Scary erratic handling, esp at high speeds... RTABs?

[TC535i]

So I finally got around to installing my coilovers and getting the car to the alignment shop. 95 M3, Ground Controls with short Konis (550/650 springs), Eibach sways, GC adjustable links.

I put the car up on jackstands that morning and put the swaybar in, lower, and drive to the alignment shop. It's wandering and driving shitty, but I need an alignment, so... I wasn't surprised.

Get the alignment. -3 up front, -2.5 out back. Front 1/8 total toe in, rear 1/4 total toe in. Dunno about caster, prolly around 7 deg up front.

Drive the car home, and altho it would turn normally at first, with any more than maybe 5-10 degrees of steering input, it would suddenly REALLY want to grab and turn in the direction you're turning it... if you were to try to change 1 lane, it would jump over 3 lanes in the same amount of time... and all of a sudden. SCARY. Fine at first, then past a point... BAM. Nowhere near linear steering response.

I get under the car, and since I set the adjustable links with the car on jackstands, when the suspension loaded it swung the sway bar back so it was basically resting on the steering rack.

Drive the car up on ramps, and adjust the links to the longest I was comfortable setting them at (~5 threads holding either end in), and now I have maybe an inch clearance off the rack?

Drive the car off the ramps and test drive... MUCH better, the car's pretty driveable. Start driving it some more tho, and notice the same thing, not as drastic as before. Also, while it might be turning mildly... give it a bit of gas, and it would do the same thing. Feel like it wants to suddenly shoot off to the side. Also notice the car wants to bounce/waver back and forth, left to right, like a rocking ship.

Later down the road, the freeway is turning right, I'm doing probably 70. We start to crest a hill during the turn, and there's a large bump across the road. Well, after the car hit that bump, instead of turning right still, it tried to shoot to the left, almost nailed the car in the next lane!!

I dunno what's up here. I'm thinking possibly bad RTABs, which would explain the waver/wander and maybe why there's some change under throttle (load up the rear?) It just feels like the car suddenly wants to snap around, dunno if the rear's trying to step out or the front's just biting in hard... either way, it's really scary getting far more turn than you expected. Not linear at all.

Any ideas guys? Is my sway bar still loading up? The car is pretty low, front is right around the top of a 235/45-17 tire, rear maybe 3/4" of the sidewall is tucked? Not sure if I need longer links, I'm getting pretty close to the control arm if I push it down much further... or is this a dead bushing issue? I think front control arm bushings are stock, I dropped the RTAB carrier before the alignment and peeked in there, and it as the bushing that comes out past where it presses in (to simulate the effect of the aftermarket shims, I guess?), I heard these are the newer style bushings, so I assume they were changed at some point... unsure on mileage.

I'm going to grease/shoe polish/whatever the bar and see if it's rubbing off on the steering rack. BTW, this turn-in symptom is also present at lower speeds, especially with throttle input... just nowhere near as nerve-wracking as highway shenanigans! :eek

Anyway... let me know what you guys think. Thanks!

[tEckniks]

jeebus, sounds like a scary ride.

[TC535i]

jeebus, sounds like a scary ride.

It's okay going straight... but turning gets freaky. I had to drive from San Diego to Los Angeles like that... ugh. Thank god I have the 540i/6 for daily duty, I need to figure wtf is up with this thing. Scary stuff.

[///w3fl3x]

Worn/bad rtabs will make your car pull to the side under hard acceleration.

Maybe your allignment is still off since the sway bar got readjusted?

[TC535i]

Worn/bad rtabs will make your car pull to the side under hard acceleration.

Maybe your allignment is still off since the sway bar got readjusted?

Sway bar doesn't affect alignment as far as I understand, it just needs to be unhooked for corner balance since changing height on one side will preload the bar. :dunno

Pulling to the side could be ONE bad rtab, but if they're both shot, could signifigant toe change under load while turning make the car want to swap ends?

[Nadroj]

way worse that bad RTABS. i would take my car back to the place i got alined at...

[TC535i]

way worse that bad RTABS. i would take my car back to the place i got alined at...

Would love to, but it's 100 miles away and I'm not gonna be back down there for 2 weeks. I'm thinking it might still be bar, altho I can't see my ride height changing ALL that much with 550 lb springs... but, shoe polish should answer that question.

It really does feel like the same issue as before (sway bar almost touching rack), just with more room to play in the middle before it gets crazy. Before, it would try to jump with almost no steering input, now you have a little room to move it before it jumps.

[Kaiv]

Yep, sounds like your RTABS for me. That how REALLY toast RTABS behave.

One day I just took my car out in the twisties and quickly slowed down after a bit of scare.

Basically say over a bump in a turn I'd have like the whole rear end shift further to the side. I would not change my steering wheel's angle and the car would just turn more/less all of the sudden.
I could redo it when smashing the gas in the middle of a turn.

I knew it was not the subframe, having a non-M without reinforcement I always keep an eye on it. It was the stock RTABS. The center metal 'barrel' of the RTAB was completely torn off the rubber.

Problem solved with some UUCs.

[Kaiv]

http://relaxkev.free.fr/E36_DIY/rtabs/CIMG1437.JPG

See the center piece ? I could slide it right off :eyecrazy

I know what you mean about scary handling/not linear steering input. Your's probably gonna slide right off too.

See my thread for a simple way to remove the stock bushing :
http://forums.bimmerforums.com/forum/showthread.php?t=799623&highlight=UUC+RTAB

[TC535i]

Yep, sounds like your RTABS for me. That how REALLY toast RTABS behave.

One day I just took my car out in the twisties and quickly slowed down after a bit of scare.

Basically say over a bump in a turn I'd have like the whole rear end shift further to the side. I would not change my steering wheel's angle and the car would just turn more/less all of the sudden.
I could redo it when smashing the gas in the middle of a turn.

I knew it was not the subframe, having a non-M without reinforcement I always keep an eye on it. It was the stock RTABS. The center metal 'barrel' of the RTAB was completely torn off the rubber.

Problem solved with some UUCs.

That was my suspicion, especially because of the way I can produce it under throttle, and the incident with the bump... seems like extreme erratic/random rear toe change, which is why I was thinking RTAB. Guess I know my "christmas break" project...

[Kaiv]

Oh and by the way if you want to just check before taking stuff appart, look for rubbing marks on either side of the rtab console.

I don't think the stock bushing should ever touch the sides. If there is marks=bushing is toast=whole trailing arm can move left or right= scary handling.

[TC535i]

btw, on your RTAB job, could you get it out just by dropping the carrier bracket, or did you have to unbolt back at the arm? I was trying to just pull it down, and I couldn't get enough clearance to get a socket/wrench in there to remove the center bolt. :dunno

[Kaiv]

Tried pushing down with your foot ?
I undid the rear shock not sure if that really helped lol but that and the carrier with the 3 big nuts is all I undid. Don't forget to undo the bracket that holds the brake line to the trailing arm (two 10mm screws) so you don't pull on it.

[The Letter M]

Wouldn't you have noticed a problem before the install of the coilovers?

Refreshing RTABS is a good idea anyway if you've never done it, but if the car felt good before the install, it might not be only the RTABS.

[bennyfizzle]

Uh, thats a shitload of toe in as well, something that could also cause exactly what youre talkign about


my alignment is 0* toe front, and 1/8" in in the rear...

[TC535i]

Uh, thats a shitload of toe in as well, something that could also cause exactly what youre talkign about


my alignment is 0* toe front, and 1/8" in in the rear...
:rofl And why would it cause that? Toe IN makes the car drive more neutrally, because the wheels are trying to drive "together", centering the car. Toe OUT is pointing outward, making the car want to go left and right. Your "0 toe" up front actually turns into positive toe once your car starts rolling and compressing the LCAB, so I'd say your alignment is far more likely to "wander" than mine.

And "a shitload"? I have 1/8" more front and rear... that's not THAT much, man. Autocrossers run 1/4 inch on EACH SIDE in the rear, it really helps put power down on exit.

And I didn't notice it before coilovers because I just bought the car and it had shit suspension in general, so I couldn't tell what was causing what.

[nick325xit 5spd]

Preload will screw your alignment. Align with no bars.

[bennyfizzle]

:rofl And why would it cause that? Toe IN makes the car drive more neutrally, because the wheels are trying to drive "together", centering the car. Toe OUT is pointing outward, making the car want to go left and right. Your "0 toe" up front actually turns into positive toe once your car starts rolling and compressing the LCAB, so I'd say your alignment is far more likely to "wander" than mine.

And "a shitload"? I have 1/8" more front and rear... that's not THAT much, man. Autocrossers run 1/4 inch on EACH SIDE in the rear, it really helps put power down on exit.

And I didn't notice it before coilovers because I just bought the car and it had shit suspension in general, so I couldn't tell what was causing what.

haha my bad, i done gots my learning fer todai :banghead:

[savage217]

I didnt read everybody's responses but in response to the possibility of worn rtab's, do you ever hear the rear tires rubbing on the rear wheel well? Thats another sure sign of bad rtab's. You can also jack up the rear take a crow bar and check for play in the rtab.

[91M5]

Given the fact you just put in some high rate springs and it will increase suspension loads dramatically, you should just replace ALL suspension bushings so you know it is all fresh instead of chasing them down one by one.

[TC535i]

Given the fact you just put in some high rate springs and it will increase suspension loads dramatically, you should just replace ALL suspension bushings so you know it is all fresh instead of chasing them down one by one.

You're right, instead of isolating/identifying the problem, I should just change EVERYTHING in hopes that it'll fix it... Let me go throw tons of time and money at the car now. Thanks for all your help! :rolleyes

[91M5]

Bushings are not that expensive and a wear item on the M3. So, relative to taking it apart several times, it would actually be a more efficient way of dealing with it. I would assume after dropping $1500 on all new suspension parts you wouldn't want crappy handling because of a $90 bushing.

[TC535i]

Bushings are not that expensive and a wear item on the M3. So, relative to taking it apart several times, it would actually be a more efficient way of dealing with it. I would assume after dropping $1500 on all new suspension parts you wouldn't want crappy handling because of a $90 bushing.
Actually I had the suspension from my last car. Changing all the bushings can be quite expensive (tie rod, lower control arm, RTAB, camber arm bushings, subframe bushings, etc), paying a shop to press old ones out, working on the car or paying someone to do it...

And if the sway bar is the culprit, all that money was wasted. Sounds like a wonderful plan of attack.

I'm gonna try to determine the cause of the handling problem, if you want to change everything arbitrarily in your own car go right ahead.

[Jrdeamicis]

Mine does that, but I need an alignment.

[91M5]

Wow, sorry I posted at all. If you don't like the advice, just ignore the post.

At the risk of a further rude response, just disconnect the swaybar and drive it and see if the problem persists. Oh by the way, a car with 3 degrees camber will tramline and pull quite a bit more than stock once there is any steering input--that is the whole point. My '95 had the original RTAB's when I bought it, despite being tracked by the two previous (idiotic) owners. It was a bit numb and wandered but nothing like you describe and my mechanic told me they were shot. On an M3 if you do the control arms, RTAB's and any ball joints that need it in the rear you should be fine.

Don't forget these are you words:


And I didn't notice it before coilovers because I just bought the car and it had shit suspension in general, so I couldn't tell what was causing what.

If the suspension has a ton of mileage on it I stand by my original advice.

[TC535i]

Wow, sorry I posted at all. If you don't like the advice, just ignore the post.

At the risk of a further rude response, just disconnect the swaybar and drive it and see if the problem persists.

Given this statement:



I stand by my original advice.

:rofl

It had stock sways with worn out links, Monroe shocks, ride height was all wrong (rear had more tire gap than the front? :wtf). I knew that was all wrong, so I installed known good parts and got it aligned. The soft suspension was obviously covering up another problem that didn't present itself till everything else was stiffened up.

It's pretty ridiculous to change all the bushings because of a single issue, but if that's really your approach to working on cars, be my guest. As it stands, I have a specific issue I'm trying to determine the cause of, and "change everything" is neither practical nor helpful. I'm not going to change every bushing in the car just because I'm installing coilovers.

I'm going to unbolt the sway bar, I just got this done over the weekend and drove back to LA at 10 last night, work at 8am this morning... haven't had a lot of time.

[stupenal]

I think the point is - the suspension bushings are well known parts that fail around 75k-100k miles. If your m3 has more mileage (I think you said yours has 150k? just a shot in the dark...), and you have no documented replacement within said mileage, it doesn't hurt to replace everything since you're doing the suspension anyways...

Checking the bushings doesnt take much time either, and if you replaced everything before the alignment, you don't have to get another alignment.

[TC535i]

I think the point is - the suspension bushings are well known parts that fail around 75k-100k miles. If your m3 has more mileage (I think you said yours has 150k? just a shot in the dark...), and you have no documented replacement within said mileage, it doesn't hurt to replace everything since you're doing the suspension anyways...

Checking the bushings doesnt take much time either, and if you replaced everything before the alignment, you don't have to get another alignment.

If the RTABs are shot, then they're allowing the bushing to collapse to an out-of-spec position, which it gets aligned at. Pop fresh ones in, and it puts everything back to where it's supposed to be... which changes your toe in the rear.

Same thing up front, and ESPECIALLY if you change LCABs with Treehouse bushings, add almost an inch of toe out up front IIRC!

[99BlkM3]

also check your power steering cables, mine was pulling to the right thought it was just the alignment and i took it in and got the alignment fixed and the shop found that the power steering cables were leaking so those were replaced and it drives perfectly now

[TC535i]

also check your power steering cables, mine was pulling to the right thought it was just the alignment and i took it in and got the alignment fixed and the shop found that the power steering cables were leaking so those were replaced and it drives perfectly now

Actually just replaced the rack and tie rods a couple weeks ago. This thing is starting to add up, but that's how it always is with a "new-to-you" car till you get 'em "right"... factored into the price.

[bmw_e30]

You get what you pay for.........

[TC535i]

You get what you pay for.........

and you get what you pay way too much for. ;)

[AxisPower]

How does it feel when you brake suddenly? If you haven't tried it, do a burst up to 60 and slam down to 10. See if you get the same response. If you just put GC in, I would wager that your suspension isn't at fault. I would maybe double check all the bolts though. Replacing bushings is a good place to start, both the LCABs and RTABs could be changed.

[TC535i]

How does it feel when you brake suddenly? If you haven't tried it, do a burst up to 60 and slam down to 10. See if you get the same response. If you just put GC in, I would wager that your suspension isn't at fault. I would maybe double check all the bolts though. Replacing bushings is a good place to start, both the LCABs and RTABs should be changed.

I'm sure that would show that loading the front doesn't affect this nearly as much as loading the rear... but with the way this thing's handling, unless I can find a deserted skidpad/runway, no way I'm gonna risk that. :rofl

I'll just swap out the rtab's next time I get a chance to work on the car.

[zmmnm3]

My son has a 99 m3 with the Ground Control coil overs and sway barbarian. He has his set just at little more over camber by reversing the shock mounting plates on the front for an additional degree or so and -2 on the rear to clear the tires. No issues. I would suspect the RTABS and the diff mounting bushings. These get stressed differently in a lowered car and can cause some quirky handling.