Steering issue

Tiny
FIXITMR
  • MEMBER
  • 1995 PONTIAC TRANSPORT
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 225,000 MILES
I bought this van with a broken strut tower. I repaired that and when I test drove it the van veered slightly right and the steering wheel turned slightly left under accelleration coming out of a left turn. Put it up on ramps and had someone turn wheel back and forth with motor not running could see nothing suspicious/loose.
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Sunday, February 21st, 2016 AT 9:35 PM

31 Replies

Tiny
CARADIODOC
  • EXPERT
If you fixed this yourself, it is most probable the upper strut mount is not in the correct location. That is critical for proper handling and steering response. Start by having the vehicle aligned. The problem here is your specialist is going to have to go deeper than we normally do, and you are going to have to tell him that.

The first three basic angles that are checked on all alignments are "camber", "caster", and "toe". Caster is not adjustable on your van, and it has very little affect on pulling on most front-wheel-drive vehicles. Caster will be wrong if the upper mount is too far forward or rearward from where it was. The most important thing is it has to be the same on both sides.

Camber will be wrong if the upper mount is too far to the left or right. Camber is adjustable on Chrysler's and GM's, but on most GM products one lower strut mounting hole has to be ground to an oval shape to allow that adjustment to be made if that has not been done already.

The issue here is simply readjusting camber, if it is wrong, is not going to solve this problem. The numbers might look good on the alignment computer, but adjusting that does not address the underlying problem. Your mechanic is going to have to look at "steering axis inclination", (SAI). All alignment computers measure that automatically when caster is measured, but we never think to look at it unless we are looking for the cause of an elusive problem. SAI is the tilt, or angle of the strut as it leans in on top. More accurately, it is the imaginary line drawn through the upper and lower steering pivot, which on your van is the lower ball joint and the upper strut mount. There is no spec given for SAI. All that is critical is both sides must be the same, typically within 0.2 degrees. A typical value might be 28 degrees.

When you move an upper strut mount in on top, that makes the wheel tip in. You can go down to the bottom of the strut and make a camber adjustment to fix camber, but that doesn't address the incorrect SAI. That is where the miserable handling comes from.

GM has another common problem related to SAI. To service their drive trains, they have to be lowered on the cross member. Some cross members on other car brands are welded in place. Some, like Chrysler's, are installed with bolts with shoulders that position the cross member. GM is the only one where there is nothing to keep the cross member positioned properly. If it is removed without first marking its location, the only way to get it back is on the alignment rack. Making the adjustment is not difficult, but you have to know about it.

When SAI is unequal on both sides, the vehicle might drift or pull, but where unequal camber is normally the most influential contributor to a pull, SAI adds a major unpredictability factor to that pull. The vehicle will tend to dart to either side when going over small bumps in the road. What it does one time might be exactly the opposite of what it does the next time. You won't want to drive a vehicle with unequal SAI for very long.
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Monday, February 22nd, 2016 AT 10:11 AM
Tiny
FIXITMR
  • MEMBER
I will check it again but what I did was measure from the front bar (what do you call it) across that holds radiator to left strut bolt and then matched that on right. Within an 1/8" I think. The van drives straight under easy driving. I had my brother rev it in drive with brakes on and right wheel seems to rock forwards backwards like a very slight turn back and forth on thrust and release of gas pedal. Other repaired side is not noticeable. I will be doing some more driving to try and narrow it down if I can. It also seems like the front ride is rough as all the little bumps in road make hard noises like solid suspension with little shock absorption. On bumper push test all shocks seem a little too bouncy.
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Tuesday, February 23rd, 2016 AT 10:35 PM
Tiny
FIXITMR
  • MEMBER
Another thing I noticed is possibly bad front frame mounts. If I jack on frame the frame seems to rise to much with out the car lifting! Possibly the hole the rubbers sandwich is rusted out? I only noticed the drivers side have not checked pass. Backs seem fine.
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Tuesday, February 23rd, 2016 AT 10:40 PM
Tiny
FIXITMR
  • MEMBER
I wanted to emphasize that what happens its like something suddenly shifts the wheel moves by itself but then it goes back into place also braking does not cause any steering issues, but like I said I will have to test drive it more after this bad weather passes to get more of a definitive feel for whats happening.
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Tuesday, February 23rd, 2016 AT 10:57 PM
Tiny
CARADIODOC
  • EXPERT
The right wheel movement sounds like the important clue. Check tie rod ends and lower control arm bushings for play.
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Wednesday, February 24th, 2016 AT 8:53 AM
Tiny
FIXITMR
  • MEMBER
I have a Saturn that was making about the same kinda jerk to steering and it turn out the lower arm bushing was loose on the arm end and the arm was sliding back and forth on the bushing housing. They have a single lower bushing unlike the two on the van. So temporary fix I drilled the arm and pinned it to the bushing, be a few days before I can check the van bushings. Like you say at least its a clue to start from.
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Wednesday, February 24th, 2016 AT 9:09 AM
Tiny
FIXITMR
  • MEMBER
I also noticed the steering feels kind of sluggish like its lacking power assist. At 225,000 miles I am guessing its just weak pump or rack? GM has had power steering issues for awhile, funny my Ford Tempos' with 300,000 miles still steered pretty much like new!
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Wednesday, February 24th, 2016 AT 9:12 AM
Tiny
FIXITMR
  • MEMBER
It also seemed to me that the power steering pulley was bigger than usual? I wonder if a smaller pulley would boost steering response? And would the belt still fit. I think it might.
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Wednesday, February 24th, 2016 AT 9:37 AM
Tiny
FIXITMR
  • MEMBER
I had a Malibu that would not steer at idle, but 400 rpm's more and up and it worked fine. Was going to try smaller pulley on that, but wife scrapped it when I was in hospital.
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Wednesday, February 24th, 2016 AT 9:39 AM
Tiny
CARADIODOC
  • EXPERT
Changing pulley size is not the answer. Power steering pumps do not have to move a very large volume of fluid, and they have plenty of reserve capacity. Higher pumping speeds, and volume, won't get you more pressure because there is a pressure relief valve already doing its thing.

When you have weak power steering assist that comes back by raising engine speed, that is due to a worn pump. This is a common problem on any cars that use the "ZF"-style pump. That's a real small unit with a kind of square body, and it usually has a remotely-mounted reservoir. Those have fiber vanes that wear out and allow leakage past them.
Be aware we called Tempos and Escorts "killer cars" because of their extremely high tie rod end failure rates leading to loss of control and crashes. Those steering systems should be inspected at least once a year at a tire and alignment shop, and anytime there is a new noise of symptom.
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Wednesday, February 24th, 2016 AT 10:03 AM
Tiny
FIXITMR
  • MEMBER
Supposedly pump was replaced so I guess rack rings were worn/bypassing? The tempo tie rods the after market ones seem to fix the separation problem from Fords clever design.
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Wednesday, February 24th, 2016 AT 1:59 PM
Tiny
CARADIODOC
  • EXPERT
Leaking Teflon rings will cause stiff steering to one direction first, and only when cold. As the problem gets worse over the next few weeks, it will take longer and longer before the assist will come back, then it will start to affect the other direction too. It is possible but not common for both directions to be affected at exactly the same time when the rack is the cause.
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Wednesday, February 24th, 2016 AT 2:29 PM
Tiny
FIXITMR
  • MEMBER
So today I looked at tie rod end and lower control arm. Tie rod end had some play but I have had bad ones before and they did not throw steering off. The other thing I noticed is that the toe in seems way off/too much. I just assumed when I fixed strut tower everything would be back to normal. This may also explain rough ride because it was like on chatter bumps the van moved slightly left or right? Will rough check toe in tomorrow I wonder what the specs are?
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Sunday, February 28th, 2016 AT 4:44 PM
Tiny
FIXITMR
  • MEMBER
Also I noticed on the power steering it steers with equal assist in both directions but is missing the pump whine at the end of travel I was always used to.
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Sunday, February 28th, 2016 AT 4:56 PM
Tiny
CARADIODOC
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If camber is not right, it will affect toe, but only very little.

I cannot remember the specs for your vehicle, but in the 1990's a majority of GM front-wheel-drive cars called for 0.00 degrees camber and 0.00" toe, front and rear.
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Sunday, February 28th, 2016 AT 6:38 PM
Tiny
FIXITMR
  • MEMBER
Okay on camber I know I see a lot of cars that the front wheels tilt in slightly compared with rear. This van does too. Wondered if suspension was just weak/worn?
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Sunday, February 28th, 2016 AT 8:21 PM
Tiny
KEN
  • ADMIN
It sounds like the bushing are plain worn out or it has been in an accident of some kind.
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Monday, March 7th, 2016 AT 3:28 PM
Tiny
FIXITMR
  • MEMBER
Set the toe in as close to 0 as visually possible drove it it is torque steering to the left noticeably when stepping hard on gas. I do think the front sub-frame mounts are bad.
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Wednesday, March 9th, 2016 AT 5:19 PM
Tiny
FIXITMR
  • MEMBER
And on the power steering feel it feels sluggish and like I said no whine in the corners.225,000 miles
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Wednesday, March 9th, 2016 AT 5:31 PM
Tiny
CARADIODOC
  • EXPERT
You are describing exactly what happens when steering axis inclination is not exactly equal on both sides, and that is affected by the location of the upper strut mount. Have the alignment checked, and be sure to tell the mechanic to check and correct SAI.
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Wednesday, March 9th, 2016 AT 5:53 PM

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