Air spring VS. conventional spring opinions wanted

[timmyc]

Hey, all.

I have an '04 4.4 that I saved from the PO. Car looks great but was rigged to stay on the road by someone who claimed to me a BMW Master Mechanic. What a joke.

A little background. Bought the car cheap with 142k on it. I knew it needed work, but was unaware of just how much it needed. The PO really did a good job of rigging things in place to make it look/feel solid.I bought this X to tow a trailer every now and then for work, it's a small 5 x 8 enclosed trailer full of carpentry tools, go camping and eventually we plan on towing a small travel trailer. 16 foot or less. The PO pulled the rear self leveling system and put in conventional springs. I don't have anything to compare the ride to but I can't complain. Feels like a bimmer to me.

So here is where I am looking for some input. Would those of you who are a stickler for having the original equipment in the vehicle, like me, take the time and effort to put that system back in? Will it make a significant difference in the ride? Will it affect towing for the better?

I have a donor car available right now that I can get the complete system from.

Thanks for your time and input!

[aureliusmax]

If there's anything questionable from the previous owner, really look out. You're in for a many many month restoration and sinking thousands of dollars and hours into fixing all the problems. Here's why; a lot of the suspension and driveline components are dampened with rubber bushings and couplings, these will wear out first with distance driven, and then age (ten years) .
Cooling system has many rubber orings which dry out with age and will fail when loaded to specification. Not to mention hoses.
Many rubber oil and vacuum lines will get brittle and break with age (ten year). A lot of these require the intake manifold to be removed to fully replace it. While youre in there, a lot of work can be done.
Oil leaks and coolant leaks take a long time to eliminate due to age and wear of sealing surfaces, coming from multiple points.

Here's something to realize with incompetent mechanics and vehicle owners:
not completing work to factory specifications and not following procedures. replacing parts instead of troubleshooting correctly to find problems. electrical by-passes as solutions to problems. incorrectly torqued fasteners. rounded fasteners. stripped threaded bores. 'short cut' work that will be determined once you take something apart, there will be revealed more problems.

very carefully have your current vehicle completely inspected by a competent mechanic (very good luck trying to get one) . I would say these are important: engine compression check. number and locations of oil leaks. coolant system pressure tests to specification - while the engine is idling. engine oil sample analysis. transmission oil sample analysis. differential oil sample analysis. coolant system sample analysis.
careful inspection on a lift to determine the condition of all the rubber mounts and driveline couplers.

then, decide based on how much you paid for it, and how much the work to bring it to a reasonable standard will cost. is it worth keeping, is it something you feel safe to drive ?

some thoughts, based on what i've been through. previous owners who are irresponsible and can't afford to maintain an european vehicle, trying to 'brand flex' and show-off are some of the biggest obstacles to us.

[amancuso]

At this point, I would just leave it alone if it works and is not worn out. You might open a new can of worms. Usually people swap out air for static if theyhave a problem they can't figure out. It could have been something as simple as a front or rear sensor, bag or a costly compressor. On the other hand it could (less likely) be a leaking air line or valve block.

[bcredliner]

I would try towing a trailer that is loaded as you will be using to see what happens to the height when there is tongue weight from the trailer and if trailer tows correctly. If it will meet your needs I wouldn't go back to air suspension.

Most posts here are not in favor of air suspension. I like the air suspension and have not had any problems with it. I like that it compensates for any load. For your needs that would mean the hitch would always be at the same height making it less critical about how you load the trailer, would have less tire wear and handling wouldn't be compromised as much.

Ride is one of those personal preference things and I haven't driven one changed over but I can say I have done considerable modifications to the suspension of my 4.6 to improve handling and have never considered removing the rear air suspension.

[timmyc]

Those are all excellent opinions!

I was looking at towing capacities and have come to the conclusion that the spring ride should be just fine for towing. As it is now, the X doesn't even know the tool trailer is behind it when driving. This is our first X and V8 bimmer and I like it!

To Aurelius; I am fortunate have a semi retired BMW master mechanic who opened his own shop as our mechanic. I took the car to him the day I bought it and left it with for 2 weeks. He came up with a list of repairs in order of importance and we are tackling that list as I can afford to. Fortunately, most of the repairs are DIY, but I give him the bigger projects that require a lift. He gave the X a good health report and discovered that all of the big ticket motor maintenance has been done, save for the dreaded front coolant pipe. Hopefully that thing holds out!

Again. Thanks for your input!