EPS Failure Rate, do they all go wrong in the end?

MACK · Post by **MACK** » Mon Jun 15, 2015 12:32 pm

Hi, Im new to the forum and Z4's and due to a change of careers i am going to be running my own car again which after some soul searching and shopping around is going to be a E85 3.0i/Si Z4. However after doing my homework the two killer faults seem to be the roof motor and the EPS issues. The cost of the EPS at circa £2,000+ is one that really worries me. It reminds me of when i have my 987 Porsche Boxster S upto about 5 years ago and back then all the talk on Porsche forums was of IMS failures and new engines cost £10k from Porsche etc. At the time you would be forgiven for thinking the failure rate was at least 50% or even that all rarely driven engines went bang. Checking back now the reality of the situation is the failure rate was between 1% and 8%.

So my question is, just how prevalent is the sticking steering issue. does every car eventually suffer from it? is the problem limited to a very small number? or is this a 50/50 chance type of deal? Does it still effect face lifted cars or had BMW got their act together by that point.

Also if you do end up fixing it i notice BBA Reman offer a repair service, has anyone used them and does it cure the sticking steering fault?

Sorry to have waffled on just want to get my facts straight before i commit to buying.

Thanks

Mark

yg54sg · Post by **yg54sg** » Fri Jun 19, 2015 11:15 am

2004 3.0ISE had it from new here, never an issue with steering or roof , with the roof the key is keep the drains clean and also use it in the winter, for the steering never had an issue i was under the impression the guys in the US with hotter climate have more of an issue with the sticky feeling.

jamesbond · Post by **jamesbond** » Fri Jun 19, 2015 11:41 am

Midhurstman · Post by **Midhurstman** » Fri Jun 19, 2015 12:02 pm

Neither are as common as it first appears, as we only usually read about the problem ones (no one posts that they have never experienced the problem until the subject crops up in a post). Keep the drains clean and check every 3 months or so and, as long as the pump and motor are not already soaked and rusting, it shouldn't happen to you. The sticky steering, as has been stated above was the subject of a 'fix' by BMW on the 2006 facelift. They redesigned the internal column mechanism to allow for expansion when hot (it seems as though a plastic bearing bush may have been the main culprit).

stupot67 · Post by **stupot67** » Fri Jun 19, 2015 12:22 pm

Hi,

From what I've read very few have had a complete failure of the EPS, and those who have had had issues with sticky steering have, by and large had great results by lubricating the centre bearing on the column.

The 2006- EPS only had minor changes from the earlier unit, these were a firmware change, dimensional tolerances on certain components and an improved synthetic lube suitable for plastic bearings and gear drive. This would indicate that tighter than optimum clearances and a less than ideal lubricant were causing high frictional loads that were causing the EPS to shut down to protect itself from overheating.

This would explain why the lubrication of the bearing seems to be so successful at curing the issue in most cases - What I'm trying to get at is I would'nt let this put you off of a particular car if everything else stacks up, even if it does exhibit sticky steering issues, it's by no way an automatic £2K+ bill.

Stu.

jamesbond · Post by **jamesbond** » Fri Jun 19, 2015 12:35 pm

GuidoK · Post by **GuidoK** » Fri Jun 19, 2015 12:43 pm

MACK wrote:
So my question is, just how prevalent is the sticking steering issue. does every car eventually suffer from it? is the problem limited to a very small number? or is this a 50/50 chance type of deal? Does it still effect face lifted cars or had BMW got their act together by that point.

Not all get it, far from it. Maybe 5-10% or so. Some facelifted cars also have the same steering column, so it's not that the facelifts do not have it.
And there seems to be a good solution now to repair those things, they figured it out on the german z forum.
It's not the greasenipple, but there is an adjusting ring that can be set correctly to fine tweak the interaction between electric motor gear and steering column gear.
I know of a few now that used this fix and it seems to be perminent.
So the cause is a misadjustment in the factory.

stupot67 · Post by **stupot67** » Fri Jun 19, 2015 12:58 pm

[/quote]

And there seems to be a good solution now to repair those things, they figured it out on the german z forum.
It's not the greasenipple, but there is an adjusting ring that can be set correctly to fine tweak the interaction between electric motor gear and steering column gear.
I know of a few now that used this fix and it seems to be perminent.
So the cause is a misadjustment in the factory.[/quote]

Hi Guido K,

Any chance of posting up a link to this post on the German forum, I think most are aware of the grease nipple/lube modification - but I certainly was unaware of altering the servo motor/gear "meshing" as a fix.

Stu.

Zikim · Post by **Zikim** » Sat Jun 20, 2015 10:59 am

I would also be interested in this solution on the German forum. Can you please post link.

MACK · Post by **MACK** » Tue Jun 23, 2015 12:23 pm

Thanks for all the responses, gives me a real sense of perspective on the occurrence of these and the fixes out there. Gives me a bit more peace of mind to go out and buy one!

panderoo · Post by **panderoo** » Wed Jul 15, 2015 10:51 am

I think this is the link from the German forum:

http://www.zroadster.com/forum/index.ph ... st-1943088

Lots of pages and I'm currently skimming through to see if i can figure out what they have done.

It seems that there is an eccentric ring between the EPS motor and the shaft that can be turned to dial out Sticky steering ...???!!! ( I dont speak german so this is only with my best efforts to translate )

hopefully someone else might be able to start looking through to see if they can drag more information out of there..

GuidoK · Post by **GuidoK** » Wed Jul 15, 2015 11:03 am

That's the post indeed. (or at least the thread. there are over 100 pages so there is a lot of good info, but its around that post that all starts becoming interesting)

On the dutch z forum there are also good responses on turning the eccentric ring, although it isn't easy. Hard to reach, the 6mm allenhead screws are tight, a lot of people struggle to get them loose.

Basically the theory about why sticky steering occurs is the friction between steeringshaft cog and electric motor cog (which is a worm wheel).
That sometimes can be solved by extra lubrication, but what the eccentric ring does is position the electric motor cog on the steeringshaft cog (so you;re basically set the slack tolerance).
The extra lubrication however won't have a bad effect when you use high quality high pressure grease (maybe something like teflon grease or white lithium grease)
I know of one guy who did this fix and said that when he was fiddeling with the eccentric ring, and he turned it too far, the steering became even too light, so there is some trail and error involved. With this guy just extra lubrication wasn't a permanent fix but from what I know after ajusting the eccentric ring it's still fine. Even after these crazy heat days.

My guess is that in the factory there is a margin of how the cogs should be adjusted, and some assemblers took the one side of the margin, other the other. And one side turned out to be too tight. From what I can see this is the only part of the steering column that needs adjusting on the assembly line, so it makes sense that if set incorrectly it gives unwanted side effects.

When you try this fix it's obviously wise to mark the factory setting of the eccentric ring so you can always go back to the factory setting.

Its the red ring between the electric motor and steering column in the picture below:

Luckily my steering works perfect so I havent had to hassle with it

(but it's nice to know if bad luck would strike me in the future)

bladeowner · Post by **bladeowner** » Sun Jun 05, 2016 1:35 pm

Well I finally got round to moving the eccentric ring today. It took me 4 attempts:
1. The German website said the bolts are 6mm hex/ allen heads - Mine are male Torx heads - put the cover back on
2. Bought some small sockets - couldn't get in with the small ratchet - put the cover back on.
3. Bought some more 1/4" drive extensions - still couldn't get in - put the cover back on.
4. Bought some spanners - Success! I bought these:
http://www.ebay.co.uk/itm/171533653969? ... EBIDX%3AIT
but just needed the E10 one really.

I moved the ring back 5mm and went for a short test drive - no errors and I thought the steering felt a little better but it's too early to tell as my sticky steering isn't too bad and even then usually only happens after extended use or it's hot.

jimbo1958 · Post by **jimbo1958** » Sun Jun 05, 2016 2:49 pm

bladeowner wrote:Well I finally got round to moving the eccentric ring today. It took me 4 attempts:
1. The German website said the bolts are 6mm hex/ allen heads - Mine are male Torx heads - put the cover back on
2. Bought some small sockets - couldn't get in with the small ratchet - put the cover back on.
3. Bought some more 1/4" drive extensions - still couldn't get in - put the cover back on.
4. Bought some spanners - Success! I bought these:
http://www.ebay.co.uk/itm/171533653969? ... EBIDX%3AIT
but just needed the E10 one really.

I moved the ring back 5mm and went for a short test drive - no errors and I thought the steering felt a little better but it's too early to tell as my sticky steering isn't too bad and even then usually only happens after extended use or it's hot.

Good work Dave......we'll give it a good test in a few weeks.

Grumpyowl · Post by **Grumpyowl** » Sun Jun 05, 2016 3:04 pm

bladeowner wrote:Well I finally got round to moving the eccentric ring today. It took me 4 attempts:
1. The German website said the bolts are 6mm hex/ allen heads - Mine are male Torx heads - put the cover back on
2. Bought some small sockets - couldn't get in with the small ratchet - put the cover back on.
3. Bought some more 1/4" drive extensions - still couldn't get in - put the cover back on.
4. Bought some spanners - Success! I bought these:
http://www.ebay.co.uk/itm/171533653969? ... EBIDX%3AIT
but just needed the E10 one really.

I moved the ring back 5mm and went for a short test drive - no errors and I thought the steering felt a little better but it's too early to tell as my sticky steering isn't too bad and even then usually only happens after extended use or it's hot.

Without having to read 100 pages, on your 4th attempt did you move it clockwise or anti-clockwise ?
It may help others

Z4-forum.com

Z4-forum.com