Hi Guus,

I have SDD v131.3 and a Mongoose cable, so with your excellent instructions I should be able to get the datalogger going. I'll let you know how it goes!

Cheers (and sweet dreams),

Don

 

Don,

I've put all my data manually in an Excel sheet but that's quite a lot of work. There is no export function in SDD. Maybe the easiest thing to do is compare if you see the same kind of sequence as in my diagram and if pressures are the same. Looking forward to hearing from you.

Guus

 

Last week the pressure gauge came in and yesterday I did some pressure testing on the front suspension. I’ve made my setup a bit different then the one 34by151 described and used Festo push on fitting and flexible air lines.

Photo 1 shows the air line as it’s normally connected.



I disconnected it, took off the olive and pushed the compression fitting higher to get enough free air line to fit it in a Festo push on fitting. I wanted to use the cars own air system to fill the bags. This way you get the actual situation (height) as it is on the car.

It’s pretty simple. The air goes from the line through a little valve with push on fittings on both sides. From there it goes to a T-connector. From there it goes goes in the push on fitting I fitted in the airbag. This is all done with normal 1/8” fittings. On the other side of the T-connector I’ve fitted my 0-16 bar pressure gauge. See photo’s 2 and 3. The valve allowed me to close of this section so I only would test the air bag.





The right side air bag sags the most so I fitted the setup there first. Started the car and let it fill the suspension. The first time the compressor stopped at approximately 4 bar and I shut of the car and closed the valve.







Within 30 minutes the pressure had dropped to 2,8 bar and after an hour less then 2 bar remained. Also checked my setup with soapy water but didn’t have any leaks so it seems this air bag is leaking.

Did the test again and this time I noticed the car came up quite a bit higher. The reason could be that the first time the whole suspension was pretty empty after standing for a week. This time the pressure also ran up to 7,8 bar.



After 15 minutes the pressure was already down to 6,2 bar and after 30 minutes to 4,8 bar.





Disconnected the setup and refitted the air line back to the right side. Then disconnected the left air line and fitted the setup to the left side. Started the car again and let it run till the compressor cut out and the car was back on the correct height.

Pressure this time was 7,6 bar.



After 30 minutes the pressure had risen to approximately 8 bar.



At first this seems a bit strange but what I think happens is that with the leaking right air bag more weight is pushing on the left one and this makes for the increase in pressure. You also see the left side has lowered a bit, I guess it can’t keep the car hight all by it’s own.

Now the good news. This morning (14 hours later) I checked the pressure on the left again and it’s still at 8 bar so this air bag seems to be good.

Guus

 

A change in height on one or more corner will show a change in the other corners

It can play with your head working it all out but there is an easy way. Google corner weighting. You will find quite a few online calcs and spreadsheets. Playing with corner weighting is something quite common for race and trackday cars so its well documented on the net

If you want to test without this becoming a factor just put the car up on stands but not enough for the wheels to be off the ground. Just relieve the weight from the springs. It will still vary a bit but not by much as it wont have much weight transfer

Another important thing if you have a fair temp change is the pressure will vary with the temp but you should be seeing similar results from all the pressures. The pressure will drop as the temp lowers

Cheers
34by151

 

Thanks 34by151, I'll have a look.

My main aim was to check the airbags and now I know the right one is defect and the left one is okay. It's a cheap setup to check this.

Guus

 

Xag, do you have a parts list/parts numbers to share for this great pressure tester using Festo Push on fittings. Do you have the fiting for both the front and rear shocks as the fitting to the shock is different. I think the parts can be found on ebay.

 

I'm currently not at home but wil try to answer your question when I'm back home.

Guus

 

I've used the standard Festo QS-B push-in fittings.

Fittings | Festo United States

Straight one: 1/8" R (with PTFE) Male to 6 mm
Straight one: 1/8" R (with PTFE) Female to 6mm
T-connector: All 6 mm

These connectors are pretty cheap so don't pay over the top on Ebay. You local plumber may have them too!

The valve is a Norgren 601112118 Minivalve 1/8" G
The pressure gauge is a ICH 306.40.16 Range 0-16 bar 1/8"G

Air line is 6 mm

Don't know the rear size connectors yet.

Guus

 

Which Jaguar SDD did you use?

 

 

Hey Xag, congratulations mate. Out of the whole internet, you are the only one that I've found to use the good stuff!
Basically, out of most industrial air pressure fittings providers, Festo is one of the best.
Working with several machine tools that had air driven spindles, I knew a little bit about air stuff before I got the Jag.
I was a little surprised about the system, as it's a very simple system, and it's a shame it doesn't have a more advanced way of keeping it under control (like pressure sensors on each corner, etc). I guess cost driven development nowadays is more important.
Anyway, if you don't mind, I will continue your thread with my own experiments.

I was having a leak on one of the bags, as I always found the car ******** overnight. I would suspect the rear right bag, but not sure. The previous owner changed the valve body and claimed it corrected the problem for a little bit, as now is dropping pressure over night, and not over an hour. He claimed he checked all the bags on the car and they were fine. So that's when I started to suspect that maybe a leak is happening on one of the air lines.
Took everything apart and checked what I need. From the local Festo dealer I've got basics of what I need.
- some 6mm pipe leftovers (front bags and tank is 6 mm)
- some 4mm pipe leftovers (rear bags and compressor is 4 mm)
- 1/8 BSP threaded quick-fit for 6 mm pipe
- 1/8 BSP threaded quick-fit for 4 mm pipe
- 6 mm T-connector (this is the smallest one available)
- 2x 6mm-to-4mm reductions
- 6 mm nipple
- 10bar pressure gauge with 6 mm quick-fit
- 2x shut-off valve

Made a setup to test the pipes similar to yours, but at the valve body side. Took apart the first right rear pipe and observed I'm in no luck, as the 4mm pipe is NOT a 1/8 BSP fitting!!! Trap for young players.
Same thing on the strut side, is not a 1/8BSP.
After long search, I've found the thread. The thread for the 4mm pipes is a UNF 5/16" 24TPI.
It's a very weird size, and no one manufactures quick-fits in this size.
So the search for UNF 5/16" to 1/8" BSP began. After 2 weeks I've found some adapters on ebay in UK, and I've ordered 6 of them, came in post several days ago.

Anyway, getting back to my setup, I've used in the meantime the original nut with the olive and some leftover pipe to test all the pipes and the pressure drop on each over night.
After 3 days/nights of moving things around and checking different sides, I've had a complete picture of the system:
- the right rear bag was obviously ********, dropping from 6 to 2 bar over night; it was not the pipe, it was the bag, as I've put the test setup directly on the top of the strut;
- there seemed to be a small leak to front right, but not really quantifiable;
- the valve body leaks somewhere. I've caught it by mistake, while I was moving the pipes around it was very quiet (11PM in the night), and I could hear this faint hissing on the compressor side (so the manifold entry). Surprisingly, when I've test the compressor line, it hold steady at 6bar over night.

I've been again to Festo, spent another $100, and got my self another set for T-connectors, a 16bar gauge this time, shut-off valves, etc (made a mistake to buy a 3/2 way the first time, and it was a pain in the *** to get that one to the point of closing but no venting ).
Tested multiple times, and got to the same conclusion.

Now, after waiting for a new bag (I've pulled the trigger and bought of ebay a Bilstein rear strut, after reading various reviews on how and why to use different options on suspension, but this is not the place to discuss these options), and playing around with it, I'm at the point where everytime I stop the car I go in the trunk and stop the valve, so the system doesn't lose the pressure on that bag (you know, the wake-up call every 30 minutes by the system to balance the whole car thing...yeah, pain the ***).
But the right front started to lose a lot of pressure now (about 2-3bar in 30 minutes). And is not the bag, because if I isolate it, it holds steady for more than 1 day.
And are not my fittings either. I believe the valve body is completely shot now, and that valve never actually closes. But my question now is why does it loses all that pressure? And where, if all the other valves are closed? Because the only place where it could vent is the compressor, and in general that valve is closed when the car is "sleeping". Or is it not?


And you were right Xag, the tank is not filling up immediately, it took mine 3 drives of 30 minutes to get to 4bar. Didn't had time to wait for it to build pressure, but I assume is holding it, as it had 4 bar overnight also; I've had to move the setup to other test side

P.S.: Ever tried to replace this shitty valve body design with a more up-to-date industrial one? Like a Festo terminal valve with some sort of controller? I know I'm very tempted.
P.P.S: I've got a bunch of parts from Festo again (another $130, I hope wifey doesn't check expenses often ) after the adapters from UNF 5/16" to 1/8 BSP arrived, to change all the fittings on the valve body with quick-fits. I've got the miniature 90 degrees bend ones in 4 and 6mm (1/8BSP thread, obviously), as the adapters would have pushed the fittings pretty high.
This weekend I'll mount the rear strut and change all the fittings...not sure if I should put back in the old "claimed to be damaged" valve body...I don't have any way to test it yet.
And I have no idea why people still struggle with nuts and breakable olives, when quick-fits are so reliable and easy to fit...maybe because of pressure rating that the classic nuts and olives have, but to be fair, the 10 bar rating of the quick-fits is within specs, they worked perfectly fine on my car for the past 3 months, and I prefer to have a $5 quick-fit burst in case of "emergency", than a bag, pipe (especially under the car), or the valve-body.
There are also high pressure 16bar quick-fits, which is what I've got for the compressor side.

 

Keep up the good work on modifying our air systems.
Making easy basic changes to improve things is always a plus.
It seems a lot of our members, just give up and switch to coil overs

 

Hi LittleMan,

Thank you for the detailed report of your work! If you can find the time, please post some photos of your fittings, your test gauge setup, etc. so we can all learn from your work!

Cheers,

Don

 

Hi Littleman,
Impressive research, please go on for our mutual benefit in keeping the air system functional.
Also very interested in knowing more on your detailed fittings with pictures

 

Hi LittleMan,

Just re-reading your post I was prompted to throw in a few ideas for consideration. First of all, the Wabco system has height sensors at three wheels (four wheels on the early cars), which would make pressure sensors somewhat redundant, and of course, all automakers are in a constant battle to minimize cost and complexity.

You answer your own question. While the car is sleeping, the ASM may periodically wake up and release pressure from up to three corners to bring the vehicle closer to level. All excess pressure must be released through the exhaust vent solenoid on the compressor - that is the only exit point designed into the system.

I may have missed it, but I don't think you mentioned that you have rebuilt your compressor with a new piston ring/seal. If you haven't done so, this is a very worthwhile project because it also gives you the opportunity to clean corrosion from the leaf valve and exhaust vent solenoid valve that may be preventing the valves from closing reliably. Also, a new seal will restore your compressor's ability to repressurize the system quickly. Our member bagpipingandy makes a very high quality replacement piston ring kit available on eBay.

I don't know if you have checked out some of the documents linked in the thread below but if not you may find them helpful in diagnosing system behavior:

Air Suspension & ECATS System Summary: Components & Operation

Cheers,

Don

 

Sorry for long time reply.
The compressor was rebuild by the previous owner.

Reporting back that the system works very well. Very easy to manage and evaluate. Bought 16+ bar pipes, fittings, quick fits and gauges; installed them permanently in the car; as soon as I have a question, I just look into the trunk and check the pressures. Placed gauges on all 6 pipes; I also have spare pipes, Ts, and valves, if I need to shut off a side on the go; takes 2 minutes to do it on the side of the road, if something is ever to fail.
Replaced valve body with a cheap aliexpress Merc S-class unit; connectors were all the same, the resistances of the solenoids were a bit different I think, but it just works. What it doesn't work are the fittings, which on the solenoid are all 5/16UNF thread, so I've used up all my adapters to 1/8BSP. But at ~$100 for the valve body unit, even if it fails every year I don't mind
If there's a big downfall or thing that I would develop in this whole upgrade system is this: find a way to have lots cheap 1/8 BSP Female to 5/16 UNF Male brass adapters.
Because as soon as you increase the thread to 1/8 BSP you find any style of quick fits, rated for 16 bar or over. I've used right angle style so made the pipes more easy to manage.

Anyway, problem now is the actual dampers. Even though I'm not losing air anywhere anymore, the ride is getting jerky day by day. 2 of the dampers are almost not doing anything anymore. And buying refurbished units I don't think gets us anywhere, as they are using old dampers. So I've pulled the trigger, and I already have 3 new units since I've bought the car (2 waiting to be installed), with the remaining good one still going to be kept unit it fails (it can be seen that I has been replaced at some point with a refurbish unit, so might still work for some time).

So all in all, if you consider a maximum of $1000/strut, and probably another $1000 to make the gauges+piping+valve body swap upgrade system I did, it should cost a maximum of $5000 to have the system upgraded to a fully functional system, easy to evaluate and maintain for the years to come.
Giving that you're basically having a mostly maintenance free air ride, that you can use daily for years and years, I would rekon that's not such a bad deal.

I've filmed the whole thing, but I've just didn't have time to go through it nicely and upload it.

 

Very interested to see the video when you have time.

 

Three things I did not see in this so far:
1) Compressor nominal pressure should be capable of 15 bar (218 psi). Relief valve set at 17.5 bar (254 psi).
2) Pressure retaining valve in compressor should always maintain 3 bar (43.5 psi) to prevent air bag damage.
3) TSB XJ204.06 has a sequence of tests, using SDD, to do preliminary diagnosis of the Air Suspension System.

 

Hi Edward,

The info in your points 1 and 2 is contained in the link in post #35.

Cheers,

Don

 

I had a similar problem at one side of the front suspension.
A compressor replacement did not improve the situation.
A corrosion problem was suspected because the well protected back suspensions are almost never affected and the used "Ford" metal parts are quite cheap.
So a gum and plastic friendly corrosion spray was procured, in this case WD-40-3-in-1. Sonax 95 should work as well.
The two upper bolts on the left and right side were slowly loosened and the front of the car dropped.
3-in1- spray was applied to the bolts, washers and below the washers. (maybe some drops got inside !)
After the two bolts were fixed again I started the engine and waited in desperation.
This is too simple, it cannot work. But after some minutes the horizon started to drop.
A succesful test drive followed.
When I got home I needed a drink.