8/25/08

After putting up with brake shudder again (see below) I looked into a more serious brake upgrade. A popular swap is the use Tundra components if you have the 16" wheels with the big rotor option already. I don't know if it can be done with the small brake package and you definately would need the proper 16" wheels. I shopped Parts America and located a set of Raybestos rotors. You can see that they are the same diameter but much thicker. Clean them with brake cleaner prior to installation as they are coated with a light protective oil. The box should indicate whether they are already turned/trued. These Raybestos ones were.

To fit the thicker rotors, you need Tundra calipers as well. There are two varieties. The 199mm wide one up to 2003 Tundras, known as the SE13E and the 231 mm wide, known as the 13WL, ones thereafter. The 199mm ones will fit pretty easily and require a bit of trimming or bending of the dust backing plate. These calipers look identical to the large package 3rd Gen 4Runner calipers except they are a bit wider to accept the rotor. It seems that some of the warping issues may be related to calipers as well as rotors because Toyota came out with the revised 231mm caliper and issued a TSB on the Tundra for vibration issues. Since the price was so close and I really wanted to solve my vibration problems I bought the 231mm versions fully loaded with Cardone's pads. To the left is a comparison to the stock large package 4Runner units. You can see that the 231's are not only wider but also longer and use a 5.25" pad instead of the 4.75".

Here they are mounted up. A pair of vice grips applied carefully to the rubber line will keep fluid leakage to a minimum during the swap. All the lines and fittings line right up but some mods are necessary. Again, the dust plate needs trimming but more importantly, the piston cross chamber needs the edge ground off to clear the wheel. Click on the picture to see up close. Be careful as this is a fluid passage. Take off too much material and your caliper will be useless. A few people have ground material from the wheel interior as well. That would require pulling all five wheels. I was able to leave the wheels in tact. I don't know if the steel spare, that I've never used in the ten years, would need trimming but in a flat situation I could rotate another aluminum wheel to the front and fix it later.

Bleeding was super easy with a magnetic one-man bleeder container. Just mount it high so the bubbles go up. The old cores got me $160 back at a local Kragen which is part of Parts America. First impressions were astonishing. Definately smoother with no vibration and much better feel. The brakes feel stronger and firmer but I'm sure fresh fluid helps too. I expect them to be even better when fully bedded in and hopefully my warping problems are gone. Be careful to tighten your wheel lugs to 80ftlbs. Over tightening them is a supposed cause of warping too. You'll be surprised how little 80ftlb is. I think I over tightened in the past.

1/9/04

After several bouts with leaking axle seals in the rear, the rear shoes had become completely soaked in oil. I drove on these shoes for many thousands of miles and every time they got hot, the truck would shudder horribly under braking. With over 70,000 miles on all the original parts, I decided to do a complete over haul.

I began with the rear drums. Seems that besides Toyota, only Raybestos makes shoes for the 4Runner in my area so I bought a set of those. After installing them and taking a test spin, the shudder was ten times worse. I took a guess that the drums were out of round and badly oil impregnated though I had cleaned them. I replaced them with new units and the problem only got slightly better.

I took everything apart and inspected everything. In hopes of better fade resistance, I had cross-drilled the shoes. Turns out that the Raybestos material was so cheap that it would immediately burn on every stop. I did notice the bad smell of brakes. I decided to spring for the expensive Toyota shoes.

When I got the new Toyota units, I closely compared the two sets. The first thing I noticed was how much better the Toyota material looked in quality. the next thing I noticed was that my backing plates had new and peculiar marks on them. Turns out the Raybestos shoes, above in red, have extra tabs as indicated by the arrows. These tabs interfere with the shoe stops and cause the shoes to sit crooked against the backing plates. This, in turn, prevents proper contact with the drum, makes them difficult to adjust and throw the emergency brake completely out of adjustment. These are things I only fully realized after getting the Toyota shoes. The Toyota shoes also come with new emergency brake arm retainer clips. One thing to note when assembling the shoes is to make sure the small ebrake cable inside the drum gets put back properly into its guide. This is an easy thing to miss.

Also, after installation check to see that the parking-brake-arm-stop returns completely so as to contact the shoe. See the lower left arrow in the picture above. If not, adjust the stops on the outside of the backing plates and/or the cable length at the handle inside the vehicle. The hand brake adjusts the rear drums. If you never use the handbrake, chances are that your drums are out of adjustment, the brakes are probably spongy and you may get brake vibration. Each time you pull the parking brake, the lever shown in the picture above tightens the shoes against the drum. If the distance between the shoes and the drum is too great, the parking arm pawl will move enough to grab another tooth on the adjusting wheel. When the parking brake is later released, the pawl rotates the adjuster wheel and thereby moves the shoes closer to the drum. With the drums adjusted properly, the difference in diameters between the drum surface and the shoes should be 0.6mm.

Other sources of braking vibration can be: warped or oiled discs or rotors, loose suspension components, bad shocks, bad or loose bearings, misbalanced or out-of-round wheels or tires. Bad tires can often amplify problems as I found out.Vibration can be tough to track down. If you get vibration while braking, try applying the hand brake only while driving to see if the vibration is coming from the rear of the vehicle.

Had the original shoes not become oiled, they probably could have lasted another 70,000 miles. In any case, after installing the Toyota shoes with the new drums, the brakes were greatly improved.

Since I was redoing the rear, I decided to overhaul the front too. The stock rotors and pads appeared to be in pretty good shape. The pads still had lots of life left and the rotors looked good except for a scar on the back side of one from some rocks that had wedged themselves in the slot cut into the pad. Nevertheless, I figured I would try for the best setup possible. I ordered a set of Powerslot rotors from http://www.RaceShopper.com. They are part numbers 794PSL and 794PSR for 4Runners with the larger brakes (16" stock wheels). Matched to these, I also ordered Performance Friction Carbon Metallic brake pads. I have previously used these on my Camaro and they greatly helped stopping power though they dust more than conventional pads. See http://pages.sbcglobal.net/larsdennert/camaro/campads.html if you are interested in the capability of these pads. As with the Camaro pads, these pads require a little bit of heat before they work optimally. The Toyota version requires less than those on the Camaro though. Basically the first stop of the day in the Toyota requires higher than normal pedal effort until they are worn in. The correct Performance Friction part number for my 4Runner is PFC0436.20. These are identical in shape as the stock pads.

You can also get the FJ80 Land Cruiser application 5024, see http://www.gadgetonline.com/susp.htm#Brakes, but besides the tabs they are identical.

For interest's sake, here are a couple of other similar pads.

After about 500 miles of driving, the pads and shoes get bedded in and reach their full braking ability. The few full threshold stops I've made indicate that the brakes have very good stopping power. The stock Toyota equipment, when new, also did but the difference should show up in the heat handling, fade and warp resistance of the Powerslot/Performance Friction combination. That, I have not yet had a chance to test, however the fixed brakes easily lock up my 33" tires.

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