[borinous]

Wow...did you get any vibration at all from the rear at speed? or did it all feel smooth

[jamherber]

How on earth did it get through an MOT with that level of movement on the rear wheels? Quite worrying but on the plus side, it'll feel like a new car when you've replaced that lot!

[zippyonline]

Originally Posted by wallsmk2

A tip for the surface rust - wire brush it then apply a rust converter like bilt hamber's hydrate 80. Cover with BH Dynax UB wax (it's black and quite tough). Spray some Dynax s50 into the small holes in the sub-frame and you should be good for a few more winters.

Yes, that’s exactly what I had in mind – I’m also a big fan of Bilt Hamber products. In fact, I have about 3.5 litres of S50 sitting here, and a proper applicator gun for use with the compressor – which makes life somewhat easier and quicker.

Originally Posted by borinous

Wow...did you get any vibration at all from the rear at speed? or did it all feel smooth

Now that could be a long story. The short version is no – it just tramlined and wandered all over the place from the rear. Initial test drive – it just shimmied a bit and I thought mileage etc – it steered straight and wasn’t alarming. Then after a few weeks of going “this isn’t right”, giving stuff a prod and a second opinion, we worked out the massive rear toe was straightening the car out (ignored geometry initially as it hadn’t been long since it was aligned). Blah blah – after new tyres and geo, it just drove like it was worn out on the rear when driving in the dry. In the wet, it got scary – and after a bit, it ate the tyres – as detailed in the first post.

At no point has it clunked, knocked, vibrated or anything like that, and clearly nothing super obvious as it passed it’s MOT and several people have given the suspension arms a tug. I’m curious what I will find when I take them apart. It just shimmied and tramlined, and well you can’t actually put much more than mild throttle on without it fishtailing/electronics kicking in.
I reckon something was going, and it’s now gone. But it’s still armchair prognosis at the moment.

On another note, I’m going to keep one of the old tyres, and cut a cross section across it to see how much carcass I had left!

[borinous]

Originally Posted by zippyonline

Yes, that’s exactly what I had in mind – I’m also a big fan of Bilt Hamber products. In fact, I have about 3.5 litres of S50 sitting here, and a proper applicator gun for use with the compressor – which makes life somewhat easier and quicker.



Now that could be a long story. The short version is no – it just tramlined and wandered all over the place from the rear. Initial test drive – it just shimmied a bit and I thought mileage etc – it steered straight and wasn’t alarming. Then after a few weeks of going “this isn’t right”, giving stuff a prod and a second opinion, we worked out the massive rear toe was straightening the car out (ignored geometry initially as it hadn’t been long since it was aligned). Blah blah – after new tyres and geo, it just drove like it was worn out on the rear when driving in the dry. In the wet, it got scary – and after a bit, it ate the tyres – as detailed in the first post.

At no point has it clunked, knocked, vibrated or anything like that, and clearly nothing super obvious as it passed it’s MOT and several people have given the suspension arms a tug. I’m curious what I will find when I take them apart. It just shimmied and tramlined, and well you can’t actually put much more than mild throttle on without it fishtailing/electronics kicking in.
I reckon something was going, and it’s now gone. But it’s still armchair prognosis at the moment.

On another note, I’m going to keep one of the old tyres, and cut a cross section across it to see how much carcass I had left!

interested to know what it was.

Only asking as i have a vibration from the rear on mine currently. handles fine goes straight and no tram lining. had my Indy give it a once over and found nothing at the rear that was loose or worn.....

ive just had to start buying bits and replace one by one till its gone.

[maxoutput]

It could literally just be the camber and toe adjustment nuts keep coming loose and alignment shifting .

[zippyonline]

Originally Posted by borinous

Only asking as i have a vibration from the rear on mine currently.

Does the vibration change with wheel speed (mph) or engine speed (rpm)? Because then one would suggest prop/driveline related vs. something wheel/suspension related.

Just got a quote back from BMW for the remaining nuts / bolts/washers and bushings I couldn’t buy from ECP with their reduction thingy. This is becoming a very expensive exercise (i.e. spending ¼ of the value of what I purchased the car for!) In for a penny, in for a pound! Lucky I own a socket set really…

[Chappers 71]

Are you sure that the adjustable rear control arms aren't causing the problem?
As you most likely know they adjust the camber, maybe these have been set up wrong.
I would have thought if the bushes etc were that badly worn it would have been picked up on mot or previous geos.

[zippyonline]

Originally Posted by maxoutput

It could literally just be the camber and toe adjustment nuts keep coming loose and alignment shifting .

Originally Posted by Chappers 71

Are you sure that the adjustable rear control arms aren't causing the problem?

It's quite possible on both accounts. But if I'm stripping down stuff, and something is worn but the other one not as badly - well then the other components aren't going to be far behind. This is why I've decided I'm doing a full strip down and component replacement. It will leave nothing possible left to be causing the problem - and everything will be new - which will stop it being a combination of factors, and I won't have a mis-match of worn out and fresh stuff.
You could argue what the best/most cost effective approach is, and where you start/stop is quite arbitrary - i.e. do I go and buy a bunch of pattern parts or go OEM, do i start with pattern parts on the most likely culprits etc.

So I've gone sod it, I'll leave no stone un-turned, and do it all properly

[borinous]

Originally Posted by zippyonline

Does the vibration change with wheel speed (mph) or engine speed (rpm)? Because then one would suggest prop/driveline related vs. something wheel/suspension related.

Just got a quote back from BMW for the remaining nuts / bolts/washers and bushings I couldn’t buy from ECP with their reduction thingy. This is becoming a very expensive exercise (i.e. spending ¼ of the value of what I purchased the car for!) In for a penny, in for a pound! Lucky I own a socket set really…

its wheel speed starts around 60mph and goes about 90mph...think i may need to start with getting road force balance done first to rule out wheel tyre issues first.

[zippyonline]

Originally Posted by borinous

..think i may need to start with getting road force balance done first to rule out wheel tyre issues first.

You must know someone else with a 3 series, or a BMW anyway. I'd borrow a set of someone to test first - as you'd know that there wheels don't have an issue (providing you borrow a set off someone who you know doesn't have a vibratey car )

[borinous]

Originally Posted by zippyonline

You must know someone else with a 3 series, or a BMW anyway. I'd borrow a set of someone to test first - as you'd know that there wheels don't have an issue (providing you borrow a set off someone who you know doesn't have a vibratey car )

believe it or not but i don't know anyone with a 3 series!! lol

thats a good point though would save £50 i guess.

Or maybe just switch the fronts and rears...see if the vibration goes to the front

[rspete]

Originally Posted by borinous

interested to know what it was.

Only asking as i have a vibration from the rear on mine currently. handles fine goes straight and no tram lining. had my Indy give it a once over and found nothing at the rear that was loose or worn.....

ive just had to start buying bits and replace one by one till its gone.

Does it make a noise when doing this? Sounds similar to my issue, different thread, but mine definitely seems to be from front. Quietens when the steering is turned slightly to left...

[borinous]

Originally Posted by rspete

Does it make a noise when doing this? Sounds similar to my issue, different thread, but mine definitely seems to be from front. Quietens when the steering is turned slightly to left...

nope no noise at all.

[MattOz]

Any update on this Chris? Just wondering if you have managed to get to the bottom of things?

[zippyonline]

Hi Matt,

In short, as of last Friday, all parts have arrived (it's a big pile of parts!), but I was away this weekend and will be away next weekend, so looks like it'll be Christmas weekend!

[zippyonline]

All OEM parts, and I've even marked them up so I don't get confused.


E91 Suspension Parts by Chris Reeves, on Flickr

This better blinking work, but I can't really see why it wouldn't!

[wallsmk2]

My floor looks identical to yours at the moment. I am going through the same process but I have a great local garage to fit. I'd get hold of an impact wrench to make life easier. I found that a good squirt of ferrosol a few days before attempting rusty bolts made my life a lot easier when I did a front suspension refresh.

did you get your nuts and bolts through BMW? how much did they all cost? as I am just about to list all the bits I need.

[zippyonline]

Originally Posted by wallsmk2

did you get your nuts and bolts through BMW? how much did they all cost? as I am just about to list all the bits I need.

Here you go!


341 (05-12-2016) by Chris Reeves, on Flickr

The control arms I got from ECP on the blackfriday deal thingy.

[wallsmk2]

haha the bolts are more expensive than all the arms/bushes put together!


edit: i see there are a few squidgy bits on that list. I got the ball joints from gsf for about £30 for 2 in the black friday sale. Like you I couldn't get the mounts from ECP etc but found that onlinecarparts were really cheap. A bit hesitant on using them as they are in germany but received them in the end.

[zippyonline]

As a kindof update.

I chopped through one of the worn tyres...


Chopped by Chris Reeves, on Flickr

And then took a couple of measurements


montage-tyres by Chris Reeves, on Flickr

So fat bit like 13.4mm, and shredded inside edge is like 5.3mm.

Assuming the fat bit is pretty much full tread and how the tyre started on the car, that's 8.1mm of tyre worn out in 718miles, which is >1.1mm of tyre per 100miles

[MattOz]

Any update yet Chris? I've been wondering whether you've got to the bottom of the woes! Happy New Year by the way!

[zippyonline]

So to give the thread some closure, I'll update as to how the problem has been resolved.

Here's the rear suspension diagram for reference:


http://www.realoem.com/bmw/enUS/show...diagId=33_1230

As you know, I purchased all the upper arms (Lemforder OEM), item numbers 14, 18 and 19. I also purchased all new fixing hardware from BMW and the bushings for the lower control arm and semi-trailing arm. Over the Christmas / New Years break, I set about replacing these - it all started well being able to undo all the bolts without resorting to the windy gun.


E91-Bu-01 by Chris Reeves, on Flickr

I took the opportunity to give everything a proper clean.


E91-Bu-02 by Chris Reeves, on Flickr

And to treat the minor surface rust on the subframe.


E91-Bu-03 by Chris Reeves, on Flickr

Then obviously the bushings were a bit of a pain to remove, but a combination of brute force, holesaw, a new sabre saw, an air hammer and some swearing got the bushings out. Well, I ignored the trailing arm bushings for now as they actually seemed alright - and it's bloody cold and misty working on the car this time of year....that can wait till it's warmer!

So all upper arms replaced, and bushings in the lower control arm replaced - in the end with Powerflex items because I just didn't have the right kit to install the OEM ones.


E91-Bu-04 by Chris Reeves, on Flickr

------------------------------------------------------------------------------------

So, the cause of the problem... well this lot have been removed from the car:


E91-Bu-06 by Chris Reeves, on Flickr

All the bushings were cracked on the aftermarket items, and the guide rod (no.19) looks almost original! The subframe to lower control arm bushings weren't too bad - but you can see how medieval I got removing them!
Now, interestingly, the ball joint for the lower control arm / hub (no. 3) was a polybush - upon removing this as it was completely knackered. It appeared to be a "Rear Upper Lateral Arm to Chassis bush" and looked like one of these:


https://www.powerflex.co.uk/road-ser...Bush/1884.html

Looking at the diagram of what powerflex bushings go where, I should have a "Rear Lower lateral arm to hub bush", which looks like this:


https://www.powerflex.co.uk/road-ser...Bush/1885.html

They do slightly different jobs.

And here's a closer up picture of what the correct bushing should look like, next to the knackered incorrect one:


E91-Bu-05 by Chris Reeves, on Flickr

I have a strong suspicion that this may well be the root cause of the interesting handling and tyre wear characteristics - and why the car had reverted to a ridiculous camber angle.

------------------------------------------------------------------------------------

After fitting everything, I popped down to my local indy with a hunter alignment rig and got everything aligned right, then went out and did 180mile+ journey from Essex to the Peak District for the New Year - the car has never felt better!

When I got back, Hilda (I've named the car) was filthy and treated to a quick 2 bucket wash.


E91-Bu-cleaned by Chris Reeves, on Flickr
Happy bunny now