Trouble going straight over 50 mph

Tacoma 2002
2.7 - 4 Cylinder - Rear wheel drive

I have a problem to keep my car running straight once I'm driving more than 50 mph.
I have to keep my steering wheel toward the left and right continuously to keep the car between the lines on the road!

The alignment already checked, and there is a new tires with good balance and tire pressures looks good and same!

Any idea how to diagnose the problem?

 

im curious the alignmnet shop did not find an issue. usually they would find issues like play in the suspension. never know, unless you have some mechanical experience, i would take it to a good independent shop. I would guess a power steering rack.

 

I was thinking about Steering & Suspension parts! What is the best way to diagnose them!
There is no leak/grease and everything look clean!

 

The alignment is either bad or 'shifting' because of something worn in the front end. Which a quality alignment shop should have found.

Mileage on the vehicle?

Did this start after a change of some type, or just begin over time?

Do you have a printout from the alignment?

Was the shop a big box turn and burn, like Firestone or GoodYear?

 

How long ago was the alignment?

When was it 'checked'? Recently?

 

4 months ago!

 

One good pothole 15 minutes after alignment can knock it out. The situation has been long enough that you have no grounds to return it for them to redo their work.

I'm assuming here your dealer doesn't offer a lifetime alignment package.

I'd take it to an independent alignment shop that does a lot of truck work. Worn components should be detectable before an alignment is done.

After it's finished, road test to see if the condition is corrected. If not, immediately return and take either the tech or manager out for them to experience the problem.

 

Ok! I shall do that with other place!
Thanks

 

the most confusing thing is that the alignment shop did not find the issue, but if the issue started after you took it to them. that might be more understandable.

 

Cross the front tires and see if it pulls the other direction or tracks straight. It’s what we in the repair industry call a tire pull. It happens on occasion, even with new tires.

 

If everyting else is tight you might try the "tack weld mod"

 

Please see attached file! I showed the car to the two mechanic!
That's the report!

 

I got that report today morning! They said it's only alignment!
Let's see!

 

The "problem" is your front caster - you don't have enough. Caster is what keeps your vehicle tracking straight (more easily) at speed.

You want it to be around 3 degrees if possible, but at least within the specified range (where .9 degrees is the low end). I'd go to another alignment shop (since for some reason the one you went to didn't seem to get this right) and tell them you want 3 degrees caster, and see what they can do for you.

 

Does your truck have a lift on it? If so, how much?

 

I disagree that 3 degrees of castor will "fix" anything. The specs say 0.9 -2.4 degrees.

If you are having issues with driveability and your castor is in that range, you have other problems that should be addressed. Adding additional castor outside of factory spec is only a bandaid fix. It doesn't look like the shop did anything to address the low castor values. That seems.... dumb. I'd want to know why they didn't, or couldn't, adjust the castor.

We have old trucks. It's a safe bet you need control arm bushings, and upper and lower balljoints. Maybe even wheel bearings.

 

Sorry, I was using 3 degrees as a good number, because this is a known good alignment from @Digiratus.

@akrinar's caster is not in spec at .6 and .3 degrees respectively; caster not in spec can cause exactly the issue he's seeing.

I agree with you that the reason for out-of-spec caster could be control arm bushings or something else.

 

I gotcha now.

I'm really curious why the alignment shop didn't correct @akrinar's castor. Doesn't look like they even tried, as the before/after numbers were identical.

 

im having a similar problem but mine started after the rack was replaced