BMW 325iX Summary Information

by Gordon Haines, iX Registry Coordinator. Membership Info

iX Registry Home | "BMW4X4 vs. 4X4 BMW" | "Winter Driving School"
-The 325iX was produced from '86 through '91 and imported into the U.S. for model years '88-'91. The iX has a viscous coupling (filled with silicone) in the drivetrain to split torque front to rear and another in the rear differential to provide a limited slip function. Handling in the dry is quite satisfactory in stock form and pretty awesome on slippery surfaces. With with a few modifications (like cutting the front springs to lower the front 1-1/2 inches, adding a stiff rear bar, installing Bilstein or Koni sport shocks and a Dinan chip, upgrading bushings and running Dunlop D40M2's), an iX will run with any E30 on a dry track. On a snowy surface, an iX fitted with a good set of snow tires (particularly with studded Hakkapelitta 10's) will absolutely leave any vehicle in a cloud of snow.*



Photo by Jay Jones, European Car
-The iX is really in it's glory in inclement weather. Yes, BMW's Traction Control is very effective in preventing spin-outs and in allowing a mind-numb driver to accelerate gradually on a slippery surface. But there is nothing like all four tires clawing at the snow. Even on the most slippery surfaces the iX can accelerate at full throttle after the first several yards. The ABS which includes a special program (not included in the ordinary 325) for low friction surfaces is also very impressive. Jeeps!, Ford Exploders, ExcuseYous, Chevy Blazeers and Subaru Doubtbacks have no idea what left them at the stop light. If you love BMWs and need a car for all seasons, this is your car!

-The U.S. '88's were available only as a 2-door in the U.S. but a 4-door was available in Canada. The U.S. '88s were loaded with standard features such as Recaro seats (see below), electric sunroof, map lights, full trip computer, truck deck spoiler and upgraded radio with tweeters in the side mirror area of the front doors. The '88 had the "old style" more massive looking bumpers with black mouding on the side, but these can be painted to match the body color. All models came with special body side moulding and 15" wheels. In '89 a 4door iX was offered, but many items which were standard in '88 became additional cost options. The '89 and later models came with a removable rear armrest and skibag and had smaller color-coordinated bumpers. These later models also had a 15" alloy spare rather than the 14" steel spare wheel "featured" on the '88 model. A driver airbag was added in most '90 and all '91 models. Asking prices in December '97 for a 5-speed in good condition in the prime Denver market (where there are always iX's in the classifieds) range from about $10K for '88s to $17K for '91s. Automatics are not as much in demand and are somewhat less expensive.

-Two "limited-slip" Ferguson-type viscous couplings are fitted on the 325iX. These are filled with silicone and are not computer controlled. The one behind the transmission splits torque front to rear (nominally 37/63%). A series of plates with holes and slots turn in the silicone fluid. Some plates are attached to the front axle driveshaft and some are attached to the rear axle driveshaft. Normally the plates turn at the same rate without relative motion. The silicone becomes very viscous as soon as it is heated by friction and shear caused by differences between the motion of the plates. This tends to lock the driveshafts. If the rear wheels and driveshaft are slipping and turning faster than the front, friction between the plates increases, slippage is reduced, the rear wheel spin is reduced and the power from the input shaft is transferred to the front.

Side View -The drive system add only 145lb. to the vehicle and is very reliable. The viscous couplings are sealed permanently and require no maintenace. The only additonal maintenance items required are changes of 1) the front differential oil (GL-5 90 weight, same as the rear) and 2) the transfer case fluid which is ATF. All drivetrain fluids should be changed at "Inspeciton II", nominally at 30K miles.

-The front wheels always have some torque transmitted to them. BMW choose a ratio of 37/63% front to rear because this corresponds to the weight distribution on each axle under full acceleration. This avoids the problem typical of front wheel drive vehicles in which the front wheels spin under acceleration due to weight transfer to the rear. Road and Track (April '88) states that "The net effect of the center differential is to act as a power-management system, transferring engine torque away from the end that is slipping and to the end with greater grip; as much as 90 percent of the torque may be shifted to the front or rear as required. This is done actively, quickly and without the occupants of the car ever being aware of it."

-Another interesting aspect: EPA figures for the iX are 17/23 and for the iS 18/24. One might expect more of a penalty for the AWD, but I recall Audi actually advertising that their Quattro system decreased overall fuel consumption because a driven wheel imparts less drag than a rolling wheel over about 20mph. I've never seen BMW discuss this issue or expliot this in their advertising.

-In it's stock form, the iX understeers slightly more than most BMWs. It is 0.4 seconds slower than an ordinary E30 from 0 to 60, and 0.3 seconds slower in the quarter mile. The rear axle ratio is changed slightly (3.91 vs.3.73:1) to minimize the effect of the added weight on acceleration. Car and Driver specifically notes that on dry surfaces, the iX stops 13 ft. shorter than an 325is, probably due to wider stock tires (205s vs. 195s).

-Although the iX does not have enough power to break the rear end loose in 3rd gear, the AWD system does provide some advantages when the car is 4 wheel drifting through a turn near the limit of adhesion. At the point where a the driver of a rear drive BMW would have to lift off the throttle slightly and countersteer, its likely that an iX would allow the driver to stay on the throttle. Power is transferred to the front axle and the front wheels will pull the car through the turn. This is certainly the case on snow, ice, gravel, etc. and the same principle applies on dry pavement near the limit. It's just at higher speed and more exciting.

-The basic technique used to drive the iX quickly is to "point and shoot". Upon entering a turn, aim to run over the apex, get on and stay on the throttle early, and allow the slight understeer to carry the car out away from the apex to the outside of the exit. Through turn keep the front wheels pointed in the direction you want to go and don't worry too much about where the rear end is going. This provides a high exit speed from the turn to carry you down the next straight. The iX and rear driver BMWs are great performers -- they are just different and need to be driven differently for maximum performance.

Interior -There's no significant difference between the 2- and 4-door models except the 4 door is about 50 lb. heavier due to the door hardware and window motors. The '88 iX seats provide lots of lateral support, are very adjustable, and have the extendable thigh support in the seat bottom. They were standard on all '88's (only 2-door iX's were imported in'88) and were optional in later years.

-Until '90 or '91, the only colors availble were red, black, white and silver. Later, a few other colors were offered, including a beautiful dark metalic blue/purple. From an enthusiasts viewpoint, the '88 iX is very desirable, but if you'd like lower mileage, an airbag, skibag and more attractive bumpers, go for a later model. In any case you’ll have a car for all seasons, weather or not!


-The drive train on the iX appears to be pretty bulletproof -- no inherent problems. Of course, fluid changes are important every 36K miles -- ATF in the transfer case and hypoid SAE90 (GL-5) gear oil in the front and rear differential. The viscous coupling units do not require any service. The transfer case only holds about 1.5 pint of ATF, so be sure to check the fluid regularly. The transfer case on an automatic can leak into the transmission with no visible sign of a leak.

-The weak link on the iX drivetrain seems to be the splines on the front driveshaft which mate with the chain-driven gear in the transfer case. These splines have stripped on several iXes which are owned by members in the iX Registry (now with about 1100+ members.) Apparently, the moly grease which lubricates these splines dries out or becomes contaminated with water and allows the splines to wear down. The only way to check the condition of the grease is to remove the front driveshaft (not a complicated procedure and is covered in one of the Registry newsletters.) If the splines strip, the front driveshaft must be replaced. If the female mating gear is ruined, the transfer case will need to be removed and the gear replaced.

-Owners are reporting that outer ball joints on the iX seem to need replacement at 120K-150K miles. Replacement ball joints are available (Zygmunt Motors, 215-348-3121) which can be pressed into the lower arms at a cost of about $40 each. BMW only sells the whole assembly lower arm assembly at a cost of $250-350 for parts for each side. Bekkers (800-624-5410) sells the arm assembly for around $180.

-Another potential problem is one that applies to E30 models with the M20 engine -- head bolts which break, causing oil leaks or worse. This is easily cured by replacing the original hex-head head bolts with newer torx-style head bolts available from BMW for around $40. These can be replaced one at a time, torquing each bolt first to 22, then rotating it through 90 degrees, then rotating it though 90 degrees a second time for a total of 180 degrees. There is also a non-BMW head bolt available (Raceware, 800-468-1977) which can be retorqued after installation, but a set of these cost around $190.

-On some early E30 models, the brake lining warning light flashes intermittently. This is usually caused by a broken printed circuit board wire or solder joint on the instrument cluster board. There is information available on BMW web sites FAQs regarding how to fix this problem and also on how to replace the rechargeable battery which operates the service interval LEDs on the instrument cluster.

-Several other items of note:

Front View -Road and Track published an excellent review of the E30 models in their April 1996 issue. The article is titled "Used Car Classic: BMW 3-Series, 1984-1992, Budget Bavarian sport and style" and covers the iX. The article states, "Finally there's the rather rare 325iX. The 2wd E30 cars are poor handlers on snow and ice, and the iX is the answer for motorists who must endure harsh winters. It's almost spooky how much extra grip it has over the rear driver."

* The rear traction bias of the iX and its balanced front-to-rear weight distribution provide superior traction on low friction surfaces when compared to the Audi 90, the Audi 90 Quattro, and the rear drive BMW325is. Road and Track ("Snow Test", Nov,'88) concluded, "Front-drive cars do not like to accelerate on slick surfaces." R and T also concludes that the 90 Quattro does not perform as well as the iX, saying, "Our acceleration champ was the iX. The AWD BMW was a blink quicker than the Quattro to 20 mph, 4.9 sec vs. 5.1 sec." In the hill climb, R and T says, "Once again, the BMW AWD system proved superior to the Quattro arangement." In the lane change, R and T says, "And again, the 325iX was the best." I've raced an M3 in the SCCA World Challenge Series and currently drive a new M3 (in good weather only). Personally, I really like a neutral handling car. I dislike the understeer characteristics of front-wheel and most AWD cars. To this end, the iX is much more neutral and handles more like a BMW that one would normally expect of a AWD car. No doubt about it both the Quattro and the iX are incredible cars, but my choice is the iX for the above reasons.

LOOKING FOR AN iX? There are usually several iX's advertised in the classified sections of the Denver papers: The Rocky Mountain News and The Denver Post.

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