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bolind
Jun 19, 2005



Pillbug
This thread is about my red E87 118i, which needs some TLC, and a bit of help from you guys.

It looks like this:



Which incidentally also shows my primary wrenching area: the parking garage under my condo. It's actually OK, I'll get back to that later.

However, first on the operating table is this '07 Astra. GTC even. Belongs to a good friend of mine. A quarter million kilometers, and suddenly only running on three cylinders:



(Note fancy schmancy Hazet magnetic bowl-for-stuff. My first and only Hazet tool. I wish I were filthy rich and could afford them all.)

"Luckily" we've been in there before, and it was the coil-on-plug. Which is a bit weird in design on this engine, as all four are integrated into one assembly, like so:



We had previously done the plugs just for good measure, but that didn't fix the problem, so on to the more expensive COP:



Which is situated deep in the valley between the OHCs, and is likely killed by the heat in that location. To further underscore the theory that this is a common failure, the replacement part had a production date of Feb. 2015...

Removal is easy: unplug the plug, and remove two T40 bolts. Then, a pretty nifty trick. inside the M6 bolt holes there's an unused M8 thread. Thread in two M8 bolts, and you have two convenient pulling handles to remove the COP, all nice and linear like:



The replacement COP was installed, car fired up on all cylinders, the CELs were cleared (much to the amazement of the owner. "You have a code reader too?!?") and he was sent on his way.

Next up, hopefully, new spark plugs on the horribly cramped and poorly designed BMW N43 engine. Also, I'm due for inspection soon.

bolind fucked around with this message at 20:48 on Mar 27, 2015

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randomidiot
May 12, 2006

by Fluffdaddy

(and can't post for 11 years!)

Is it just me, or do the Astra's coils look like butt plugs? :stare:

I didn't realize how little they changed the Astra before selling it as a Saturn in the US. It looks identical, aside from the badge. It was a huge flop here, and was only sold for 2 years. Wikipedia claims less than 20,000 were sold.

bolind
Jun 19, 2005



Pillbug
Spaced-three-inches-apart-and-capable-of-delivering-a-high-voltage-zap buttplugs? Well, why not, I ain't judging. :)

And holy, hell, wasn't aware that they brought over the Astra as a badge engineered Saturn.

Just learned that I might end up car-sitting my folks' 440000km '95 Volvo 850. Wagon. If I have the time I'll take it to my mate's shop and give it a once over, change the oil and such...

Simkin
May 18, 2007

"He says he's going to be number one!"
Yeah, they didn't even bother renaming it. I took one for a teat spin when new but my parents ended up with a mazda3 instead because domestics are scary...

Saga
Aug 17, 2009

Simkin posted:

Yeah, they didn't even bother renaming it. I took one for a teat spin when new but my parents ended up with a mazda3 instead because domestics are scary...

First butt plugs and now teat spinning.

This thread is not causing me to rethink Danish stereotypes.

randomidiot
May 12, 2006

by Fluffdaddy

(and can't post for 11 years!)

Simkin posted:

Yeah, they didn't even bother renaming it. I took one for a teat spin when new but my parents ended up with a mazda3 instead because domestics are scary...

Teat spin? :quagmire:

I looked at them before I settled on my Ion, but I would think parts would be difficult to find - I don't think they used that engine in any other USDM car, and it was only sold in the US for two years.

Left Ventricle
Feb 24, 2006

Right aorta
I seem to recall someone with a 1 Series a while back posting a thread about changing out the front seats, going from full manual to full power, and how much of a hassle it was. Was that you, bolind?

bolind
Jun 19, 2005



Pillbug

Saga posted:

First butt plugs and now teat spinning.

We managed to keep the thread wholesome for four whole posts.

Left Ventricle posted:

I seem to recall someone with a 1 Series a while back posting a thread about changing out the front seats, going from full manual to full power, and how much of a hassle it was. Was that you, bolind?

Yup, that was me, and nope, project still isn't fully finished. :suicide: Hence the first part of the thread title.

I've had one of those crappy weeks where you're super stressed yet gets nothing done, so tonight I'm going to do the plugs, and I've booked time for inspection tomorrow morning.

bolind
Jun 19, 2005



Pillbug
Spark plug time! Or Why Bavarian Engineers Should Be Forced To Maintain Their Own Designs.

The patient prepped for surgery. Completely sterile, not dusty at all. You'll notice the longitudinal engine sitting way back. Good for handling, bad for servicin'.



Step 1: Remove plastic covers "aft of the shock towers" as the Haynes manual so Britishly puts it.



Step 2: Remove plug on passenger side. I think it's an ambient air temp sensor bug I'm not sure:



Step 3: Remove plug for bonnet closedness sensor. By the way, little almost-one-way clips will hold the wire to the cowling thingamajig:



Step 4: Remove cabin air filter housing and cowling plastic thingamajig. Fun fact: one of the screws holding down the air filter housing is missing, and the car had only been dealer serviced before I got it. So much for four figure dealer visits. Before removing the CPT, unclip the holders for the A/C hoses that have to be right over the engine, and in the way of routine maintenance jobs:




Step 5: Remove the BMW///M plastic engine cover. This is constructed thus wisely that it is clamped between the oil filler cap and the engine, meaning that the oil cap has to be removes in order to remove the engine cover. Pray and hope you don't drop anything into the engine during this operation. (The way to go is to remove the oil filler cap, lift up the cover, and quickly replace the cap.):



Step 6: Now the ignition system is exposed:



But you'll need every millimeter of wiggle room you can get, so you need to remove the bolt for the factory chassis stiffness brace thingie. At least it gives you a chance to use and show off your E14 socket:



Step 6: Remove the coil-on-plug by flipping up the retainer for the plug, and then pulling it out:



Fun fact: it took BMW at least three tries to get these COPs right. There was a recall, and these are the latest version. The previous versions didn't have the nifty triple layered steel sleeve. At least it's per cylinder unlike on the Opel.

Step 7: Remove the spark plug:



Which is easier said than done, for the following reasons:

  • It requires a special socket, 10 or 12 point 14mm, I'm not sure.
  • The spark plug is at least 10cm down the hole for the COP.
  • It is loving angled slightly from the axis of the COP and accompanying hole!!!. This means that it's super easy to cross thread the plugs, and that my one BMW spark plug tool simply doesn't fit, and the other only barely fits, and only after some on site cement floor modifications. Christ. I'd love to see how the pros do this.
  • Accessibility sucks progressively as you work your way front to back.

Yes, this is a special socket, a 3/8" to 1/4" adapter, and a 1/4" extension. Further back I had to use two 1/4" extensions. Even with a 3/8" extension, I wasn't physically able to tilt the whole setup enough to get on-axis with the plug, and I think even now I could use another degree or two:




Oh, and a magnet-on-a-stick becomes really handy, because of the two special BMW spark plug tools, the one that is useless is the one that is fitted with a magnet:



Step 8: put in new spark plug, carrrrrefully threading it in, making sure not to cross thread it. Torque to spec (23Nm) and ignore the fact that your torques are way off since you have a foot of 1/4" extensions. Assembly is reverse of removal, yaddayadda, Haynes book o' lies, etc.

This concludes today's maintenance activity. A mandatory biennial inspection has been scheduled for tomorrow, so wish me luck. I have been sure to print out a copy of the German-language certificate saying that, yes, this car is allowed to run ultra-lean in idle, and the Inspector will either pass it, or find my speed wobble, so bonus either way. More on the speed wobble soon, by the way. I'll probably need you guys' help.

bolind fucked around with this message at 21:27 on Mar 27, 2015

InitialDave
Jun 14, 2007

I Want To Believe.
A short offcut of rubber hose is often really good for doing the initial locating and screwing in of awkward spark plugs.

bolind
Jun 19, 2005



Pillbug
Yeah, and I did that last time around, and it worked well, but the only hose I could be arsed to dig out this time had been rolled up since 2009 or something and was way too curvy for the concept to work. Instead I fed the new plug down the hole with the magnet-on-a-stick and spun that around aimlessly for a bit, and that actually worked.

bolind
Jun 19, 2005



Pillbug
Got a postcard! All the way from the U. S. of A., more specifically the proud, beautiful, zero sales tax, weird gas pumpin' laws, state of Oregon:





Thanks, blk! I actually never made it to Portland, but if I do, the Japanese Garden just made the list. By the way, did you ever pair up the headset? I made a little easter egg for you, so do that and post a screenshot... :)

In bimmer news, it passed inspection with flying colors. Good for another two years!

Alarbus
Mar 31, 2010

bolind posted:

Yeah, and I did that last time around, and it worked well, but the only hose I could be arsed to dig out this time had been rolled up since 2009 or something and was way too curvy for the concept to work. Instead I fed the new plug down the hole with the magnet-on-a-stick and spun that around aimlessly for a bit, and that actually worked.

When I did plugs on my first N52 engine, I bought the BMW plug installation tool from Turner motorsports here. It's a couple of bucks for exactly the right piece of tubing. I wonder how long it was used internally before someone slapped a number on it and sold it.

Raluek
Nov 3, 2006

WUT.
Sounds like you need to get you some wobble extensions.

CommieGIR
Aug 22, 2006

The blue glow is a feature, not a bug


Pillbug
gently caress that sparkplug hole :stare:

bolind
Jun 19, 2005



Pillbug

Alarbus posted:

When I did plugs on my first N52 engine, I bought the BMW plug installation tool from Turner motorsports here. It's a couple of bucks for exactly the right piece of tubing. I wonder how long it was used internally before someone slapped a number on it and sold it.

Ooooooh. I wonder if they ship abroad and whether their rates are $RAPE. Not so much the piece of hose, that could probably be DIY'ed, but they have a really nice cast oil filter housing adapter. The stamped one I have now sucks.

Raluek posted:

Sounds like you need to get you some wobble extensions.

Yeah, but the spark plug socket I have would actually still rub on the inner wall of the hole. I should probably even grind off some more. The one Turner has seems more thin walled still...

CommieGIR posted:

gently caress that sparkplug hole :stare:

Amen.

OK, Gentlemen, on to the next task at hand; the car has some sort of driveline vibration issue:
  • It's very pronounced at low speed (~10 km/h) where the whole chassis rocks from side to side, especially if you hit just the right speed.
  • It's reduced to a slight shimmy at higher speeds. It can be felt very lightly in the steering wheel.
  • It happens, curiously, across both winter and summer wheels. Now, I'm not one to rule out two faulty wheelsets, but still.
  • It doesn't seem to be flat spotting from sitting for a few days; it remains even after a drive long enough to heat up the compound.
My wheel sets consist of:

Summers: 8x18 in the rear, 7½x18 in the front (I might be off by ½", could be 8 and 8½) staggered setup, but running 225/40R18 all around. Very nice M-parallels, a bit curbed on one side though. New tires and balanced autumn '13, so one season on those.
Winters: crap noname 16" 195/55R16. Don't remember the width, but 7" sounds about right. The tires on these are running on their last season. I had them balanced before putting them on in the fall. Tire guy commented that one was slightly out of round and we put that on the back. Same size all around, but directional, for what it's worth.

Now, what I've tried:
  • I had the car on a lift and spun the wheel, while having a 6mm punch mounted in a magnetic dial gauge holder. I measured out both the outer and inner edge/rim of the wheel itself, and they looked dead straight to me.
  • I did the same thing for the tires, and they deviated about 5mm in out-of-round-ness, but, as my much more mechanically inclined buddy said: 1) they can be flat spotted from sitting and 2) they flex way more than that during driving.
  • While spinning the wheels I checked for brake drag. With all my might I could probably make the wheels spin 1-1½ revolution, which could be a little on the small side.
  • Borrowed a super nice Fluke IR thermometer and measured the temps of my brakes after my drive home from work. Difficult to get a consistent reading, and in any case, one side was never more than around 20C hotter than the other, and they weren't very hot to begin with (70-90C at the most.)
So, AI, what do I try next?

Edit: There's a guy who has a set of 16" original steelies with new crappy crappy runflats on for not much money. Looks like takeoffs to me, and he's local. I don't really have the space for another set of tires, but maybe they could be a cheap diagnostic tool?

bolind fucked around with this message at 10:33 on Mar 31, 2015

The Prong Song
Sep 7, 2002


WHITE
DRIVES
MATTER

bolind posted:

...OK, Gentlemen, on to the next task at hand; the car has some sort of driveline vibration issue:
...

Worn guibo/driveshaft loose?

bolind
Jun 19, 2005



Pillbug
Wouldn't rule out the guibo, to my knowledge it's the original (and I've been meaning to put in a new one anyway.)

Any tests I can do to determine whether that's it?

Bulk Vanderhuge
May 2, 2009

womp womp womp womp
http://www.rogueengineering.com/mm5/merchant.mvc?Screen=CTGY&Category_Code=GUIBO

Does it change when you accelerate/decelerate or is it constant?

bolind
Jun 19, 2005



Pillbug
Thanks for the link. I experimented a little on my way home from work today, and accellerating/coasting/engine braking/coasting in neutral doesn't really seem to make any difference.

Alarbus
Mar 31, 2010
Front control arms? I was just lucky enough to have to have mine replaced. My vibration was different than you described, it was minimal most times, except it was very pronounced when braking around 55mph.

I blame Philly roads, my '06 never had this issue up in Vermont, and had a lot more miles. This poor '09 is getting beat.

bolind
Jun 19, 2005



Pillbug
Could be, but a) I've inspected and yanked and pushed, pulled and prodded everything under the drat var without being able to find anything and b) it just passed inspection without the guy finding anything wrong with it, so...

blk
Dec 19, 2009
.

bolind posted:

Got a postcard! All the way from the U. S. of A., more specifically the proud, beautiful, zero sales tax, weird gas pumpin' laws, state of Oregon:





Thanks, blk! I actually never made it to Portland, but if I do, the Japanese Garden just made the list. By the way, did you ever pair up the headset? I made a little easter egg for you, so do that and post a screenshot... :)

In bimmer news, it passed inspection with flying colors. Good for another two years!

Haha, thanks bolind - I'm embarassed to admit that I couldn't figure out how to pair it, and the lack of an LED light after charging it made me assume it just wasn't holding a charge. I got so busy I forgot to revisit it - finally figured it out now :) The mechanism is pretty sweet now that I understand it, and sound quality is great - thanks again!

spog
Aug 7, 2004

It's your own bloody fault.
Thanks for the interesting post.

The difficulty of that plug swap is insane. It's like the designers had never swapped a set in their life.

Or that they assume they will last the lifetime (i.e. warranty period) of the engine.

bolind
Jun 19, 2005



Pillbug

blk posted:

Haha, thanks bolind - I'm embarassed to admit that I couldn't figure out how to pair it, and the lack of an LED light after charging it made me assume it just wasn't holding a charge. I got so busy I forgot to revisit it - finally figured it out now :) The mechanism is pretty sweet now that I understand it, and sound quality is great - thanks again!



Yeyyyyy! :dance: As you've probably deduced, I make the software for these little buggers. The light off is actually a feature; it turns off to preserve power. There's a pretty good manual available here.

Sorry for pestering you so much, but I didn't want my little easter egg to go to waste... :)

spog posted:

Thanks for the interesting post.

The difficulty of that plug swap is insane. It's like the designers had never swapped a set in their life.

Or that they assume they will last the lifetime (i.e. warranty period) of the engine.

It's actually not super difficult, it's just tedious and cumbersome. I guess that this is just the way things are when you want RWD in a four meter long four-seater. If it's combined with other service activities (cabin air filter, engine air filter) it helps a bit.

Now, we'll have to interrupt our scheduled beemer programming, as it has been abducted by my freeloading brother, and I have, instead, been equipped with this behemoth:



It ticks many AI boxes, seeing that it's not only from an exotic, nearly defunct European manufacturer, but also manual:



As well as AWD and diesel powered:



And with a dual tailgate:



But what I really wanted to show you is the bizarre, yet cool Danish concept of the "yellow plate car":



Best part, what used to be the rear seat footwell can now hold all sorts of junk while the rest of the car still looks tidy:



As you're probably aware, cars in Denmark are taxed to hell and back. For very small, very inexpensive cars, it's merely bad, but as soon as we're talking a full-size sedan with a load of options from a high-end brand, we're well into "ridiculous." However, businesses and business expenses are largely exempt from all this, so trucks, commercial vans etc. are taxed much lighter. What qualifies as a commercial van, you ask? Well, it used to be proper station wagons as well as, of course, Transits, Transporters etc. Now, people got a little too creative just yanking the rear seats out of normal cars that happened to be wagons and getting them for half price, so that tax bracket was upped, and the tax benefit only applied to (IIRC) vehicles with a weight above 2500 kg, hoping that it would thwart the home gamer while keeping actual van-buying businesses unaffected.

As is the case with much legislation, reality moved much faster than law makers, so this was instated right at the start of the SUV craze during the turn of the millenium. Que everyone and their cousin borrowing against their newly found hot air home equity and buying Tuaregs, X5s, Cayennes, MB MLs, Q7s and to a lesser extent XC90s and Range Rovers with no rear seats. Great idea, let's take the biggest, least economical vehicles on the road and then make sure that it's impossible (and also very illegal) to actually put more than two people inside them at any given time.

This has been curtailed lately, however, due to a mix of rising gas prices, change in vehicle taxation rates, so these cars are now available for pennies on the dollar, with a huge amount of deferred maintenance (new tires, for instance, can easily be USD300 per corner on these things.)

This particular example, which belongs to my folks, and is their second XC90, was no posermobile, though. My old man used to be a veterinarian, driving all over the backroads of rural Denmark tending to the farms, carrying a huge box in the back with all the required paraphernalia for that trade. It took up the entire cargo area, was made out of glass fiber by a caravan company, and cost the equivalent of USD 1500 25 years ago.

bolind
Jun 19, 2005



Pillbug
So, I'm back in the beemer and back to the vibration problems. I vice-gripped-and-zip-tied a camera mount together and recorded two videos of each of the rear wheels:

https://www.youtube.com/watch?v=BONlpsFWvi4

https://www.youtube.com/watch?v=d6biTCp-u-4

Speed was 10-20 km/h and I tried to hit where the vibration is most evident.

I personally can't see much from the videos, but maybe someone else can?

Edit: Hmm, maybe the bead area on the RR shows a little runout?

bolind fucked around with this message at 20:01 on Apr 9, 2015

Boaz MacPhereson
Jul 11, 2006

Day 12045 Ht10hands 180lbs
No Name
No lumps No Bumps Full life Clean
Two good eyes No Busted Limbs
Piss OK Genitals intact
Multiple scars Heals fast
O NEGATIVE HI OCTANE
UNIVERSAL DONOR
Lone Road Warrior Rundown
on the Powder Lakes V8
No guzzoline No supplies
ISOLATE PSYCHOTIC
Keep muzzled...
That Volvo is basically a pickup with a camper shell. That kicks rear end!

CommieGIR
Aug 22, 2006

The blue glow is a feature, not a bug


Pillbug
I'd kill for a diesel Volvo like that.

bolind
Jun 19, 2005



Pillbug

Boaz MacPhereson posted:

That Volvo is basically a pickup with a camper shell. That kicks rear end!

You could say that. I'm actually (at 6'1") able to lie down in the back. Taking it on a camping trip is definitely on the bucket list.

The configuration comes in all sorts of cars, and in a medium to small station wagon it's actually a really cool combo, sort of like a ute, only with enclosed space. the mid-00s Forester XTs could be had this way, and I've seen an Impreza wagon too. My old man used to have a Volvo 850 wagon with only front seats as well (preceded by two 240 wagons and succeeded by two XC90 wagons. Yeah.) The 1-series is very popular in this configuration too, and 3 and 5 series wagons aren't uncommon either.

CommieGIR posted:

I'd kill for a diesel Volvo like that.

Just checked, and apparently diesel Volvos that aren't semitrucks don't really exist in the US.

But back to the vibrations. What should I do? Record the front wheels as well?

bolind fucked around with this message at 12:09 on Apr 14, 2015

KozmoNaut
Apr 23, 2008

Happiness is a warm
Turbo Plasma Rifle


bolind posted:

The configuration comes in all sorts of cars, and in a medium to small station wagon it's actually a really cool combo, sort of like a ute, only with enclosed space. the mid-00s Forester XTs could be had this way, and I've seen an Impreza wagon too.

I know a guy who has an Impreza WRX as a yellow plate car. Haulin' rear end and carrying poo poo in the back.

bolind
Jun 19, 2005



Pillbug
I think we're talking about the same Impreza (and the same guy) actually. Has a tire shop, races Porsches, runs an online karting shop?

KozmoNaut
Apr 23, 2008

Happiness is a warm
Turbo Plasma Rifle


bolind posted:

I think we're talking about the same Impreza (and the same guy) actually. Has a tire shop, races Porsches, runs an online karting shop?

Indeed we are, I keep forgetting that you know him too :)

He's been out of the game for a little bit due to an injury sustained while rock crawling in Hawaii (totally not jealous), but you can tell he's just itching to get out there again. Last time I saw him he was driving a VW van that he'd bought because he didn't want to take the train home from Aarhus :v:

bolind
Jun 19, 2005



Pillbug
Ha! I hadn't heard the latest updates but I am in no way surprised!

By the way, while I have you. You used to ride motorcycles in our beautiful country; is lane splitting legal here? I see it more and more, and I don't really know what to think about it.

Anyway, not much to report. I saw a Toyota GT-86 not once but twice. They're super rare over here, but it might actually have been the same car. Also an M550d. I want.

Oh, and this thing:



Then I did the biannual swith-the-summers-and-winters-around for first a 5kkm Polo GT-something-or-the-other and then a 15kkm Skoda Fabia Kombi. Working on the new cars is weird. They're so clean. Peak weirdness was achieved with my co-workers brand spanking new Citroen C3 he showed off yesterday. Plasticy as hell on the inside though.

On the vibration front, I tried to swap tires front-to-rear on the driver's side, using this fully approved jacking technique. No change.



My mate and I tried to alternately drive the car and look, and we couldn't tell where the rocking originated. Actually, it wasn't noticeable from the outside, and my mate couldn't even feel it while driving... maybe it's all in my head? :tinfoil:

Considering finding a way to determine whether the vibrations seem to match rotational speed pre or post diff. I'm thinking to do the guibo regardless... but I'll basically have no time this side of mid-May, so...

KozmoNaut
Apr 23, 2008

Happiness is a warm
Turbo Plasma Rifle


bolind posted:

By the way, while I have you. You used to ride motorcycles in our beautiful country; is lane splitting legal here? I see it more and more, and I don't really know what to think about it.
I would still be riding if my bike hadn't been stolen :argh:

As for whether lane splitting is legal, the definitive answer is yes and no and yes and not really, but maybe?

The law is not at all clear on the subject. On a first glance, you're not allowed to overtake on the right, so that would seem to put the kibosh on splitting. But in bumper-to-bumper traffic, you're allowed to pass people on the right, which is different from overtaking. You're also allowed to pass/overtake another vehicle in your lane if there is enough room for both vehicles to drive side by side within the lane markings, but you can still only overtake on the left side.

So as far as I see it, in slow bumper-to-bumper or completely stopped traffic, it's probably OK to split lanes slowly, but it's not strictly legal. There just isn't any applicable laws that disallow it definitively. You should stay on the right side of the lane markings, just to be in accordance with the "passing in the same lane" law, and be prepared to have to explain yourself to a very irate police officer, as some of them do consider lane splitting illegal, or at least very irresponsible.

I've seen plenty of lane splitting (and filtering to the front at lights), especially in rush hour traffic, but I don't do it myself. People don't expect you to do it, and I prefer not to upset the tiny fragile mind of the average Danish motorist. Plus, I've seen shithead pull out right in front of bikes to block them, just like the jerkbags who straddle the line coming up to merges to prevent others from "cheating".

bolind posted:

Then I did the biannual swith-the-summers-and-winters-around for first a 5kkm Polo GT-something-or-the-other and then a 15kkm Skoda Fabia Kombi. Working on the new cars is weird. They're so clean. Peak weirdness was achieved with my co-workers brand spanking new Citroen C3 he showed off yesterday. Plasticy as hell on the inside though.

The plastic-ness of newer French car interiors saddens me a lot.

My 2000 Peugeot 406 has very nice soft-touch materials everywhere, the really thick well-cushioned stuff, and it still looks (and feels) like new. Not even the slightest UV damage on top of the dash.

It probably outgassed a hell of a lot of very toxic chemicals for the first couple of years, but that's just the tradeoff you have to make for comfort and a quiet cabin :france:

bolind
Jun 19, 2005



Pillbug

KozmoNaut posted:

I would still be riding if my bike hadn't been stolen :argh:

Aw man, that sucks...

KozmoNaut posted:

Lane splitting infodump.

Thanks, that was very informative. It kinda makes sense in a roundabout weird way.

So I had an epiphany driving to work the other day, and it turns out a number of vibration loggers form smartphones and tablets exist. I ended up on Vibration. Today, a nice quiet Sunday morning, I went for a drive on the freeway at 100 km/h, as indicated by the GPS, put on cruise control, and vibrated my iPad with my car. Here's the resulting frequency plot (FFTed):



Same plot, but with a cursor at the peak, and double that (for 2nd harmonic):



The app will convert to RPM for you, so right at 875 RPM there's definitely something. Let's do some math:

The circumference of my winters, at 195/55R16 is right around 2 meters, so 0.5 revolution per meter.

100 km/h is roughly 27.8 m/s, or 1666 meter/minute.

1666 meter/minute * 0.5 revs/meter = 833 RPM.

Actually the circumference of the wheels is off by a bit, but I'll call that a match.

According to bmwfans.info my car is equipped with a 1:3.38 diff. This means at a 100 km/h the drive shaft spins 3.38 times faster than the tires, or around 2800 RPM. I'm not sure if the peak around 2700 could be that:



Thoughts?

bolind fucked around with this message at 14:09 on Apr 26, 2015

Fuelslt1
Jun 23, 2007
Maybe if I sell enough undercoating, I'll eventually stop being a gigantic prick.
I'd assume any vibration from the drive shaft would be speed dependent and you would notice it variably.

10 km/h (no vibration) 50 km/h (slight vibration) 100 km/h (heavy vibration) 150 km/h (your teeth have rattled out)

bolind
Jun 19, 2005



Pillbug
But the same would be the case for the wheels or axles, right?

IOwnCalculus
Apr 2, 2003





bolind posted:

But the same would be the case for the wheels or axles, right?

I've had tire vibrations that would actually improve over a certain speed, but be really awful around 60MPH.

bolind
Jun 19, 2005



Pillbug
So I finally changed back to the summers, and they only vibrate a tiny small amount...? :confused: The jury is still kinda out, though, I'll have to do my 10 km/h-in-traffic-on-the-smooth-as-glass-freeway to see what's what.

In related news, I got to drive a Porsche! 2001 Carrera, probably the second fastest thing I've ever driven, after a Tesla S. Very awesome, although the running costs is a huge nope. Each rear tire, for instance, is roughly a grand USD and last for a season.

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bolind
Jun 19, 2005



Pillbug
Did a major road trip in the beamer over the long weekend, and it did the stunt it's done a handful of times before. Basically the steps-to-reproduce is to drive for a couple of hours on the highway, turn off car, turn on again shortly thereafter, and the power steering yellow steering wheel light of death comes on, leaving the car with no power steering (and holy gently caress is that a PITA and probably in no way good for the steering rack.)

Luckily it happened on the street in front of the condo (had to take a bike off the roof carrier before going into the parking garage) so I wrestled it down there, and it was fine again this morning.

It's not an uncommon problem, and fixing it requires a new steering column + coding, which is $$$. It's a very rare occurrence, but it's a bit of a major thing when it happens, so I'm a bit on the fence about addressing the issue.

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