Quote:
Originally Posted by arcturus
For what it's worth,I fitted electric power conversion to my 144 and it has ruined the feel of the steering. Pump up your biceps and put a couple of extra pounds pressure in your front tires
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Adding a column mount EPS does nothing to alter the steering linkage kinematics of the Volvo's steering mechanism. Most of what passes for feel in the 140's steering system is friction / drag. The equivalent of the friction damper that used to be stuck on some motorcycles 50+ years ago. The amplification effect of a column EPS power steering tends to dilute that friction effect.
If you want to improve the feel of your steering increase the amount of caster. The 140 came with the absolute minimum safe amount of caster (0 to +1.0 deg) to minimize steering effort (more caster = more steering effort). Any less caster and the front wheels would wobble like the front wheels on a shopping cart. With the 140's minimalist caster the mechanical gain inherent in EPS makes the steering overly sensitive to user input at higher speeds. Increasing the caster increases the tendency of the steering to track straight ahead once the car is moving with any significant speed. The self aligning effect of increased caster increases with speed and you will perceive this as resistance / feedback in the steering wheel. Modern cars with power steering tend to run +5 deg or more of caster.
Two other factors to consider. The first factor is that Volvo equipped the 140 with a very large diameter steering wheel to provide mechanical gain in the steering system. With power steering that mechanical gain is unnecessary and contributes to overpowering the 140's minimalist caster. A 13" - 14" steering wheel is a much better choice when retrofitted with power steering. The second factor is that the 140 has a lot of slop in the steering mechanism which translates into a fairly large dead zone (vagueness in the steering) when the steering is on center. A lot of this originates from the flexible break away coupler that Volvo uses in the 140 steering column. The 140 steering box also has a dead on center effect even when its perfect. You can adjust this out; but, at the risk of increased wear to the steering box. The dead zone is equivalent to hysteresis which is not your friend when you increase the forward gain (power steering) in the control system.
With my column mount EPS system I have a 14" steering wheel and Michelin 185 all season tires.. When I installed the EPS I replaced the Volvo break away column section with a collapsible splined column. There is nothing I can do about the slop in the 140 steering box unless I try to replace it with a rack. I am currently running about +1.8 deg of caster. At some point I may consider experimenting with a further increase in caster; but right now I am reasonably satisfied with the level of steering feel associated with increasing the caster to +1.8 deg. If you retain the original 140 hula hoop steering wheel and 165 tires you might want to consider increasing the caster to something more than +1.8 deg because of the inherent mechanical gain associated with the large steering wheel. You could also consider adding a hydraulic steering damper; but, that is more of a bandage rather than trying to address the underlying problem.