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Posted by: Tdskip Jan 19 2020, 12:37 PM

Just as a thought exercise – if you had to pick a new – modern sports car that had proper hydraulic, rather than electric, power steering what would it be?

Just walked past about a 7 year old Audi R8, hence the question.

I’m sure the last generation Cayman would have be on the short list...

Posted by: injunmort Jan 19 2020, 01:22 PM

98-02 bmw z3 with 2.8 or 3l six. imho

Posted by: Mark Henry Jan 19 2020, 01:32 PM

With the title I'd be thinking more of a late 70's car at most.

Posted by: DickSteinkamp Jan 19 2020, 01:50 PM

I don't get it.

What are the advantages of hydraulic over electric? I can only see advantages for electric (lighter, infinitely adjustable from the cockpit, no leaks or fluid to check, no burst hoses). There is a big after market biz converting hydraulic to electric. None going the other way.

Posted by: Mark Henry Jan 19 2020, 01:53 PM

I'm going to be installing an electric rack in a customers 997 shortly.

Posted by: Chi-town Jan 19 2020, 02:15 PM

996 non turbo/986 MY1999.

No nannies, cable throttle, well tuned ABS

Posted by: Tdskip Jan 19 2020, 02:54 PM

Feel - I prefer cars without any assistance but kind of hard to find a modern car with power steering. Personally I find hydraulic systems have better feel/ communication.

Posted by: infraredcalvin Jan 19 2020, 03:23 PM

Define analog. Once you get into abs and stability control I think the term “analog” goes out the window....

Posted by: Superhawk996 Jan 19 2020, 03:27 PM

Posted by: DickSteinkamp Jan 19 2020, 03:33 PM

Most OE and aftermarket EPS systems can be tuned to individual preferences from the driver's seat. Some can do it automatically based on road speed.

I also dislike "numb" steering systems. I have found lots of hydraulic systems (especially in older cars) to be in that category. I've yet to find an EPS one that I didn't like...or couldn't tune to like.

Also I think it is easy to find a modern car with power steering. Even the small and inexpensive cars seem to have it.

Posted by: Superhawk996 Jan 19 2020, 03:35 PM

What in the world are you comparing to as the baseline?

A manual rack is the benchmark for feel, feedback, communication what ever terms you want to call it by.

Hydraulic and Electronic Power Assist Steering (EPAS) are all over the map from OEM to OEM as well as within trim series so I don't know that I'd buy into a generalization hydrualic steering has better feel but I do concede that it is all about personal preference. In either Hydraulic or EPAS, it is all about how the system was tuned. Torsion bar (steering torsion bar - called a T-bar) sizing in either case has a lot to do with feel. Hydraulic has added complexities tolerances associated to the assist valve griding, hydraulic hose compliances, and even hose routing. I don't miss the days of tuning hydraulic steering systems at all.


Feel is just as influenced by steering geometry particularly caster but also scrub radius, tire mu, tire tread patterns and sidewall stiffness just to name a few.

Posted by: Tdskip Jan 19 2020, 03:37 PM

There’s a difference between “feel “and “effort “. No doubt that electric systems are almost instantly adjustable for effort, but that doesn’t mean they were communicating like the older systems.

To each their own, but regardless of effort I find most electric systems numb.

Posted by: Superhawk996 Jan 19 2020, 03:40 PM

What in the world are you comparing to as the baseline for a "good" hydraulic steering sytem?

A manual rack is the benchmark for feel, feedback, communication what ever terms you want to call it by. Most modern cars have simply gotten too heavy for a unassisted steering system to be feasible.

Hydraulic and Electronic Power Assist Steering (EPAS) are all over the map from OEM to OEM as well as within trim series so I don't know that I'd buy into a generalization hydrualic steering has better feel but I do concede that it is all about personal preference. In either Hydraulic or EPAS, it is all about how the system was tuned. Torsion bar (steering torsion bar - called a T-bar) sizing in either case has a lot to do with feel. Hydraulic has added complexities & tolerances associated to the assist valve griding, hydraulic hose compliances, and even hose routing. I don't miss the days of tuning hydraulic steering systems at all.


Feel is just as influenced by steering geometry particularly caster but also scrub radius, tire mu, tire tread patterns and sidewall stiffness just to name a few.

Steering feel is really a systems engineering thing. No one thing makes or breaks a sytem including whether it is hydraulic or EPAS.

I'll still take EPAS for a host of other reasons not the least of which is lack of steering moan (NVH issues) and pump wear issues over time. Let's not even discuss leaks and/or the number of engine fires that have occurred over the years from ruptured hoses that atomized power steering fluid and had it get on hot manifolds. Yup. Don't miss hydraulic one bit.

Posted by: DickSteinkamp Jan 19 2020, 03:48 PM

The ONLY thing that both hydraulic and EPS can do is reduce effort. That has a lot to do with "feel", of course. Both systems can overly reduce effort which isn't much fun . All the other "feel" variables are not associated with the method of reducing effort.

Posted by: Maltese Falcon Jan 19 2020, 03:51 PM

CGT

Posted by: Tdskip Jan 19 2020, 03:57 PM

For a second I actually thought you meant this



First time I drove my MGB-GT on the 405 where the pavement is grooved I actually thought something was wrong with the car, I just never felt the grooves in the road that so clearly before.

@siperhawk996 - just about every BMW 3 series and 911 that I’ve driven after the cut over to electric steering was disappointing.

Posted by: Superhawk996 Jan 19 2020, 04:12 PM

I'll make an observation on your observation (which I don't disagree with).

The days of the Ultimate Driving Machine are over.

In both cases, BMW & 911, the demographic has changed. More so with the BMW's. Most drivers of these cars now value light parking efforts over communication or feedback. Most drivers of these cars are now driving these brands for lifestyle purposes, not for driving pleasure and driving dynamics. OEM's are chasing customer satisfaction of their curent customers . . . not their legacy customers that are quickly aging out. Of the OEM's. I still think Porsche has some of the best steering feel out there regardless of which type (old hydraulic vs. modern EPAS).

The other thing that has happend in the last 10 years or so is the packing on of pounds and ever increasing size of wheels. 19" and 20" wheels are now very common. Unsprung weight and rotational inertia also have a direct impact on steering feel.

Posted by: Superhawk996 Jan 19 2020, 04:18 PM

You didn't mention if there was a change in tires involved in this.

Tire tread patterns and tire construction have a huge effect on rain groove wander. I regularly drive cars that are EXACTLY the same in all regards from a vehicle dynamics component stand point (measured springs, bars, bushings, etc.) and just changing tires can vary rain groove wander from unnoticeable to unacceptable on the same stretches of pavement at the exact same speeds.

Posted by: Ansbacher Jan 19 2020, 06:03 PM

How about a 924S or an early 944?

Posted by: Tdskip Jan 26 2020, 08:02 AM

Addresses the feel issue

https://www.youtube.com/watch?v=y7s6JwCR29A

Posted by: Superhawk996 Jan 26 2020, 08:52 AM

@http://www.914world.com/bbs2/index.php?showuser=21666

Not so much. Other than he agrees with you.

Althouh it is a good video primer on EPAS there is no technical discussion in there that explains why EPAS would have less feedback.

Let's not forget that hydraulic power assist is not magic. For years everyone complained that all power assist was . The video author talked about damping but the fact is the damping of an EPAS rack is far more adjustable than the damping of a hydraulic system which is also damped by the fluid dynamics of steering fluid flows though tiny orrifices and power steering hydraulic hose expansion/contraction.

EPAS most definately can be made to have communicative feedback.

As was posted earlier there are a technical reasons EPAS isn't as communicative as a manual rack. The primary reasons:


1) The nature of mechanical leverage is working against any assisted steering (EPAS or hydraulic) with respect to up stream feedback from the road. The purpose of the system is to make steering efforts lighter. This is done with mechanical leverage. In the example of a gear, if we have a 4:1 gear, you get 4 times the output for 1 unit of input. Same principle pertains wheter the leverage comes from gearing, hydraulics, or electric motor assit.

In the case of steering, the unit of input torque is at the steering wheel and the 4 units of output is at the road wheels. Now work that backwards from the road. 1 unit of input of road force (or feedback / communication with the road) is now only 1/4 of what you feel at the steering wheel.

2) Customer demand for "light" steering efforts. Though this may not be you (or me), take a quick informal "survey" on your next drive. How many people do you see driving with one hand? Wrist flopped over the steering wheel at 12:00? One or two fingers? Driving with knee while eating a burger or sipping Starbuck? How about driving with hands a 10 & 2? All these these jacked up steering positions give the driver less mechanical advantage on the steering wheel than 9 & 3 and then translates to the need to "boost" the steering assist further just to make them happy.

The demand for more assist to lighten steering efforts works directly agaist communicative feedback . . . basically goes back to point #1 above.

I'm actually torn on whether this is #1 or #2 thing that degrades road feel & communication feedback. The customer data is clear, most drivers want LESS effort and LESS road feedback. As sports car guys, we are the oddballs.

The more any brand like BMW or Porsche caters to non-drivers that are simply buying their cars as a lifestyle statement, and want nice light steering efforts so they don't have to expend as much effort to drive, the worse your steering feel will get. Likewise the older your buying demographic gets, the worse your steering feel will get.

3) One of the downsides of EPAS is a controls / motor issue that can occur if too much damping is taken out of the system and the controls are made to be too responsive. The assist motor will go into an instability which is just a small amplitude uncontrolled oscillation (i.e. steering shudder). I'm not talking about massive steering wheel movement, but only a perceptible vibration in the steering wheel that shouldn't be there. It is a byproduct of the system compliances & tuning. Damping is added in the controls algorithm to address this. Damping is variable as a tunable parameter at the discretion of the engineer tuning it. Hydraulic steering can have the same shudder problem but to a lesser degree because the system is less "stiff". In the case of hydraulic's the damping is added by tuning hose, diameter, lengths, and expansion characteristics or via orrifice sizes within the control valve. There is actually more compliance in a hydrauic system due to hoses, brackets, etc. that make the hydraulic system less prone to instability (i.e. steering shudder) but belive me when I say I've spent a lot of time dealing with hydraulic power steering moan, shudder, and assymetric efforts.

4) The location of the EPAS motor location matters. Column mounted EPAS systems typically feel worse, more numb, and communicate less road feedback. Rack mounted EPAS tends to be more communicative in my experience. Regarless, either are highly dependent on how they were tuned and what the rest of the system steering system dynamics are (low/high scrub radius, high friction ball joints, high friction struts, etc.) that can seriously degrade road feel too.

OK, I'm tired of typing. If anyone really cares, we can deep dive further

Posted by: 914_teener Jan 26 2020, 10:08 AM

As far as the Cayman is concerned, the 987.2 had hydrualic...the 981 had steer by wire.....so anything before 2014.

The Cayman had problems...mostly tracked cars.....with overheating with the fluid.

As far and the feeling...I prefer the hudraulic rack although I get why they went to an electric one.

Posted by: Steve Jan 26 2020, 10:12 AM

993 Manuel

Posted by: Tdskip Jan 26 2020, 10:14 AM

I think this would have to be on the shortlist ...

Posted by: Superhawk996 Jan 26 2020, 12:38 PM

Love the styling even though engine is in the wrong place. Can't speak to the steering dynamics. Aston would be on my short list if I hit the lottery!

Posted by: Superhawk996 Jan 26 2020, 01:37 PM

Just a nuance Cayman isn't steer by wire. It is EPAS. Electric Power Assisted Steering.

Steer by wire implies that that there is no mechanical linkage between the steering wheel and the steering actuation.

Nissan was 1st to market with a quasi steer by wire system and also had to recall shortly after it was launched.
https://www.popularmechanics.com/cars/a9940/infiniti-recalls-steer-by-wire-system-16276674/

The reason I say quasi steer by wire is that by Federal Motor Vehicle Safety Standards the steering must have a mechanical linkage. In the case of the Nissan, it had a mechanical linkage that could be reengaged if the steer by wire portion of the system failed.

The main reason for steer by wire is that it becomes a path toward autonomous vehicles by easily enabling elimination of the steering column altogether.

Posted by: horizontally-opposed Jan 26 2020, 05:21 PM

This used to be a hard question to answer. "Best for what?" I'd mumble as an out.

Then I spent 1,200~ miles on great roads in a Carrera GT. Once enough of the intimidation factor wore off (it took about 200-300 miles), it was like a bigger 914. With a Judd V10. On acid.

66,000-mile CGT video, with great sounds:
https://www.youtube.com/watch?v=BtJmt5q67rk

Black CGT drifted up a mountain pass in Europe; too bad about the talking over the audio...
https://www.youtube.com/watch?v=ajqSQ1NyQ_4

And in case you forgot the Judd, or never heard one in a sport car…
https://www.youtube.com/watch?v=2lYrjKQqOfs

Back down in the realm of reality, the 986/996 had very sweet steering (better, I thought than the much-lauded E36 M3 steering) with the 987/997 being very similar though no longer 1:1.

Posted by: Maltese Falcon Jan 26 2020, 05:46 PM

CGT...I would just install a Fuel Safe (brand) fuel cell & an OMP sourced fire suppression sys
Perfect Driver !

Posted by: 914_teener Jan 27 2020, 01:40 PM

Ah....yes thanks for the clarification.! Good info.

I'd say for the "feel" factor with respect to the EPA....the EPAS version in the 981 feels different in that it feels a little"twitchy" to me. Always a subjective thing.

Posted by: Rikyrat May 7 2020, 10:18 AM

I just read this, and had a chuckle.

A few years back I took my 2010 Acura TL, to the service station across the street from my office, needed to change the oil.

When I went to pick it up, they had noted that the had 25k miles on it, and should have the power steering system flushed, I look at the guy with a puzzled look in my and stated "But, it has electric steering", he replied, it still needs to be flushed. Needless to say, I never went back.

I wonder how many people he duped with that one.

I like my EPAS on my new TLX, at low speeds in a parking lot, it is very easy to maneuver, but as you get to highway speeds, it get tighter and tighter, the things is that you don't really even notice. Sorta like the speed adaptive sound system.

I entertained the idea of putting it into my teener, but have not decided to do it. It seems like it would be fairly simple to do, since the steering column, takes a zig to the right, before it goes into the fire wall. If one were to pick up a spare column, the it would be completely reversible, if you decided to sell it.

Posted by: ClayPerrine May 7 2020, 12:59 PM

1995 or older 993 with a manual transmission. Air cooled, cable throttle, and almost no electronic nannies. The only nanny it has is ABS.

The reason for 95 or below, no drive block connected to the ECU.

Posted by: burton73 May 7 2020, 02:28 PM

Power-steering racks. In my experience, power-steering racks seem to leak more often in later cars. I am not sure if the pump runs at a higher pressure or if there is some other design issue, but my early 928s’ power-steering racks have been trouble-free, while my later cars have all required at least one new or rebuilt rack.


928 is the ticket. My Shark 1986.5 Original Paint. 44,000 miles



Bob B