Why does a 1997 Toyota 4Runner shake and when stopping it even shakes worse?

Answer 1

4rUNNERS HAVE A LOT OF WEIGHT FORWARD (OVER THE FRONT TIRES). ANY CHANGE IN TIRE PATTERN EITHER THROUGH WEAR (UNEVEN TREAD WEAR), INCREASE IN TIRE PRESSURE (32 IS RECOMMENDED FOR COMFORT, YOUR TIRES MAY RECOMMEND A HIGHER LOAD PRESSURE), A MORE AGGRESSIVE TIRE PATTERN (MUD / ALL-TERRAIN TIRE) OR WHEEL ALIGNMENT CAN ALL EFFECT VIBRATION. AS FAR AS BRAKES AND/OR BRAKING, REPLACING ALL THREE RUBBER BRAKE LINES (2 FRRONT/1 REAR) WITH STEEL BRAKED LINES WILL ENSURE MAXIMUM BRAKING PRESSURE TO THE FRONT DISCS AND REAR DRUMS. IF YOU HAVE ALREADY REPLACED THE CALIPERS THEN CONSIDER REPLACING THE MASTER CYLINDER IF YOU HAVE A 95 OR OLDER. ALWAYS REPLACE THE BRAKE FLUID AND BLEED THE LINES IF YOU CHANGE LINES/CALIPERS OR IF IT IS "CONTAMINATED" (YOU BASICALLY CAN SEE 'THROUGH' THE FLUID). .

another reason for the car shaking even worse when braking is that the calipers may need resurfacing. along mabe with a tire balancing.

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I brought my 1997 4-Ruuner limited with 145,000 miles on the vehicle from my brother. It was a NYC car, althought meticulously maintained following all the mfg guidelines. The car's handling and vehicle dynamics were border line dangerous. I am an amature auto and motocycle roadracer, therefore I am extremely demanding of how a vehicle perform. Listed below are the poor behavior that it exhibited after I bought the car, and the solutions that I employed to rid of most of those bad behaviors. For some of them, I actually improved their behavior beyound the manufaturers original objectives, while maintaining the vehicle's comfort level as a day to day commuter vehicle. My daily commute starts from Brooklyn in NYC, thru the entire length of Manhattan, and finally crossing George Washington Bridge and into New Jersey. Every aspect of my 4-Runner is put to extreme test at least twice a day. The condition of these roads, the other crazy drivers, high speed (60 -90 MPH) driving on the extremely twisty and rough FDR drive, and of course the occassional emergency evasive manuvers and max braking for that broken down vehicle, parked right around the many blind turns and usually right on the other side of the many crest. So here goes for all you Baja Racer want-to-be's. Problems and solutions: 1. The car's back tires would lose traction at speed much lower then the posted speed on highway on and off ramps on dry and clean surfaces without any power being applied. Solution - Throw those Brigestone Dueler A/T 683 or 687 that came with the car when new, and the same ones that the dealers always seem to replace the worn out ones with. They are the worst tire that I have ever driven on. Go on the web or call TireRack and get 4 new Bridgestone Dueler A/T Revo. They are superb (Sport Sedan level) traction on wet, dry, snow and ice surfaces, quiet, even and long lasting wear characteristcis, comfortable, provide immediate and precise steering response with tire pressure between 35 - 37. They are extremely sensitive to tire pressure, so experiment with the pressure one pound at a time to suit you driving environment and style.

2. Car sometimes would exhibit a high frequency - low amplitude vibration and/or the steering wheel shimmy similar to tires being out of balance at random. I balance the original ones many times with many different performance oriented auto facilities, to no avail. Here are the 2 part solution: First the new Revo's reduced most of them on relatively smooth highway and surface streets. I suspect the OEM (683 or 687?) ones has a tire compound, tread block and belt design problem. It caused a cupping effect on the treads, in plain English, the circumference of the tire is not truly round anymore. Some tread block would be lower then the others, so on a certain combination of road surface and speed, the tires surfaces are essentially hopping from one small ripple to the next, creating that high frequency vibration and/or shimmy of the steering wheel. Even with the new tires, I still get these vibration ones in a while, but their frequencies (a slower up and down vibration) and amplitudes (the car goes up and down higher during these spells of vibration) are different then the ones I got wit the OEM tires. Then I suspected the problem might be coming from the combination of the tire/wheel's weight due to their size (265/70-R17) and the damping rate of the shock and spring. One of the major criteria among many that contributes to a good handling vehicle is the reduction in un-sprung Mass. Tires, wheels, brake rotors, brake calipers are all components of un-sprung mass in a suspension design. They are things that if not properly contrained by the springs and shocks, each corner will bounce up and down at a different rate, height and duration when they are being influenced by external factors (Rippled Road surafces, pot holes, expension joints on freeways etc...). When this happen, the tires are essentially hopping from one ripple or bump to the other, and won't stop doing so for a long duration depending on the spring rate and shock damping selections. That is where the vibration are coming from. SUV suspension design are typically bias towards off road conditions with long suspension travel, at moderate traveling speed, and tires with low pressure settings and soft sidewalls. Under those driving conditions and with following the factories settings, these vibraion would hardly be noticeable. Althought most SUV are driven on paved roads at high speeds, owners of most SUV are still buying tires that are designed for off road purposes, some of them are upgrading to larger width and diameter for either appearance and/or better traction on hard dry pavements. With no regard to also upgrading their shocks and springs to control those extra weight. Later model SUV of many manufacturer are changing their suspension settings with shorter wheel travel, enabling the use of stiffer springs, shock valving with better high speed damping to keep the tires on the road surface as much as possible at high speed like a passenger car and tires selection towards all season type rather then off road type to better suit what SUV's are really use for. Urban highway and byways with paved surafces that has irregular and different surafces. When you applied the brakes, it will shake even worse, because now you are adding more un-sprung mass to the 2 front tires due to weight transfer of the vehicle, so now they bounce even more.

That is why high performance cars and race cars often use light weight material (Aluminum, Magnesium) for the wheels and and Composite material for their brake rotors and suspension components. All in the interest of eliminating the un-wanted out of sync movement of the tires relative to the road surfaces. Especially on my 1997 Limited, back then SUV suspension design were still require to have a strong off road performance, so all the things that I described above were all designed in. Then for the Limited, they spec'ed the bigger and wider tires for appearance (otherwise, those wheel well extensions will look pretty stupid with skinny tires, the funny part is that skinnier tires actually work better off road, in snow and wet roads :-)) But the shock valving and spring rate didn't seem to be any different then the skinner tire models. So here does our mysterious and seemingly un-fixable vibration. Solution - Call Tirerack again and buy yourself a set of KYB Gas shocks along with a set of Eiback springs. your vibration will go away as long as you keep them balance, and the car will handle in wet or dry at high speed on highway ramps and country roads that you would never expect an SUV to do (Except the BMW X5, which is designed like a tall sports car, with high performance wide street tires. Those things are terrible off road, my Audi A4 Quattro on Bridgestone RE950 can probably give it a run for their money on unpave roads. I drove my lowered A4 in Oregon's many paved road without any problems). I out handle most Sport Sedans with average drivers during my commute everyday, especially when I can fly over those pot holes, swer drains, and whatever lumps that pops up all over NYC's highways.

So go do it and enjoy yourself, I have 189,000 miles on mine now. I installed a set of Bosch Platinum +4, did an oil change and changed the air filter yesterday. And boy, is it cooking.

Shake at road speeds is probably tires being out of balance, out-of-round, or both. 4Runner wheels are hub-centric, which means that to balance them properly they need to be removed from the vehicle and spin balanced on a machine with a "fingers" attachment that locates the wheel relative to the lugs. A good tire shop should have a machine and the proper fixture to do the job correctly.

If your tires are significantly out-of-round they will need to be replaced because rebalancing won't cure the problem. Jack the car up and spin a front wheel by hand. Watch for runout at the tread surface. You can also hold a piece of chalk and gradually move it in to the tread as the tire spins, until it makes a mark. If the mark is not continuous the tire is not true.

Shake while braking is usually warped brake rotors and/or drums. I think Toyota recommends replacing rotors with more then .003" of rotor runout. Remove a front wheel and mount a dial test indicator against the rotor. Rotate the rotor slowly and watch the indicator. If the rotors are warped badly you can see it with your eyes and won't need a dial indicator. Rotors can usually be resurfaced but I recommend that you replace your rotors if they are warped. They are easy to replace. One reason rotors warp is over-tightening of the lug nuts. If you replace the rotors don't overtorque the nuts when you remount the wheels. And if you go to a tire shop demand that they tighten the nuts by hand, with a torque wrench (not an air-powered impact wrench).

Another thing - check all suspension components for wear and looseness, especially the tie rod ends. Tie rod ends are subject to wear and can cause the front end to shake badly, especially on braking. This is because the wheels are changing alignment (in this case, toe-in) while stopping. Worn tie rods can cause severe handling problems and if the tie rod breaks it could be catastrophic as the wheels will no longer track straight.

I also experience some shaking (more than mild, not as much as extreme)when braking to stop. The shaking comes from the wheel and not the pedal. It doesnt exist while driving only when braking. Also, it doesnt happen everytime I brake, sometimes it'll be just fine. I add these comments in hopes that someone can provide a solution further than calipers or tire wear. Plus, I'm not sure if its related but I hear a snap coming from my undercarriage, like a tense cable being released, on occasions. I have not been able to determine the source of the noise?

check front brake disk for cracks and check distorsion. A distorsion of 0.1 mm can create vibrations as you describe.

I bought a used 97 Limited 4Runner and test drove in Parking lot. Had 73000 miles. Looked good. On drive home, at 50 - 60 mph, the vibrations came on and got worse on braking. Called the dealer - he claimed ignorance and cited 'As is' Sale.

Anyway, took it to a trusted Nissan dealership, Yes that is Nissan and not Toyota because trust one mechanic there. He recommended, upon inspection - New TOYOTA rotors, New TOYOTA pads, Wheel Balancing,

Wheel Rotation, Alignment, and Bushes for suspension. I had the parts brought over from the TOYOTA dealer and had them installed.

The 4Runner now runs 90% better. NO VIBRATION on Braking; Still a little vibration - from uneven tires; did not change those because they have a lot of tread left.

Originial parts, trusted mechanic, proper tools - no vibrations.

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