mtnfreak

When taking a curve I notice significant understeer. I turn the wheel to correct but get little relief until I reach some magic point where I get oversteer and have to back-off. This started some time ago, but was barely noticable at highway speeds and not at all at lower speeds. Since then it has been getting more noticable and the speed at which I notice it has been dropping. I've checked everything I can - steering wheel, shaft, gear box, Pittman & idler arms, center link, tie rods, knuckles, ball joints, wheels, tires, PS pump and hoses. Nothing seems defective so I'm suspecting that the problem is inside the gear box. Has anyone run into this problem before? I'd like to hear from the experts before I start replacing parts based on semi-educated guesses.
Thanks!

ewong

um.. slow down?

A 4Runner is NOT a sports car.

Anywho - Me suspects is
a) sway bar bushings / links
b) alignment
c) tires (75 series sidewall "tucks under")
c) Springs - stock torsions are pertty soft

How fast and what types of corners?

What suspension mods if any do you ahve
What shocks are your running - brand, model number, age - (oil and nitro pressure and valve stack if you know - but me thinks if you knew that you wouldnt be asking the question)

mtnfreak

Speed is not the problem. Speed is almost never a problem with the 3.0.
Sway bar - No abnormal body roll + not connected to the steering system, so it's out.
Alignment - no other symptoms indicating bad alignment, so I doubt it.
Tires - don't think sidewall flex would cause this. Plus, I put many thousand trouble-free miles on the tires before this started happening.
Springs - are you suggesting I get some? No ride quality issues + not connected to the steering system.

Shocks are new, problem is the same as before the switch.

Problem isn't noticed on sharp turns or at speeds below ~40mph. Sweeping curves at 40 - 60 mph is where I notice it most. I haven't pushed my luck by trying them at higher speeds.

ewong

The 4Runner is a truck not a sports car - hitting off ramps / curves at above posted speeds (aka btw 40-60mpg) is bound to be a handfull.

That being said - lets start with the baseline... that the truck DIDNT do this before (same turn, same speed) and its doing it now.

Whe I see statements such as
I think - maybe the person making the statement needs a brush up on "Suspension 101"

A sway bar has a HUGE IMPACT on oversteer/understeer

In general - a front sway bar induces UNDERSTEER

Its why its first on my list - if the bar "sticks" somehow and then "slips" at a different suspension travel range - that would induce the effects that you describe
-- bar is "stiff" - under steer
-- bar is "slack" - less understeer = oversteer

I would suspect that the stud washers/bushings where the sway bar enteres the lower A arm are wonky. The bolt "hangs up" until the arm gets to a certian angle (under compression - as in outside tire) and then the bolts "slips through" the hole and thus - oversteer....

Um... poor caster (i.e. not enough set back) will make the handling "darty" w/o causing "bad tire wear" etc... and can lead to weirdness as the steerign is cranked over - esp if you have uneven caster left/right.


It sure does at the race track (friend autocross/road race) - its why we do the shoe polish / tread temp thing and adjust tire pressures accordingly.
Check your tire pressures.

Also - a tires handling changes over time and as the tread wears...


I was wondering if you were still stock or not

The stock torsion springs are rather soft. THe allow quite a bit of control arm movement. If the arm moves alot and then hits the snubber - the spring rate changes - possibly affecting the front end dynamics (how - Im not so sure off the cuff - but its an occasional race car trick to set the springs such that they bottom out on purpose - ref Daytona and Donhue's Can Am racer).

Also if the rear leaf is broken - it will handle wonky as the axle unloads - if the rear axle starts losing its "location" as the spring is unloaded - it sure can induce oversteer....

I also wanted to understand if you had any traciton bars (generally act as a giant sway bar and induces oversteer) or other mods

Other one (tho very un likely) is a shock that sticks at a certain leve - thus stiffening the rear and induces over steer.

Any - start with the sway bar linkage - remove the bolts from the lower control arm and make sure the washers are there and in oggd shape,t he rubbers are good (or replace with poly (which squeeks) or better yet - rod ends) and make sure that the hole in the lower A arm isnt "egged" out.....