07-09-2014, 10:04 AM | #1 |
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My s28i doesn't feel planted at high speeds
Does anyone else have this issue? BTW I drive a 2013 x1 s28i, non-msport.
At speeds up to 65 miles an hour, the car feels like it is glued to the road. It is very solid and I feel like I can take turns and ramps at higher speeds than most other cars. But once I get up to 70+ miles per hour, the car feels like it loses its planting and there is noticeable lateral movement when on the highway. It almost feels like the car is getting blown around by wind, even though I look at the trees and grass next to the highway and it appears that there isn't wind. I've only recently noticed this as I have also been driving my wife's car which feels very planted at speeds 70+. BTW, there isn't any noticeable steering wheel shake and the car does not appear to be pulling one direction or the other while on the highway. I can be holding the wheel straight to maintain center of lane and all of the sudden the car shifts to the left a bit or shifts to the right a bit and I have to adjust my steering. Also the steering feels very lively at 70+ speeds where the slightest movement of the wheel seems to make dramatic effect on on my course which is the opposite of what you want when driving at faster speeds. |
07-09-2014, 10:17 AM | #2 |
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I use to experience that when I drove a Mazda MX5. To fix it I bought a digital tire gauge and made sure the right and left tires were always within half a pound of each other. I haven't had that issue with the x1, even when I haven't adjusted pressure in over a month.
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07-09-2014, 10:27 AM | #3 | |
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07-09-2014, 11:02 AM | #4 |
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Drives: 2011 e91
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Question, what types of vehicles did you have in the past?
This could be from wider tires than what you're used to. Some of it is also the electric steering not having the same tightness as the hydraulic unit. Also, the height of this car plays a roll in stability (no pun intended). Because it sits a bit higher than a car but lower than a normal SUV, the air under the car lifts it quite a bit, causing it to be more loose.
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07-09-2014, 11:19 AM | #5 | |
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07-09-2014, 12:08 PM | #6 |
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I have a 2013 28 sdrive with M Sport and it's as steady as a rail car at over 100. I would guess tires, All Seasons vs Summer performance, over inflated, alignment? I would check how the tires are wearing, are the insides or outsides wearing faster. I've never had a BMW that wasn't extremely steady at 100 plus and I'm on No. 15 plus a Mini.
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07-09-2014, 05:02 PM | #7 |
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I have cruised at 110 and the vehicle is very stable. 65 and 110 actually feel pretty much the same. Sounds like something is wrong with your x1.
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07-10-2014, 12:21 AM | #8 |
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fyguy400,
Your assessment is spot on! My Euro Delivery s28i M Sport does that exactly, and I have staggered tires stock which you'd think would mitigate that. In Germany, I'd follow faster cars at 120mph, and it was all over the road. It's like it is sucked up, and waddles left to right, and in wind it will change lanes for you. I did top it out at 152 mph (speedo), and it was scary which I don't need to do again. I put 12mm Burger spacers only on front, and I can get up to 130mph (speedo) before it starts that dance. You should try 12mm spacers on front even if you have same tires all around, or 12mm all around. I have the summer Pirelli p7's, and measure tread depth occasionally to check for out of alignment. The wear went from 9.5/32 to about 7.5/32 all around in 8k miles, and it's very even so I don't see need for alignment. Last edited by 0w40X1; 07-10-2014 at 12:28 AM.. |
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07-10-2014, 12:58 PM | #9 |
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The X1 is pretty high off the ground and small changes in air pressure and wind direction can cause significant torque to transfer to the base of the steering column from the body and wheels.
The problem you are noticing is due to the EPS implementation. Hydraulic steering constantly applies pressure where as BMW's implementation of electric power steering in the X1 is purely torque reactive. The EPS motor is reading the torque on the column via light beams passing through slits and then apply countering torque to the column. The reaction is pretty slow (50-150ms due to DAC and motor inductance) and you notice it. Hydraulic steering act as torque shock absorber that will mask small changes in torque while transmitting large ones. This is the "feel" that people talk about. EPS can be designed to completely mimic hydraulic steering although you usually need sensors on the axle and tuning while making it a more costly and complex setup. With EPS, it becomes an issue of sensor location and signal processing to create any kind of feedback "feel" that you want. The technology is superior to hydraulic steering while individual implementations may not be. Whether the car is planted or not is a function of the airflow, engine, weight, sprung and unsprung weight, and grip. What you feel through the steering wheel has little relevance in terms of the actual performance of the car. To get a good EPS system, you need electrical, systems, or computer engineers which are not typically found in the auto industry.
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Last edited by dsx724; 07-10-2014 at 01:09 PM.. |
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07-10-2014, 07:03 PM | #10 |
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I find this pretty funny since the new M3, M4 and M235 all have EPS and yes I own a M235. Never had any issues with my X1 and since it's been in the US now for 2 years why would this all of a sudden be an issue for a couple people. I doubt seriously it has anything to do with EPS since it's not an issue with 3 series owners being unstable or floating but simply a height, tire or other unknown issue. Someone drives their X1 152mph and it feels unstable, why would someone want to drive an X1 152. I owned 3 M3's and never drove 152, just saying these are not sports cars their small SUV's. The original post mentioned not having M Sport so probably not staggered tires (just guessing) and they never responded regarding All Seasons or Performance tires. My point being a couple people out of thousands of owners sounds like something other than EPS. If it were EPS 3 series, 5 series and other owners would have this issue.
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07-10-2014, 11:02 PM | #11 |
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dsx724,
I was able to get 20 more mph (130+) before it does that with front spacers. The steering is much firmer now, but I don't think the EPS is moving back and forth at high speed. No doubt the front end is catching wind, and the high bubble roof will suck up, also. I think some guys not noticing this have a Heavier 35i which would shift more weight to front to hold it down. Next tire set will be .5 inch lower to ground (225/40r18 instead of 225/45r18) which will help a tiny bit, and maybe more acceleration. |
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07-11-2014, 08:33 AM | #12 | |
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07-11-2014, 09:26 AM | #13 |
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I would surely get a full alignment and check the tire pressure. It may be a function of road surface as well; I noticed a bit of this on FL roads, which may be higher crowned to allow for rain runoff. I haven't noticed it here at home, tho' PA roads are hardly a day at the beach. I did do a berzerker pass of a truck on Beffert Mountain on a two lane; I had no idea that I'd seen 110 'till my bride pointed it out to me...it felt quite planted.
Moon ETA- I did get mine aligned when we got back from FL, having noticed a bit of wander down there, plus some feather on the outside edge of the front tires. Now I'm getting a bit of feather on the inside edges. Go figure. M |
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07-11-2014, 09:27 AM | #14 |
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Rear camber is normal for BMW. If you don't drive aggressively and/or track, you'll wear the inner tread off early.
Our X Line 35i is far from stable over triple digits. Our 135i was similarly squirrelly though both on staggered RFT's and staggered summer non RFT's. Even with a much shorter wheelbase, my M Coupe was much more stable than either the 1er or X1, plus it actually had steering feel and wasn't under assisted, unlike the other two. |
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07-11-2014, 07:40 PM | #15 | |
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07-11-2014, 09:46 PM | #16 | |
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It's a good safety measure for uninformed drivers in slick conditions, but when I get an alignment I dial some out like to -1.5 deg so the car will turn easier. Get a tread wear gauge and measure across tread to see where tire wears more. If the alignment is off it will show tire wear. I wouldn't touch alignment unless to save tires. My X1 seems aligned right, but still does what you said at speeds around 120 mph. My spacers did enough for me, and I only hit about 110 mph on my track. |
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07-12-2014, 10:31 AM | #17 |
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I am really glad somebody brought this up.
I had something similar happen to me last winter when I was driving out west. Cruising at 75 mph with a gusty cross wind I was blown into the next lane several times. It felt like I was airborne for a split second. It was so weird because even at maximum alertness after the first incident I was unable to react fast enough to keep the in a straight line when it happened again. I kept thinking to myself there is something wrong with this car. I then slowed to 65 and had no further incidents but I have never had anything like this happen to me with any other car I have owned. I assumed it was entirely from freaky weather conditions and have since forgotten about it. Now I am not so sure. |
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07-12-2014, 10:40 AM | #18 |
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Not sure what the problem being discussed is here. Is it that the car is not stable at high speeds or that the car is not stable at high speeds with the wind blowing?
Given that the X1 is taller than a car and much lighter than most SUVs, for sure it will get blown around more during windy conditions. I for sure have not encountered problems at high speed when it is not windy. |
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07-12-2014, 12:17 PM | #19 |
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I thought this was just a weather related phenomenon when it happened to me which is why I forgot about it initially, but my other car is a Toyota RAV4 which has more clearance, is overall higher and 400lb lighter than the X1. I have taken it out west many times and never gotten blown into the next lane.
I have had this happen on two other occasions but not nearly as dramatic, just a sudden subtle loss of control of the car. I do not recall that there were any gusty winds at the time. But I was going 75 - 80 mph both times. I can say with confidence that I have passed cars and run the speedo up to 105 mph and the car felt absolutely stable during these short spurts. I am not sure what is going on but I think flguy400 is on to something. |
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07-12-2014, 10:15 PM | #20 | |
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Wind in front would allow it to happen at lower speeds by amount of front wind speed. When I drove 120 in Germany, one time there was strong side wind gusts which changed a lane for me. At those speeds I was watching for it because it was already rolling from side to side. It's what I'd expect from a tall body with narrow wheel track. Like I said, widen your track with 12mm to 15mm spacers and it'll cure most of it to any speed people can use. I'm not usually a fan of spacers, but they only weigh about 1#, and I'll get rid of up to 5#/wheel next time I buy non runflats. The reason everyone feels different ride from their cars is that 35i's have more weight on front, and some cars have square setup instead of staggered like mine. |
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07-12-2014, 10:28 PM | #21 |
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I just looked up x35i which is a whopping 361# more than s28i with most of that weight over front.
I bought the s28i for it's lighter weight, but I can tweak to minimize trouble. I think if I put 361# weight on front end, I'd never notice the sway. |
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07-13-2014, 09:20 AM | #22 | |
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Ah, just noticed you're also comparing the sDrive. So you do have the additional 120 or so pounds of xDrive fluff up there on the 35i plus a little for the more complex hydro steering rack with servotronic. So you probably do have a little different balance in the s28i. We changed from a 135i to this and both have a nearly equal weight balance and neither were terribly stable at high speed, something a 911 achieves with only 35% of the weight on the front wheels. |
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