power steering
#2
12-01-2007, 06:49 AM
RE: power steering
It's possible. How strong are you? How much endurance do you have? Unless you can answer 'very' and 'a lot' to these questions you shouldn't consider it. Having said that, it's easy to try, and easy to go back if you can't live with it (I tried it briefly when I was trying to diagnose some problem or other, I couldn't have lived with it and I'm fairly strong).
If you want to increase steering 'weight' then I'd reccomend increasing your caster angles as much as is possible by any and all means possible. There are a few ways to do this, one is (for Mac strut) to fit an adjustable upper strut mount (i.e. pillowball etc) to pull the top of the strut backward, another (for Mac strut or double wishbone) is to shorten the radius rod that runs from the lower control arm to the front subframe (to pull the bottom of the strut or upright forward). If you have a double wishbone set up then it's possible to modify the upper wishbone to pull the top of the upright backward.
Get good proffesional advice on the hows of any of this, you can create significant problems if you don't know exactly what you're doing.
Increasing caster will not only increase steering'weight', but also improve on-centre feel, return to centre, and is beneficial for steered camber angles. This means that you will create actual dynamic improvements instead of merely an increase in weight but with no real change in the handling etc.
By 'steered camber' I mean the changes in camber that occur as the front wheels are steered, being caused by caster angle (more caster = more steered camber change). The outside wheel will gain additional neg camber and the inside weel will gain additional pos camber. Both of these affects are good because they act to counteract the undesirable camber gains created by body roll (and even with stiffer springs, ARBs etc, there will still be enough body roll to cause significant unwanted roll camber changes, even if the chassis feels like it corners fairly 'flat').
This is especially the case with Mac strut suspensions because such suspensions have a very poor 'camber curve' (compared to double wishbone), camber curve being the degree to which the wheels gain neg or pos camber with bump and rebound (which comes into play with body roll).
To be more precise, the steered camber changes are directly caused by the caster angle, but the improvements in 'weight', on-centre feel, and return to centre are directly caused by an increase in 'trail'. Trail is defined as the nominal longitudinal distance between the centre of the contact patch to the point at which the steering axis intersects the ground (being in front of the contact patch centre). Trail increases as a by-product of increasing the caster, so 'weight', on-centre feel, and return to centre are improved onlyindirectly as a result of caster increase.
Unless your car comes standard already with a lot of caster angle (?), you want to add as much as you can.Manycarsnowadays (as opposed to thoseadays)are coming from the factory with quite high caster (10° is not outrageous these days, and many race carsuse a lot more). This is only posible when PS is fitted, as high caster makes the steering onerously heavy without it (why many race cars these days retian or fit PS).
When you increase caster, you'll get the benefits as outined above, but you are also likely to make a real improvement to steering response (i.e. 'real' as opposed to a 'feeling'), and you'll most probably find that smaller steering inputs are generally required than if the caster were less. This is almost like fitting a faster ratio steering rack, except that a faster rack doesn't actually do anything for thehandling!
If you want to increase steering 'weight' then I'd reccomend increasing your caster angles as much as is possible by any and all means possible. There are a few ways to do this, one is (for Mac strut) to fit an adjustable upper strut mount (i.e. pillowball etc) to pull the top of the strut backward, another (for Mac strut or double wishbone) is to shorten the radius rod that runs from the lower control arm to the front subframe (to pull the bottom of the strut or upright forward). If you have a double wishbone set up then it's possible to modify the upper wishbone to pull the top of the upright backward.
Get good proffesional advice on the hows of any of this, you can create significant problems if you don't know exactly what you're doing.
Increasing caster will not only increase steering'weight', but also improve on-centre feel, return to centre, and is beneficial for steered camber angles. This means that you will create actual dynamic improvements instead of merely an increase in weight but with no real change in the handling etc.
By 'steered camber' I mean the changes in camber that occur as the front wheels are steered, being caused by caster angle (more caster = more steered camber change). The outside wheel will gain additional neg camber and the inside weel will gain additional pos camber. Both of these affects are good because they act to counteract the undesirable camber gains created by body roll (and even with stiffer springs, ARBs etc, there will still be enough body roll to cause significant unwanted roll camber changes, even if the chassis feels like it corners fairly 'flat').
This is especially the case with Mac strut suspensions because such suspensions have a very poor 'camber curve' (compared to double wishbone), camber curve being the degree to which the wheels gain neg or pos camber with bump and rebound (which comes into play with body roll).
To be more precise, the steered camber changes are directly caused by the caster angle, but the improvements in 'weight', on-centre feel, and return to centre are directly caused by an increase in 'trail'. Trail is defined as the nominal longitudinal distance between the centre of the contact patch to the point at which the steering axis intersects the ground (being in front of the contact patch centre). Trail increases as a by-product of increasing the caster, so 'weight', on-centre feel, and return to centre are improved onlyindirectly as a result of caster increase.
Unless your car comes standard already with a lot of caster angle (?), you want to add as much as you can.Manycarsnowadays (as opposed to thoseadays)are coming from the factory with quite high caster (10° is not outrageous these days, and many race carsuse a lot more). This is only posible when PS is fitted, as high caster makes the steering onerously heavy without it (why many race cars these days retian or fit PS).
When you increase caster, you'll get the benefits as outined above, but you are also likely to make a real improvement to steering response (i.e. 'real' as opposed to a 'feeling'), and you'll most probably find that smaller steering inputs are generally required than if the caster were less. This is almost like fitting a faster ratio steering rack, except that a faster rack doesn't actually do anything for thehandling!
#3
12-04-2007, 08:09 AM
Unregistered
Posts: n/a
RE: power steering
You sir rock! Thank you for the great advice and explanation.
I have had the car for about 2 months and just upgraded from stock rims to some enkei ones. The enkei rims are VERY light. The are so light in fact that before the upgrade I had decent steering response but once I swapped out the rims the steering has become very light. I am going to upgrade my suspension to eibach springs and dampers next month and will try your "alignment" suggestions.
Thanks again
I have had the car for about 2 months and just upgraded from stock rims to some enkei ones. The enkei rims are VERY light. The are so light in fact that before the upgrade I had decent steering response but once I swapped out the rims the steering has become very light. I am going to upgrade my suspension to eibach springs and dampers next month and will try your "alignment" suggestions.
Thanks again
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