If caster were easily adjustable on the EVO would you change it from the factory setting, what do you feel would be optimal, and why??


What is optimal caster on a lowered, stiffly sprung EVO?

What would be the advantages/disadvantages of more caster angle??


EVOlutionary

 

I think it would really depend on how much camber or lack thereof your tire likes. I would think with the poor camber curves it would often be more than you can realistically get. 6+ degrees.

d

 

I'd say as much as you can get, without causing your car to eat up axles like they are going out of style.

How much caster you run is more a result of suspension design limitations, and track layout than it is ride height or spring rates. Running positive caster has a self-centering effect which helps with high speed stability, and also improves a car's negative camber gain during compression (although not by much). There is some research out there that adding positive caster will hurt the car's corner balance though. I forgot where I read it, but the results showed drastic changes in corner weights when the wheel was turned.

 

so if im at the track would i be safe with 3 deg pos caster and 2 deg neg camber?

 

Stock should be more than that, but yeah that's plenty safe.

d

 

ok so 3 and 2 more than stock is still safe?

 

Has anybody actually gotten that much (> 6 degrees)?

d

 

The most I've seen is ~5 to 5 1/2 degrees of caster.

 

I think the largest effect castor is going to have on a car with stiff springs is the diagonal weight transfer (think go karts, or wedge if you know nascar). Increasing the castor is going to increase the oversteer balance of the car with increased steering angle. Sure it also adds negative camber with steering angle but i think for the most part you can achieve an appropriate static camber angle with these cars.

Other aspects are that the balance of the car becomes speed dependent, ie higher speed turns need less steering angle, thus less of the castor driven oversteer is present. Also the diagonal weight transfer works to lift the inside rear tire off the ground, which for the rear diff challenged will result in wheel spin.

so optimum setting? i have no clue.

 

i REALLY don't like the steering feel with a lot of caster....maybe it's just me.

But getting 5 to 6 degrees is definitely nice and certainly worth it.


- Andrew

 

I'm also not a huge fan of what caster does to steering feel and feedback but do love camber gain.

 

What is your opinion on this article? (this was the article I was referring to earlier)
http://www.honda-tech.com/zeropost?c...ly&id=31851047

Specifically, this part:

"There's nothing like a good example so here are some actual numbers from the use of data acquisition, a set of electronic scales and an alignment machine. With caster + 3.5, camber -1.5,when the tires are turned 7 degrees as typical for sharp hairpin, the camber gain was 0.35 degrees (not much!) however the corner weights changed by 22 on just the outside rear tire. With caster +5.0, camber -1.5, and 7 degrees toe-in, the camber gain was 0.50 degrees (still not much), but the corner weight changed 35 lbs. on the outside rear tire, which is just too much. The most interesting item in these examples is actually how little the camber gain changed. This stuff applies equally to FWD and AWD cars, but for slightly different reasons."