View Full Version : does your rear end wander at highway speeds?
bmdubbayoo
08-04-2009, 10:40 AM
I'm just posting this up in case some of you are trying to troubleshoot this issue. At speeds under 55mph my car drives great, but when I would get up to highway speeds of 70mph or higher, it felt like my rear end was loose and would wander left and right depending on the grooves or imperfections of the road. This also caused a lot of clunking over bumps. This could be due to many other things, but in my case, it was my right rear control arm. It was straight and looked fine to the naked eye, but after closer inspection, I noticed that the lower tab that holds the washer and bolt in place had clearly sheared off. I'm not sure what caused this. I'm thinking that my suspension coupled with all the track time has put a lot of stress on these tabs. The driver side looks perfect. I'm sure i'll be knocking that out soon.
Notice the tab missing in the picture below.
http://i102.photobucket.com/albums/m107/bmdubbayoo/exhaust003.jpg
Here's what it is supposed to look like.
http://i102.photobucket.com/albums/m107/bmdubbayoo/exhaust004.jpg
I replaced my passenger rear control arm last night and it took me about an hour and a half. I completely removed my swaybar so I can access and remove the top mounting dif bolts. Then I removed my upper control arm bolt by jacking up the dif enough to wiggle out the bolt. Other than that, the job was fairly simple. Just something to check out if you are having the same symptoms.
Theodore
08-04-2009, 10:55 AM
Sounds like dead RTAB's as well...
bmdubbayoo
08-04-2009, 11:29 AM
it could have been, but not in my case as i just replaced them a few months back with oem rtabs and rogue engineering shims...
EastBayBimmer
08-04-2009, 12:23 PM
Wow. If you haven't already, make sure you replace the upper ball joint and upgrade the lower bushing to a ball joint.
WOW thats insane!
love how these cars are complete POS.
Brent 930
08-04-2009, 02:11 PM
Seriously the OE lower controls suck pretty bad. Do yourself a favor and upgrade to at least SPC.
Balthazarr
08-04-2009, 02:16 PM
WOW thats insane!
love how these cars are complete POS.
How's come you own one, if that's the case?:D
Seriously the OE lower controls suck pretty bad. Do yourself a favor and upgrade to at least SPC.
no way man...
if your going to do something do it right the first time.
Go UUC or grouncontrol the FIRST time.
Balthazarr
08-04-2009, 02:20 PM
Seriously the OE lower controls suck pretty bad. Do yourself a favor and upgrade to at least SPC.
They are designed to be a failure point to minimize damage to the car in other areas such as ripping the chassis apart at the RTA mounting or damage to the diff and halfshafts.
bmdubbayoo
08-04-2009, 02:31 PM
They are designed to be a failure point to minimize damage to the car in other areas such as ripping the chassis apart at the RTA mounting or damage to the diff and halfshafts.
this is exactly why i went oem...i don't have castor/camber issues with my setup...so i don't mind replacing these since its easy and cheap...
Brent 930
08-04-2009, 02:37 PM
They are designed to be a failure point to minimize damage to the car in other areas such as ripping the chassis apart at the RTA mounting or damage to the diff and halfshafts.
Urban legend my friend, you will sustain x amount of damage regardless of what arms you have. Only difference is what damage you will get based on what controls you do have.
You might as well get a Police battering ram on the front of your car to minimize front end damage.
My SPC's saved my custom diff, while the OE arms would have allowed the axles to push on the diff way more and probably would have broken it. I think either way the pocket could tear. You aren't suppose to get into a wreck in the first place.
Balthazarr
08-04-2009, 02:42 PM
Urban legend my friend, you will sustain x amount of damage regardless of what arms you have. Only difference is what damage you will get based on what controls you do have.
You might as well get a Police battering ram on the front of your car to minimize front end damage.
My SPC's saved my custom diff, while the OE arms would have allowed the axles to push on the diff way more and probably would have broken it. I think either way the pocket could tear.
Well, if you're launching the damn thing into a curb, I'd say there'll be damage elsewhere, but for something like a little fishtail into one, the LCA will give first, reducing the impact in more expensive areas.
You aren't suppose to get into a wreck in the first place.
And you shouldn't piss into the wind, but it happens.
Hey OP:
Mine tram-lines at hwy speeds too. Maybe I've got the same problem. Techs that have inspected the undercarriage have always said it was all good, but things like this are easy to miss.
Well, if you're launching the damn thing into a curb, I'd say there'll be damage elsewhere, but for something like a little fishtail into one, the LCA will give first, reducing the impact in more expensive areas.
And you shouldn't piss into the wind, but it happens.
I think some may have misunderstood the comment by Balthazarr. He's right on about the designed failure. You'd figure that most auto manufacturers (and especially our beloved Bavarian one) would build in failure mechanisms that firstly avoid catastrophe failure as well as more costly failure.
It's like why it's better to build core strength and joint stabilizing strength ahead of "machine assisted" brute muscle strength first (uh oh... I'm gonna get all sorts of heat from strength trainers now... :devillook)
Brent 930
08-04-2009, 04:18 PM
^The falacy in your statements is that the OE lower controls will fail without getting into an accident. Just ask the guy who made this thread.
Therefor they're junk IMO.
Balthazarr
08-04-2009, 04:24 PM
^The falacy in your statements is that the OE lower controls will fail without getting into an accident. Just ask the guy who made this thread.
Therefor they're junk IMO.
Wanna try that one again?
^The falacy in your statements is that the OE lower controls will fail without getting into an accident. Just ask the guy who made this thread.
Therefor they're junk IMO.
:confused
Fallacy? Has to be a single incident overload? Accident?
Tony Soprano
08-04-2009, 05:33 PM
hmm, ive got to go look at mine now.
Brent 930
08-04-2009, 05:43 PM
Wanna try that one again?
No need to.
Balthazarr
08-04-2009, 05:51 PM
No need to.
Look at what you wrote...it makes no sense.
I know what you were trying to say, but you didn't.
Brent 930
08-04-2009, 05:59 PM
^OK, I don't agree that BMW designed the lower controls to fail like they do.
Balthazarr
08-04-2009, 06:06 PM
^OK, I don't agree that BMW designed the lower controls to fail like they do.
Ta-da...
Do you agree that there are crumple zones on the car?
Were they designed that way?
Brent 930
08-04-2009, 06:14 PM
Apparently so.
I suppose they were designed that way, but they went too far.
If anyone hasn't looked under their car yet they should. I bet at least 1 out of 10 people would find at least one bent control arm.
Balthazarr
08-04-2009, 06:17 PM
Yes and yes for intentioned design and no and your guesstimate is a fair one.
I've looked at mine and they aren't bent.
I will have to check to see if those nubs are intact, though.
Also, fair warning to anyone who needs to have these cars flatbedded, watch the hookup and make sure those arms aren't compromised.
evandro
01-23-2010, 06:56 PM
Has anyone bent a rear trailing arm yet, and found that to be the cause of instabilities at highway speeds?
m3cliff
01-23-2010, 10:27 PM
Bent suspension parts cause alignment issues which causes the driving or wear problems. They can be bent and weakened, not structurally sound but hard to diagnose if one isn't experienced.
Also very good point about watching how your car is towed, or tied down when flatbedded. I know some truck drivers that only use straps, not chains, to secure cars, as long as the parking brake is functional or auto trans car. This isn't a good idea if the driver isn't careful and and or inexperienced.
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