Demosthine

Hey Guys.

I know these issues are hard to diagnose, so here goes...

1998 Toyota 4Runner SR5

About a year ago, I started having vibrations in my my braking/steering system, but it only occurs when I brake. At slow speeds, the pedal pulsates slowly, but at higher speeds (30+ mph), it starts vibrating the entire truck violently. I can feel the vibration in both the clutch and brake pedals, as well as the steering wheel vibrating back and forth.

To further aggravate the issue, if I am braking and going over a series of bumps, such as railroad tracks, the brake pedal vibrates even more violently and seems to go soft. It doesn't brake anywere near as well, either.

I've done a lot lately to fix it:

In terms of troubleshooting, I have definately narrowed it down to front end because I can lift the entire truck and with only the rear wheels turning, nothing vibrates at all. If I put it in 4H, the ride is smooth as silk until I start braking. Dropping one front tire on the ground (so that it doesn't turn), the vibration occurs the same as normal driving. Alternating which front tire is on the ground and which is turning does not change anything.

01.) Brake rotors and drums have been turned. Prior to the first time, both were warped severely. Second time from a different shop, they confirmed first job was perfect. Each time, new pads/shoes were installed, though there was no abnormal wear on the old pads. Turning the hubs by hand gives a smooth feel, so no abnormal rubbing is there.

02.) Tires have been balanced by three different shops and an entire new set has been placed on the truck. Each time resulted in cross-rotating as well.

03.) Although it needed replaced, replacing both front wheel bearings had absolutely no affect.

04.) In amongst this issue, I lifted the truck using the Sonoran Steel 2.1 Lift kit. Everything installed perfectly, but it did not change the vibration for better or worse.

05.) Right after installing the lift, the shop that did the alignment informed me the rack and pinion needed replaced, so that was completely removed and a brand new one installed. New tie rods were used as well. The alignment was completed after the rack and pinion replacement.

The only thing I have been able to find so far on the forum that I haven't tried is that the bolts for the front differential may be loose, but I replaced two of them and tightened them to specs when I did the lift, so I can't imagine that being the problem.

I have a friend coming over to help out. We'll put the truck on jacks and I'll crawl under to watch everything while she gets the truck going and then brakes. Hopefully that'll give me an idea.

Any other ideas, guys? The truck is at 296,000 miles, so she's well used, but in excellent condition otherwise.

cox380

A easy way to tell if its the front or rear is to pull the e-brake and see if it vibrates. If it doesent, It the front.
I saw on a simular posting that one guy had to replace his front calipers to fix the problem.
please keep us up dated. I have the same problem.

dbcx

washing your wheels while they are hot can warp the rotor also sometimes deep water crossings with hot brakes can cause that problem.
At least you turned your rotors when you bought them

seaofnames

If you have alloy wheels, make sure all lugnuts are tightened at the same torque(usually 85-90ft/lbs).

Adjust rear brakes if they need to be as well.

These two things probably wont fix your problem, but two things I've always made sure to do when I do a tire rotation/oil change.