iXchange Issue #13


A newsletter for BMW 325 iX Enthusiasts.


Members' iXperiences Page
- Driving School & Skid Pad 1
- K&N Air Filters 1
- Three Problem Areas 2
- Speedo/Odo Fixes 3 - Vibration & Ball Joints 4
- 170,000 iX (S)miles [8^)
- iX Ups and Downs 5
- Head Gasket Replaced 7


Members' iXperiences

Thanks to all members who contributed in helping keep each other informed about our iX's ! Particular thanks to Barry Ritchey of Albuquerque, NM, for three articles in this issue!.
David Roach of Silver Spring, Maryland writes:

I've taken my box-stock '91 iX to three drivers' schools at Summit Point. I've found that it understeers rather badly, but have been able to get it much closer to neutral with wildly differing tire pressures: 46 psi front, 28 psi rear. This was with worn-out (or rapidly wearing out) Centennial Z-rated mud and snow tires; things may be different with my new Dunlop D40M2s.

The big discoveries came at the skidpad. The first time out, I found the car quite willing to snap around when transitioning from wet to dry; it seemed very hard to control. The next time out, however, I discovered the truth: I was giving up on the car way too soon. You can get these cars just about 90 degrees sideways and still recover, if you keep your foot on the gas and employ a little preemptive opposite-lock steering. In a slide, with my foot on the accelerator, I can feel the four corners of the car searching for grip. It's really amazing. The lessons I've learned are (1) be pro-active and (2) don't give up!

I've only done serious gravel driving once, and not since my discoveries at the skidpad, so I haven't yet mastered all-wheel-drive control on gravel. I've read Gordon's treatise on handling, and I've watched "Michele Mouton and Markku Alen Explain Rallying" a few times, so I'm looking forward to my next practice session. Essentially, I think I need to turn in to the apex earlier and to keep my foot on the gas. I'll be laying out the 1997 BRM precheck (a two-day rally on primarily unpaved mountain roads) this fall, so I'll have plenty of opportunities to practice.

Recently, I replaced my worn-out Centenials with new Dunlop D40M2s, and at the same time I replaced the stock wheels with Moda (by BBS) five-spokes of the same size. The offset is slightly different (35 mm versus 41), but I've had no problems so far, and the wheels are a whole lot easier to keep clean.


Article 1 from Barry Ritchey from Albuquerque, New Mexico writes of his experiences with Air Filters :

I used to motocross, back in my pimple days. I also worked my way through college as a motorcycle mechanic. I was completely immersed in motorcycles (street and dirt) for almost a decade. In that time, I changed and cleaned a lot of air filters. Paper, oiled gauze (K & N typifies this bunch), oiled foam, dry foam (some people would forget to add the oil), no air filter (the ultimate free-flow dice roll).

There were basically two camps for the performance motorcycle air filter market - Oiled foam and oiled gauze (K & N). In my own motocross bikes, I always ran oiled foam. The ultimate filter for filtering and service was dual-stage foam filters. The outer 'sock' was a course filter that removed the majority of particulates. This outer filter could alone be changed when it got clogged. There was an inner foam filter that finished the job with a much finer celled foam.

In a day of racing, the filter would usually get changed twice. Sometimes just the outside sock, other times the whole pair. Off road racing, when it's dusty, is a challenge to an air filter. Back in the shop, I would often get to service peoples race bikes that used K & N filters. Since it was my job to find things wrong with motorcycles as a mechanic, my fingers would always probe intake boots (downstream of air filters). In almost all of the bikes that I would work on that used K & N's, I could feel grit in recesses of air boots or stuck in the oily throat (2-strokes use premix) of the carbs. Maybe it got there when changing filters...or with a different type of filter, but oiled gauze filters always seemed to let more particulates downstream than an oiled foam filter. If you can feel it, just think what got through that's too small to feel. Oiled foam filtered bikes always had a cleaner intake tract (except for that time I failed to tighten the filter &/#$%@!) Notice I said oiled foam. I'd often get bikes in that had dry foam filters. Usually when quizzed, the customer was just trying to get rid of all that oily mess and just cleaned the filter without reoiling. Ignorance is bliss...

With all that said. You're probably thinking that this ancient wisdom doesn't apply to BMWs and the road. But remember, I quote the great Forrest Gump, "air is air, and particulates are particulates."

Race Face...

K & N filters were designed for the 'race' environment. They are a great racing filter! I think their best application is for ROAD RACING. They flow great and filter out the majority of the big stuff. They aren't really that effective at filtering the small stuff. They don't have to be the ultimate sub-micron filter for most race applications. K & N's are much better than an open or screened intake. Race motors don't get the chance to wear out, due to ingesting years of micron sized particulates. Race engines don't usually wear out their rings from getting blasted with abrasive intake tract particulates. Race engines usually break rings due to too many RPMs...not wear. Oiled foam filters better and has nearly the same flow rate.

Off-Road use - you already know my opinion there.

Street use - The lowly paper filter is best. Why? It filters the best. Really ask yourself, "where are 99% of my miles driven?" "Do I plan on keeping and driving my car for over 100-200K miles, or am I just going to trade it in early before it would make any difference?" Just think how many cubic feet (or liters) of air your engine pulls through itself over the course of it's life (that would be a nice reply for those with a handy calculator...hint, hint).

The Problem...

The problem with most street stock setups is - the airbox is usually more of a maze than a straight shot. A lot of the performance gain from aftermarket filters, is due to a less restrictive airbox (or no airbox) which naturally flows better. You can't blame the factory too much. What happens when you go through that deeper than expected puddle and suck water into the engine? Wet paper doesn't flow very well. The airbox has to be well protected. And due to a lack of room in that congested engine bay, the poor engineer that has to design an airbox isn't usually given much to work with, the intake is probably going to be inherently restrictive.

A lot of the performance gains from aftermarket filters, is due to an increased surface area of the replacement filter. All things equal, increasing filter area increases air flow.

The hidden greed surfaces...

What I WANT for a street setup - an aftermarket filter that has larger surface area than stock, is less restrictive in path (yet somewhat protected), is paper or dual-stage oiled foam, resonance tuned, and costs under $100.

One more testimonial involving a Ford.

A friend of mine has a '88 Ford van. My Ford van is a '79. Both are 351 Windsor. We both drive a lot of dusty New Mexico highway miles chasing wind (we windsurf). BMWs don't have enough room to haul the prolific amount of 'boardhead' gear...even the touring models.

He uses that really expensive AMSoil and a dual oil filter setup and has his oil analyzed (like aircraft owners do). I just use premium mineral 20W50 and 1 filter changed at 3-4K. His van just got completely rebuilt at around 150K (burning oil, low/uneven compression...). My van is still running fine with the original engine (not rebuilt) at 245K miles.

He used (not present tense) a K & N. I use OEM paper (usually Fram).


Article 2 from the same Barry Ritchey (still from Albuquerque) who now advises of Tthree Items To Watch out for in our iX's:

1. Press-fit elbow coming loose at the thermostat housing area.
Just recently, I serviced the cooling system (new hoses, thermostat, and coolant) in my '90 325iX. As I was pulling off the small hose that runs from the thermostat housing to the throttle body, I noticed that this hose was moving the elbow (about 1/4" ID) that is a press fit into the thermostat housing on the cylinder head. The original owner had mentioned a problem in this area, when I asked about the bailing wire tied around the thermostat cover area. This elbow had popped-out a few years ago and was 'permatexed' back-in by the original owner (his wording). The wire was in place as a backup. The BMW dealer where I purchased my used '90 325iX, said that there was 'no coolant system problem' in that area (they just snipped off the wire and looked for leaks). The whole area was fairly encrusted with green dried antifreeze.

The fix -- I cleaned-up the original 'goop' fix from both the elbow and bore in the head with solvent and emery paper. I was lucky that there was no corrosion. I roughened up both surfaces (to give 'tooth' for the epoxy to come) with very coarse sandpaper. To make a slightly tighter fit (you could seat the elbow with just finger pressure), a center punch was used to put dimples on the male surface of the elbow. This made for more of an interference fit. And finally, a medium time curing epoxy was used to totally seal and bond the elbow in place. An aluminum filled epoxy would have been better (definitely avoid '5-minute' class epoxies for any repair involving water contact).
The next time you E30 owners are working around the thermostat area, give that elbow a yank to see if it's tight. If it comes out or rotates, you have potential quarter-inch hole in your cooling system. The result could be more serious than lost coolant...

2. Rubbing Engine Reference Sensor

During the above mentioned coolant system maintenance, I also replaced the engine reference sensor (the combination engine speed & TDC pick-up that reads off the toothed ring on the front of the engine). Mine had worn through the outer insulation (no big deal) and about 80% through one of the two conductors (time bomb). It seems the last person to change out the timing belt, failed to route the sensor through the two little clips (and/or broke them) that keep the sensor wiring harness from rubbing on the water pump pulley.
There are two little plastic clips that fasten to the front of the timing cover. The clips are a little on the lame side. The clips also hold another cable (engine oil level I believe?) away from the pulley. And incorrectly in my instance, the spark-plug tach lead. The correct route for the tach wire (senses off the sparkplug lead) is over the distributor, instead of under.
I rerouted my sensor cable to not even go through the little plastic clips. I routed it along the metal radiator hose pipe and used cable ties to fasten.
Check those plastic clips. They're cheap (under $2). Your engine won't run if the engine reference cable gets sawed through. Actually, the motor will run (according to a trained BMW mechanic), but it won't restart if the sensor wires gets cut

3. Missing timing belt cover.

The same 'mechanic' that caused the above sensor wire problem, probably caused this one too. There is a rubber cover that just snaps over the front of the cast aluminum timing belt housing. This cover is on the left side of the engine (intake side) and protects the timing belt from the elements. Mine was missing. The $12 (US) part is fairly easy to install. Just make sure it snaps over the front portion of the cover housing. With the cover missing, you're probably taking more of a chance in creating a potential 'black hole' for dropped nuts and bolts (None of the fasteners that I ever drop in the engine bay ever hit the ground. Where do they go?) than a problem with keeping out dust and water.


And Article 3 from Barry Ritchey -- info on bad 325 speedometer/odometers :

Several months ago my '90 325iX started to have speedometer/odometer problems in the mornings. The speedo would stay at 0 and the odometer would not advance. The problem worsened with the onset of Fall and cooler mornings. The speedo/odo would usually wake-up after about 5 to 10 minutes/miles of driving...and stay working until the next morning or cold start. Here's a long winded account of my quest to fix the speedo/odo.

1. My first attempt at a fix was to crawl under the car and check the connector at the rear differential. Maybe it was loose or the wiring was frayed/damaged. Everything appeared fine.

2. The next step was to post for help on the digest and pick Gordon Haines' brain. Most e-mail replies (Thanks to those that replied!) suggested I check for bad solder joints on the instrument circuit board. I dreaded pulling the instrument cluster (later I learned it's a quick job) and would pursue other avenues 1st.

3. Since I didn't have a ETM, there was no easy way of tracing the wiring into the instrument panel. I thought I'd start at the source and tap into the two leads (parallel connection) at the differential connector. I soldered some female connectors to some 14 gauge wire and then soldered wire to my standoff connections. I ran the tap wiring through the drain slots in the spare-tire well into the trunk, out the trunk, and then into the interior by way of carefully closing the rear door (I have a 4-dr) on the wiring. I could now have a DMM located at a convenient location (the console) to monitor voltage at the differential connector. A regular DMM wasn't telling me much after a few days so I borrowed a Fluke scope meter (portable LCD scope). When the speedo worked, there was a nice pseudo-squarewave (0 - 8V). When the speedo slept, there was just mV noise. I now suspected the speedo or instrument board.

4. Reflowed all the speedo board solder joints as described at web site: (http://www.aros.net/~pinkston/). It's not that hard to pull the instrument cluster, but... IT DIDN'T WORK in my case. Looking back, a bad joint solder joint might be the cause if tapping the dash or hitting bumps causes the speedo to jump or turn off. My speedo was always steady on or off when driving bumpy roads or when the dash was hit (I did tap/pound the dash out of frustration a few times).

5. I borrowed the Fluke Scope meter again. This time I disconnected the cable at the differential and just measured the voltage across the two leads. It was always 8 volts DC (actually 7.9 volts). There was no significant AC component. After 4 days of cold morning starts and rock steady voltage at the connector, it was time to measure across the transmitter leads coming out of the differential. The Scope meter, displaying resistance vs. time, showed a nice high resistance spike occurring about every 2.5 ms at around 30 mph when the car was warm. The switch was normally closed (~0 ohms) and was momentarily opening up into the megaohm range. For 4 mornings the meter would just read 0 ohms for the first few miles of driving and then suddenly show the opening spikes of a working sensor. The transmitter was bad!!

6. To make this too long of a story shorter, I ordered the differential transmitter (and o-ring) from my local dealer in Albuquerque for under $35, installed it, and the speedo and odometer are working fine for two weeks now.

7. I performed an autopsy on the old sensor. It's a switch (glass tube encased contact rods) that's normally closed. When in the presence of the magnet that resides in the sensor housing, it opens. There must be a flange inside the differential fits between the sensor and the magnet. This causes the switch to close (the magnetic field is blocked by the flange. The flange is slotted, which allows the magnetic to momentarily act on the switch to open it. I guess my bad switch tube was just sticking closed until the heat of the differential, oil churning, or vibration caused the contacts to start opening (pure speculation).

Lesson learned: check the easy and obvious first. You don't need to have a oscilloscope to diagnose this problem. You can slowly roll the car and look for resistance staying low and then momentarily going high to spot a good transmitter. A bad transmitter (in my case) stays closed (low resistance) when you roll the car (or spin a wheel with the car on jacks). BTW -- A cable driven speedometer sure if a lot easier to fix and troubleshoot.

Here's the part numbers for my '90 325iX:
62-16-8-357-020 Transmitter ($37.28 list)
33-11-1-206-166 O-Ring ($1.40 list)


John Shreve of Wilmington, Delaware tells of Replacing The Ball Joints on his iX:

Here's my set-up as of 10/21/96: '88 iX 2 door, Diamond Black Met. / Gray Leather , 5 speed, all the nice M-Sport stuff; steering wheel, seats, spoiler etc. Dinan Chip, Bosal Free-Flow exhaust, Kirban/K&N Intake system 5 spoke Dial Elysee Wheels w/ Goodyear Eagle GT+4 205/55-15's

Just turned 100k - car runs very strong - especially upper revs (Thanks Dinan!) All the usual maintenance has been done religiously - with the most interesting project being the dreaded control arms (ball joints):

The iX was running great, but I started getting a lot of vibration all through the car. I thought I had rough idle problems (checked for vacuum. leaks, couple bottles of Techron, etc..) then, replaced motor mounts, which were okay, but after 100k did them anyway. Still a lot of vibration. I knew I needed control arms but I was delaying it due to the cost factor and the premise that new control arms wouldn't make that much of a difference anyway. (WRONG!!)

So ... here's the first tip. I found brand new OEM BMW iX control arms at Bekker's import (Roundel Advertiser) for about 1/2 of the $300 dollar dealer list. I know a lot of iXer's delay this maint. item due to cost so call Bekker's ... these are the control arms w/ ball joints OEM .. for real cheap!! So the control arms get installed and eureka, I've got a brand new car!!! The handling is amazing!! and the rough running/ vibrations ... completely gone!!! Apparently due to our iX's "unique" drive train, the control arms are responsible for 'soaking up' a lot of engine/drive train vibrations ... as well as doing the obvious suspension thing. iXer's out there ... don't put off control arms. To this day, it was the one maint. item that made the hugest, most significant, positive result/change in how my iX ran & handled!!!!

In my opinion the iX is the pinnacle of the E30 class. I think other Bimmerphiles are beginning to realize this also. With a few modifications to an iX, you can match the performance of any E30, yes, even an M3 !!! ... but no other E30 can give you all-wheel drive!!! Hang on to your iX's folks, they are quickly turning into gold!!!


Dan Guliano of Nahua, New Hampshire (see you for O'fest '97) provides his article "170,000 mile in an iX" which appeared in his Chapter Newsletter column, "iX Marks the Spot.":

When last we discussed the iX and mileage we had just turned 100,000. That was in the late summer of 1994. In the past two years we've put another 70,000 miles on the iX. Here's what's happened.

Routine Maintenance:
* Oil Changes, stand alone service
* Engine Oil Service: 1
* Inspection II: 1 (at 116K, another scheduled for this week)
* Inspection I: 1 (at 141K)

Miscellaneous Repairs and Expenses:
* Replace Oxygen Sensor: 104,000 miles. A real 'no brainer' needed to be done, ran better after.
* Replace Lower Control Arms: 107,000 miles. LOOK OUT for this one, you won't believe the expense, there's really nowhere else to get these...
* Rebuild Parking Brakes: 109,000 miles. Making a horrible screaming noise in reverse. Tried not using reverse but significant other made even more noise...
* Replace left side dash light: 110,000 miles. Illuminated the speedo, hardly ever looked at, hence the misunderstanding with a Mustang and MA Trooper.
* Replace four tires: 123,000 miles. Another set of Dunlop D40M2's. Outstanding tires for this vehicle, got over 40k miles on this set.
Replace antenna mast: 126,000 miles. Again.
Reseal Transfer Case and Install MM Short Shift Kit: 129,000 miles. Transfer case was leaking from everywhere, so we dropped it and replaced all the seals. While it was out we installed a MM short shift kit. Major difference, shifting was greatly improved. (would have NEVER added to a domestic vehicle with 129k)
* Replace Timing Belt and Water Pump: 137,000 miles. Had to do it at 90k, add 50k and you get 140k. Be really safe than sorry on an 'interference' engine, replace the belts at the appropriate interval. While it was apart, replaced a seeping pump.
* Replace a badly scoured front windshield: 140,000 miles. Took a major league stone during last winter, insurance paid most of the bill.

What Needs Doing:
As mentioned, an Inspection II is scheduled for this week. Also, the Sebring exhaust is really starting to corrode at the hanger. Looks like another set of tires will be required, but will put the snows on in December and buy new tires in spring. Overall, the iX runs strong at 170k and remains the "every day driver".


James.Ferguson of Fairview, Alberta, Canada tells of the Ups and Downs of owning his iX:

I bought my 1988 4-door iX (mileage 120,000 km) last November chiefly because I had moved to a small town in Northern Albera, Fairview, which is approx. 1000 km North of the 49th parallel. Needless to say snow, ice and sleet are factors on the road for a good part of the year and there are no alternatives for getting around like taxis and public transit.

I picked up the car in the middle of a blizzard and drove to my destination 100 km away late at night on roads that were covered in as much as 3 in of snow with summer tires still on the car. My warning on setting out had been "Tap lightly, tonight". Accustomed to driving rear wheel drive cars in conditions like these, I found that the car has a built in resistance to swapping ends. This quality was so strong that my speed was only limited by visibility. When I arrived I felt refreshed and relaxed. I was definitely going to like this car.

The car appeared to be in great condition and I got it at a discounted price because the owner resisted taking it to Edmonton, the nearest metropolitan centre and BMW dealer 500 km away, for a proper inspection. Only the relatively high drivetrain noise, which seemed to be coming from the front end, seemed noteworthy. Was that normal? I would eventually find out. (BTW, never buy a used car that is clean underneath - they cleaned it so you can't see the leaks.)

Over the next couple of months the Check Engine light came on - new oxygen sensor, and a pattern of hard starting when the car was warm became evident. A call to the BMW dealer in Edmonton, Bavaria BMW, and the problem was diagnosed as a leaking check valve in the fuel pump. The suggested fix, a new pump for $450, seemed like overkill; would it not be possible to put a new check valve in the fuel line? A trip to the local auto parts distributor and $10 later I had a check valve and the hose and clamps required. Paul, the Service Manager at Bavaria BMW graciously helped me install the valve over the phone while I was in Fairview! Henceforth the warm starting problem disappeared.

Warm starts are only a problem if cold starts are not. After the second failure to start while being plugged in at -20 (Celsius), I again consulted with Paul at Bavaria BMW. A main relay replacement failed to fix the problem and I was advised that the car was probably not turning over fast enough -- there may be something wrong with the battery. The battery was fine so I spent some time routing a 120 V wire through the car to plug in a battery warmer in the trunk. Henceforth the cold starting problem went away as well.

When the warm weather returned I noticed that the large number of cranks to start the car from cold was not entirely due to ambient temperature - it still took 3-5 seconds of cranking to start the engine. Bavaria BMW installed new and improved fuel injectors and the car has started well ever since. (As an engineer, I am sympathetic to the fact that things do not always work as planned; I applaud BMW for making and coming forth with the improvement)

But what about that occasional hiccup while the car is idling (engine uses no oil)? Why does this persist with the new injectors? Here BMW never did come up with an answer. The position of both BMW dealers in Alberta was that the car should run fine on Regular unleaded fuel. BULL. On Regular the engine quits at 5000 rpm while with 91 Octane Premium it keeps going until 6000 and feels stronger as well. The idle hiccups continued despite the switch to premium. An Edmonton mechanic, Alan Nathan of AJ Motors, finally clued me in. A half a bottle of fuel injector cleaner with every fill or so and the hiccups almost go away. Still some unevenness in the idle but who is complaining? Half a pie is better than no pie. If I had the head pulled and cleaned up (remove carbon buildup) the rest of the problem would probably go away.

The smooth sailing ended abruptly when I was 2 blocks away from my destination in Fairview at the end of a 600 km trip. A loud clicking noise started at the front of the car that was proportional to vehicle speed. After spending some time jacking up each front wheel and rotating it by hand, I had the problem figured out. The spline on the front driveshaft where it takes drive from the transfer case had failed. Disassembly indicated that a seal had failed on the protective cover, allowing rust to start. The resulting slop allowed the two splines to hammer away at each other until they failed. Neither BMW dealer had heard of this happening but an Edmonton service shop had repaired two other cars with the same problem.

Now this was looking like a major$$$$ repair. Get this - BMW updated the transfer case on later cars (to match the new European 5-series iX?) and they do not stock parts for the old design. This means that the part in the transfer case that the front driveshaft fits into is not replaceable. Only the case is common between the old and the new so we are talking $3500 for the parts and a rebuild or $4000 for a BMW rebuild exchange. Plus $500 for a new front driveshaft.

As luck would have it, some unfortunate BMW driver put his IX on its roof a few years ago and an Edmonton used auto parts store sold me a transfer case and front driveshaft for $1300. These were shipped to Fairview and in no time I would have them installed and ready to go. All right - time to start. Car up on the hoist and a quick inspection of the underside of car revealed that ... this was going to be a just a tad more complicated that I expected. First there was the exhaust to deal with. Then there were those bolts way up on top of the transfer case going into the gearbox. Could it be done? Yes. Was I going to do it? With increasing certainty I knew I would not.

Something told me that this was just not right. My first car was a lemon yellow TR-7. I did all the work on it including rebuilding the engine and transmission. This was in harmony with the universe since my skills as a mechanic were probably on a level with the engineering that went into the design for that car. But here I was about to start pulling apart a BMW? No, it was not right. Had to be a better way.

With lateral and creative thinking fully engaged, I reexamined the driveshaft and transfer case. Notice how deeply the splines are cut into the transfer case and up the driveshaft? Maybe somehow I could get the driveshaft further into transfer case. There certainly seems to be extra room when the driveshaft is fitted. Calipers in hand, a quick check and, yes, the driveshaft could be 7 mm longer and still fit in the room provided. But 7 mm might only get me as far as the first big bump. More length could be created by pushing the driveshaft further into the transfer case but go too far and the bolts on the differential end will hit the bell housing. Available room check out at 5 mm. The original driveshaft engaged the transfer case using 18 mm of spline. 12 mm is in the same order of magnitude so it should work.

A quick trip to a machine shop in a nearby town and I was all set. I was going to make the repair without the transfer case. The machine shop welded the spline from the used driveshaft to the good end from mine so that they were 7 mm longer and checked the result for balance. They also cut some spacers and modified the part that centers the driveshaft onto the differential to accommodate the extra 5 mm. 30 minutes of assembly (new O-rings for the seals on the protective cover) and I was finished.

Now that that was over, I resolved to have the car inspected by BMW to avoid any future failures. It was only when they went to change the oil in the transfer case that they found it had been running empty. The seal where the drive is transferred to the front was leaking badly. In the 10,000 km since I bought the car (presumably the seal went just before the car was sold) the noise from the transfer case had probably become worse but I had not noticed it. You know the rest of the story - the used transfer case found a home after all.

The only other major area that needed to be set right (besides new brake rotors, front and rear) was the front suspension. When sweeping off-ramps started to feel like a soap box derby I knew that the comment in Road & Track about unusually high wear on the ball joints was correct. I too shelled out the $400 per side for the new lower control arms, but some things are worth doing right and I did not have a reputable source for replacement ball joints. I certainly will try Zygmunt Motors the next time. I am having the flex fittings at the top of the front struts checked for wear as well.

A note about the front suspension - I had the front rotors replaced by the BMW dealer approx. 2000 km before the ball joints were replaced. In that time the loose ball joints succeeded in causing the rotors to warp such that the steering vibrated heavily under light braking. Harder breaking seemed to damp out the vibrations. The rotors were turned under warranty repair by the dealer, but they warped again within 10 000 km. After 20 000 km the shake in the steering while braking was severe. The dealer then replaced the rotors under warranty, and at my request, lubricated the pistons on the front calipers. From these events the following conclusions may be drawn:

1. The relationship between front suspension slop and rotor warp is through the steering. Note how on all cars the calipers are mounted either in front or behind the steering axis (never on top). The reason for this is that the small runout of any rotor (nothing is perfectly flat) will cause an oscillating moment (twisting force) on the wheel as the caliper pistons is pushed in and allowed to move out. The steering axis allows this small movement without a large reaction (force) . If the caliper were mounted on top of the steering axis, the room to move would be too small (limited by the flexibility of stiff suspension joints), large forces would be generated which would act on the rotor to magnify the runout, thus "warping" the rotor.

Now if the front suspension is allowed to move around by loose ball joints or steering links, the assumption that the steering axis will allow for rotor to move without generating large forces is invalid. The wheel may be in the process of moving one way due to the slop in the suspension while the rotor wants to push it the other way. This leads to the large forces which result in magnifying the runout and "warping" the rotor. Similarly, a sticking caliper piston will do the same thing by not yielding when the rotor runout tries to compress it.

1a. Slop in the front suspension (including steering) will cause your brake rotors to warp.

1b. A poorly lubricated (almost seized) front caliper will cause your brake rotor to warp.

1c. Those stories about braking too hard, water contact, and braking lightly, evenly, or on and off causing rotors to warp are CROCK. With normal street driving a pair of rotors will last as long as your front suspension (including steering) is tight.

Having said all that, McPherson strut suspension are MUCH more prone to wear than upper lower wishbones which other manufacturers use. The tradeoff is in steering response and feel which BMW products have in spades.

Despite the challenges that I have had getting my iX back into shape, the experience has been altogether positive and I have learned a lot as well. Would I do it again? You bet, having the best AWD car on the road is worth a lot, but I probably would just put the replacement transfer case in to start with the next time.


Head Gasket Replacement

William Buckwalter , recently moved to Canton, Georgia details his iXperience of Replacing The Head Gasket on his '89 iX:

Last May a small ATF leak in my car drove me to change out the front main automatic transmission seal. Once that was complete I was feeling good about no fluids falling to the garage floor (no small feat as the car's stablemate is a 1986 Caravan w/230,000 miles and a shakey four cylinder.). That bliss did not last long. The car's head gasket began to leak oil down the passenger's side of the block. I splashed a question out on The BMW Digest on the Internet and received responses from "mine has leaked from when I bought it to when I sold it, no big deal" to information indicating this is not uncommon and a new, upgraded gasket will remedy the problem. I was hoping someone would approve turning a little more on the headbolts as a solution, but that was unanimously rejected as a bad idea.

So I ordered a head gasket set and new headbolts and scheduled a weekend with the car. The Bentley manual steps through the process with good detail, however I did take a few short cuts. I did not need dowels to align the head and head gasket on reassembly as there are guide pegs set into the block to facilitate this. I did not remove the exhaust pipes from the exhaust manifold, and was able to pull the manifold back against the frame and hold it there out of the way w/some wire once unbolted from the head. I also did not replace the timing belt as it had just 11,000 miles on it and was in excellent shape. That allowed me to leave the radiator, fan and shroud on the car. Additionally, I did not isolate the battery and got away with it, however the starter cable terminal on the solenoid is very exposed and I took extra care to not make sparks while cleaning around the starter and removing/installing the dipstick tube. This saved me from rebooting the aftermarket alarm system (a mild pain) and figuring out how to reset the radio and clock. I recommend isolating the battery (do as I say, not as I do), especially if you clean with gasoline or do not plug the fuel lines when pulling the intake manifold.

My propensities for cleaning everything did however provoke extra work. The head gasket set did not include new O rings for the injectors or the gasket between the throttlebody and the intake manifold. Disassembly of these parts is not essential to replacing the head gasket, however I took everything that came off the car apart for cleaning/inspection and felt the O rings and this gasket should be replaced. Closer inspection revealed the O rings to still be pliant (after 111,000 miles!), so I cleaned and reinstalled them. This was also the first opportunity to get at some of that original undercoating/preservative that over sprayed onto some of the engine parts. Carbon buildup in the combustion chambers was light and easily removed with parts cleaning fluid (gasoline). After cleaning the head, prior to installation I applied some break-in lube to the camshaft lobes. After installing the head I poured a quart of oil over it's moving parts before bolting on the cam cover as everything was clean and dry. Also, with the head off, replacing the front camshaft seal was a simple task.

Everything came off with no problems. Even the exhaust manifold bolts wound off effortlessly with an overnight soaking of penetrating oil. Reassembly was routine with the usual extra care on headbolt torque (bought a new torque wrench for this) and timing belt tension set.

After all the parts were on, I removed a coolant hose from the throttle body housing (as a vent) and loaded the coolant. I also drained the oil and left the oil drain plug off while I charged the cooling system. With no antifreeze running out of the oil pan, I plugged the pan and added engine oil. Startup took about 10 seconds of cranking while the fuel rail loaded. The cooling system still had some air to work out as it warmed up. After topping off the coolant, a test drive revealed everything was working normally. The "check engine" light did come on initially, but disappeared when I restarted the engine and throttled it up to about 3 grand. Some gunk and a power washer blew away the thin veneer of oil/dirt on the bottom of the engine prior to reinstalling the belly shroud. Now the oil is staying inboard and the engine bay has never looked cleaner.