2WD C10 Modern/Performance Alignments

[BMERDOC]

It seems that alignments aren't talked about enough on the forum and a starter thread encouraged me to talk more about alignments. Here is that thread:
http://67-72chevytrucks.com/vboard/s...94#post4933494

I wish to make this thread simple enough for all to understand so I will not start by explaining the elementary angles which are toe, caster, camber, and thrust angle. I encourage you to research these topics for yourself so that I may get on with the meat and potatoes of it all. I expect all disagreements to be handled in a delicate manner with a decent explanation of your disagreement and would ask that you thoroughly read the posts so that answer repetition is minimized.
If you have had an alignment and wish to discuss it please post a copy of your print out so that we have clarification.
This thread will discuss 2WD C10s from ’63-‘87 but if you bring up a specific example of another truck that this site is dedicated to, myself or someone else will be glad to address the situation. Keep in mind that the contents of this thread are for a modern alignment and will swing towards a performance oriented alignment. I will warn you if I feel a severe angle will burn tires up.
One last thing, I’m a car guy that knows about alignments. I am not an engineer for Goodyear, Michelin or Hunter.

[BMERDOC]

As I stated in the previous post...negative camber, positive caster, average of "Specified Range" Toe and "0" Thrust Angle. Follow these rules and your truck will handle and drive better than it ever has!

I will start by saying to check YOUR OWN vehicle for loose or bent parts and sagging springs. All bushings must be in good condition (be sure to check your trailing arm and panhard rod bushings!!), wheel bearings should be properly adjusted and no steering or suspension components can be bent. Keep you steering box, rag joint and column condition in mind also. Check your tire pressures and make sure they are even. If you let something slide expect your alignment to reflect it.

Never let a service center perform a Two Wheel alignment. They must refer to it as a Thrust Alignment or a Four Wheel Alignment . If they use either two of those terms you are in good shape and there is no need to question them further. Look for a shop that will work with you to align your vehicle as you wish. The rest of your truck is custom and your alignment soon will be. If they won't work with you find someone who will.

OK! The first angle is Thrust Angle. Thrust should be zero but .1 or -.1 will be fine. Consider a closer look if your Thrust Angle is closer to or over .2 (either positive or negative). This angle reflects how square the differential is to the chassis. If it is out of square it will cause the truck to rear steer like a fork lift and you will find yourself counter-steering to compensate for it. It will also affect the front toe alignment. If you see a vehicle tracking badly as it goes in a straight line either its bent or the Thrust Angle is waaaay off (ed. or they got a two wheel alignment). Again, make sure your trailing arm and panhard rod bushings are in great shape to insure the best possible alignment. Anything else affecting it is probably bent.

Moving to the front caster and camber will be aligned next. Front toe should be the last angle aligned as the other angles will cause the readings to move around.

NOTE!!! I will be aligning my truck in this thread in an experimental manner as I have little to no experience aligning a shimmed vehicle!! I will use my truck to show what alignment angles are feasible with this front suspension. This does not negate my knowledge of alignments, however.

Let’s talk about camber. First, camber should always be negative because when you enter a corner the tire top will want to tip to the outside of the vehicle, rolling over the contact patch. If your camber is 0 or positive expect it to handle poorly in turns because it is already on or past the contact patch of the tire. If it is negative it will roll onto the contact patch maximizing grip. Depending on how you want your truck to be set up have your aligner set it between -.25 to -2.00. -.25 is very reserved and -2.00 is the outer limits of a Daily Driver. For you guys wanting to take advantage of a modern alignment, request -1.00 to -1.5. You will experience some inner wear over the life of a set of tires if your alignment is set closer to -2.00. As a reference track cars usually ask for -3.00 but these are off road and are tossing into turns, setting the contact patch and don't really care much about tire life. For you lowered guys, this is a good rule of thumb so that you will know what to expect when you get your print out.

The next angle is Caster. You always want to dial in positive caster for self –centering steering and good straight line tracking. The more positive caster that is added the more the steering wheel wants to return to center so entering and exiting corners is improved and high speed stability is improved. If the caster is more towards negative then you will need more steering input to keep it in a straight line. As I said in the previous post you’ll notice that when you perform a u turn you can let the steering wheel go and it will want to spin back to center (research steering axis inclination). The Specific Range for my ’67 is 2.00 to 3.00. I would want 3.00 or more if I could achieve it. Again, I will be posting alignments on my truck and will provide specs that are realistic.

There is a theory that one wheel can be set with more positive camber (.25 to .50) than the other to compensate for road crown. It is true that the vehicle will want to “drift” in the more positive direction. I feel that making both sides equal is more desirable because unless your town is 90% crowned roads, your truck will want to “drift” to that side on flat roads. I would rather counter steer into a road crown so that my truck will glide straight at 80mph.

The last angle I want to talk about is Toe. I would stay within the confines of the Specified Range because toe is affected by steering and suspension more than any other angle. If the tie rods are too long or too short they will not pivot on the same plane as the lower control arm (bump steer). You lowered or raised guys may already be victims of bump steer and we don’t want to aggravate the situation. I will use my ’67 as an example again. The Specified Range is .08 to .15. Notice they are in the positive range. This is due to the fact that these trucks are front steer, that is to say the steering gear is ahead of the front crossmember. As the truck rolls the tires are pushed out to pull tension on the tie rods and center link giving the steering a tight, confident feel. If the toe is too much toward 0 the steering will tend to wander because the tie rods do not have enough tension on them and the joints will want to ”roll around” in the sockets, too far out and inner tire wear will occur. Remember, as strange as it sounds alignments are set statically and driven dynamically so I like to see an average of the range, so .15 - .08 = .07, .07/2 = .035, .15 - .035= .115, .08 + .035 = .115. A toe setting of .11 or .12 is acceptable. As the vehicle is driven imagine the numbers constantly changing, by setting average you are more likely to stay in the specified range and save tire wear. If more cornering performance is desired you can go more positive but stay in the range. As a side note for you guys that like to talk about alignments fractionally, 1/16th equals .18 which is mildly out of spec. I don’t know if I’d go that far on a street truck but wouldn’t hesitate on a truck I planned on tracking and didn’t care about tire wear.

I know I’m probably missing some stuff. I started this late last night and finished it up tonight. I know the chassis fabricators are probably gonna blow me outta the water but my information has been gathered over a life time of studying and on the job training. It is meant as Alignment 201 so be kind. Once again, I will be using my truck to find out what specs are achievable. I need to install poly trailing arm bushings, a panhard rod and a left upper A arm cross shaft so hopefully I’ll have the first posts up by Friday. I will include the measured thickness of the shims so that you can do the initial alignment before heading to the shop to save you time and possibly money. I hope I have helped you guys understand a little better about alignments and the benefits of straying away from the original specs. It is not a far stretch for me to say the original specs are scary and can be dangerous especially in a collision avoidance situation.

[BMERDOC]

67/68 Alignment specs:

[BMERDOC]

Some extra notes: Camber is a tire wearing angle but will not wear as harsh as toe. If toe is ok the the tires are rolling straight and camber will wear tires over the long term. Toe, however, will scrub the tire because it is "dragging" it as it rolls. Caster is a non wearing angle.

Tire pressures are up to you but I think that the 20 psi range is too low and the 40 psi range is too high for a street truck. Currently my pressures are at 35 psi. If you want to know more about tire pressure there are charts online that explain tire pressures affects on oversteer, understeer and neutral handling.

[bo-w]

good stuff BMRDOC.

[chevyrestoguy]

Mods: Please consider making this a sticky. This info is too valuable to get lost in the archives.

[meter swinger]

Awesome
Posted via Mobile Device

[BMERDOC]

"If the toe is too much toward 0 the steering will tend to wander because the tie rods do not have enough tension on them and the joints will want to ”roll around” in the sockets"

This is B.S. I put it in there as filler while writing the information so that I could come back later and word it properly, it somehow slipped through the cracks.

It is my belief that as the toe is set closer to 0, road feel is numbed. The truck would lack a certain confident feel. It may be good for a vehicle traveling in a straight line but not for a vehicle that you would actually want to dip in and out of corners with.

[TR65]

Nick,

I think that the ideal toe is zero when in the dynamic running condition. That's why I set as close to zero within the spec. I think the specs take into account the dynamic condition. In any case after a thousand miles you can check the tread depths on each shoulder and see if it is too much toe out or too much toe in.

When toe is not zero dynamically the tire is constantly cornering and thus the high rate of tire wear. Camber is not as penalizing on wear as you mention because camber doesn't create a lot of lateral force.

A question. Since we can't put any negative camber on the rear of our trucks like your bimmers do, wouldn't the negative camber in the front lead to a very over steering condition??

I have always tried to do my alignments in the garage with simple tools. Do you have any thoughts on that?

Good thread, thanks for the info.

TR

[Mike_82_Shortbox]

Originally Posted by BMERDOC

"If the toe is too much toward 0 the steering will tend to wander because the tie rods do not have enough tension on them and the joints will want to ”roll around” in the sockets"

This is B.S. I put it in there as filler while writing the information so that I could come back later and word it properly, it somehow slipped through the cracks.

It is my belief that as the toe is set closer to 0, road feel is numbed. The truck would lack a certain confident feel. It may be good for a vehicle traveling in a straight line but not for a vehicle that you would actually want to dip in and out of corners with.

Nick,

In refreshing my memory about alignment theory, I found the following about toe-in:

Ideal toe-in is 0°. But that is at road speed.

Tires have a certain amount of "rolling resistance," which is the rearward force exerted on the wheel by the road, and by air pressure, as it is pushed forward by the vehicle frame.

There is a certain amount of flexibility in the A-arm bushings (assuming they are the stock rubber ones), and this flexibility responds to the rolling resistance. At highway speeds, the static toe-in angle is negated by the suspension system flexibility, and the total rolling toe-in ends up being 0°.

The static toe specifications assume the factory designed A-arm bushings, which are much more flexible than, say, polyurethane bushings. Therefore, any vehicle with polyurethane or custom performance bushings will probably require far less static toe in than a stock vehicle. Such vehicles with polyurethane bushings using factory toe-in specifications will probably be unstable, and may be observed to wander at high speeds, because of too much toe-in.

Mike

[VA72C10]

Great info!!!!

[BMERDOC]

I finally finished installing all my suspension pieces to tighten up the existing suspension before I move to lowering the entire truck, it does have two inch blocks right now. I installed the trailing arm bushings and adjustable panhard rod thinking that these parts would correct my 34' thrust angle. To my suprise the angle did not change at all!! What happened? I pushed the bed side to side to attempt centering the suspension with no change. I pryed between the frame rail and could only muster 25' which was still no good. I did look for an accepable tolerance and found that GM allows -20' to +20'. I didn't feel good at all about putting the rear suspension in a sideways bind to try to correct this problem. As I was only experimenting tonight I moved onto check adjustments of the front caster/camber (more on that later).

I went home to study my alignment sheet and found my problem. I will now make a correction, something I hadn't thought about before and now makes perfect sense. It washed over me that I was paying too much attention to thrust angle and NONE to rear toe! I previously said that rear toe doesn't matter because its not adjustable. I now know this to be wrong. Look at the picture, the driver's side has positive toe (in towards center) and the passenger side has negative toe (away from the center line). Please pardon my illustration, I'm not a graphics expert! The axle is not straight in the chassis. A double check of the wheelbase would confirm this, the dr's side would be shorter than the passenger side. This would cause the rear to steer right causing me to steer right to counter act the rear steer. When the truck gets back up on the rack I will support the trailing arms, loosen the u-bolts, move the dr's side of the axle towards the rear and the passenger side towards the front. Hopefully the ubolts/axle/trailing arms will have enough play to allow this. If that doesn't correct it that probably means the frame may be tweaked This would not warrant frame straightening but elongating the u-bolt holes in the axle saddles MAY get me to 0 thrust angle. We'll have to see.

Eventually, I will want this truck to handle extemely well. When I installed the adjustable panhard rod I noted that by installing just 2" blocks the rod was almost parallel to the ground. Looks like one of those Super Duper Panhard Rods will be in my future!

[BMERDOC]

My Evil Plan worked! By loosening the u bolts and pulling the dr's side back while pushing the passenger side forward I was able to set the thrust angle at 06' (dr's= 03' pass= -10'), which is inside my self imposed -01' to 01' Specified Range and well within the -20' to 20' Specific Range I found on several GM vehicles. Now that the rear is set I can move onto the front for rear More on that after I eat dinner

[Mike_82_Shortbox]

Originally Posted by BMERDOC

My Evil Plan worked! By loosening the u bolts and pulling the dr's side back while pushing the passenger side forward I was able to set the thrust angle at 06' (dr's= 03' pass= -10'), which is inside my self imposed -01' to 01' Specified Range and well within the -20' to 20' Specific Range I found on several GM vehicles. Now that the rear is set I can move onto the front for rear More on that after I eat dinner

Nick,

Many years ago I was working at a Goodyear shop (I used to be an ASE certified Master Auto Technician), and a big four-wheel-drive Ford truck came in with horrible wheel alignment. The thing was so big it wouldn't fit on the alignment machine, and so we were reduced to aligning it with tape measures.

With the rear axle, we did pretty much exactly what you did, which was loosen up the U-bolts and slide the axle back and forth until we had the parallel and cross frame measurements within about a 16th of an inch. Many leaf spring locator pads have a pin to positively locate the spring to the axle, but fortunately this one didn't, and if it did, we would have ground it off.

We couldn't measure the results of our efforts, but the before-and-after drive results were a world of difference away.

[lilpoindexter]

You left the socket on the panhard rod bolt.

[BMERDOC]

Yeah I saw that. I took that pic just before I pulled the panhard rod off to swap it for the adjustable unit.

[BMERDOC]

Ok. So I got the Thrust Angle in good shape. It was time to move onto the front. I took the time to go through all C10s from 60-87. These are Hunter Specs. Here is what I found:

1960-62

Camber: 0*00' to 1*00'
Caster: 0*30' to 1*30'
Toe: 0*08' to 0*15'

1963-78

Camber: -0*15" to 0*45'
Caster: 2*00' to 3*00'
Toe: 0*08' to 0*15'

Note: 1969-78 did not specify a caster angle. It also did not ask for a frame angle so I included them with the 1963-68 specs.

1979-81

Camber: -0*19' to 0*41'
Caster: Not specified
Toe: 0*08' to 0*15'

Note: Notice the camber range shifted to negative camber.

1982-87

Camber: 0*11' to 1*11'
Caster: Not specified
Toe: 0*08' to 0*15'

Note: What happened to camber here?

All trucks listed had a Specified Range of 0*15' to 0*30' for total toe

1982-87 was the only alignment that had a Specified Range for cross camber and cross caster. Both were -0*30' to 0*30'

[BMERDOC]

A funny thing happened on the way to the Alignment machine...
I was now set to adjust the front. I wanted to set camber at -1.00 and camber as far back as would make safe sense for the space between the cross shaft and frame while still leaving enough threads on the bolts. I called up NAPA, my favorite parts people, for a "shim kit". Turns out they sell shims seperately and not in a kit! Dang! What to do? I couldn't run out to buy the shims to correct this alignment knowing that the truck would come off the rack to immediately be lowered only to have to reshim it. So I deceided to remove all shims to see what it looked like with no shims in it. I have included a picture of the print out. It seemed like a good base line to me. Please note that this is MY truck's results and results may vary. Notice the left camber "Actual" angle, -0*23'? Right side is -1*55'. I think I should have at least made the toe "green" to see the affects. If you look at the toe specs before and after, positive toe was pushed negative as camber went negative.

***NOTE*** This is the best reason you want an alignment after lowering!!! Negative camber is added and causes the toe to push out. Remember, negative camber is better than having toe too positive or negative because toe "scrubs" the tire, dragging it sideways. If toe is good camber is less crucial.
Nothing exciting to mention about caster except that I drove it around the parking lot after this alignment session and noted that there was almost NO return to center.
I lowered the front of the truck tonight so I will align it again and buy the proper shims from NAPA to gain the angles I'm looking for. I'm also looking over the "Make it Handle" thread to see if I can find any info on counter-acting bumpsteer. If your watching stay tuned!!

[YBNORML]

Subscribed!
Great info, thanks.
Jason
Posted via Mobile Device

[BMERDOC]

I haven't been able to mess with the truck in the last couple of days but I was reading robnolimit's Make It Handle thread. Turns out he suggested (post #94) that the panhard SHOULD be level at ride height. Turns out I'm fine as long as I don't mind the short bar. Just a short note I wanted to post before I forgot to mention it!

[Mike Bradbury]

Great info, I will be watching this one for sure

[BMERDOC]

Thanks Mike, I read Robnolimit's Make It handle thread and he got me thinkin'. I've gotta revisit Toe and clear up some things.

[Conundrum]

Watchin this one, one day I may even have enough time to read it. lol

[robnolimit]

Thanks for doin this Doc, I'll be watchin.

[BMERDOC]

Thanks Rob!! No pressure there!! I will say that I've known about you and your company for years now and I feel like someone who likes Bball having a NBA player wanting to come out and watch them play!

I will say that after reading your thread it made me have to start over and relearn Toe. I think I may owe TR65 an apology about his take on toe. I am still trying to figure it out. I am researching info on the topic. I am still convinced you can't go wrong with an average of the Specific Range but I am having to reassess my beliefs in toe out (negative) vs. toe in (positive) vs. 0 toe. Currently I am pacing the floor, trying to visualize how a rear wheel drive vehicle has a tendency to induce 0 or toe out.

I'm processing all the info I have gained on my truck and will have it back on the rack soon. I hope to have some good info soon!