The small case 168 differential on the four-cylinder petrol BMW 1 Collection and E90 3 Collection ranges is a bit troublesome. There is no such thing as a apparent motive for this to be so – it’s a very well-made unit, machined to extremely advantageous tolerances, and makes use of bearings from well-respected producers. Nonetheless, many start to whine by 70,000 miles and might get actually noisy. Whereas it’s uncommon for a diff to fail, I just lately changed a diff in a 2008 BMW 320i Coupe (E92) that was near a giant failure and a lack of drive.
In regards to the Sort 168
The Sort 168 has been BMW’s small diff without end – the smaller-engined E30, E36, and E46 vehicles used this diff dimension, and the 168 apparently refers to an inside measurement. The medium-size diff is the Sort 188 and the actually huge one is the Sort 210.
The 168, first fitted to the 2004 1 Collection – 116i, 118i, 120i, and the 04-07 Euro 118d – differs from the earlier E46 kind unit in a single main respect: it replaces the earlier taper curler bearings for the pinion and crown wheel aspect bearings with ball bearings. This was achieved to cut back friction and make the diff simpler to show – which is noticeable when you might have the older and newer kind diffs aspect by aspect. Additionally, the oil used was a a lot thinner artificial 75/90 versus EP90.
Lastly, the solar and planet gears used within the precise differential unit are sintered metal, likely cheaper to make than the older kind gears utilized in E30 and E36 models. This diff was additionally used within the E90 3 Collection – in Europe the 316i, 318i, and 320i plus within the U.S., the 323i.
What Goes Mistaken?
A lot of the blame may be attributed to the shortage of a drain plug for the diff and no official oil change interval. The manufacturing facility fill oil is there without end except you might have a device to attract the outdated oil out, and no one ever bothers.
Whereas the differential aspect bearings very not often put on, the pinion ones definitely do, with the smaller finish bearing nearest the driveshaft flange being the worst. BMW used three bearing producers: INA, FAG (German), and Koyo from Japan. I’ve rebuilt a number of diffs and located that the newer the automotive, the extra probably it’s to have noisy bearings. They’re undoubtedly very top quality however appear much less in a position to deal with long-life diff oil. The sintered solar/planet gears additionally begin to pit and ultimately break up.
Can I Rebuild My Differential?
Sure, however they’re troublesome, requiring each an excellent device equipment and a ‘really feel’ for issues mechanical. The differential meeting is secured into the iron diff housing with a giant circlip all sides, and these double up as shims to set the crownwheel and pinion lash accurately. The pinion bearings are very exhausting to take away and change. As soon as the pinion is out, the large and small bearing outer cages must be pushed out utilizing a mix of brute drive and cautious talent. Refitting the brand new huge bearing outer cage is actually exhausting work, and I’ve discovered the easiest way is to warmth the casing in very popular water and have the bearing cage within the freezer. There’s a spacer shim below the bearing cage as nicely, and through bearing elimination it’s very simple to mark the mushy forged iron diff casing – this have to be rectified, or the brand new bearing is not going to sit accurately.
Assume that’s dangerous? Now you must get the large bearing internal cage off the pinion, and it’s pressed on with a number of tons of drive. A puller is not going to grip it, so you must rigorously grind away sufficient of the bearing cage till it splits by itself with out marking the pinion.
Then you must match the pinion with the brand new crush tube and set it up. Sound like enjoyable?
How Do I Inform A Good One From A Unhealthy One?
Simple. Flip the pinion flange, and the turning movement ought to really feel fairly easy. If it feels tough, noisy, or graunchy, it’s scrap. Get the appropriate diff as nicely. The 168 unit has seven bolts securing the rear alloy cowl, and the prop flange is round with 4 bolts. Look on the white high sticker, and you’ll see the ratio and half quantity. The assorted ratios are 3.91, 3.73, 3.64, 3.45, 3.38, 3.23, and for the 118d, 2.47. Put the VIN out of your automotive into Realoem, and you’ll find out what diff your automotive has.
Vehicles with auto stop-start may be very fussy on ratios. Match a automotive that had a 3.64 from new with a 3.91 or a 3.23, and the automotive’s ECU will choose up the distinction in street/engine velocity and object, rendering the cruise management inoperable and infrequently placing the automotive into limp dwelling mode.
Can I Make A Whining Differential Final Longer?
Debatable, however an oil change received’t harm. Draining the outdated oil and refilling with one thing like EP90 and even EP140 (good thick stuff) can typically quieten down an ailing diff and make it final a bit longer, however as soon as they’re actually howling, it’s the tip of the street. In case your diff remains to be good, an oil change will assist its possibilities, and plenty of BMW specialists suggest an artificial 75W/140 oil at round 13 quid a litre – simply in need of the 1.1-liter capability, however you’ll all the time have a little bit of the outdated stuff within the diff you possibly can’t fairly suck out.
Can I At Least Exchange It Myself?
Positive – it’s a three-hour wrestle for a newbie or lower than half that on a ramp for a BMW professional. It’s secured to the rear subframe by two 18 mm bolts (use loads of Plus Fuel on vehicles from damp climates) and a single 21 mm rear bolt and nut. The output shafts are secured by six E12 Torx bolts on all sides and the driveshaft by 4 E12 Torx. You’ll discover that the driveshaft remains to be caught to the diff with the bolts out – DO NOT strike the aspect of the driveshaft with a hammer to free it as you’ll harm it. As an alternative, use a hammer and chisel to drive it off the diff flange longitudinally (in the direction of the entrance of the automotive) whereas turning the driveshaft to free it off evenly.
The diff is heavy at 30 kg, so you will want to make use of a jack to elevate it whereas inserting the three bolts. Exchange the 16 driveshaft Torx bolts with new ones or use thread locking fluid on the outdated ones and torque them to spec.
Half Numbers
BMW diff half numbers are sometimes one digit out on authentic match and alternative (supersession) numbers. BMW swapped diffs round from mannequin to mannequin, and it could take a month of Sundays to record what every mannequin had fitted. Once more, realoem is your good friend, so enter the final seven digits of your VIN to see what diff it ought to have. This can be a information to diff half numbers and supersession numbers plus a few of the vehicles they have been fitted to.
[Top Image: Andrew Everett]
