Would completely shot upper control arm bushings cause wondering and steering play. I have a lot of that plus the idler moves a decent bit. Just trying to figure if its gearbox play or not. 1997 s10 208k miles and 4x4.
Suspension inspection Tutorial and Alignment Fundamentals/Procedures
9
Recently I have noticed an increase of forum members with questions and concerns regarding suspension parts and alignments. A large portion of handling issues like a left or right hand pull, wandering, squeeks, rattles, clunks, and shaking have to do with one or more suspension parts being worn to the point of either having play outside of a specified tolerance or to complete falure. I'll be covering all of the methods used to inspect your front end parts and well as what to look for in regards to play and what is considered acceptable or not. I do not claim to know everything about all suspension systems. I am an ASE suspension and steering certified alignment tech with about 7 years experience, so while I haven't done this as long as some, I feel I have above average knowledge of the subject. Some images posted are ones I've taken myself, while others are from a general search as I have either lack of examples at my disposal or lack of time to make a diagram.
First I'll cover alignment fundamentals and how certain measurements and settings effect handling.
Camber-*
Camber angle is the measure in degrees of the difference between the wheel's vertical alignment perpendicular to the surface. Negative camber being that the top of the tire is leaning inward toward the engine and positive when leaning outward from the engine. Negative camber is becoming increasingly more popular because of its visual appeal. The real advantages to negative camber are seen in the handling characteristics. Zero camber results in more even wear across the tread of a tire. Positive Camber is most often used on offroad and agricultural vehicles due to it providing a lower steering effort.
![]()
Caster-*
Caster is harder for most to understand, but is defined as the angle created by the pivot point of the steering from the front to back of the vehicle. Caster is positive if the line is angled forward and negative if angled backward. Positive caster will result in more stability at higher speeds and faster return of the steering wheel to level, but will increase tire lean while cornering as well as increase steering effort. Most road vehicles will have Cross-Caster, which means there is a difference in the caster angle on each side of the vehicle. (Example: 3.0 degrees on one side and 3.5 degrees on the other) This is actually a safety feature to cause un-manned vehicles or drivers who lose steering control to drift away from instead of into oncoming traffic. However, generally vehicles are set to drive as straight as possible, which often requires a cross-caster split of about half of a degree to compensate for crown in the road, always more positive on the passenger side. (Example- 3.0 Degrees on the diver's side and 3.5 degrees on the passenger side)
Toe-*
This is the easieast to vizualize. This is the angle which the tires are pointing when viewed from the top down. Toe is the biggest factor in how your tires wear. If the tires are pointed inward or outward, they will scrub against the surface of the road and cause wear along the edges. But sometimes tread life can be sacrificed for performance or stability. Positive toe will provide straighter driving characteristics at the cost of turning ability. This is found mostly in rear wheel drive vehicles. At speed, the tires will straighten out, helping to reduce excessive tire wear. Front wheel drive vehicles often have negative toe for the opposite reason. Their suspension arms pull slightly inward, so a slight negative toe will compensate for the drag and level out the wheels at speed as well as increases cornering ability. This sacrifices straight line stability though.
![]()
Inspection
Everyone has a different way to check certain things. This is how I do my inspections at work. The pictures shown are of a 1994 2WD Blazer.*
![]()
After getting the vehicle racked and at working height, I first check all bushings for cracking or tears. Minor cracking like what is shown on these swaybar end links and mount bushings, isn't of much concern. More severe cracking or tears would warrant replacement.
![]()
![]()
These control arm bushings on the other hand, are due for replacement, even though no abnormal movement is found.
![]()
Next, lift the vehicle by both control arms and make sure its stable. While grasping the tire by the top and bottom (red arrows), shake the wheel by pushing and pulling on alternating hands. Try to effect the camber. You may feel a slight amount of play in the wheel bearings. Very slight play is normal for S-series trucks without hub assemblies (S10, Sonoma). Vehicles with hub assemblies should have zero play (Blazer, Jimmy). Bad ball joints or upper control arm bushings may also be found doing this. Next grab the tire on each side (blue arrows) and use the same alternating force. This is used to find play in the center link, idler/pitman arms, and inner/outter tie rod ends. Ball joints can be checked for vertical play by placing a pry bar under the tire and ground and prying upward with moderate force. Any play warrants replacement.
![]()
Labeled in this picture are the tie rod ends (2&3 at the center link, 5&6 are attached at the spindle), Pitman arm (4), and Idler arm (1). Any movement other than twisting of the ball type joints (which under normal driving will be minimal) is considered excessive play. 2WD vehicles have a non wear pitman arm. If play is found here, the center link must be replaced.
![]()
Here is the before and after of an alignment I did earlier today on a 1997+ 4WD Jimmy. The after specs are what you are looking for in a quality alignment. This vehicle drove straight with no pull, wandering, or any other symptom.
![]()
I hope this helps clear up some of the confusion/questions regarding checking parts and what alignment terms are and how they effect each other. Feel free to ask any questions I left unanswered and I'll try my best to answer them.
First I'll cover alignment fundamentals and how certain measurements and settings effect handling.
Camber-*
Camber angle is the measure in degrees of the difference between the wheel's vertical alignment perpendicular to the surface. Negative camber being that the top of the tire is leaning inward toward the engine and positive when leaning outward from the engine. Negative camber is becoming increasingly more popular because of its visual appeal. The real advantages to negative camber are seen in the handling characteristics. Zero camber results in more even wear across the tread of a tire. Positive Camber is most often used on offroad and agricultural vehicles due to it providing a lower steering effort.
Caster-*
Caster is harder for most to understand, but is defined as the angle created by the pivot point of the steering from the front to back of the vehicle. Caster is positive if the line is angled forward and negative if angled backward. Positive caster will result in more stability at higher speeds and faster return of the steering wheel to level, but will increase tire lean while cornering as well as increase steering effort. Most road vehicles will have Cross-Caster, which means there is a difference in the caster angle on each side of the vehicle. (Example: 3.0 degrees on one side and 3.5 degrees on the other) This is actually a safety feature to cause un-manned vehicles or drivers who lose steering control to drift away from instead of into oncoming traffic. However, generally vehicles are set to drive as straight as possible, which often requires a cross-caster split of about half of a degree to compensate for crown in the road, always more positive on the passenger side. (Example- 3.0 Degrees on the diver's side and 3.5 degrees on the passenger side)
Toe-*
This is the easieast to vizualize. This is the angle which the tires are pointing when viewed from the top down. Toe is the biggest factor in how your tires wear. If the tires are pointed inward or outward, they will scrub against the surface of the road and cause wear along the edges. But sometimes tread life can be sacrificed for performance or stability. Positive toe will provide straighter driving characteristics at the cost of turning ability. This is found mostly in rear wheel drive vehicles. At speed, the tires will straighten out, helping to reduce excessive tire wear. Front wheel drive vehicles often have negative toe for the opposite reason. Their suspension arms pull slightly inward, so a slight negative toe will compensate for the drag and level out the wheels at speed as well as increases cornering ability. This sacrifices straight line stability though.
Inspection
Everyone has a different way to check certain things. This is how I do my inspections at work. The pictures shown are of a 1994 2WD Blazer.*
After getting the vehicle racked and at working height, I first check all bushings for cracking or tears. Minor cracking like what is shown on these swaybar end links and mount bushings, isn't of much concern. More severe cracking or tears would warrant replacement.
These control arm bushings on the other hand, are due for replacement, even though no abnormal movement is found.
Next, lift the vehicle by both control arms and make sure its stable. While grasping the tire by the top and bottom (red arrows), shake the wheel by pushing and pulling on alternating hands. Try to effect the camber. You may feel a slight amount of play in the wheel bearings. Very slight play is normal for S-series trucks without hub assemblies (S10, Sonoma). Vehicles with hub assemblies should have zero play (Blazer, Jimmy). Bad ball joints or upper control arm bushings may also be found doing this. Next grab the tire on each side (blue arrows) and use the same alternating force. This is used to find play in the center link, idler/pitman arms, and inner/outter tie rod ends. Ball joints can be checked for vertical play by placing a pry bar under the tire and ground and prying upward with moderate force. Any play warrants replacement.
Labeled in this picture are the tie rod ends (2&3 at the center link, 5&6 are attached at the spindle), Pitman arm (4), and Idler arm (1). Any movement other than twisting of the ball type joints (which under normal driving will be minimal) is considered excessive play. 2WD vehicles have a non wear pitman arm. If play is found here, the center link must be replaced.
Here is the before and after of an alignment I did earlier today on a 1997+ 4WD Jimmy. The after specs are what you are looking for in a quality alignment. This vehicle drove straight with no pull, wandering, or any other symptom.
I hope this helps clear up some of the confusion/questions regarding checking parts and what alignment terms are and how they effect each other. Feel free to ask any questions I left unanswered and I'll try my best to answer them.
41 - 60 of 67 Posts
Admittedly, I skimmed through all of that and got the jist of what you are trying to say. So, I'll address just main points.
How many degrees isn't the way you should be looking at it. There is no set amount that tire pressure will effect the specs as it will vary from vehicle to vehicle. Tire wear will also effect camber readings. For example if you have front tires that have severe edge wear (inner or outer), it will cause the tire to prefer to lean one way or the other, therefore effecting the specs. This is why it is prefered that an alignment is done when tires have either been replaced, rotated, or already show signs of minimal edge wear. Again, the amount it effects the specs is different depending on the amount of wear, bushing integrity (which is one of the first things that should be checked), tire pressure, tire size, and type of suspension the vehicle has. Toe can be effected, but usually isn't except for extreme situations.
Vehicles with rack & pinion style suspensions are more susceptible to parts being changed. I've seen many where simply changing the lower control arm required, at the least, loosening the bolts connecting the strut to the knuckle. When you do that, camber changes. Very often, I find myself making camber adjustments to vehicles with struts.
![]()
So, that takes me back to that being a "driveway alignment" which is meant to get you close enough to get it to a shop. Which can be done even easier and cheaper with a tape measure. Either way, a visit to your local mechanic for a REAL alignment is highly advised. Also, an alignment at the shop I work at is half the cost of the tool you linked (assuming shims aren't needed and a vehicle has all the adjustment points needed).
Tire pressure effects the specs of a given vehicle's alignment depending on the difference between each wheel from side to side. (IE- Driver's Front is at 35 psi vs Passenger Front being at 20psi would result in a different camber reading, and in some cases toe, than if they were even.)mojarraman said:
How many degrees isn't the way you should be looking at it. There is no set amount that tire pressure will effect the specs as it will vary from vehicle to vehicle. Tire wear will also effect camber readings. For example if you have front tires that have severe edge wear (inner or outer), it will cause the tire to prefer to lean one way or the other, therefore effecting the specs. This is why it is prefered that an alignment is done when tires have either been replaced, rotated, or already show signs of minimal edge wear. Again, the amount it effects the specs is different depending on the amount of wear, bushing integrity (which is one of the first things that should be checked), tire pressure, tire size, and type of suspension the vehicle has. Toe can be effected, but usually isn't except for extreme situations.
Correct , I used the wrong word which can be misleading to someone who doesn't know the difference. If not abused or other issues arise with bushings and the like, an alignment will stay true until outside forces (collisions our failing parts/bushings) come into play.mojarraman said:
No. A driveway alignment is not meant to be a final solution. Using a tape measure will get you close, but not where it should be in order to assure proper tire wear for the life of the tires (Tread wear warranties are now upwards of 100,000 miles on some models of tires). Even a computerized alignment can't guarantee proper wear over that length of time with out routine checks and adjustments if needed. Many thing effect tire wear. Improper tire pressure being the leading cause next to improper alignment. Proper tire pressure isn't what your door placard or tire sidewall states either. Proper tire pressure is the pressure your tires have the optimal contact patch given your vehicle weight and current tire size.mojarraman said:
If you replace a part like a control arm, strut, tie rod, etc. you need an alignment. Flat out. If a part is replaced, there was a reason for it. Parts don't wear out in just a day or even a week. If you have a part that is worn out, it has already thrown your specs out of acceptable tolerance, which will not necessarily be the same if you just slap a new part in there. Even counting threads when replacing a tie rod or tie rod end will not get you back to "acceptable specs". Control arms are the same way. You can't guarantee that a control arm from one manufacturer is 100% perfect in their production of a part, even if they say "OEM quality or better".mojarraman said:
Vehicles with rack & pinion style suspensions are more susceptible to parts being changed. I've seen many where simply changing the lower control arm required, at the least, loosening the bolts connecting the strut to the knuckle. When you do that, camber changes. Very often, I find myself making camber adjustments to vehicles with struts.
This would fall under "driveway alignments". That is unless you can 100% guarantee that the platform the alignment was performed (I assume you're thinking a car port slab) is perfectly level on both axis. Even then I would still take it to a reputable shop to be sure (this is where researching the shops and meeting the technicians comes into play).mojarraman said:
While I appreciate your drive and will to learn about these things, a lot of what you said was misinformation resulting from theoretical education (lots of books and limited real world experience). As I said in my original post, I'm by no means 100% perfect nor do I know everything there is or ever will be to know about suspension and alignments. Just last week I learned something new. However, my 12 years of hands on experience in a shop dealing with thousands (not exaggerating) of vehicles over the coarse of that time, has shown me that Chilton/Haynes/FSM while very good starting points for understanding how these things work and what effects different things at different times are limited in most areas.mojarraman said:
While the difference between 0.0° and 0.1° seams very small (and it is), there is a BIG difference when you are talking about total toe, much less individual toe. To put it into perspective, the machine I use at work reads 0.01° for both individual toe an total toe. That's 10 times more accurate. In terms of tire wear, which is most effected by total toe, that is the difference between a nice even wear pattern and this:mojarraman said:
So, that takes me back to that being a "driveway alignment" which is meant to get you close enough to get it to a shop. Which can be done even easier and cheaper with a tape measure. Either way, a visit to your local mechanic for a REAL alignment is highly advised. Also, an alignment at the shop I work at is half the cost of the tool you linked (assuming shims aren't needed and a vehicle has all the adjustment points needed).
41 - 60 of 67 Posts
