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FWIW, fq88, which part number did you get? The -40 is known for this problem on early production run ISFs, the -41 is supposed to have significantly alleviated that with some other improvements to the assistance curve. The -42 (the part I have) has all those quirks fixed and provides the best feedback for a gradual power assist curve, esp on the corners. It's also more pronounced when in sport mode. If you got the -40, you probably got the one with a defect. If it's the -41, then could very well be a physical issue. If it's the -42 and it's still doing this, it's physical.
My steering NEVER binds, even when I was on the original EPS for my 2014 350C. The -42 EPS just got rid of that over exaggerated boost, gave dead center much more feel/effort and provides added, gradual effort when canyon carving, vs. what really just feels like an on-off switch with these cars.
Oh, hmmm.. so while it could still be a physical issue, that might be your problem. I'm surprised no one on this thread mentioned the -40 propensity to bind/have a notchy feel. That's why the 40 is usually much cheaper than the 41, 42 versions. Most ISF owners have swapped out their 40 for the newer versions.
Oh, the issue is commonly referred to as "notchy" steering or "binding" vs the "sticky" feel that is in the thread title. Just in case you want more info on looking it up. There's also a couple of TSBs that describes ways to possibly fix it physically, but that includes actually having to replace steering components or the steering rack itself. Generally, it seems like the 41+ upgrades were the more common solution. However, anything is possible now that these cars have much higher mileage and are much older, so it might be one or more issues causing this, but I'd look at the 40 EPS as being suspect.
Oh, the issue is commonly referred to as "notchy" steering or "binding" vs the "sticky" feel that is in the thread title. Just in case you want more info on looking it up. There's also a couple of TSBs that describes ways to possibly fix it physically, but that includes actually having to replace steering components or the steering rack itself. Generally, it seems like the 41+ upgrades were the more common solution. However, anything is possible now that these cars have much higher mileage and are much older, so it might be one or more issues causing this, but I'd look at the 40 EPS as being suspect.
Yep, I originally had the -40 version for a few months, didn't fix the problem, bought the -41 version for a 2011 ISF and now I don't have that "dead space" issue where it feels like power assist stops working for a second. Fixed my issue for sure
What would be a suitable grease to re-grease the steering shaft u-joints? Think I would stay away from cheap lithium spray grease as it tends to dry out (low viscosity), it can actually dry up into a white lithium soap, lol
Yep, I originally had the -40 version for a few months, didn't fix the problem, bought the -41 version for a 2011 ISF and now I don't have that "dead space" issue where it feels like power assist stops working for a second. Fixed my issue for sure
Originally Posted by MikeFig82
So if I'm looking at the diagrams correctly the AWD has a different steering shaft.
AWD sealed close to steering rack.
RWD is an exposed joint.
Originally Posted by primavera
What would be a suitable grease to re-grease the steering shaft u-joints? Think I would stay away from cheap lithium spray grease as it tends to dry out (low viscosity), it can actually dry up into a white lithium soap, lol
Those joints are not ment to be serviced. They are staked into place... So the test is to remove the shaft and rotate each joint through its axis feeling for binding or notchiness. If present, it's damaged and needs replaced.
Granted this is an extreme case but lube won't undo mechanical wear.
