zedfourthreelitre
Member
Ah fair enough I presumed it would b a different rack
Scary/Twitchy feel over 65mph!
- Thread starter Marc'sCoupe
- Start date
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Anonymous
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I'm running 38 rear and 35 front, from memory this is what the Alpina Zed's recommend for none RFs
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Anonymous
Guest
I'll give it a try tomorrow, thanks. I did previously run them sightly lower and still had the steering pull and found the tyres wore unevenly, but will give it another try with the tracking done and winter tyres on!
I think it's something underlying, but nobody can seem to find out what it is!
I think it's something underlying, but nobody can seem to find out what it is!
Just a couple of observations based on my experience of successfully ironing out tramlining, then wander with suggestions from the Forum 
Ditching RFT's 6 years ago cured the tramlining and demonstrated the dramatic effect tyres have. My local tyre guy is pretty knowledgable owning BMW's and recommended brands with a rounded shoulder profile (like Falken) rather than square edged, as the rounded profile climb rather than resist shallow ruts which cause tramlining.
All was good until I switched from 17s to staggered 18s and Goodyear Eagle F1A2s and I developed a tugging wander particularly on motorways. I played with pressures which improved things a bit, changed front ARBs, lolypops and track rod ends all of which were servicable but worn. Things were better, but not perfect. Lubricating the steering linkage UJs (visible alongside the engine driver-side) and two different 4 wheel set-ups then replacing a broken rear spring for with standard height sachs, finally cured things :trampoline:
Looking at your journey you have non-standard toe angles and a notchy rack. With the unique set up on the E85/6 EPS it's vital to remove ANY resistance or slack in the steering system end-to-end ,as the steering input torque sensor is constantly comparing input loads with steering angles and adjusting. It's my theory that inconsistencies resulting from any tightness in the system Vs steering angles and feedback loads cause the constant tug-and-weave effect. Remember toe angles affect tyre resistance hugely, dialling in more toe to theoretically damp the steering and improve straight line stability may be having the opposite effect due to the EPS system. Any tightness in the system the same. Any slack in any of the bushes both front and rear needs sorting as movement on the rear will provide unwanted side-to-side inputs to the front (like a tiller on a boat). So I'd
Sort the notchy rack
Lube the steering shaft UJ's
get the wheel alignment on-spec
re-check all the bushes front and rear
go for tyres with a rounded shoulder profile (Eagles are kind of mid-way)
Check you are as close to standard as possible with suspension components (all 4 wheel set ups are based on standard spec, changes to standard spec require guess-work by the operative).
Check these damned springs!
Good luck, it's lovely when it's sorted
Ditching RFT's 6 years ago cured the tramlining and demonstrated the dramatic effect tyres have. My local tyre guy is pretty knowledgable owning BMW's and recommended brands with a rounded shoulder profile (like Falken) rather than square edged, as the rounded profile climb rather than resist shallow ruts which cause tramlining.
All was good until I switched from 17s to staggered 18s and Goodyear Eagle F1A2s and I developed a tugging wander particularly on motorways. I played with pressures which improved things a bit, changed front ARBs, lolypops and track rod ends all of which were servicable but worn. Things were better, but not perfect. Lubricating the steering linkage UJs (visible alongside the engine driver-side) and two different 4 wheel set-ups then replacing a broken rear spring for with standard height sachs, finally cured things :trampoline:
Looking at your journey you have non-standard toe angles and a notchy rack. With the unique set up on the E85/6 EPS it's vital to remove ANY resistance or slack in the steering system end-to-end ,as the steering input torque sensor is constantly comparing input loads with steering angles and adjusting. It's my theory that inconsistencies resulting from any tightness in the system Vs steering angles and feedback loads cause the constant tug-and-weave effect. Remember toe angles affect tyre resistance hugely, dialling in more toe to theoretically damp the steering and improve straight line stability may be having the opposite effect due to the EPS system. Any tightness in the system the same. Any slack in any of the bushes both front and rear needs sorting as movement on the rear will provide unwanted side-to-side inputs to the front (like a tiller on a boat). So I'd
Sort the notchy rack
Lube the steering shaft UJ's
get the wheel alignment on-spec
re-check all the bushes front and rear
go for tyres with a rounded shoulder profile (Eagles are kind of mid-way)
Check you are as close to standard as possible with suspension components (all 4 wheel set ups are based on standard spec, changes to standard spec require guess-work by the operative).
Check these damned springs!
Good luck, it's lovely when it's sorted
A
Anonymous
Guest
Thanks for the in depth reply!
It may help to say I didn't do this when I bought the car with ~42000m on the clock. I can't expect the steering rack suddenly became the problem? Especially when it's only notchy on full RH lock, it's buttery smooth on the rest of the rack.
I thought the UJs caused 'sticky' steering and it was solved in post-fact lift models?
The alignment set up I have at the moment is as close to standard as the mechanic could get. The ride height was spot on during setup, but rear camber couldn't be adjusted to the TIS suggested -2.5 as the bolts maxed out - this could be part of the issue.
The front and rear toe , and the front camber are spot on, TIS states total toe of 0.14 and mine is 0.15 front, rear 0.22 TIS vs 0.2 measured, and front camber of -57' and mine is slightly uneven at 51' and 55'.
I did notice the caster is out, but this is not changable.
So, two things I can think of, what could affect front caster and what would need changing to bring the rear back to -2.5 camber?
I'm almost certain the issue is mechanical, as mentioned with the EPS off, it still happens to the same extent, but with heavy steering!
Springs are in great condition too, two mechanics have checked these already.
It may help to say I didn't do this when I bought the car with ~42000m on the clock. I can't expect the steering rack suddenly became the problem? Especially when it's only notchy on full RH lock, it's buttery smooth on the rest of the rack.
I thought the UJs caused 'sticky' steering and it was solved in post-fact lift models?
The alignment set up I have at the moment is as close to standard as the mechanic could get. The ride height was spot on during setup, but rear camber couldn't be adjusted to the TIS suggested -2.5 as the bolts maxed out - this could be part of the issue.
The front and rear toe , and the front camber are spot on, TIS states total toe of 0.14 and mine is 0.15 front, rear 0.22 TIS vs 0.2 measured, and front camber of -57' and mine is slightly uneven at 51' and 55'.
I did notice the caster is out, but this is not changable.
So, two things I can think of, what could affect front caster and what would need changing to bring the rear back to -2.5 camber?
I'm almost certain the issue is mechanical, as mentioned with the EPS off, it still happens to the same extent, but with heavy steering!
Springs are in great condition too, two mechanics have checked these already.
carl2990 said:
No prob's 8)
re the UJ's they specifically don't cause the forum scurge of classic EPS sticky steering, thats thought to be down to binding inside the EPS unit in the worm gear. The UJs are very exposed to heat and muck and despite theoretically being sealed bearing units do loosen up if they are given some basic lube. It made an instant difference to mine and several others. They can cause binding, which is capable of being 'read' by the torque sensor and so starts a cycle of push pull between the torque sensor, EPs and angle sensor. For the sake of a dosh of lube it's worth a try and takes 5 mins and no tools.
Thought :scratchhead:
Castor can dramatically affect stability and steering inputs. Why is your castor out? It's not adjustable on these cars and there are only two things that can really affect it, incorrect front/rear ride height or worn/damaged front suspension struts/mounts/ties.
Castor can dramatically affect stability and steering inputs. Why is your castor out? It's not adjustable on these cars and there are only two things that can really affect it, incorrect front/rear ride height or worn/damaged front suspension struts/mounts/ties.
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Anonymous
Guest
Ewazix said:
Exactly my thoughts too....ride heights are spot on. What should I check in the struts, mounts and ties? Every mechanic who's looked says it's a good example and very clean underneath so could it be usual wear and tear to these components?
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Anonymous
Guest
http://www.hunterkorea.com/_uploads/_bbsFiles/WinAlign V12 BMW (English).pdf
Found the Hunter alignment guide online, page 28 states that cars with active front steering (steering-adaptive power assisted steering) requires calibration after an alignment.
Could this be the cause of the issue?
Also trying to figure out why the caster may be out, people have suggested looking at the suspension mounts on other forums, is it a 'common' issue for the mounting points to be distorted?
Found the Hunter alignment guide online, page 28 states that cars with active front steering (steering-adaptive power assisted steering) requires calibration after an alignment.
Could this be the cause of the issue?
Also trying to figure out why the caster may be out, people have suggested looking at the suspension mounts on other forums, is it a 'common' issue for the mounting points to be distorted?
I doubt you are going to find a single silver bullet to sort this, the reason people with the shimmy have such difficulty pinning down the culprit part is that it's almost certainly a cumulative problem of wear, distortion and misalignment in several parts - hence why it's advisable to sort one thing at a time to establish small improvements.
With where you are now and focussing on the fact you have incorrect castor you need to double check ride height is correct, both front and rear springs are not damaged or sagging and are matched and correct for the car. Most Z4s had rear springs break within a few years (mine at 3 yrs 20k miles and a second replacement set at 13 yrs 46k miles) and its easy to fit sport instead of SE or aftermarkets that are not the same, I reckon a lot of cars could now have mismatched front rear spring sets. BMW TIS has correct ride heights for models, measure from bottom edge of wheel rim lip to underside of wheel arch, and from memory with 80kg in each seat and the boot/trunk (need to check that).
Front strut top mount bearings do wear and are rarely checked. The rubber should be crack free with no side-side movement when wrenched around with the wheel jacked off the ground or bounced up/down on the ground. Any noised, creaks, groans and clicks are a sure sign.
see https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0648
The RTAb (part 8 on link) can be tricky to locate properly on the end of the lower wishbone, unless its seated properly on the wishbone spur and again would jigger fore/aft alighnment and castor.
https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0642
The drop links supports (part 5) locate the set up as well, play in the bushings or any bent/damage will put things out
https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0649
and the nasty one........... any history of front end repairs? A jig would really be needed, but a 4 wheel alignment would flag problems like unexplained alignment issues, which is what the castor being out is of course.
With where you are now and focussing on the fact you have incorrect castor you need to double check ride height is correct, both front and rear springs are not damaged or sagging and are matched and correct for the car. Most Z4s had rear springs break within a few years (mine at 3 yrs 20k miles and a second replacement set at 13 yrs 46k miles) and its easy to fit sport instead of SE or aftermarkets that are not the same, I reckon a lot of cars could now have mismatched front rear spring sets. BMW TIS has correct ride heights for models, measure from bottom edge of wheel rim lip to underside of wheel arch, and from memory with 80kg in each seat and the boot/trunk (need to check that).
Front strut top mount bearings do wear and are rarely checked. The rubber should be crack free with no side-side movement when wrenched around with the wheel jacked off the ground or bounced up/down on the ground. Any noised, creaks, groans and clicks are a sure sign.
see https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0648
The RTAb (part 8 on link) can be tricky to locate properly on the end of the lower wishbone, unless its seated properly on the wishbone spur and again would jigger fore/aft alighnment and castor.
https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0642
The drop links supports (part 5) locate the set up as well, play in the bushings or any bent/damage will put things out
https://www.realoem.com/bmw/enUS/showparts?id=BU53-USA-06-2007-E85-BMW-Z4_30si&diagId=31_0649
and the nasty one........... any history of front end repairs? A jig would really be needed, but a 4 wheel alignment would flag problems like unexplained alignment issues, which is what the castor being out is of course.
Very intersting reading through this thread.
Was a bit concerned with my own steering as i had exactly the same twitchy phenomenon and was planning to investigate.
It wasn't a huge problem and i had more pressing issues to deal with on the car so i left it.
By the time it came to put the winter wheels on (225x50 r16's all round) i couldnt believe the difference- all of the twitchyness has disappeared completely, no dead spot and incredibly smooth and relaxed steering on the motorway! The difference is day and night!
So now i'm wondering which way to go when the winter wheels come off; back to the original staggered 18's, fresh rubber on the back and a hunter alignment or go for a square setup of 225x40 r18's?
Also, ewazix, what lube did you use for the uj's? Ive got some high temp ceramic grease knocking about. Suitable or something thinner?
Was a bit concerned with my own steering as i had exactly the same twitchy phenomenon and was planning to investigate.
It wasn't a huge problem and i had more pressing issues to deal with on the car so i left it.
By the time it came to put the winter wheels on (225x50 r16's all round) i couldnt believe the difference- all of the twitchyness has disappeared completely, no dead spot and incredibly smooth and relaxed steering on the motorway! The difference is day and night!
So now i'm wondering which way to go when the winter wheels come off; back to the original staggered 18's, fresh rubber on the back and a hunter alignment or go for a square setup of 225x40 r18's?
Also, ewazix, what lube did you use for the uj's? Ive got some high temp ceramic grease knocking about. Suitable or something thinner?
A
Anonymous
Guest
No history of front end damage, no sign of this either, underneath looks very tidy. Like I say it didn't do this when I bought the car (where is the 'scratch head' smiley). Started doing it after a few months of ownership.
Forgot to mention the drop links have already been replaced, same time as the lower front control arms.
Three mechanics have checked for looseness by rocking the wheel at different positions, full lock, straight etc, 10 and 2 o'clock, 12 and 6 and so on.. Looked at the inner and outer tie rods, wish bones, RTABs, rack, test driving....unless three fairly good mechanics have missed something, there's nothing loose that's easily accessible.
Also checked the strut mounts in the engine bay today and the alignment pin is still in so I'd say they're in the stock position. Noticed on other forums signs of cracked strut mounts etc but nothing on the sort (luckily!!).
Good call about the strut bearings and rubber. To check this do I have to remove the strut?
All four springs are in very good condition, no paperwork to say they've ever been replaced and ride heights when loaded during alignment where spot on compared to the TIS low sprung sports suspension spec (attached).
Out of interest Chris, is yours also the sports suspension with the 18" rims? Apparently the 2 and 2.5l models never have this issue due to the smaller rim size.
Thanks for the help on this, its such a tricky thing to diagnose.
Forgot to mention the drop links have already been replaced, same time as the lower front control arms.
Three mechanics have checked for looseness by rocking the wheel at different positions, full lock, straight etc, 10 and 2 o'clock, 12 and 6 and so on.. Looked at the inner and outer tie rods, wish bones, RTABs, rack, test driving....unless three fairly good mechanics have missed something, there's nothing loose that's easily accessible.
Also checked the strut mounts in the engine bay today and the alignment pin is still in so I'd say they're in the stock position. Noticed on other forums signs of cracked strut mounts etc but nothing on the sort (luckily!!).
Good call about the strut bearings and rubber. To check this do I have to remove the strut?
All four springs are in very good condition, no paperwork to say they've ever been replaced and ride heights when loaded during alignment where spot on compared to the TIS low sprung sports suspension spec (attached).
Out of interest Chris, is yours also the sports suspension with the 18" rims? Apparently the 2 and 2.5l models never have this issue due to the smaller rim size.
Thanks for the help on this, its such a tricky thing to diagnose.
Attachments
Chris_D said:
The UJ lube definitely made a difference to mine and several others and I re-do mine a couple of times a year and have had no further problems, several lubes have been suggested, but I initially gave a squirt of a thin cycle oil to 'get in there' then some Red Line synthetic grease after a run. Probably all wrong but it worked fine and TBH anything will be better than a dry grotty UJ (but not WD40 that will flush out lubricants and leave things dry)
Interesting. Will be putting some new boots on the rears come the end of winter. If the twitching returns i'll be giving this a shot as a first step for curing it...Ewazix said:Chris_D said:
The UJ lube definitely made a difference to mine and several others and I re-do mine a couple of times a year and have had no further problems, several lubes have been suggested, but I initially gave a squirt of a thin cycle oil to 'get in there' then some Red Line synthetic grease after a run. Probably all wrong but it worked fine and TBH anything will be better than a dry grotty UJ (but not WD40 that will flush out lubricants and leave things dry)
A
Anonymous
Guest
Morning Chris!
Did you manage to get the fuse pulled? Did it make any difference or do you get the same result?
Did you manage to get the fuse pulled? Did it make any difference or do you get the same result?
Chris_D said:The UJ lube definitely made a difference to mine and several others and I re-do mine a couple of times a year and have had no further problems, several lubes have been suggested, but I initially gave a squirt of a thin cycle oil to 'get in there' then some Red Line synthetic grease after a run. Probably all wrong but it worked fine and TBH anything will be better than a dry grotty UJ (but not WD40 that will flush out lubricants and leave things dry)
Interesting. Will be putting some new boots on the rears come the end of winter. If the twitching returns i'll be giving this a shot as a first step for curing it...
carl2990 said:Morning Chris!
Did you manage to get the fuse pulled? Did it make any difference or do you get the same result?
Chris_D said:The UJ lube definitely made a difference to mine and several others and I re-do mine a couple of times a year and have had no further problems, several lubes have been suggested, but I initially gave a squirt of a thin cycle oil to 'get in there' then some Red Line synthetic grease after a run. Probably all wrong but it worked fine and TBH anything will be better than a dry grotty UJ (but not WD40 that will flush out lubricants and leave things dry)
Interesting. Will be putting some new boots on the rears come the end of winter. If the twitching returns i'll be giving this a shot as a first step for curing it...
Ummm Carl, no plans to pull any fuses. U might have ur wires crossed a little bit there in referring to previous messages.
I responded to Ewazix' idea about lubing the UJ's, not pulling any fuses....
However, if relevant I lubed my UJ's recently and while it doesnt make any discernible difference with my winter wheels on it will be interesting to see if it cures the twitchyness with my summer wheels when they go back on....
Just wanted to add my own experience to this thread, it could possibly save others some time and money.
I had the exact same problem as the OP, over about 65mph the car seemed to wander, especially on slight bends. Going round a right-hand bend on the motorway, you'd steer right but the wheel would feel like it was pulling left and you'd have to put in more effort than usual, then suddenly the wheel would go loose and the car would cut into the corner so you'd have to keep correcting the steering wheel. It felt very unstable and above 80mph it was downright dangerous.
I had the car 4 wheel aligned on a Hunter machine at a place recommended on a couple of other forums (MX5 and Alfa), but no change. I renewed lollipops, then track rod ends having the car aligned after both but neither solved it. The tyres are Pirelli and have stacks of tread left so I wasn't going to spend money replacing them. I saw several posts about Steering Angle Sensor resets and began to wonder if it was that. I removed the power steering fuse and test drove it, but the feeling was still there and worse if anything.
I took the car into Autokraft (recommended on here) and they said it was 100% alignment, take it to the place they use and they'd sort it. I took it to their aligners and they said there was too much toe-in on both the front and rear which was making the car 'dance' at speed. They aligned it properly and hey presto, it's now bang on.
My advice to anyone with this problem is to try a couple of different alignment places before you start replacing too many parts!
I had the exact same problem as the OP, over about 65mph the car seemed to wander, especially on slight bends. Going round a right-hand bend on the motorway, you'd steer right but the wheel would feel like it was pulling left and you'd have to put in more effort than usual, then suddenly the wheel would go loose and the car would cut into the corner so you'd have to keep correcting the steering wheel. It felt very unstable and above 80mph it was downright dangerous.
I had the car 4 wheel aligned on a Hunter machine at a place recommended on a couple of other forums (MX5 and Alfa), but no change. I renewed lollipops, then track rod ends having the car aligned after both but neither solved it. The tyres are Pirelli and have stacks of tread left so I wasn't going to spend money replacing them. I saw several posts about Steering Angle Sensor resets and began to wonder if it was that. I removed the power steering fuse and test drove it, but the feeling was still there and worse if anything.
I took the car into Autokraft (recommended on here) and they said it was 100% alignment, take it to the place they use and they'd sort it. I took it to their aligners and they said there was too much toe-in on both the front and rear which was making the car 'dance' at speed. They aligned it properly and hey presto, it's now bang on.
My advice to anyone with this problem is to try a couple of different alignment places before you start replacing too many parts!
