[Surly73]

Originally Posted by Luky

Started the rears and got the top 3 nuts on each side loosened. Also got the big bottom nut loose on each side. Was going to pull off the rear arm for removal per the video, but I broke my neighbors T40 socket getting the front end links torqued (craftsman too). The lower rear ball joint also uses the T40... So I am heading up to Lowes to get a new one this morning. Although I think I will remove the federwell liner instead now that I have read that piece of wisdom.

With well liner removed there's no need to remove anything else (as I see you're going to try next). I also broke my T40 retorquing sway bar links.

I got new top plates and spring pads for both front and rear so I can keep the originals as full assemblies. The new self threading screws for the front top are more robust. The original were E12, but the heads on the new ones were E16. Same threads and length. Also the lock nut on the front lower wishbone bolt is different. The original has a nyloc style insert with a built in washer, and the new ones are simple flange nuts with "tight" threads on one end (definitely single use) This looks to be a cost reduction effort (we do a lot of this at work). I put some blue lock-tite on these as the 66 ftlbs from TIS seemed low...

My originals were hex head and seemed much lighter weight than the replacements. Not that those are highly torque or anything. I'll have a little more to say on those bolts in my second part update coming soon.

As I see you've written later, the bottom fork to wishbone bolt is NOT 66 ft-lbs. It's 66 ft-lbs to joint and then 180 degrees. That is REALLY tight. If you're at 66, don't drive. I could only manage about 160 degrees on those without my spidey sense telling me I was going to break something. Meanwhile, all the youtubers do a couple bangs on a 3/8" drive electric impact on the same used bolt and call it a day.

Any fastener shown in TIS with a joint + angle I will never reuse except in emergencies (and temporarily). Call me overly anal if you like - so are the Germans who designed this thing

I do have a question from the TIS torque chart. For the front strut bottom bolt (RWD) it says to torque to 90 Nm (66 ftlb). This seemed loose compared to the removal force. However it also say 180 degree? Does this mean to torque to 66 ftlb and then go another 180 degrees?

The front end links have a similar callout of (45 Nm) 33 ftlb & 45 degree....

You've got it

Also the rear shock bottom bolt torque chart calls out M16 = 250 Nm (184 ftlb) or M14 = 165 Nm (122 ftlbs) so looks like you have to measure the bolt threads to see which size you have.

Going from memory different models have different bolt sizes. You'll see that only one size applies to the F10. I think the F10 M5 is one of the models which has the smaller bolt (oddly).

Originally Posted by MatthewLC

@Surly73 good luck with the rest, hopefully it all works out well! I have no idea how much additional complexity an xi adds to this job but it seems like you've figured out a decent process.

A lot. I'm still a little nervous about my front CV joints which slid apart internallly during the process on both size. I don't BELIEVE that I will have allowed any front diff fluid to escape into the gaiters. I think you have to pull the drive shaft for that to happen. Honestly I don't know and I still have that nagging in the back of my mind. Everything worked find on the test drive.

Like I mentioned earlier the only issue I had with mine was getting enough droop to get the OEM spring/shock combo out in the front. Everyone seems to have a different method of achieving that, my goal was to take as little apart as possible. I just loosened the front rack a little to give the suspension so more droop and was able to get everything out without removing anything else (including sway bar or any other control arm). I think this may only apply to a RWD though.

I don't think that would simplify it enough on an X-drive with the driveshafts. If you dropped the rack I think that means you had to remove the stiffening plate. Watch out for those single-use torque to yield fasteners there too. I order them in sets of 10 from ECS now.

I was fortunate that I had an impact gun to remove the rear lower shock bolt so it wasn't a struggle for me. You will need a shallow socket, swivel and extensions to get at it as it's pretty tight.

I am a little surprised that swivels would transmit enough torque without breaking. Cool. I got it loose on the back with a breaker bar. I don't think I could have loosened my LF (which was tighter everywhere than RF) without air impact. It took 3 rounds of the complete 8gal tank on my compressor to get it off. That's the 66 ft-lbs + 180 degrees one.

You just need to figure out the process that works for you. Once that's done the job becomes pretty quick. The first time I did mine it probably took me 4 hours. Now that I know what works, I could probably swap everything over in an 1.5 hours.

I found that in the rear. The front took me a long time. Lots of thinking, back inside to look at torques and TIS again. Devising undocumented helpful things like pulling the front sway entirely. Thinking things through so that I wouldn't have to undo any single-use fasteners to redo something. I did RF first and thought I figured out stuff but then different stuff slowed me down on the LF.

I basically unpacked, built, bled, tested my Quickjack and raised the car on Friday AM. Day job Friday PM. Got started on the rears and I think got one corner 100% complete Friday PM. Had some other things to take care of Saturday AM until about 10-1030 when I started again, and I finished at 8PM. I worked alone, no helper, stopped for a few breaks and research here and there. Working alone increased time to get the strut tops aligned and things like that for sure.

[Surly73]

Lessons learned PART 2:

Now where was I? Ah yes, #11

step 0/ start with prayer. Not kidding.

11/ it's a bit of a recap but again I'll talk about replacement fasteners. The front lower bolt strut fork to wishbone. It's pretty meaty and TIS specs 66lt-lb to joint plus 180 degrees. Again, I had the biggest breaker bar HF sells and this got tough after 90 degrees. I did not get completely to 180 degrees without something in my brain telling me "that's enough".

12/ It's important to note that torquing in NORMAL position is required for both upper wishbone bolts and the lower fork bolt.

13/ Be careful of the height sensor in the LF. There are multiple ways this could be taken apart and disconnected. I ended up disconnecting the metal attachment from the plastic sensor arm. This was the path of least resistance with the salt corrosion present and allowed the sensor arm to fall flat against the body of the car and be the most out of the way. It's one 10mm nut.

14/ Strut tops/hats - they're aluminum and come with no threads. The first time the single use bolts are threaded in they cut new threads. I was working alone with no helper for alignment of strut tops front or rear. I held the new struts up in place with one hand and threaded a new bolt in just a turn or two.

15/ Front reassembly I figured made sense - a/ get the strut mostly in position b/ insert the bolt only in the strut fork/wishbone to get some control over where the strut flops c/ line up the hats in the towers and hand thread a turn or two of the new bolts d/ with them hanging perform any rotation necessary to perfectly center e/ check everything f/ start inserting upper wishbone bolts - front slides in, rear will have to turn in a couple of turns g/ check everything h/ you may or may not have to pull the strut top bolts again to allow the strut to move more to drive the upper wishbone fasteners i/ if you removed them, get the top bolts threaded in a couple of turns again j/ raise suspension to normal position k/ fool around with all the crap you need to do to get proper torque on the wishbone l/ call Hercules to fasten the lower bolt m/ get your hand tools and nicely switch evenly between the three strut top bolts until tight, torque precisely n/ lower suspension.

16/ For sensor and other lines I only had to pull them from their guides, I didn't have to outright disconnect any. Don't forget to reattach them to their guides and hook up the height sensor again.

17/ If you don't have an 18mm spanner I found I really could have used one in a few places to make things easier. I forgot I had an offset box wrench in 18mm until the end of the job, they weren't with the rest of my tools yet.

18/ put protection on your fender lip. I had three layers of masking tape. Some of the parts you're wrestling with are heavy, have sharp edges and inertia. It wouldn't take much of a "slip" to have nasty cosmetic damage.

I'm not sure that I've completely escaped collateral damage. I hope my front CV joints are OK and that there was no route for diff fluid to escape into the joint. (I don't believe so).

Impressions: I've only been on a 10-15 minute drive and the start of that was very cautious and close to my home listening and feeling for anything out of the ordinary.

It's firmer, but I still think I'm acting my age. I have about 1 finger of fender gap and will fine tune that a little. I sensed I needed an alignment before but now I can't even tell. I think having dive, squat and roll more under control means things don't get out of shape as easily.

I took a couple of reasonably well known routes where undulations or whatever would cause mid-corner corrections, porpoising, bump steer and all that - all gone. For instance I can again (like on my E90 and E39) come into a quick left hander, spot my apex, spot the leading edge of the road median on exit, roll on the power before arriving there and track exactly where I intended.

I was observing that despite being ridiculously soft, on my summer rubber I was noticing cracks and broken pavement felt really harsh. That's improved now despite the extra firmness. No "crashing" over stuff just "oh there it is".

Steering maybe feels a little heavier and more direct. It turns in faster, even though that doesn't make a tons of sense. It's still numb, but that's the good ol' F10. I wonder if bushing mods to increase caster would change that any.

Dive and squat is very noticeably reduced, but not gone like some youtubers seem to show. It's much better and gives me more confidence on the brakes for sure. I'm sure it helps that the alignment isn't changing so much during heavy braking too. It's now much easier to confidently put power down and feel like things are going just how you want them drama-free. Stock suspension, not so much since installing MHD.

So - pretty great so far. My F10 now deserves to wear the PS4S I've put on it, IMO.

For sway bars I was getting so tired at the end of the job I left them alone. I was thinking of swapping to the factory front bar since I had the front off anyways but I didn't want to go to the back and start taking things apart to swap it to either factory or 650i rear bar too. I remember the rear bar being a struggle to get in/out around the suspension.

I've got no problem with the stiffness of the bars at the moment. As a matter of fact, it works better. On the stock suspension with upgraded bars the chassis is all over the place and you can feel where the bars are working and actually bounce or oscillate. So far with the coilovers keeping the body more in control the negative side effects of stiffer bars don't show as much. (In the whole 15 minutes I was out anyways)

[Luky]

Was shooting for 1/2" lower when I set them up but after install it is exactly 1" lower on each corner... Set each corner exactly 1/2" below manufacturers "high" limit for this application so I guess if I had set right at the "highest" it would have lowered it 1/2"... It drives nicely (set at full soft #1 on each corner). Guess I will wait to see if it rubs anywhere before I try to "raise" it up as it is a bit low for my tastes. (Old Fart)

Before:





After:

[Surly73]

Originally Posted by Luky

Was shooting for 1/2" lower when I set them up but after install it is exactly 1" lower on each corner... Set each corner exactly 1/2" below manufacturers "high" limit for this application so I guess if I had set right at the "highest" it would have lowered it 1/2"... It drives nicely (set at full soft #1 on each corner). Guess I will wait to see if it rubs anywhere before I try to "raise" it up as it is a bit low for my tastes. (Old Fart)

I'm going to keep looking at my ride height. I think the car looks "good" now, not too low (although spacers on the rear would probably be a good idea cosmetically). I still have one finger of gap. Looks aren't everything though and I predict that even though I have the non-sport front and rear bumpers I'll start having trouble in the winter, I won't be able to drive up on my ramps for oil changes etc...etc...

Since KW adjusts preload and ride height together I'm not just going to change it willy nilly. I'll drive a couple of days and assess. If I had independent adjustment I would probably bring it up 10mm at least.

[Surly73]

So far the ride height is around 350mm, not the 340mm I thought it would be. It might still be settling.

Might be just a smidge harsh for me but I'm leaving the settings alone while I get used to it. Might back off the compression setting a click and see what I think. What I really feel is how much faster the spring rate is especially in the rear. Been floaty-boating for so many years...

For the first time in the F10 I can feel the beginning of understeer scrub once or twice from the front. Never felt that communication on this platform yet.

[Luky]

Originally Posted by Surly73

So far the ride height is around 350mm, not the 340mm I thought it would be. It might still be settling.

Might be just a smidge harsh for me but I'm leaving the settings alone while I get used to it. Might back off the compression setting a click and see what I think. What I really feel is how much faster the spring rate is especially in the rear. Been floaty-boating for so many years...

For the first time in the F10 I can feel the beginning of understeer scrub once or twice from the front. Never felt that communication on this platform yet.

Go out to an empty parking lot and try some hard 30-40 mph turns. Finding mine has a fair amount of understeer now. Need to try setting the rear shocks to 4 or 5 (found I cannot reach the knobs with the tires on ), maybe reduce rear tire pressure a couple PSI (running a 255/35-20 square set up now @ 38psi). If that doesn't do enough I may take the M5 competition package front sway off and go back to stock msport front sway. Already have the H&R rear sway.

How/where are you measuring 350mm for your ride height? I am measuring ~24.5" (622mm) from the bottom edge of the wheel (rim) to a marked spot directly above the wheel center to the edge of the fender with 20" wheels. (Checking this way takes tire pressure and tire side height out of it.)

After sitting for a week and driving about 50 miles it does not seem to be settling anymore. Will probably try to raise the front about 10mm and the rear about 15mm next weekend. I am shopping for an electric impact wrench and looking at the Dewalt 20v XR 1/2" drive, monster torque to take anything apart but it is a really big device. Thinking that realistically I would be better off with the 3/8 drive version that will do ~150 ftlbs which should be plenty for 98% of what I'll use it for (lugs, brake jobs, etc). It's much smaller and I can leave it in the trunk... My work gave everyone a $100 Amazon gift card "thank you" (we are all working 50-60-70 hour weeks to support making Ventilators) so I may as well buy something useful.

[Surly73]

Originally Posted by Luky

Go out to an empty parking lot and try some hard 30-40 mph turns. Finding mine has a fair amount of understeer now. Need to try setting the rear shocks to 4 or 5 (found I cannot reach the knobs with the tires on ), maybe reduce rear tire pressure a couple PSI (running a 255/35-20 square set up now @ 38psi). If that doesn't do enough I may take the M5 competition package front sway off and go back to stock msport front sway. Already have the H&R rear sway.

I agree. I haven't done any of the parking lot "skidpad" tests to check the balance. I was thinking (but didn't ever tell anyone) that I wondered if it tended more to understeer than ever before and now you've said the same thing. That's interesting because it would have to mean that the front has gained a lot of firmness relative to the back, but if anything I feel the rear received the biggest boost in firmness. It sounds like we're running very similar sway setups except I have the M5 front, not M5 CP front.

See my other post on tire inflation and load ratings. On my summer package the door sticker recommended 35/39 became 36/37 if you consult the load tables. That's going in the wrong direction, I know, but still interesting.

I could look at going back to non-sport stock front end. A non-sport front sway paired with an H&R 20mm rear sway should/could oversteer like crazy. Part of me would love to get the original sway with proper end link orientation back on the front as long as the balance was sorted...

I can say that the platform is WAY more predictable than before. I can confidently enter into turns without wondering what mid-corner adventures await me when I encounter any mid-corner road undulation or when the floaty suspension "bounces" off of the sway bars. I can also say that it seems confirmed that ultimately there is less grip to go with that control (since compliance increases grip, e.g. drifting cars are super firm) and now I'm to the point where I could probably break things loose while still in control. With stock suspension PS4S never came anywhere near to breaking free from what I could detect. It just felt like you weren't going to make it.

There's simply no time or place to do any real testing - still working on that.

How/where are you measuring 350mm for your ride height? I am measuring ~24.5" (622mm) from the bottom edge of the wheel (rim) to a marked spot directly above the wheel center to the edge of the fender with 20" wheels. (Checking this way takes tire pressure and tire side height out of it.)

I am measuring the "old" way - from spindle center to fender. I remember when working on my E39 I would look up ride heights and stuff and it was all spindle center to fender. Looking up the F series now it's wheel lip to fender which I think is dumb. Now there's different tables for different wheel sizes in TIS and it only gives you measurements for the wheel diameters that platform came with. Easier to measure, sure, but ugh. I converted everything from multiple sources into spindle-center measurements and keep it in a spreadsheet with other working numbers.

I believe I will be raising my rear a few mm. I will probably also be softening a couple of clicks. I want to research multiple sources on tuning rebound and compression. I'm awaiting some advice from KW since altering ride height also alters pre-load.

I have some techniques which apply to bikes stating that rebound is a characteristic of vehicle weight (with occupants) and suspension and that there is only one correct setting which can be determined my test driving off of a drop. (best filmed in slow mo with a phone outside of the vehicle) Considering many lower tier adjustable suspensions are only rebound adjustable I find this interesting.

The same tuning advice says that compression setting is where "preference" enters, and where the real input on what the driver wants the vehicle to "feel" like comes from. I would want the dampers to break in a little more before doing any critical settings but it would be interesting to play with. I might take my rear speakers out and head out some time when I have time on my hands and do some playing. I'd have to see if I could come up with a way of reaching the rear compression adjustments while out on the road. I expect I could reach the fronts by turning the steering.

I'm interested to hear anything more from anyone regarding over/understeer following coilover installation - particularly KWv3s. With my E39 and E90 I could really just feel where things stood. The F10 seems a lot more complicated.

[BimmerHausPerformance]

I feel like may car is perfectly balanced as it sits right now, but it is rwd. I'm sure that makes a difference. CO, h&r sways front and rear, front strut bar, and shortened end links to set the front sway at the correct angle.

[Luky]

Originally Posted by BrowBMW

I feel like may car is perfectly balanced as it sits right now, but it is rwd. I'm sure that makes a difference. CO, h&r sways front and rear, front strut bar, and shortened end links to set the front sway at the correct angle.

What end links did you get for the front? I had started a post about adjustable end links for the F10 but doesn't seem like something most people consider when lowering. I can see the divots in my plastic shroud where my end links have rubbed. I also found there is no adjustable end link for the F10 rear as the studs are two different sizes. (I considered buying two sets of adjustable (M12&M10 I think) and swapping one end out on each and then selling the extra set to another F10 owner). Race shop I spoke with really did not think it was cost effective for a DD that was not going on the track (was asking about corner balancing ) since BMW are so good from the factory.

I raised my front 1/4" and my rear 1/2" today. Now I think the ride height/look is perfect for my taste. Even gap (1/4"-1/2") between tire/fender all around Also set tire pressure to 38 fr/36 rr (Pilot Sport AS3+). Set dampers to 4 out of 10 all around. It definitely improved the handling/feel. Car hooks up, chirps into second in WOT, is almost neutral (slight understeer) with controlable drifting. Set up my dragy and tried a couple runs on a long protected/divided, (mostly) straight with no traffic. Using launch control I got a 0-60 in 4.65s, 1/8 in 8.33s and 1/4 in 12.77s. Not bad for a Dad car. started to feel a little floaty about 130 when I shut it down. (Never had it up that fast before). Now I need some more time behind the wheel to get used to the new feel. I am definitely liking it.

[BimmerHausPerformance]

Lucky, I posted a whole thread on this because you got me thinking about it. Check out the thread. I had some issues with my CO I am working out and then I plan on posting more about the end links and how I overcame the issues on the m12/m10 size differences. Basically I am creating a threaded sleeve to make it work with some bimmerworld links.

[Luky]

Originally Posted by BrowBMW

Lucky, I posted a whole thread on this because you got me thinking about it. Check out the thread. I had some issues with my CO I am working out and then I plan on posting more about the end links and how I overcame the issues on the m12/m10 size differences. Basically I am creating a threaded sleeve to make it work with some bimmerworld links.

Saw your thread. Just did a search for end links and had this pop up. Looks interesting...

https://steinjager.com/shop/products/builders-parts

[Surly73]

Originally Posted by Luky

Also set tire pressure to 38 fr/36 rr (Pilot Sport AS3+).

Car hooks up, chirps into second in WOT, is almost neutral (slight understeer) with controlable drifting.

Why higher front pressure than rear? That's never been a BMW spec - always higher in the rear. Higher pressures reduce compliance and grip. The sharper handling felt from higher pressure comes at a cost and is often confused for grip (based on decades of observing the Internet ).

If you run the rears higher than the fronts you may dial out the remaining understeer (although slight understeer bias is almost certainly safer for a "dad car" not always driven with a high degree of focus.

Accident avoidance in the rain while out for groceries, for instance, would be better if you scrubbed a little rather than spun.

[Luky]

Originally Posted by Surly73

Why higher front pressure than rear? That's never been a BMW spec - always higher in the rear. Higher pressures reduce compliance and grip. The sharper handling felt from higher pressure comes at a cost and is often confused for grip (based on decades of observing the Internet ).

If you run the rears higher than the fronts you may dial out the remaining understeer (although slight understeer bias is almost certainly safer for a "dad car" not always driven with a high degree of focus.

Accident avoidance in the rain while out for groceries, for instance, would be better if you scrubbed a little rather than spun.

I am not running standard BMW size. Also NRF tires. And I do like to drift around corners. It's not fast but it is fun... People here cannot drive in the rain and crash often. I grew up outside Chicago driving on snow and ice so when it is wet here its time to have some fun.

Google "how to reduce understeer". I raised the back, stiffened the rear shocks and reduced tire pressure 2 psi. It helped make it more neutral.

Ways to Correct Understeer: ( go opposite to fix oversteer)
Raise front tire pressure
Lower rear tire pressure
Soften front shocks and stiffen bump
Stiffen rear shocks
Lower front end
Raise rear end
Install wider front tires
Install narrower rear tires
Soften front sway bar
Stiffen rear sway bar
Increase front negative camber
Increase positive caster
Soften front springs
Stiffen rear springs

[Surly73]

Originally Posted by Luky

I am not running standard BMW size. Also NRF tires. And I do like to drift around corners. It's not fast but it is fun... People here cannot drive in the rain and crash often. I grew up outside Chicago driving on snow and ice so when it is wet here its time to have some fun.

Google "how to reduce understeer". I raised the back, stiffened the rear shocks and reduced tire pressure 2 psi. It helped make it more neutral.

Ways to Correct Understeer: ( go opposite to fix oversteer)
Raise front tire pressure
Lower rear tire pressure
Soften front shocks and stiffen bump
Stiffen rear shocks
Lower front end
Raise rear end
Install wider front tires
Install narrower rear tires
Soften front sway bar
Stiffen rear sway bar
Increase front negative camber
Increase positive caster
Soften front springs
Stiffen rear springs

Except that the authour has the pressure statements backwards, like so many people do. You reduce pressure to increase grip (within safe operating range of "properly inflated" of course). All the others are the right way around.

This is what I was saying - the Internet is full of people who feel the faster response and "hard" feeling of higher tire pressure and confuse those characteristics for grip.

TL;DR - go back to 35/39 as an experiment and see if some of your understeer is dialed out.

[Surly73]

OK - something's come up. Documenting this in the DIY thread... I have never seen what I'm about to document mentioned in any suspension DIY thread I read for any chassis type while preparing for this job.

COVID has really changed my driving patterns and, as it happens, I really haven't done much full night driving since I installed the KWs. Running a couple of blocks through town near my house doesn't really count and I realized after thinking about it that's all I've done.

I noticed on Sunday night about 5 minutes into a 1h highway trip that my headlights seemed high. The more I watched the more I was sure something wasn't right.

As part of the coilover install the LF ride height sensor gets disconnected and the LR one isn't touched. I was careful about executing this disconnection - I observed no drama, no accidents, nothing was bent, and by my recollection the linkage was reassembled correctly.

Before getting into things I searched online and apparently on various 3 cars (E9x and F3x) it's common for the rear sensor to be assembled wrong and they get their lights pointing way too low after lowering. Easy fix for them. There's less reading on the lights being too high but everyone who reported it eventually found their linkage was assembled wrong or disconnected in error.

I went in and double checked everything. On the F10 there's only one proper way everything goes together. It matches the pictures in ISTA and there isn't anything clearly wrong with the sensor, bracket, link etc... that it may have been damaged. With the car on the ground I could not reach and disconnect the rear sensor to test whether it was functioning (other than trying to bounce the car and seeing the lights react), but I could turn the front wheels to the right and reach the LF sensor. I disconnected the linkage and moved the sensor arm by hand. It was clear that it still seemed to be working and that the levelling system had the headlights at the top of their adjustment range all the time. THE FIX IS NOT TO RE-AIM USING THE ADJUSTERS - or you'll end up with the manual "aim" adjustment being at the lower limit of travel and the self-levelling motorized adjustment being rammed to the high limit of travel.

I was wondering if the sensor was faulty, or giving glitchy readings, or if the rear one was bad. I connected ISTA and went to the ride levelling service function and executed the program.

It asked wheel size and some other questions, then informed me that I am to achieve the nominal ride heights of R 628mm and F 642mm (as measured from the bottom rim lip - the "new way") I said "OK".

Then it asked me to measure the LR ride height and enter it into the box - should be 628mm - is measured 602mm. "Are you sure", warnings about entering incorrect values etc... Yes, I'm sure. "You entered 602mm, the car reads 603mm". Cool, I thought. That confirms things are working right and it has some real intelligence of the ride height not just keeping things "level". I accepted the values and moved to the front.

Front target height 642 - I measure 620 - are you sure? YES. Car reads 583! Well - that's quite different. Why is that? I told it to accept the values, it re-leveled the headlights and now everything is fine. The motorized self-leveling went back to the mid-point of travel and all is good.

So - if the LF sensor seems to be mounted and working fine, and not bent out of shape, why does/did the car think the front was much lower than it was? I intend to go back out with ISTA and run the leveling adjustment again. I had an idea after finishing - I wonder if a second time around it will still tell me that the car thinks the front ride height is at 583 or whether the calibration was "saved" and it will now agree with reality.

If the car still says 583, maybe I have a faulty sensor? But it's working fine other than that.

If the car now says 620 like it should - someone miscalibrated it? Or the linkage was incorrectly assembled before and someone calibrated it with it put together wrong? Or the car mysteriously lost it's calibration for front ride height only?

Other than my indy shop that corner balanced and aligned the car, no one but me has wrenched on it for....years possibly. The results of my repeat ISTA calibration will give me some more indications and I'll write back when I've had time to do that.

Any similar experiences? The car is only dropped an inch and sits level with no rake. Even if my front sensor wasn't way off, I feel that a levelling procedure should probably be part of the recommended DIYs for suspension work like this even though I've never seen it mentioned. In theory it shouldn't need it, but I did.

[Surly73]

UPDATE:

Connected ISTA and performed the very same ride height reset. Interestingly my ride heights measured 611 R and 612F this morning.

The important part is that during the programming when ISTA told me what ride height the car though it had both front and rear were within 2mm of what my tape measure said. So, I'm going to guess that somehow, bad front sensor calibration data got stored in the ICM. No idea how, when, or how long its been like that.

The possibility exists, I suppose, that MUCH earlier work on the car (dealer replaced both front struts for free under warranty many years ago) led to the ride height sensor not being connected properly mechanically and then the system was calibrated. Perhaps I reassembled it correctly and it was off by 40mm?

At any rate - I recommend using ISTA to perform ride height calibration after doing suspension work and letting things settle.

[Unspec]

Originally Posted by Surly73

UPDATE:

Connected ISTA and performed the very same ride height reset. Interestingly my ride heights measured 611 R and 612F this morning.

The important part is that during the programming when ISTA told me what ride height the car though it had both front and rear were within 2mm of what my tape measure said. So, I'm going to guess that somehow, bad front sensor calibration data got stored in the ICM. No idea how, when, or how long its been like that.

The possibility exists, I suppose, that MUCH earlier work on the car (dealer replaced both front struts for free under warranty many years ago) led to the ride height sensor not being connected properly mechanically and then the system was calibrated. Perhaps I reassembled it correctly and it was off by 40mm?

At any rate - I recommend using ISTA to perform ride height calibration after doing suspension work and letting things settle.

Also important to make sure tire pressure is correct.

[Surly73]

Originally Posted by Unspec

Also important to make sure tire pressure is correct.

Uh, true, but that won't affect the reading from the lower lip of the rim to the fender by 2 inches, causing my headlights to point into the trees

[Unspec]

Originally Posted by Surly73

Uh, true, but that won't affect the reading from the lower lip of the rim to the fender by 2 inches, causing my headlights to point into the trees

Ah, I was referring to the 2mm difference in measured ride height for your second post

I think when you detach the sensor, it kinda just goes nutty and hence why it needed a forced "relearn"

[Surly73]

Originally Posted by Unspec

Ah, I was referring to the 2mm difference in measured ride height for your second post

I think when you detach the sensor, it kinda just goes nutty and hence why it needed a forced "relearn"

LOL 2mm was the last of my concerns TBH, when I first ran the ISTA routine, I was impressed that it had some idea of what the actual height was, not just an analog-ish routine that just used sensor positions to adjust the headlights.

I suppose technically it's because of all of the options - air, active leveling and all that. There can be 4 sensors and active systems setting the ride height.

ISTA/TIS says that if a sensor is replaced that this calibration should be done, but it doesn't say if it's unfastened and refastened. I'm just happy that it appears to be fixed relatively easily and inexpensively.