AHC Damping Force Accuator Accumulator Replacement (1 Viewer)

[hkeller]

Guys, I have search, but I cannot seem to find what I think is available on Mud. I need the pages from the field service manual (FSM) showing how to replace the accumulators (spheres). Does someone know where they are or can they post them? Thank you,

 

[LBridges]

sent you a message

 

[PADDO]

Here is the rather brief FSM description on removing/replacing the damper accumulators. I suspect it's not really what you're after. Were you looking for how to actually change the accumulators in-situ?

 

[hkeller]

Thanks. Yes, was also looking of the post change, how to bleed section, but tracked it down.

I am replacing with the Citroen modified spheres. I will post results once done.

 

[hkeller]

Replaced the spheres and flushed the fluid. Ride is still harsh. Neutral pressure was in spec before replacement. Do I need to check it again? Anything else I should be checking? Thanks,

 

[maxse01]

Maybe the shocks are shot? Are they seeping/leaking?

I did a flush and replaced all 4 globes (111k) and my ride is back to the cloud it was when new.

 

[CanadianRockyCruiser]

Replaced the spheres and flushed the fluid. Ride is still harsh. Neutral pressure was in spec before replacement. Do I need to check it again? Anything else I should be checking? Thanks,

Yes, check the neutral pressures again.

 

[PADDO]

Do you know what the charges are in the new non OEM spheres? If they're different to OE then you'll need to experiment to find the optimum damping point. Either way you'll need to remeasure pressures as it stands now to have a baseline to start from.

 

[hkeller]

With new spheres, which I assume add pressure to the system, do I need to reduce tension on the torsion bars or increase it? It would seem I need to crank them down a bit. I am suspicious there is another issue.

 

[PADDO]

With no reference points like present neutral pressure, vehicle heights and the charge pressure in the Citroen globes compared to OE my advice is flip a coin - heads higher, tales lower. Do one turn a day for a few days and if things improve then that's great. Otherwise reverse the process. Optimizing this system and identifying any underlying problems really needs to start from a solid data base. Happy to help, but hey, the coin approach has a 50% chance of being correct.

 

[hkeller]

Roger that, Paddo. You and uHu are great resources. If it will warm up a bit around here, I will give it a try and report back.

 

[uHu]

With new spheres, which I assume add pressure to the system, do I need to reduce tension on the torsion bars or increase it? It would seem I need to crank them down a bit. I am suspicious there is another issue.

The pressure will be the same, with new or old spheres. It's the force applied by the weight of the car and the force applied by the steel springs which decide the ahc pressure. The ahc system will pump up the pressure until the height is "right".

The difference between different spheres will be how much they are compressed. Worn out, or too weak, spheres will be compressed so much that they bottom out, and thereby giving a harsh ride.

It is still the Neutral Pressure that decides whether you should crank TB and/or change coils. The ahc system has no idea about the state of the spheres.

 

[hkeller]

Harsh ride and getting a C1762 Abnormal Pressure at Pump trouble code. Any thoughts? System goes from low to high just fine and Off light is not blinking or anything. I have read all the threads and I am stumped.

I have TechStream and don't know how to check it. Thanks!

 

[PADDO]

C1762 is a common dtc, often as a result of a transient hiccup. Just clear it (engine with eraser symbol) and investigate if it returns.

 

[hkeller]

Will do. However, why the harsh ride, with neutral pressures in spec? Really wanted to keep AHC, but I have almost not front suspension travel at this point and it is sketchy to drive.

 

[PADDO]

Need to know (numbers, dimensions) your neutral pressures and height measurements to get this ball rolling. Are you on the bumps? You could have a failed height sensor, could have pressures way out. There are many tests and checks that can be done to isolate or eliminate elements - but it all starts with the fundamentals. Can you post a screen shot of techstream AHC data list screen on raising to N from L?

 

[hkeller]

Paddo, you are the man. It will be 5 degrees most of tomorrow and then I head out of town for work. Will get back on this next weekend. I am not on the bumpstops. I appreciate the help.

 

[hkeller]

OK. Everything seems to be functioning as it should (except the ride remains horrible). It goes into low, goes into high, and I have at least 12 graduations of fluid change between low and high. Before swapping accumulators, I had about 7. New accumulators are supposed to have same pressure charge as OEM.

I cleared the C1762 DTC code and it has not returned. Here are some screen pics from Techstream:

Wow, that's a bad pic.

FR Height Control Sensor shows 0.1
FL "" shows -0.7
Rear "" shows -0.4
Front Pressure is 6.5
Rear Pressure is 6.2
Accumulator is 10.6
Steering Angle is -137.25
Front and Rear Step show 8, regardless of where I have the comfort setting.

Don't know why the steering angle shows what it does. Wheels were straight and angle under the VRGS tab shows 0 degrees.

Thoughts?

 

[PADDO]

If you are on level ground then ensure you are cross level, adjust TBs as necessary. Cross level is important because it helps alignment and equalizes spring damping response for your front suspension. Recheck sensor read outs, you may need to adjust your FL height sensor to read closer to 0, front sensors should have less than 0.3inch variance from 0. You should check and set overall front and rear heights and adjust sensors as necessary to get the correct heights (19.75 front, 20.5 rear - hint for accuracy take the front trim center caps off and mark the hubs grease cap center with a marker so you can be consistent and accurate).
Once cross level and heights correct set your front neutral pressure to 6.9MPa as that's the design pressure (for new, stock, OE). The tolerance of +/- 0.5MPa is the acceptable deviation from 6.9 - don't expect optimum damping performance at the outer limits of the tolerances. It's a Gaussian performance curve, not on/off. You may find a better point for you and your vehicle's variables (i.e. tires, worn bushings etc) from 6.9MPa but start there. I like 6.8 with 5.7 rear but that's me.
Do a vgrs steering initialization and calibration, after driving you should have "steering angle valid flag" as "yes" and should have a reading closer to 0.
Height accumulator pressure is normal, nothing to do there.
Steps of 8 and 8 (damper setting) are normal for being stationary - hook up Techstream and go for a drive and watch how they change with speed, braking, damper switch settings.
Confirm you SW1 and SW2 change, toggling on/off with the damper switch.

 

[hkeller]

Thanks. When the snow melts, I'll crawl around and give this a shot.