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DMAXAlli, could you post the front end specs for the 2002 Chevy/GMC 2500 HD.


Thanks,


Randy
 

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Camber +0.25 Range -0.3 to + 0.8 degrees


Caster (Left) 4.0 Range 3.0 to 5.0 degrees


Caster (Right) 4.75 Range 3.8 to 5.8 degrees


Toe (Left) +0.05 Range -0.05 to +0.15 degrees


Toe (Right) +0.05 Range -0.05 to +0.15 degrees


I'm currently running my truck at:


Camber -0.1 degrees (It's always been my experience with GM trucks, to keep the camber on the low side. Minimizes outer tire wear)


Caster (Left) 3.6 degrees


Caster (Right) 4.1 degrees


Toe (Left) +0.05 degrees


Toe (Right) +0.05 degrees


This was as high as I could get the caster. Don't recall which side, but after setting the torsion bars to where I wanted the ride height, I max'd out the adjustment on one side. I ended up doing a balancing act on adjusting the torsion bars and adjusting the cams on the upper control arm to finally achiever these settings.


BTW, When I put the truck on the alignment rack, the factory setting for caster was in the 2.?? degrees. Don't recall where camber was at. I had already adjusted the torsion bars so it was no longer in the factory setting anyway.


Specs are also posted here:


http://dieselplace.com/forum/forum_posts.asp?TID=2513


DaleEdited by: Notsdale
 

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The question is, when you change to a wider tire (read more rolling resistance) does the stock toe still apply? I would guess the increased rolling resistance would require more toe-in than the stock tire setting. I am running 315/70-17, so I added 1/8" toe-in, and a little less caster to help ease up on the steering effort. Perfect tire wear so far at 8000 miles, and it always suprises people with how well it corners for its size and weight.


Most mechanics fail to take into account tire changes, lift height changes, or how the driver actually uses the truck. The stock alignment specs should only be used litterally for a truck that has no suspension or tires changes.


Although I am no longer a mechanic, one of my certifications was in alignments, and did several of them each day for many years. I still do all my own alignments, and have for as long as I can remember. It great to play with the torsion bars or leaf spring packs, and immediatly be able to see how it impacted the alignment, correcting it right in the garage. Saves alot of money too. Edited by: Amric
 

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Amric,


I agree with you wholeheartly. There are a lot of people out there doing alignments, expecially in the retail outlets such as Sears, K-Mart, Pep Boys, etc, etc, that only know how to do alignments based on what the computer tells them. They have no idea why they are making the adjustments other than the fact that the current setting is out of "manufacturers specs."


In the years that I've been doing alignments, I have set a lot of vehicles out of the "manufacturers specs" in order to get correct tire wear or to correct driveability problems. The recommended settings by the manufacturer are an engineer's calculations on where the alignment should be set. It assumes a best case condition with all good front end parts. The range of tolerances defined by the engineer works for about 95% of the cars on the road. However, it's knowing where to set the alignment within that range that only comes with experience.


For the other 5% it comes down to a gut feeling based on the current alignment settings and the current tire wear. At this point it's trial and error. Sometimes you get it right, sometimes you have to realign it a couple thousand miles down the road. In the end, my only goal is to get the maximum mileage out of the tires. The vehicle will always tell you what it likes and dislikes. It's up to you, the mechanic, to read what the tires are telling you.


As far as what you mentioned above, I normally don't change the toe in reference to the bigger tires. I do however change camber. As the tire gets bigger, wider, or both, the impact of tire wear due to the camber angle increases significantly.


When possible, I like to interview my customer on their driving styles. Especially if I'm aligning a sports car. You tell me how you want to drive, how much tire wear you want to give up and I'll set the car up accordingly. Of course, when you first ask the customer their driving habits, you get this "It's none of you business" look until you explain to them why your asking. It also throws people off because they're not expecting it.


One final comment on myself. As stated above, I've been doing alignments for many years. I currently work at a Sears store in Colorado Springs, Colorado and have been there for over six years. This is my hobby. It's what I do for fun. Many people, including my wife, does not understand this. She thinks I should quit. One day I will. In the meantime I get to do what I want to do without worry management bothering me and without worry of having to earn a good weeks wages to pay the bills. My only concern is doing a good quality alignment and taking care of the customer. In turn, the customer takes care of me.


Dale
 

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Amric,


What air presure's do you have in your H2's? ... I quess what I'm really asking is how did you determine what pressure's to run?
 

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I'm running 50 psi in the front, and 28psi in the rear (unloaded). I use a pyrometer to determine temperature across the tire contact patch to determine if I need to add or remove air to get even temperature across the tire. The pyrometer is also a great tool to determine if there is too much or too little camber. I put on the H2 tires without raising the front suspension. In fact, I lowered the front suspension 1", so my weight balance front to rear would probably be different than most others who are running the H2 tires. What I am saying is that these pressures might not be the best for others. I also removed a rear leaf, spare tire, spare tire mount, and jack. Most would have more weight in the back, and would need more than 28psi.
 
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