@Bill400 I'm taking your advice and getting my tires rebalanced. Then I will tear down the parts and again reassemble, searching for any binding along the way. If nothing changes, I will replace the lower arms again.

If anyone has input on the Autel live data readout, I know this stuff is dry but I would greatly appreciate some alternatives.

 

Sean,
The duty cycle for 2007-09 appears to be 400Hz, on or off. The solenoid is operated by a 400 Hz Pulse Width Modulated (PWM) signal from the Adaptive Damping Control Module. When energized, the module applies a 1.3 Amp "push" current for 75 milliseconds to move the valve and 0.5 Amp to "hold" the valve.
We can see the "hold" current but the "push" current is a bit too fast.
I'm still hoping that the new tire balance was somehow off and your problem will be easily resolved.
Did the tech bend a wheel? Or fail to calibrate the balance machine?
If wheels and balance are good, that brings us back to suspension.
You have seen the 0.5 Amp signal on each damper. However, status of the 1.3 Amp "push" signal and actual valve setting are unknown.
Other than performance, confirming the "push" signal and valve operation is difficult.
Just a wild thought: before further disassembly, try connecting the DC power supply that you use for SDD work for awhile before starting the engine.
Turn the DC off only after start and normal idle. Take the car out for a test drive having started (and ADCM initiated) under supplemental power.

Keep us posted.

Bill

 

Thank you for that information Bill. It helps a bit in understanding what it represents but I don't understand why its displaying in percentages. I would think the display would be a value vs. percentage.
Me too. They overbooked - said it was a computer glitch that let people book online even with a slot filled. Back in the morning. Should know more tomorrow.
About the only option I see here is to disconnect a valve while at idle to see what changes.
Yes I could do this, but not sure of the goal. Can you clarify?

 

Wheels balanced - two front were out of balance, which is strange/frustrating because new tires were put on in April and I haven't been able to but more that 700 miles on the car. I used Discount Tire today. I've had enough of the constant up-selling at Tires Plus. At any rate, thank you Bill for the observation. The steering wheel vibration is gone but the harsh ride is not, but progress still.

As an aside, this is a particularly rough part of the freeway where I test drive. No potholes but a lot of dips as you can see in the video. I took my wife's SRX out on the same road today and while I can feel the same dips, they are ever so slight and a non issue. Body slightly undulates as it should.

As I drive along in my XK, I look at the bodies of vehicles passing me and I see the springs and shocks doing there job. Little to no body movement. This morning after leaving the tire shop, I had the good luck of seeing a lowered Subaru catch up to me on my test run and I kept pace with him for awhile and we bounced up and down in sync.

My take away is that the lower arm(s) are binding the lower shock mount in such a way that the springs and shocks can't do their job.

I did a little more research on the duty cycle to try and gain an understanding and it tells my that the left front damper for example, receives a pulse 22.75% of the time? Regardless of the modulation, all seem consistent with each other and that, combined with no codes, leads me back to the physical. I will however look in the CCF to see what data if any is displayed regarding adaptive damping.

I will also try starting the car with the DC power supply attached, disengage it once the car comes to idle speed and record the outcomes.

 

good thinking. but binding…. never heard of that. how?

I’m not following the value of an added electrical source though.

 

Why would all dampers go stiff after work on the rear suspension?
What if you just loosened all bolts you have touched on the rear suspension and take it for a short test drive?

 

hmmm, implying over torqued?

 

Quote:
Originally Posted by Bill400 View Post
Just a wild thought: before further disassembly, try connecting the DC power supply that you use for SDD work for awhile before starting the engine.
Turn the DC off only after start and normal idle. Take the car out for a test drive having started (and ADCM initiated) under supplemental power.

Sean: Yes I could do this, but not sure of the goal. Can you clarify?

Bill says: When energized, the ADCM applies a 1.3 Amp "push" current for 75 milliseconds to move the valve and 0.5 Amp to "hold" the valve.
Although your diagnostic says 14.2V, my wild guess is that the 1.3Amp spike may be missed for some reason and the 0.5Amp is not sufficient to move the valves into the "soft" position. Just grabbing at straws, a diagnostic easier than re-torqueing the suspension bolts.

Bill

 

Really interesting. I've noticed (could be placebo, I suppose) that the CATS seems to be softer when my battery is fully topped up. Couldn't figure why, but Bill's comment about a triggering amperage is interesting. I looked at the status of the CATS on my HT200 and they are steady at .5A (meaning soft). I kept the HT on live data and floored the car, and the CATS status changed from "on" (meaning soft) to "off" (meaning hard) for a moment. I was on a street, so couldn't test it for long. I think I'll find an onramp, and leave the record live data on to see what the amperage does.

 

Exactly - and yet the data says they aren't running stiff. Yes loosening all is easy enough. Unless my torque wrench suddenly fell out of calibration, torque specs are from the manual. I posted about some conflicting torque numbers posted in the manual and have tried both but yes, at this point, why not just loosen them all? Won't be today, 30 degrees and snowing but the snow won't last and we'll have a couple of days in the low 40's here this weekend.

@guy By binding, I simply mean the bushes aren't perfectly aligned with the mounts. I had no difficulty installing them and movement was free up and down by hand until of course the shock and hub bolts are installed but again, everything rose and fell with the jack and appeared to move freely.

I even tried a test drive with the stabilizer links disconnected which should have no impact except lateral movement and as expected, no impact.

 

Today was fun - I re-did the entire job following the manual step by step. The only thing I did differently was torque.
All Control arm bolts were torqued to 75 ft pounds.

Results are smoother ride on blacktop and some freeway but the rough road I test drive on is still rough but I'll phrase it a little differently. I no longer consider the drive harsh or stiff. Over the stretch of freeway it's still bouncy bouncy but other than that, no hard clunks on bumps or dips. The difference is dramatic enough to discard concerns over the CATS suspension functions.

So what next? I'm going to first check the calibration of my torque wrench. That said, I think it's fine but I'm not comfortable being so light on the torque settings. Any ideas because some of these specs call for 120 ft pounds?

 

Have you mixed the bolts? Sounds like you clamp something in the supension so Cats don't work. I bet if you loosen all the bolts a little more the ride will become even smoother and work properly.:-)

 

it seems you’re on to something. And Apologies, I never asked; the components you installed are identical to the originals?
I get your “it was binding” thoughts. True, I do purposely do two things when attaching a bolt to a nut, anti-cease and under torque. I have no issue with checking the car on frequent occasion and confirming that nothing has loosened up. But I would have thought as you that if the suspension moves appropriately while lifting and dropping the car, that all is fine.

Don’t laugh! I went down to the shop bench and loosened the upper and lower A arms on my son’s remote control car . (no, its a professional, fuel powered, off road rc car, about .5 m in length). Then as I always do, held it about waist level and dropped it. But as expected, the torque on the bolts had nothing to do with the expected dampened reaction. In my mind there should be no additional friction from the bushing to its case unless it was very significantly over torqued which caused unnecessary compression of the bush.

I don’t want to misinterpret your statement of bouncy. I for one expect varying levels of ‘dampened’ but never bouncy. Nor do I expect a ride of an go cart without suspension or jarring.
Im interested. please keep us informed.

 

I thought of that and great question. No didn't mix them. The lower control arms came with a new set of bolts and the two inner bolts are the same length. The outer is of course longer. The uppers are too short to put in the lower arms.

 

Sean,
What is your theory on the improved suspension performance?
Do you attribute the suspension/ride improvement to proper torque on the bushings or appropriate control arm positioning?
If the bushing fasteners are required to be torqued at normal ride height, it would seem that the design intent is to create torsional resistance in the bushing.
A bit too much fastener torque should not change that effect. Too little fastener torque may allow bushing center rotational slippage and reduced torsional resistance.
Did you reduce fastener torque to allow "self-adjustment"?
It would seem that too little fastener torque may allow lateral or axial movement that could cause a "knunk" between the fastener and bushing sleeve.
So, what is the secret?

 

Bill, now it's next weeks problem. Honestly I can't say. I under torqued everything and last night went for a drive and posted the feedback. Then today I checked the calibration of my wrench and it's fine. I set the rear wheels at ride height and tightened them a bit more but still not fully to spec and it all went firm again. Nothing wrong with CATS imo.

Next week we should have a couple of days in the forties but I've thought about peterV8's comments and although I didn't mix up bolts, I think I will order all new OEM from Lemforder. Each bolt looks a tiny bit different the what is shown in the EPC.

I just may order an entire new set of arms. This should not be this complex. I've done many a suspension in my day and haven't encountered anything like this.

 

Sean - Maybe I missed it in one of the posts above, but have you done a back to back comparison of with and without CATS?
Drive the course with CATS connected where you feel the too harsh of a ride. Then unplug the CATS and drive the same course. Is there a difference?
Maybe the dampers get the signals and the current is correct, but the dampers aren’t actually functioning correctly. Maybe damaged internally during your suspension work?
Just a thought.

 

Thanks Ken. Yes I have more than a few times (just remove fuse 14 in the CJB). Sometimes it felt the same and sometimes not following an adjustment. With regard to changing out the lower arms, you simply unbolt the bottom of the shock and it slides forward. Installing the upper and lower requires no manipulation of the dampers, like the front ones. I'm ordering new arms and starting over. I've probably spent 25 hours on a 5 hour job already. I surrender. If it ends up being the parts, Rock Auto will take them back I'm sure as they are Mevotech.

 

I suppose that the new lower rear arms you fitted had the correct “Rose” type bushes fitted.
Poly bushes will give you a hard ride as they do not allow the correct movement.
Just a thought.
As an aside, my CATS were stuck in hard setting when I bought the Jag. No codes or lights. It turned out to be the wire carrying the speed from the cluster to the cats module had grounded out along the way so the speed info was not reaching the module (X100).
I hope you get it sorted soon. Cars can be frustrating and faults obsessive!


These are Rose type bushes that allow plenty of movement.


There is one omni directional large rubber bush and two rose type bushes to allow the wishbone to “flex” for want of a better description.

 

Neville,
Thanks for the excellent photos. The ground off spots are understood to obscure ID to allow after-market distribution by the OEM supplier.
What brand are they? Are you satisfied that they are OEM or equivalent?

Bill