Thread: Suspension, what am I doing wrong?

G'day Nomad!

I'm going to assume you are running OEM airbags in your Rangie?

A few questions before I fire off answers!

When you are lifting your Rangie off the ground, are the diffs hanging from the springs, or are they being supported during jacking/hoisting?

Are the bags new or old (what condition)?

One of the issues with jacking a P38 is that the bellows will pull off the pistons if they are left to hang when the vehicle is on a hoist or axle stands under the chassis. Standard shocks are enough to rip Arnott Gen III springs to bits, so standard springs will be quite stretched at full droop.

Cheers
Keithy

Hi Keithy,
Ok, so the car is on a hoist supported by the chassis, I can remove and replace the bag quite easily in this situation, the bags as far as I know are standard, they are Dunlop ones bought from Eurospares in the UK, the date stamp on the top is 06 13 which I assume is June 2013 so they are quite new, they look new. The shocks are standard, again as far as I can tell. The right hand bag is fine, inflated perfecttly. I think I have been letting the vehicle back onto the wheel/tyre to early with not enough pressure in the bag, hence the creasing and "popping" off.

I'll wait to see what you suggest, I can see what you are talking about when I look underneath, there must be a fine line between right and very wrong.

My intention this afternoon when I get home is to install the bag, start the engine with the car on the hoist, wheels off the floor and let things run until the compressor stops. If the right hand side bag is OK I can't see any rhyme or reason why the left hand bag shouldn't be the same.

I'll wait and see what you or others come back with. My mistake was when I fixed the valve block and the car was on the bumpstops I lifted the vehicle on the hoist to do the exhaust which created a vacuum in all the air bags as I lifted the vehicle off the floor, realised this to late, I should have started the vehuicle and re-inflated everything before I lifted the vehicle up. A lesson learned.................

What I do when there is no air in the bags is lower the car to around highway height on the corners with no air. Then start the car and choose high mode so the car lifts off the jack.

Can start at standard height to be extra safe but needs to be below high height to lift off

I had the top of my left rear bag pop out of it's holder during inflation after doing some work on the eas recently, it made the same whoosh sound you describe.
I jacked up that corner of the body enough to allow access under the wheel arch, I could see the bag had indeed come away from its proper position, pulling the air line out as well, which casued the whoosh sound.
With the body still jacked up, I had to remove that circular weight attached to the diff to gain access, very easy, just two bolts from memory.
Then I was able to pull the top air bag pin and the air line out, ended up pulling the bag right out to check everything was ok. It's a bit tricky manouvering it out over the axle housing, but it will come out.
There was no damage to the air line or bag, so I replaced the o rings while I had it out, then put the bag back into position, reseating the top of the bag into its correct position with the air connection poking through the top of the mount. Then insert the pin and air line again, giving it a pull to make sure it is connected properly.
Then I dropped the jack, re inflated the system again, and it has been fine ever since.
Hope that is of some help!

Hi Pete38 and PeterH,
Interesting answers, Pete38 I am going to assume that the other three wheels are on the deck when you did your inflate. I am using a hoist which I suspect is compounding the problem, on the hoist the vehicle automatically goes to "super high mode" I'm assuming this is because the sensors read chassis high, suspension no load.

In answer to you PeterH, you describe a lot of similarities except possibly the last sentance. I haven't had any problem getting the bag in and out, getting pretty good at it now takes about a minute and a half. The circular weight you talk about is something I will have to investigate further, I don't seem to have one of these, the problem I have right now is taking priority over that bit.
My main issue is the air bag seems to crease in the middle, folds on itself and then goes over at such an angle that one of the ends pops off the mounting plate, this happens before the bottom section of the bag rolls over the mounting plate.

I have tried to fold the bottom mount into the bag, after a couple of beers and a lot of swearing I gave up. TV seemed a far better option at that point.

As mentioned earlier when I get home I'm going to put the bag back and leave all four wheels off the floor start the engine and wait until the compressor stops, or the bag comes off completely, a little bit of "***** or bust". The righthand side bag is fine with the wheel off the floor and folds perfectly over the bottom mount, I was on the verge of taking the R/H one off and changing that over to the left hand side, thought better of it after the second beer.

I'll report back how I go.

Good luck with it Nomad9, hope you have better luck next try!
The circular weight I am talking about is called a mass dampener (from memory), it might only be on later model P38's, may not be on yours if it's an earlier model.
If you can get your bag out already then it's not an issue.
Just a thought, maybe it's the hoist that is causing your problems, I'd try putting the bag into position and then putting the wheels on the ground before inflation instead.
That's what worked for me at least.

Originally Posted by Nomad9

Hi Pete38 and PeterH,
Interesting answers, Pete38 I am going to assume that the other three wheels are on the deck when you did your inflate. I am using a hoist which I suspect is compounding the problem, on the hoist the vehicle automatically goes to "super high mode" I'm assuming this is because the sensors read chassis high, suspension no load.

In answer to you PeterH, you describe a lot of similarities except possibly the last sentance. I haven't had any problem getting the bag in and out, getting pretty good at it now takes about a minute and a half. The circular weight you talk about is something I will have to investigate further, I don't seem to have one of these, the problem I have right now is taking priority over that bit.
My main issue is the air bag seems to crease in the middle, folds on itself and then goes over at such an angle that one of the ends pops off the mounting plate, this happens before the bottom section of the bag rolls over the mounting plate.

I have tried to fold the bottom mount into the bag, after a couple of beers and a lot of swearing I gave up. TV seemed a far better option at that point.

As mentioned earlier when I get home I'm going to put the bag back and leave all four wheels off the floor start the engine and wait until the compressor stops, or the bag comes off completely, a little bit of "***** or bust". The righthand side bag is fine with the wheel off the floor and folds perfectly over the bottom mount, I was on the verge of taking the R/H one off and changing that over to the left hand side, thought better of it after the second beer.

I'll report back how I go.

Whenever I have my car lifted on a hoist I turn off the EAS with my isolation switch I fitted. Or before I had that leave a door open so no extended mode is triggered. I think with all thw wheels hung on the end of the shocks the system probably lets all the air out of the bags to lower it thinking all sensors are too high. Then you lower it down with no air and the bags get creases.

So if there is no air in any of your bags I can't see why lowering the car very slowly with the car running and all doors closed. Eventually it will get low enough to lift itself off the hoist. Don't lower it too quickly otherwise the system won't partially inflate/pump the bags up before the car hits the bump stops and folds the bags.

I also have the emergency air inflation so when my bags are emptied of air when the car isn't on the bump stops (jacked up and air let out of the system) I could manually pump air into the bags.

I have never had the car jacked up without the EAS turned off or bypassed so some of this is all thoughts, not experience.

Hi Pete38,
You make a very good point about the EAS and lifting the car off the floor, what you do is what I SHOULD have done, just had a moment, I was that keen to get my new exhaust on I just forgot.
With all four wheels off the floor the extended mode comes into play. I tried inflating the bag a little bit by opening and closing the raer passeger door and then lowering onto the floor the blasted thing still creased, I just don't think I put enough pressure in.

I believe at one point the bag was creased in half and sitting on top of the two halves, the ride hight sensor sensed that the vehicle wanted to go up, so introduced more air, at that point the seal broke and the bag popped off, then the rear of the vehicle came down, the R/H sensed things had gone down, so lowered, quite impressive to watch actually, that was after I had got over the shock of the bag popping off.