Caster (lack of):

Is this the final? Did they say why they can't do anything? Some suspension types, like Neway, are welded. Alignments can still be done, but more labor intensive. Your toe is out and both drives are out to lunch too. Cross caster isn't bad, I would not touch it. What kind of truck is this, what kind of suspension do you have?

 

There are no shims left on the pass side . They are saying frame shop. Truck is a kw t600 don't know the axle manufacture.. the drives can be adjusted.

 

It has to go to frame shop for the alignment? I seriously doubt that.

 

Just curious, what kind of caster numbers work the best on a 97 379 with 290" wheel base?

 

Most highway trucks are happy in the 3.5 to 5.5 degree range. You want decent directional stability, which is no wandering and good returning to center after a turn. Some guys like it a bit stiffer, others are ok with a looser feel. Also, no two trucks are the same, so there really isn't a "perfect" number for caster.

 

Hi mate, found this thread when reading up on caster on the net. I own an alignment shop in Australia and took a liking to what you were saying and was hoping to have a chat to you in regards to caster as I’m a firm believer it’s the most critical part of an alignment that almost every alignment shop here overlooks.

What are your thoughts on raising caster on a parabolic spring setup vehicle? With an influx of European trucks down here, im seeing more each day roll into my shop...

 

In North America, that is pretty much all we have. Yes, it is imperative to a good alignment to have caster up where it needs to be. Increasing caster is easy in most cases. Most of the trucks I see have caster is in the mid to low 3 degree range with no shim installed from the factory. So it is just a matter of loosening the ubolts, jacking up the spring, and slipping in a new shim. I only put in a shim where the center bolt still protrudes into either the axle itself or the spacer block. So this does sometime limit how much I can add. I do have more details further back in this thread, but if you have any more questions I didn't cover there, feel free to ask to any time!

 

I have a tonne more questions, however I agree with being limited by the center bolt at times. Most new trucks we see here be it American, European or Japanese are set up from factory with 1-2deg on the left and 0-1deg on the right (opposite high side to you guys). I like to bump them up to around 4 on the left and 3 on the right with a cross caster of over 40mins and under 55mins. This generally suits our roads and is a nice happy medium between line haul and local working trucks... however sometimes this is unobtainable due to center bolt for the reasons we both mentioned. We work for all the dealerships in our area, so we don’t bend camber based on their recommendations and the results we get are still great as long as the axles are within spec or close to it. When they are out of spec slightly, we just stay on top of rotations, but when they are drastically out of camber spec, we advise the customer to speak to the dealership in regards to fitting a new axle.

I do find sometimes that certain trucks like more cross caster than others.

As I mentioned parabolic leaf springs earlier, there are people here of the idea that running caster on them around the 4lhs and 3rhs mark is too high and could snap the spring, however I don’t see this being a problem unless you have no idea what you are doing and fit a negative wedge on one side of the truck and a positive on the other. As long as they are both positive wedges, I feel it’s fine. Your thoughts?

 

Trucks like 4 to 5 degrees. Never had a spring break, ever. I have no idea what they are talking about in that regard. If you have extremely large spacer blocks between the spring and axle you will increases chances of spring wrap under hard braking, but that has nothing to do with caster. Most trucks have their caster built in with a lower rear hanger compared to the front, so they produce about 3 degrees with no shims. So installing shims to get that 4-5 sweet spot is only a simple matter of adding 1 or 2 degree shims most time. They are relatively thin and really don't change how the truck sits. Lots of Petes come from the factory with 1/2 or 1 degree shim installed backwards on the left side to get the crosscaster where they want because the caster is just naturally high due their spring and hanger design. Ultimately, all that matters is you get the results you want, and everything is assembled safely.

 

Thanks. I don’t have enough posts to start a conversation with you, but what alignment system do you use? Hunter?