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So, last weekend I replaced front and rear accumulators and flushed the ABC system. I was getting white ABC error messages after big bumps.
The whole process seemed to go well. No issues. No leaks afterward. Ran rodeo for about 10 minutes.
The first drive around on surface streets went perfect.
Then I got on an expressway. At 60 mph, I start to hear a sound sort of like "playing card in bicycle spokes". Very lightly. But, as speed increases, so does the intensity. 65 mph is completely out of the question. It is sounding violent before then.
It sounds to me like it is coming from the driver rear side. So, maybe I did not get a hydraulic line secured and it is banging on something? I'll pull the wheel well and inspect tonight.
Today, I got brave and pushed the speed a little higher. The driver side rear sound is intense, but then it also starts, separately, at the passenger side rear. I know I didn't mess with the hydraulic line on that side (other than to open the bleeder).
Anyhow, let me know if you can think of anything I should check out.
Last night I raised the rear, pulled both rear wheels and tried to spin it up to speed. Unfortunately the traction control won't let me, even when I have it switched off. The rear brakes apply at about 1500 RPM (speedo does not register with the rear end off the ground...?)
At idle speed in drive, I see nothing out of the ordinary. Half shaft boots are intact. Nothing unusual with the prop shaft.
Thanks for listening. All input welcome.
Last edited by tydriver; Aug 23, 2019 at 02:17 PM.
Did you remove any of the fender linings during your ABC service? I am pretty sure you had to in order to replace the accumulators.
Is everything properly secured and fitted?
As the speed increases, wind increases and one of the fender liner corners may be moving/bending and touching the tire or wheel. My guess is, there is something loose in the fender area that is moving and touching with the wind speed increasing.
I'll double check. I also forgot to raise the ride height during my drive today. When I checked it last nite the suspension was at full droop. Maybe the car is lowering at 60 MPH, initiating whatever interference is happening.
That is exactly what supposed to happen. (Look up your manual)
Anyway, I notice my car was missing few of the plastic nuts holding the underbody panels. After replacing them all the whistles are gone.
Thanks. I'm aware it lowers at some speed, but the manual does not say what speed, and over what speed range (i.e. what speed does it start lowering, and what speed does it stop lowering). Also, it does not say if the lowering is affected by the ride height selected (does it lower to the same height regardless of which setting is selected?)
I tried a road test with the ride height set to the highest setting, and there was no difference in the onset speed or severity of the noise.
Knowing the answers would be helpful in determining if the automatic lowering is why the noise is completely absent below 60 mph, and goes from mild to REALLY, REALLY LOUD ;0 in the space of 3 MPH above 60.
Or, I can get it back in the air and use SDS to command the suspension to lower and check for interference somewhere. I guess that will be the plan, tomorrow evening.
Vehicle speed is taken from the left-front wheel, so the speedometer should read 0 MPH in this case.
Automatic lowering is dependent upon which ride height has been manually selected and whether or not ABC's "Sport" mode is active.
If you have ABC set for "comfort" and ride height is normal, then at a speed of 62 MPH the suspension will automatically lower 15 mm.
Good info, thanks. If it lowers the whole distance in one fell swoop, then it does not support my theory. If it lowers over a range of speed, as Rudeney posted, then the theory is not yet blown. The manual just says:
"With increasing speed, ride height is reduced
by up to approximately 0.5 inch
(12 mm).
With decreasing speed, the ride height
is again raised to the selected vehicle
level."
If it lowers over a range of speed, as Rudeney posted...
Yes, that is how it works. My post implies that it abruptly drops 15 mm, but that is not the case.
To elaborate upon and correct my earlier post, if you are not in Sport mode and have not selected one of the two raised suspension settings, then the vehicle is lowered above a speed of 40 MPH. Between 40 MPH and 62 MPH the degree of lowering is proportional to the vehicle speed. Above 62 MPH the degree of lowering is fixed at 15 mm.
OK, I think I found the issue and have made a temporary 'fix'.
The rubber coating on the driveshaft coupler got nicked somehow.
You can see where it has been 'polishing' the heat shield edge and the parking brake cable sheath.
For now, I cut the offending flap off. I'll test drive it tomorrow. Long term I'll replace the coupler.
Good thing it had nothing to do with ABC lowering, because my SDS does not seem to have the option to change ride height calibration.
the only thing to be found in Control units > Chassis > ABC > Control unit adaptations >
is "Control Module Programming", which "requires online connection to the central systems". [edit] Ah, I just looked at bterry99's thread "Using Star Diagnosis to adjust suspension height" and see that inability to adjust height calibration on 07's without a connection to the mothership is a known issue. Glad I'm OK with the stock height.
Last edited by tydriver; Aug 23, 2019 at 02:08 PM.
And, I should add that the accumulator replacement (and flush) had a noticeable, positive effect. From the day I drove it home, I had kept the ABC on 'sport' setting, because I found it wallowed just a little on uneven pavement when in 'normal' mode. Now, it is completely composed in 'normal' mode. Nice. I haven't even tried 'sport' mode. The downside is, I have a few 'new' interior rattles to track down now.
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