me Explain:

The Rear Drum Brakes has a Self Regulator that Moves the Rear shoes towards to the rotating Drum as they wear, in order to maintain the same distance between shoes and drum, that keeps the same travel on the Pedal before the Shoe touches the Drum, even if the shoe is worn.

But since the Rear shoe Regulators fail to adjust the Shoes towards the Drum, the Rear wheel brake cylinder has to move its piston in a longer travel before the shoe touches the Drum, because the Shoes are
"Far Away" deregulated.

That means: When anybody pushes the Brake Pedal, the Front Pads will engage pressing the rotating Disc, while the Rear Shoes are doing almost Nothing to brake the Car, due to the
"Far Away" deregulated Shoes, they barely touches the rotating Drums.

So, the Front Disc Brakes will take the 90% of the Braking effort, while the Rear Drum Brakes will rotate almost freely...

You Notice that your car has
"Far Away" deregulated Shoes on the Rear drum brakes, if:
  1. You Need to Pull up the parking brake lever handle to the Top to hold the Car.
  2. The Brake Pedal feels too Low or it goes Deep before really braking the Car
  3. You have to push even "Deeper" the Brake Pedal while going in Reverse.

So Basically talking, with those Faulty Rear Shoes Regulators, you have a four wheel car, being stopped -almost only- by the two front wheels, that Really leads to an extreme Heat working conditions on the Rotors, for their extra effort; so that explain the Warped Rotors and the Premature Wear on the Pads; isn't it?
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Old 09-26-2012, 11:19 AM Thread Starter
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First, I changed the Rear brake shoes and manually regulated the Brakes to the Top; the Pedal was stiff and Brake power good; while the Parking Brake Lever had enough power to Hold the car in the first two or three tooth. ... ...

After three weeks of everyday use, the Brake Pedal got Lower, while the Parking Brake lever needed six or seven tooth to engage. ... ...

After two Months of Use since the first regulation, the Rear Wheels' brakes where doing nothing, because the wear on the brake shoes was not compensated by the faulty self adjusting regulators, so the Shoes where too far away to let the rear wheel cylinder brakes do enough pressure to stop the car with the Brake Pedal, also the Parking Brake became a li'l less than Useless. ... :banghead: ...

After Trying to Clean everything up in the Rear Brakes, also trying the Self-regulating procedures used in other cars (Such like Applying the Parking Brake while the car is Moving Forward / Backward with and without pressing the Brake Pedal, etc...) without any success, many many times, I ended doing the Manual adjustment every Month.

Tired of that Monthly rear drum brakes Disassembly / Cleansing \ Regulation; I went to the Local Kia Dealer to buy a pair of Brand New Rear drum brake self adjusting Regulators, The Rear Drum Brake system found on the Second Gen Sephia does Not have a "Star" Adjuster, it uses a Ratcheting Cam (Named "Strut" by Kia) that is suposed to take up play as Brake Shoes wear:





I Really Don't know why Kia named those as "Struts" ... ... Maybe I'm Lost in Translation again.


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Old 09-26-2012, 11:20 AM Thread Starter
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So I Solved the Mistery:

Lots of People have experienced that same problem, Brake Pedal Fade and premature wear of the Front disc brakes ... and some never found the Answer to the Mistery; as you can Read few examples on this Links:

01 Kia Sephia brakes - Car Talk

rear brake adjustment on 2001 sephia - Mombu the Asian cars Forum

https://www.kia-forums.com/2g-1998-20...djustment.html


And illogically, I found that the Answer was on the Rear Drum Brakes!!!

Let me explain: The Rear Drum Brake system found on the Second Gen Sephia uses a Ratcheting Cam (Named "Strut" by Kia) that is suposed to take up play as Brake Shoes wear, but definitively, such thing doesn't work at all due to their bad design, and as the rear brake shoes wear, their surface gets farther from the rotating drum and during braking, the rear wheels spin freely while the fronts are doing the braking effort, because the rear brake pumps can't handle well the extra distance without a useful automatic shoes adjuster, that means that the rear shoes are barely "Touching" the Drums under Braking, while the fronts could be at Maximum clamping force.

So, in order to compensate the normal wear on the rear shoes, the car needs Monthly adjustments to the Rear Drum Brakes to Keep said shoes as near to the Rotating drum as possible, and thus means to have a firm & tall brake pedal, and ensure that it has the proper braking power to be Safe.

However, I changed the old Faulty self adjusting regulators with the New ones, only to discover that those are Faulty too ... They're are very Bad designed: some sort of Lifeless Lump that does Nothing to adjust the rear shoes... The old ones and the new ones Never worked; that must be a major design flaw from Kia ... ... Just like the tiny Hole behind the Backing Plate for adjusting the said strut adjusters: Both are Completely Useless, there's No Tool capable to slip thru such tiny, misaligned hole to "Adjust the Adjusters" ... ... nor the Adjuster works as intended.

The Rear drum Brakes on the Second Gen Kia Sephia has another problem related to those Bad designed self "Strut" adjusters: Both sides Never ever wear the Shoes equally, and thus means that the side with more wear is the side that does more braking effort.

In those Rear Drum Brakes of the Second Gen Kia Sephia, I noticed that the Driver's Side, trend to retain the Adjustment for more time than the Passenger's side, which loose it faster; it makes me think that Tire Rotation and its Vibrations might has something to do with that phenomenon: The "Strut" adjusters might suffer from that since they're Weak, while the Old-School style "Star" Adjusters were Stronger.

In Short words, that tendency of the Second Gen Kia Sephia of Loosing the Rear Drum Brake's Adjustment in one side faster than the Other, makes Emergency Braking more Dangerous, since one of the rear wheels could Lock while the other spins freely...

So, the Sephia with Regulated Rear Shoes and the New Proportioning Valves has an Excellent Brake System; the Brake pedal become way more Sensible and the Brake Power is really Good ... but only while the Rear Shoes are Adjusted properly, and said adjustment only last a month ... ... The Self Adjusters are Completely Worthless and Weak.

I need to do Monthly adjustments of the Rear shoes (to compensate their normal wear) in order to keep a firm and tall brake pedal and thus means a Safer car to Drive, and that monthly adjustment means to disassembly the Whole Drum setup, because the tiny hole that they have in the Back (on the Backing Plate) is Useless: I never found a Tool that "Magically" slips thru it and could handle the "Strut" Adjuster to the Proper position... That is another Design Flaw!

Once properly adjusted, the Whole car's Braking Performance is Great.

The only Real Solution for this problem was found by Kia years ago, to install Rear Disc Brakes! ... But only Premium models of the Kia Sephia came with Factory Rear Disc Brakes, and Kia sold very Few of those...

I Started to Search for Rear Disc Brakes on Second Gen Kia Sephias at Junk Yards, Wish me Luck!

Edit: About the Search of Rear Disc Brakes for my Wife's "KiaStein", please read this Thread on the Subject:


~► https://www.kia-forums.com/2g-1998-20...akes-swap.html
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Old 09-26-2012, 11:21 AM Thread Starter
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Lightbulb Master Cylinder Bose Size

I Never has to Touch the Master Cylinder, nor the Brake Booster or the Brake Lines; everything related with those were alright.

For those who has Weak Brakes and believe that by Changing to a Bigger Master Cylinder could help, Remember:

A bigger bore master cylinder will Not improve braking power; It will make the pedal engage higher and feel firmer, but the braking force at the wheels is reduced for the same pounds of pressure applied to the pedal. So you'll actually have to Push Harder on the pedal to get it to Stop as quick after "upgrading".

Master cylinder bore size is in balance with the Wheel cylinder bore size; Go too Small and the pedal will hit the Floor before the brakes are at maximum Clamping force. Go too Big and you'll run out of leg strength before hitting maximum clamping force. Simple hydraulics: the piston ratio between the master and the wheel cylinders gives you the mechanical advantage.

So, to use a Master Cylinder with increased bore, could Help in certain situations, such like those Brakes designed with a Lot of free travel on their Brake Pedal, to reduce the free travel while gets rid of the Spongy Pedal by stiffening it; but in cars where there is very short free travel on the pedal, a Bigger Bore Master Cylinder could make braking even worse, becoming too stiff the pedal, and thus means to push very hard the brakes for the same stopping power.

A Change in Master Cylinder diameter should be done with enough analysis and measurements taken, and Tests done with the Trial & Error method on a safe area, before driving the car on the streets.

In the Case of the second gen Kia Sephia, Kia Motors chose to change the Regular 7/8" Master Cylinder that is found on the Regular Sephias with Front Discs / Rear Drums brake setup, to an upsized 15/16" for those Premium Sephias with Factory Rear Disc Brakes.


__________________________________________________

So I will seek to Upsize the Master Cylinder on my Wife's Sephia, when I could get the Rear Disc Brakes, which I'm searching actively, with the Kind Help of other Kia-Forums' Members in USA, as you can see details here:

~► https://www.kia-forums.com/2g-1998-20...akes-swap.html

Kind Regards.


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Old 09-26-2012, 11:21 AM Thread Starter
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So, the faulty self adjusting regulators for the Rear Brake Shoes, are the Culprit of the premature wear of the Front Rotors & Pads, plus they are culprit in part of the Weak Brake Power, because the deregulated shoes let the rear wheels to spin almost freely, while the front wheels take almost all the braking effort.

However, despite that I changed the Faulty self adjusting regulators, those are very Bad designed and are some sort of Lifeless Lump that does Nothing to adjust the rear shoes... The old ones and the new ones Never worked; that must be a major design flaw from Kia ... They're Completely Useless.

If you have a second gen Sephia with Rear Drum Brakes and you want to know how the deregulated shoes affects the overall braking behaviour, you must be aware that the deregulated shoes reduces dramatically the overall braking power, while makes the brake pedal to be Spongy and travel free a lot before engaging the brakes. That is why lots of people won Lawsuits against Kia years ago: Those Brakes are Dangerous, especially during Panic Braking.

You can do a simple test to see how the brake pedal raises and becomes firmer with the Regulated Shoes, without the need of doing the manual adjustment: you only need to Pull the Parking Brake lever few teeth 'till the rear shoes starts to touch softly the rotating Drum, raise the lever but not very strong; the idea is to let the shoes to be as close to the rotating drum as possible, while still they let the rear wheels to spin; then drive the car and apply the brakes with the parking brake lever standing there: You will notice how the Brake Pedal becomes firmer and needs to travel way less to stop the car, while the car stops easier with less leg effort. That is due to the four wheels stopping the Car, not only the two front wheels.

But you can not leave the lever up like that, that was a short test only; you must do the Rear shoes' adjustment or take your Sephia to a qualified mechanic to do such adjustment for you.

Important Note: The more you use the Parking Brake, the Less that the Rear Shoes' adjustment will last. The use of the parking brake deregulates the rear shoes adjustment faster than regular braking.

So, I'm somehow "Condemned" to do a Monthly Rear drum brakes disassembly in order to Adjust the Rear Shoes to compensate their wear. (Unless I swap Rear Disc Brakes there) In that way, the Car's Brakes works Great.

______________________________________


So, the Sephia with Regulated Rear Shoes and the New Proportioning Valves has a great Brake System, the Brake pedal become way more Sensible since the car has the New Proportioning Valves, and the Brake Power is like many of the other brands' Similar cars.



After I Solved the Mystery of the Weak Brake Power and Premature Wear on front Brakes' parts; Beside Changin' the Faulty Proportioning Valves and the Rear Shoes' Self adjustment regulators; I decided to Change the Front brake's Disc Rotors & Pads:








And I did the Best Brake Job I Could.




The Car does perform Flawlessly since then

Except that I need to do a Monthly manual adjustment to the Rear wheels' Brakes.

... ...

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Old 12-17-2012, 08:27 AM
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Is this an early 2000 Sephia?
If so, look at the fully assembled discs and calipers.
The metal backing of the brake pads rubs against the rotor hub. They self-machine a groove into the hub. This is a very poor design:P
On the post 2000 models, bigger discs and different calipers are used. The major difference: A groove is cut into the hub of the new rotors. Quite the fix:P

But I do agree those self-adjusters are useless.
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Old 12-25-2012, 04:44 AM
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Isnt there a TSB for this already? I think I read it somewhere and Kia (at least Kia USA) knew about this and made the new parts.




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