by "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
Published 05/10/2017 at 09:25
by "DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
Published 05/10/2017 at 09:25
No Tags
STARS: 2
I found this article and though it was pretty interesting. Just though I’d post it here and see what y’all think of it. It’s about how to mod EPS (Electric power steering) so that there’s less assist. I don’t have an EPS car, but if I came across an F30(or whatever) BMW I’d probably try to do this with my mediocre electrical skills.
http://www.autospeed.com/cms/article.html?&title=Modifying-Electric-Power-Steering&A=111532
TL;DR- You wire a variable resistor in series with each of the sensors that goes into the EPS, thus tricking it into thinking there’s less force at both the wheel and steering wheel, so that it provides less assist.
"Rico" (ricorich)
05/10/2017 at 09:41, STARS: 0
I remember when I drove a 911 Turbo S the first thing that hit me was how heavy the steering was, it was awesome. Car steering should be heavier to further convey that you’re piloting a two ton machine and not a golf cart.
"Sweet Trav" (thespunbearing)
05/10/2017 at 09:43, STARS: 5
Typically, don’t fuck with EPAS. Especially concerning the current that runs through them, unless the resistor is sized accordingly, you could run into so major issues with heat or fire. Second, everyone bitches about EPAS. EPAS is 1000x times better than most power steering from the beginning of time until the early 1990's.
"Wrong Wheel Drive (41%)" (rduncan5678)
05/10/2017 at 09:44, STARS: 2
Hmm interesting, I wonder if this could apply to the ND Miata. That EPS was so upsetting to me, made me dislike the car entirely.
"WilliamsSW" (williamssw)
05/10/2017 at 09:44, STARS: 2
It’s interesting, but my primary beef with EPS is the lack of feel, not the weight - a lot of people mix them up, but they’re really not the same thing at all.
I DD a GS 350 F-Sport (with EPS), and it has a couple of modes - the Sport+ dials up the steering weight a bit - probably in the same manner this article describes, I presume. A fair number of EPS cars have something like this - though a lot don’t.
The steering weight in normal mode is OK, except at very low speeds, it’s ridiculously light (on any kind of bank it will turn downhill if you take your hands off the wheel at 2-3 mph). What it really lacks, though, is feedback - I also have an E46 BMW, and the steering in that car provides a lot of feedback through the wheel, that enhances my confidence that I know what’s happening at the contact patch.
tl;dr - I think this could help some EPS cars with non-adjustable steering, but probably won’t get at my core complaint about EPS.
"WilliamsSW" (williamssw)
05/10/2017 at 09:56, STARS: 0
I haven’t driven the ND yet, but I’ve read in several places that the EPS on that car is actually better than most EPS cars. Makes me sad to hear you hate it that much - I had high hopes. :(
"DipodomysDeserti" (dipodomysdeserti)
05/10/2017 at 10:05, STARS: 1
No way am I screwing with the EPS. I definitely wouldn’t recommend it if you have mediocre electrical skills. BMWs EPS isn’t as good as their hydraulic units, but it is still better than your average vehicle. After owning an E30, and an E90 335d and 328i I always thought my wife’s X1 had light steering. Then I started DDing a Wrangler and now her steering feels amazing.
"Wrong Wheel Drive (41%)" (rduncan5678)
05/10/2017 at 10:11, STARS: 1
Well I only drove it once. And I had never driven anything else with EPS. And this was immediately after driving my NB Miata with a normal hydraulic rack to the event. I actually noticed that I was no longer aware of the steering issue when on the short autox course they set up at the test drive, so that was a good sign. On course, it was accurate and provided adequate feedback and felt the same as my own car. It was just when moving around at parking lot speeds that I was confused why the steering just felt so light.
I think simply pulling the fuse for the rack would immediately solve that problem. Or doing the mods indicated in the article, that would certainly add some weight to it. It wasn’t necessarily bad, just way too light for my liking. I’d really like to try Porsche’s EPS someday to compare it.
"KusabiSensei - Captain of the Toronto Maple Leafs" (kusabisensei)
05/10/2017 at 10:12, STARS: 0
My ‘07 BMW Z4 (E85) has EPS. It’s not *awful*. The sport program weights the wheel a bit better and is usually preferable, and I can take the jumpier throttle to have slightly less wheel assist.
It still provides useful feedback for me on track, so I’m not upset about it, and not demanding that BMW or anyone else stop using it.
"KusabiSensei - Captain of the Toronto Maple Leafs" (kusabisensei)
05/10/2017 at 10:15, STARS: 0
I’d take EPAS on my pickup, since it’s a diesel, and I have hydroboost brakes. So you can steer, *or* you can stop with power assist, but you can’t really do both during a panic stop (Thanks GM!)
"WilliamsSW" (williamssw)
05/10/2017 at 10:15, STARS: 1
I hope to drive one soon to judge for myself - the light steering at low speeds may not be that critical, but it would just feel wrong in that car. Also, if you have an older Miata, we both have an issue with high standards. I have an older BMW - both of those cars set a pretty high bar for steering feel. Pulling the fuse does seem like a possible option on the ND, though I wouldn’t want to do it in a bigger car.
"Wrong Wheel Drive (41%)" (rduncan5678)
05/10/2017 at 10:25, STARS: 2
I think it was just somewhat comical to me. Everything else felt so similar. The interior was obviously nicer but I felt the same in the car. The power delivery was very similar but there was just more of it. Suspension travel and response felt identical. There were many other tiny details that really just felt like I was driving my car with some upgrades on it. Somewhat wild how Mazda has managed to achieve that.
Shit, compare that to like a Honda civic. Try driving a 2001 Civic and a 2017 Civic back to back. Or even better, take the 1991 Civic. You will have a VASTLY different car in almost every way imaginable. The fact that Mazda captured so much of the original car is just nuts to me.
"Textured Soy Protein" (texturedsoyprotein)
05/10/2017 at 11:05, STARS: 1
My concern with this is in most cases, the EPS is tied in with the stability control, and I don’t know how messing with the steering torque signals might mess with the stability control.
"Sweet Trav" (thespunbearing)
05/10/2017 at 12:47, STARS: 0
We have a vehicle in our fleet with hydroboost (98 C2500 7.4l), it does not exhibit this problem.
"davesaddiction @ opposite-lock.com" (davesaddiction)
05/10/2017 at 13:44, STARS: 1
The electro-hydraulic system in my car has been tuned to remove some assist, and I can also increase the weight/feel even more with the touch of a button for back roads and track (ends up being super heavy in parking garages in this setting). I love it.
"DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
05/10/2017 at 16:58, STARS: 0
So is an electro-hydraulic system one that uses hydaralics for the steering, but the pump is electrically powered?
"davesaddiction @ opposite-lock.com" (davesaddiction)
05/10/2017 at 17:22, STARS: 1
Yeah, I think that’s right. Found this:
“The E9x M3 has a rack & pinion steering system with hydraulic assist from a belt driven pump. It has the Servotronic system, which I believe is located on the pump in this car. It is basically 2 wires that run from the JBE (body control module) to the Servotronic valve that controls the steering assist. I am pretty sure it is completely variable in it’s adjustment range. There are 2 settings that you can select from the M-drive menu, but I am sure it uses more than this depending on vehicle speed.
Here is some info I dug up on it:
Servotronic
The Servotronic controls the power-assisted steering of the power steering depending on the speed by means of the Servotronic valve (electro-hydraulic converter). To do so, the flow of hydraulic oil of the power steering is throttled to varying degrees by the Servotronic solenoid valve .
Brief description of components
Servotronic valve
The Servotronic valve is an electro-hydraulic converter located in the hydraulic oil circuit of the power steering. The valve has a variable shutter that throttles the oil flow to varying degrees depending on activation. The shutter diameter is varied by a speed-dependent flow characteristic curve
Control module
The Servotronic function is integrated in the junction box electronics (JBE). The Junction Box electronics regulate the Servotronic valve. The characteristic curve for the speed-dependent activation of the Servotronic valve is stored as codable in a non-volatile memory.
The following messages or signals, among others, are required for the Servotronic function:
Road speed from the DSC control module via the PT-CAN.
Status of engine from the DME control module via the PT-CAN.
Terminal status of the CAS control module via the K-CAN.
Function
The system regulates the power-assisted steering on a speed-dependent basis. The Servotronic valve variably throttles the flow of hydraulic oil in the power steering. The degree of throttling depends on the current used to activate the valve.
The characteristic curve for the Servotronic valve specifies the current depending on the speed.
The characteristic curve is described by reference points, whereby the speed and current are coded for each reference point.
The Servotronic only activates the Servotronic valve if terminal 15 is on and the engine is running. As long as there is no speed signal at engine startup, the maximum possible steering power assistance is set. When the correct traveling speed is received, the specified value is taken from the electrical characteristic curve.”