FAO: derin re: e39 touring rear wheels

[madou]

Derin

Not registered at the other place

http://forum.bmw5.co.uk/viewtopic.php?f=11&t=2...

but the answer is the the touring has self levelling rear suspension, which limits the room for the wider ( staggered ) rear wheels which are seen on the saloon, confirmed in conversation with Phil Crouch ( CPC )

Wider rear wheels could change the handling balance towards under steer

I do not know of any other difference in spring rate, damper, or otherwise which could make the ride less compliant on the touring than the saloon. My observation is that the same as other large, heavy cars, the maker ends up having to specify higher rated suspension to control the body mass, in addition to fulfilling "sporty" conceptions from the marketing department

Regards

Edited by madou on Saturday 12th April 14:59

[derin100]

Thanks very much, Madou!

The more I research the topic the more complex it becomes! This morning I bought/ordered one of these Ediabas 'things'...I don't even really know what it is!

But apparently I can use it to adjust the rear ride height on the Touring and thus alter the compliance of the rear suspension. Hope I haven't wasted £70-quid.

On the E39 the actual self-levelling 'bags' are well in-board and away from the wheels so I can't see how they would limit space for the wheels per se. However, as I understand it the layout of the rear suspension on the Touring is different? Certainly, reference to part numbers on realoem shows different parts for 540i in either Saloon or Touring guise (and different for each variant whether equipped with 'standard' or 'sports' suspension).

Nevertheless, I've been increasingly coming round to the opinion that what lies at the heart of it is, as you suggest i.e that this is just inherent to the design of the particular model.

Thanks again.

[derestrictor]

Derin, any more 'works of art' in the pipeline?

[derin100]

Well, since it's you who's asking...

I wasn't going to put this up here yet as there's no text by way of explanation yet...but here ya' go:

http://www.bmwclassics.co.uk/gallery/index.php?spg...

[derestrictor]

Derin, liberal use of the term 'genius' has diluted it's impact but where you are concerned, Sir, it is wholly inadequate.

Holy Mary, that is nothing less than sensational.

I am bewitched, entranced by the loving attention to detail; pure concours - dare I say it, surgical - precision?

You deserve a knighthood for services to car prep obsession.

[derin100]

Thanks Der!

I had hope to get my knighthood for services rendered to the world of medicine...however, as that likelihood has now receded irretrievably - due to my ever increasing disinterest in the health service in this country - you have offered me renewed hope that I may yet scrape my way on to the honours list via a new and novel route! I mean, even an MBE would do! And it seems you can get one of those for almost anything these days?!

The car isn't quite 'finished' yet...at nearly a quarter of a century old are they ever? Principal on the list remains for me to figure out why the cruise control which was working perfectly before the car went into the bodyshop no longer functions. Everything else works.

I'll do a full write-up on the car soon.

Thanks again!

[Scamp's Walker]

Derin, the "new" set of wheels that you have on the car, are the actually new or just a very good refurb? If they are a refurb, where did you get them done?

Edited by Scamp's Walker on Saturday 12th April 19:10

[derin100]

They're refurbished. I get them done through Moseley Motorsport (where I get all my cars serviced) but they're kind of done as a 'favour'. They get sent off but I don't know exactly where they get sent.

I've actually got these ones reading to go on my next project...when and if I ever get it back from the bodyshop!

http://www.bmwclassics.co.uk/picsvarious/DSCN3299....

http://www.bmwclassics.co.uk/picsvarious/DSCN3301....

http://www.bmwclassics.co.uk/picsvarious/DSCN3303....

[madou]

derin100 said:

But apparently I can use it to adjust the rear ride height on the Touring and thus alter the compliance of the rear suspension. Hope I haven't wasted £70-quid.

Derin

Further to your other thread on subframe bushes

I think this is just changing ride height, rather than changing spring rate or damping, however the mounting point may have more compliance than orthodox adjustable suspension

Also check tyre pressures, start at the factory 2.4 bar front / 2.8 bar rear for unladen, and vary according to tyres ( side wall stiffness ) and how you perceive the ride and handling

Regards

[derin100]

Thanks Madou

I've played around with the pressures today (dropping the rears to 34) and also tried the car with some small degree of load which palpably improved things.

The theory (as I have gathered from a U.S 5-Series forum) is that reducing the ride height (i.e reducing the amount of air or air pressure in the self-levelling containers) increases the compliance. Thus perversely and in contra-distinction to 'normal', simple spring and damper suspension arrangements lowering the ride height in these cars actually softens the ride!

This also seemed to be what my Indie was being told over the phone when he enquired of one of his contacts who had more experience with this matter.

That's the theory as I understand it anyway.

If it doesn't work with this Ediabas thing I've probably flushed £70-quid down the toilet today because I probably won't have a clue how to work all the other functions it's supposed to do!

It would be good to hear the thoughts of any BMW Techs on this forum.

[derin100]

Damn! Looks like I may have chucked £70-quid down the drain after all...just got this reply on a U.S forum:

[i]Correct! Nothing wrong, it's just the way it is. You are going thu what just about every person who buys a used 540iT goes thru. Was just giving some suggestions that improve things, but none of them will make it ride like the sedan.

In time you will discover more quirks of the car, with most of them ending up being normal. For example most 540's have a slight tick/knock sound that will come from the center of the right side engine valve cover. Will only occur when the engine is warm and running at the very low idle speed (500 RPM or less), which occurs when the A/C is off and battery is fully charged.[/i]

Edited by derin100 on Sunday 13th April 00:29

Edited by derin100 on Sunday 13th April 00:33

[madou]

derin100 said:

Damn! Looks like I may have chucked £70-quid down the drain after all...just got this reply on a U.S forum:

[i]Correct! Nothing wrong, it's just the way it is. You are going thu what just about every person who buys a used 540iT goes thru. Was just giving some suggestions that improve things, but none of them will make it ride like the sedan

Derin

Never mind, I have wasted several thousand on after market suspension over the years on various cars, none on which was really a better comprise for road use than the factory setup. With the 540iA Sport Touring I am just trying to get back to good factory condition

My 2c is that the high speed bump is a bit harsh, so if you hit a pothole unladen you certainly feel it, but that the suspension starts to make a lot more sense as the forces on it, generated by speed or load increase. This view is from driving the car in conditions ranging from unladen, pothole and speed hump ridden cites, through to wine laden on French D and N roads

Regards

Edited by madou on Sunday 13th April 12:57

[HarryW]

Whilst one the subject of the rear ride quality (mines poor banging/thumping over ridges too - 528 non sport touring).
What rear pressures do you all run, I'm on standard (as per door slam sticker) and the rears seem to wearing the centre section quite quickly indicating to me that's over inflated

[derin100]

madou said:

derin100 said:

Damn! Looks like I may have chucked £70-quid down the drain after all...just got this reply on a U.S forum:

[i]Correct! Nothing wrong, it's just the way it is. You are going thu what just about every person who buys a used 540iT goes thru. Was just giving some suggestions that improve things, but none of them will make it ride like the sedan

Derin

Never mind, I have wasted several thousand on after market suspension over the years on various cars, none on which was really a better comprise for road use than the factory setup. With the 540iA Sport Touring I am just trying to get back to good factory condition

My 2c is that the high speed bump is a bit harsh, so if you hit a pothole unladen you certainly feel it, but that the suspension starts to make a lot more sense as the forces on it, generated by speed or load increase. This view is from driving the car in conditions ranging from unladen, pothole and speed hump ridden cites, through to wine laden on French D and N roads

Regards

Edited by madou on Sunday 13th April 12:57

Yes, I agree certainly at speed it feels much better. I think probably whilst unladen, with a little reduction in tyre pressures I'm going to live with.

Many thanks

[derin100]

HarryW said:

Whilst one the subject of the rear ride quality (mines poor banging/thumping over ridges too - 528 non sport touring).
What rear pressures do you all run, I'm on standard (as per door slam sticker) and the rears seem to wearing the centre section quite quickly indicating to me that's over inflated

I normally run all my cars a bit below the recommendation on the door-shut as this is always given by BMW as for up to 4 passengers with no luggage. As nearly all the time it's just me in the cars with no load I too have worn tyres out in the central portion only by following those recommendations.

[M3John]

Derin, you should change your occupation from sergeon to artist ! That is unbelieveably good - as always. Can't wait to see the pictures from your next project as you know i've a soft spot for them

Edited by M3John on Sunday 13th April 14:53

[derin100]

Thanks John!

The next one is in the hands of the bodyshop...nearly everything else was completed before it went. So, if I ever get it back from them it shouldn't take too long to finish.

[M3John]

derin100 said:

Thanks John!

The next one is in the hands of the bodyshop...nearly everything else was completed before it went. So, if I ever get it back from them it shouldn't take too long to finish.

Be sure to give me a when you mate as if you ever get a free hour or two on a weekend i'd love to come up and see the `work-in-progress`. Oh and before i forget, car is all sorted now with the dreded SMG thinggy. :fingerscrossed:

[SJobson]

Going back to the first post for a moment, there are plenty of people on BMW5.co.uk who have put the wider rear tyres on their Tourings with no ill effects. The self-levelling suspension should make it perfectly OK, provided they don't rub when unladen (and they don't seem to). 18" wheels weren't offered on the Touring either (possibly because they're only fitted as a staggered set?)

Odd that BMW still don't offer the wider rears or the largest wheels on the E61, though...

[Scamp's Walker]

Did you get the car back, and have you had any joy with the Ediabas "thingy". Was it useful?