Front End alignment on a GMT400 (or any vehicle)

[racedaymechanic]

I get asked from Time to time what kind of fancy alignment jig we have for setting up race cars I tell them we don't, we use String and tape measures to set them up even at places like Daytona or Talladega, Why not some high dollar laser guided jig? Because the way Im going to show you is more accurate, this will not only Align your front end it will center your steering wheel, you will need 2 small tape measures, 10 feet of string, 2 jack stands, to sets of grease plates and a pair of toe plates, the grease plates are just 2 pieces of .050 aluminum 18"x18" with a little grease between them, the toe plates are .090 aluminum 26" wide x 13" tall with a 1" lip top and bottom to keep them straight, The size is not as important as the fact that they are identical, on each end of the Toe plate cut a slot about an inch up and 1 1/2" deep for the tape measures, you can get all of this at any local sheetmetal shop for less than 50 bucks cut and bent

This picture shows Brutus with the toe plates in front of the tires, be careful driving on them as when you hit the brakes the plate will want to slide ahead

Then make sure you steering wheel is centered and locked so it can't move

Next set up your Jack Stands with the string between them and stretch the string tight, the frame is straight from the back of the cab to the front kick up and thats where you will measure to get your string square with the frame

Move the jack stands in or out until you have the string parallel to the frame rail, when thats done measure in to the left front tire at the point where the string runs past the tire be sure you use the same point front and rear of that tire to be accurate, the measurement at the rear of the tire is 5 3/8"

Here is the front measurement, it is 5 5/8"

And the rear is 5 3/8" so the wheel is toed in 1/4"

 

[racedaymechanic]

Ok so now we have to Toe the wheel out 1/8" the straighten up the steering wheel ( 1/8" on the front will take the toe out, spray some good penetrating oil on the adjuster and break the to nuts loose (13mm) about 2 turns then with a small pipe wrench go up on the wrench about to go out, it took 1 complete revolution to get the LF straight

Now you can see the measure ments are the same and the steering wheel is centered

Now you can set your toe, Here are my toe plates I made them over 20 years ago I had to cut them out to fit over the Hub

This is kind of a 2 man job put the Toe plates against the front tires solid I used my foot to hold the plates against the tires and put the tape measures thru the Plates front and rear where the slots you cut in the plates are, as you can see the Tires are toed in about 3/16" so I have to bring the front of the tire out about 1/8" ( you need about 1/16" toe in)

about a Half turn on the adjuster and I am at < 1/16" Perfect, Lock everything down and drive the truck around the block and recheck the toe and you have just done something that alot of people think is some kind of Black Magic but really is fairly easy, and I have checked alot of So Called " Proffesional" alignments and found them to be way off

 

[racer55]

One note that a lot of people pro's included forget,is that the very first thing that needs done is check tire pressure on all 4 corners!

Any chance you might get to caster/camber in this write up?
Road crown lead with caster or camber might be an important thing to include as well?
If you do,then toe is the last adjustment to be made for a full alignment.

 

[Brooklyn Tow]

One note that a lot of people pro's included forget,is that the very first thing that needs done is check tire pressure on all 4 corners!

Any chance you might get to caster/camber in this write up?
Road crown lead with caster or camber might be an important thing to include as well?
If you do,then toe is the last adjustment to be made for a full alignment.

KINGPINS

 

[racedaymechanic]

One note that a lot of people pro's included forget,is that the very first thing that needs done is check tire pressure on all 4 corners!

Any chance you might get to caster/camber in this write up?
Road crown lead with caster or camber might be an important thing to include as well?
If you do,then toe is the last adjustment to be made for a full alignment.

Ive got it planned, and yes you do have to set the toe after you adjust Caster, but not camber, and I forgot to say air up the tires

 

[racer55]

KINGPINS

Forgot about the straight axle HD models.

 

[THEFERMANATOR]

Ive got it planned, and yes you do have to set the toe after you adjust Caster, but not camber, and I forgot to say air up the tires

ANY adjustment with the GM IFS requires resetting toe. With the offset upper a-arm mounting it makes pretty big toe changes with small caster or camber changes. As for how to set caster and camber, a 3 foot level and tape measure work pretty good.

 

[racer55]

ANY adjustment with the GM IFS requires resetting toe. With the offset upper a-arm mounting it makes pretty big toe changes with small caster or camber changes. As for how to set caster and camber, a 3 foot level and tape measure work pretty good.

I would need some visual aids to get the level and tape method figured out,always used a rim clamp gauge or mag mount/spindle mount gauge.

 

[THEFERMANATOR]

I would need some visual aids to get the level and tape method figured out,always used a rim clamp gauge or mag mount/spindle mount gauge.

Don't have any pics, but you park the vehicle on level ground. Put the level in front of the spindle straight up and down and measure out a distance from the bottom ball joint and then from the top ball joint to the level. Go to the other side and put the level straight but the same distance from the lower ball joint as the other side, then measure the distance to the top ball joint. It should be teh same distance or fairly close if caster is correct. As for camber I use the same level and the same basic method, except instead of measuring the distance from the ball joint I measure the distance to the bottom and top of the rim. it's not an exact method, but I have gotten more than 1 close enough that when it was taken to an alignment shop no adjustements were needed.

 

[RI Chevy Silveradoman]

Excellent thread! Thanks for doing this for us Bruce! :thumbsup: And thanks for all of the input from our members here.

 

[3500GMC]

Looks good.

BrOOOOtus!

 

[jmiller]

Bruce,

Great write up. It helps demystify the magic of an alignment.

 

[OrionThade]

One note that a lot of people pro's included forget,is that the very first thing that needs done is check tire pressure on all 4 corners!

I ran into this exact situation this weekend.

I took the truck in 2 weeks ago for a post-new front-end alignment. They told me that there was a slight pull to the right still that was likely due to the wear of the front right tire. It's fairly worn and will be replaced soon. I drove it for about 120 miles that day and confirmed the pull to the right.

Fast forward 2 weeks. The truck was parked while I was waiting for and repairing the A/C system. I took the truck on the exact same drive I made 2 weeks ago, but checked the air pressure before taking the drive.

Lo and Behold, my left front tire was over-inflated by 15 lbs. I equalized the tire pressure. Guess what went away? The pull to the right. Truck tracks perfectly now. Well, except for the fact that now my steering wheel is pitched to the left when the truck is running straight.

Gonna take the truck in insist that they correct the issue free of charge.

 

[rxgreen]

I have been having problems with my alignment, they never get it right at the shop and they always say its in the green then tires start to wear on the inside hope to get it right myself

 

[dka99burb]

Have you checked your hub bearings & joints? I am rebuilding my front end this weekend and was just reminded by my brother that we probably need to check the hub bearings. Alignment changes while travelling down the road if you have worn/loose parts.

 

[tanman_2006]

Your alignment at a shop SHOULD start with checking all the gear. I usually sit and watch it get done and for some reason they dont miss steps! I only take trucks in for alignment AFTER I replace parts, adjust T bars, or if getting new tires. They shook their head when they checked my Idler and Pitman but said the upper ball joints will last a little while longer but need replaced sooner than later.

I might try the 'Bruce alignment method' next time! This should be in the Tech articles or a sticky IMO

 

[88gmctruck]

Great writeup! I've given my trucks alignments this way for years, both as IFS and solid axle. Never used the plates to do it though, smooth garage floor seemed to work well enough and a nice sized straight-edge with a helper.

 

[L98TPI]

One caveat. With some cars/trucks its tough to find a line that is parallel to the vehicles center line. They don't have flat sided frames or any frame at all. But I got around that by measuring off ball joint zerks and the edges of brake backing plates and marking a line on the floor or just laying a long piece of steel on the floor. Those plates are nice. I am embarrassed to say I just sprayed soap on the floor and strapped drywall T squares to the tires with bungee cords :hihi: Afterward I had two clean spots on the floor.