Brake caliper question
06-15-06, 06:12 PM
#1
Driver
Thread Starter
Brake caliper question
Well let me start by saying thatr this problem has been haunting me for too long now .I've been having problem with my right rear brake squeling at cruise speed 0-10mph As per two shops checking it, and one rebuilding the caliper.,this only to solve problem for a short period of time after taking it back and changing brakes with akebono ceramic new rotors and bleeding system its still has the problem. this is how it all goes down ,I can drive for about 10-30min in trafficthen when they seem to get warm it begins to sound like a whistle, sometime stopping when I apply the brakes , sometime when I accellerate just yesterday I decided to check it myself again and noticed the pin boots were gone and one pin had major resistance as far as moving freely my question is are the pin removable on all models and what is the process for doing the removal
Hey man I need help
Greg
Hey man I need help
Greg
06-15-06, 10:36 PM
#2
Lexus Champion
Remove and jackstand the rear wheels. Safety is your prime consideration, don't rely on any style of jack alone.
The bottom bolt and slider sleeve is removed (12mm head) and the caliper swung up from the pads to inspect, if necessary.
Wire up to the spring with a piece of coat hanger wire.
Suggest using synthetic hi-temp caliper grease to lubricate these slider bolts and sleeves. Common auto parts stores carry it. (CRC or Lock-tite brands, for example)
Additionally, the caliper grease is used to "lightly coat" grease on both sides of the black inner shims and the steel back plate of the pad, where the shim would be in contact with it. A little dab where the pad ends contacts the steel caliper pad retainers. They tend to rust at these upper and lower contact points; then squeak when vibrated as the brakes are applied.
Do not grease the caliper cup face, as it contacts an outer stainless steel shim.. This prevents brake squeal or squeaking when brakes are lightly applied at low and medium speed.
(Referenced proceedure - Lexus TSI # BR95-002 August 18,1995 All Models)
Correct operation is indicated by the pads retracting slightly from the disk, both inner and outer pads, by the suction action of the master cylinder restoring. Any air pressurizing in the brake system would prevent this from occuring and the pads would drag consistently on the rotor. Any brake fluid leak also means an air leak into the system.
Are the stainless steel pad support plates installed at the pad ends where they fit into the caliper? Refer to the PDF attachment below as an example.
Are the black and stainless steel brake pad anti-squeel shims in place on both inner and outer pads, rear calipers? The stainless shim should be visible through the wheel, outside shoes in the caliper pad holders. That's, the stainless shim on the outside and the black painted shim inside, as fitted in the caliper holder. The black inner shim has locating tabs that are located away from the disk, towards the stainless shim, when the shim set is installed. The shims should be installed on all eight brake pads, the four front and the four rear; regardless who manufactured the pads.
Do the inner and outer pads match in wear on both rear brake calipers? Meaning are there one or two pads appear more worn than the others in the rear set?
This would indicate a worn or rusted slider bolt and sleeve. This may be your problem and they are in need of replacement. Remove and clean to inspect for wear or rust corrosion. Replace the rubber boots, if necessary.
Lexus should carry a replacement kit, including the boot and slider sleeve..
Were the replacement rear rotors OEM Lexus? Are there holes or slots in the replacement rotors or solid disks like the originals?
Do the axle drive shaft inner and outer boots appear to be in good, sound shape, with no grease leaking or cracks.in the CV joint rubber boots and any missing boot retaining bands ( two retaining each boot to the drive shaft)? This may indicate a near worn CV joint on that axle driveshaft. (Lexus "driveshafts" are the half shafts located between the differential and the wheels)
Are you equipped with anti-lock brakes feature? If so, was the ignition "on" when the brakes were bled; thus bleeding the activated ABS pressure pump. The caliper was removed and air allowed into the system. The pump is sometimes difficult to bleed without a toyota branded service tool.
And, least not forget the torque of the wheel lugnuts - 76 Ft Lbs. Too tight may warp the rotor on the hub. (engage the parking brake, torque the lugnuts to spec, release the parking brake, rotate the wheel by hand. Feel and listen for any hub bearing noise, CV joint noise or squeek, or excessive disk pad drag.
Just checking for the little sometimes forgotten points of interest. An aerosol can of brake cleaner is also handy for any cleanup tasks.
I'll attach a PDF on the RX technical service information (TSI) bulletin for the shims, as an example. Your's are slightly different, but you get the idea with the writeup. The front and rear are basically the same design, regarding the shims and pads.
Best of luck with your inspection and hope you find what's at fault..
The bottom bolt and slider sleeve is removed (12mm head) and the caliper swung up from the pads to inspect, if necessary.
Wire up to the spring with a piece of coat hanger wire.
Suggest using synthetic hi-temp caliper grease to lubricate these slider bolts and sleeves. Common auto parts stores carry it. (CRC or Lock-tite brands, for example)
Additionally, the caliper grease is used to "lightly coat" grease on both sides of the black inner shims and the steel back plate of the pad, where the shim would be in contact with it. A little dab where the pad ends contacts the steel caliper pad retainers. They tend to rust at these upper and lower contact points; then squeak when vibrated as the brakes are applied.
Do not grease the caliper cup face, as it contacts an outer stainless steel shim.. This prevents brake squeal or squeaking when brakes are lightly applied at low and medium speed.
(Referenced proceedure - Lexus TSI # BR95-002 August 18,1995 All Models)
Correct operation is indicated by the pads retracting slightly from the disk, both inner and outer pads, by the suction action of the master cylinder restoring. Any air pressurizing in the brake system would prevent this from occuring and the pads would drag consistently on the rotor. Any brake fluid leak also means an air leak into the system.
Are the stainless steel pad support plates installed at the pad ends where they fit into the caliper? Refer to the PDF attachment below as an example.
Are the black and stainless steel brake pad anti-squeel shims in place on both inner and outer pads, rear calipers? The stainless shim should be visible through the wheel, outside shoes in the caliper pad holders. That's, the stainless shim on the outside and the black painted shim inside, as fitted in the caliper holder. The black inner shim has locating tabs that are located away from the disk, towards the stainless shim, when the shim set is installed. The shims should be installed on all eight brake pads, the four front and the four rear; regardless who manufactured the pads.
Do the inner and outer pads match in wear on both rear brake calipers? Meaning are there one or two pads appear more worn than the others in the rear set?
This would indicate a worn or rusted slider bolt and sleeve. This may be your problem and they are in need of replacement. Remove and clean to inspect for wear or rust corrosion. Replace the rubber boots, if necessary.
Lexus should carry a replacement kit, including the boot and slider sleeve..
Were the replacement rear rotors OEM Lexus? Are there holes or slots in the replacement rotors or solid disks like the originals?
Do the axle drive shaft inner and outer boots appear to be in good, sound shape, with no grease leaking or cracks.in the CV joint rubber boots and any missing boot retaining bands ( two retaining each boot to the drive shaft)? This may indicate a near worn CV joint on that axle driveshaft. (Lexus "driveshafts" are the half shafts located between the differential and the wheels)
Are you equipped with anti-lock brakes feature? If so, was the ignition "on" when the brakes were bled; thus bleeding the activated ABS pressure pump. The caliper was removed and air allowed into the system. The pump is sometimes difficult to bleed without a toyota branded service tool.
And, least not forget the torque of the wheel lugnuts - 76 Ft Lbs. Too tight may warp the rotor on the hub. (engage the parking brake, torque the lugnuts to spec, release the parking brake, rotate the wheel by hand. Feel and listen for any hub bearing noise, CV joint noise or squeek, or excessive disk pad drag.
Just checking for the little sometimes forgotten points of interest. An aerosol can of brake cleaner is also handy for any cleanup tasks.
I'll attach a PDF on the RX technical service information (TSI) bulletin for the shims, as an example. Your's are slightly different, but you get the idea with the writeup. The front and rear are basically the same design, regarding the shims and pads.
Best of luck with your inspection and hope you find what's at fault..
06-17-06, 04:36 AM
#3
Driver
Thread Starter
I'm wondering about the suction on the master cylinder on that wheel (right rear) I mean no brakes applied just rolling along and I get aconstant squeal sounds like the pads are in contact with rotor, if I lube the pins & adjust retracting spring it works great for awhile then slowly gets back to the squealing condition.
gonna try new springs and pins first I guess and the have master sylinder pressure tested if possible
Tammy thanks for the valuable info
Gman
gonna try new springs and pins first I guess and the have master sylinder pressure tested if possible
Tammy thanks for the valuable info
Gman
06-17-06, 07:57 AM
#4
Lexus Champion
I wasn't clear...
>> A fresh thought !!! <<<
Closely inspect your flexible rubber brake line suppling to the failing caliper. Look for a "bubble" in the rubber outer hose or a small soft spot when flexing the hose.
When these flex lines fail, they leak from the inner hose into the paper packing between the inner hose and outer hose casing. The packing swells as it absorbs the brake fluid, closing off the inner hose. This creates, in effect, a one way valve. Press the brake, brake fluid is forced past the leak in the line. Release the pedal, suction pulls closed the inner hose at the bad spot and maintains pressure to the caliper. If in doubt, remove the short flex hose and blow through it in both directions. Should be as a straw, with very little restriction. (took me three months to find this one, on a Volvo)
where were we...
The suggestion was that if air is in the brake line suppling to this caliper; the pedal pressed, air would pressurize with the brake fluid. Then when the brake pedal is released, depressurized fluid pushed back to the master cylinder and to the caliper, preventing the caliper cup from centering the caliper and pulling the pads away from the disk. The pads then drag...
If the other rear caliper appears to function as discribed, the master cylinder seems to be working correctly. Master cylinders are known to leak within itself, or leak fluid into the brake vacuum booster, causing the brake not to clamp. Rather than sucking back brake fluid, it's sucking in air from the moving caliper cup o-ring seals. You're not loosing brake fluid.
A previous post refered to an individual that needed to replace with a remanufactured caliper from the dealer...
They tried a caliper rebuild kit with a cup reseal with new o-rings, but the caliper cup cylinder was worn and pitted from rust. At times, the caliper seemed to become stuck in it's bore. Specialized boring machines are required to resurface the caliper cylinder. Without reboring, the rebuild lasted but a short while, and the problem returned. Many rebuild exchange units from auto parts stores are not bored, just cleaned and new o-rings installed. If it leaked again, they will exchange it with another. Parts rebuilders don't have to make the part function.
The OEM factory remanufactured caliper cup and cylinder assy fixed their problem.
>> A fresh thought !!! <<<
Closely inspect your flexible rubber brake line suppling to the failing caliper. Look for a "bubble" in the rubber outer hose or a small soft spot when flexing the hose.
When these flex lines fail, they leak from the inner hose into the paper packing between the inner hose and outer hose casing. The packing swells as it absorbs the brake fluid, closing off the inner hose. This creates, in effect, a one way valve. Press the brake, brake fluid is forced past the leak in the line. Release the pedal, suction pulls closed the inner hose at the bad spot and maintains pressure to the caliper. If in doubt, remove the short flex hose and blow through it in both directions. Should be as a straw, with very little restriction. (took me three months to find this one, on a Volvo)
where were we...
The suggestion was that if air is in the brake line suppling to this caliper; the pedal pressed, air would pressurize with the brake fluid. Then when the brake pedal is released, depressurized fluid pushed back to the master cylinder and to the caliper, preventing the caliper cup from centering the caliper and pulling the pads away from the disk. The pads then drag...
If the other rear caliper appears to function as discribed, the master cylinder seems to be working correctly. Master cylinders are known to leak within itself, or leak fluid into the brake vacuum booster, causing the brake not to clamp. Rather than sucking back brake fluid, it's sucking in air from the moving caliper cup o-ring seals. You're not loosing brake fluid.
A previous post refered to an individual that needed to replace with a remanufactured caliper from the dealer...
They tried a caliper rebuild kit with a cup reseal with new o-rings, but the caliper cup cylinder was worn and pitted from rust. At times, the caliper seemed to become stuck in it's bore. Specialized boring machines are required to resurface the caliper cylinder. Without reboring, the rebuild lasted but a short while, and the problem returned. Many rebuild exchange units from auto parts stores are not bored, just cleaned and new o-rings installed. If it leaked again, they will exchange it with another. Parts rebuilders don't have to make the part function.
The OEM factory remanufactured caliper cup and cylinder assy fixed their problem.
06-17-06, 03:10 PM
#5
Driver
Thread Starter
brake
Tammy :
I'm going to inspect the line as you described ,it happens to be one thing I havent check so far. So far the only real issue was the caliper pin boots deteiorated which I have on order, mine was slightly resistant but not much but i decided th replace them being there no that expensive, but ht eline sound mkore like a more common problem as I have seen them swell and develop **** on them i happen to be a auto electrician so I have to learn more about these brakes eventhough the seem like a vert simple system as far as the calipers are concern I'll get back with you tahnks again
Greg
Gman
I'm going to inspect the line as you described ,it happens to be one thing I havent check so far. So far the only real issue was the caliper pin boots deteiorated which I have on order, mine was slightly resistant but not much but i decided th replace them being there no that expensive, but ht eline sound mkore like a more common problem as I have seen them swell and develop **** on them i happen to be a auto electrician so I have to learn more about these brakes eventhough the seem like a vert simple system as far as the calipers are concern I'll get back with you tahnks again
Greg
Gman
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