The small case 168 differential on the four-cylinder petrol BMW 1 Collection and E90 3 Collection ranges is a bit troublesome. There isn’t any apparent cause for this to be so – it’s a very well-made unit, machined to extremely high-quality tolerances, and makes use of bearings from well-respected producers. Nevertheless, many start to whine by 70,000 miles and might get actually noisy. Whereas it’s uncommon for a diff to fail, I lately changed a diff in a 2008 BMW 320i Coupe (E92) that was near an enormous failure and a lack of drive.
In regards to the Kind 168
The Kind 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 inner measurement. The medium-size diff is the Kind 188 and the actually huge one is the Kind 210.
The 168, first fitted to the 2004 1 Collection – 116i, 118i, 120i, and the 04-07 Euro 118d – differs from the earlier E46 sort unit in a single main respect: it replaces the earlier taper curler bearings for the pinion and crown wheel facet bearings with ball bearings. This was executed to cut back friction and make the diff simpler to show – which is noticeable when you’ve the older and newer sort diffs facet by facet. 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 sort gears utilized in E30 and E36 items. 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 Unsuitable?
A lot of the blame could be attributed to the dearth of a drain plug for the diff and no official oil change interval. The manufacturing facility fill oil is there without end except you’ve a instrument to attract the previous oil out, and no one ever bothers.
Whereas the differential facet bearings very hardly ever put on, the pinion ones actually 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 automobile, the extra seemingly 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 finally break up.
Can I Rebuild My Differential?
Sure, however they’re tough, requiring each an excellent instrument package and a ‘really feel’ for issues mechanical. The differential meeting is secured into the iron diff housing with an enormous circlip either side, and these double up as shims to set the crownwheel and pinion lash accurately. The pinion bearings are very onerous to take away and change. As soon as the pinion is out, the large and small bearing outer cages have to be pushed out utilizing a mix of brute drive and cautious talent. Refitting the brand new huge bearing outer cage is actually onerous work, and I’ve discovered one of the best ways is to warmth the casing in highly regarded water and have the bearing cage within the freezer. There’s a spacer shim beneath the bearing cage as properly, and through bearing removing it’s very simple to mark the smooth forged iron diff casing – this have to be rectified, or the brand new bearing won’t sit accurately.
Assume that’s dangerous? Now you need to get the large bearing internal cage off the pinion, and it’s pressed on with a number of tons of drive. A puller won’t grip it, so you need to fastidiously grind away sufficient of the bearing cage till it splits by itself with out marking the pinion.
Then you need to 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 Dangerous 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 correct diff as properly. The 168 unit has seven bolts securing the rear alloy cowl, and the prop flange is round with 4 bolts. Look on the white prime sticker, and you may see the ratio and half quantity. The varied 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 automobile into Realoem, and you could find out what diff your automobile has.
Vehicles with auto stop-start could be very fussy on ratios. Match a automobile that had a 3.64 from new with a 3.91 or a 3.23, and the automobile’s ECU will decide up the distinction in street/engine pace and object, rendering the cruise management inoperable and sometimes placing the automobile into limp house mode.
Can I Make A Whining Differential Final Longer?
Debatable, however an oil change gained’t damage. Draining the previous 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 lots of BMW specialists suggest an artificial 75W/140 oil at round 13 quid a litre – simply wanting the 1.1-liter capability, however you’ll at all times have a little bit of the previous stuff within the diff you’ll be able to’t fairly suck out.
Can I At Least Substitute 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 either side 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 facet of the driveshaft with a hammer to free it as you’ll injury 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 automobile) whereas turning the driveshaft to free it off evenly.
The diff is heavy at 30 kg, so you have to to make use of a jack to raise it whereas inserting the three bolts. Substitute the 16 driveshaft Torx bolts with new ones or use thread locking fluid on the previous 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 number of the vehicles they have been fitted to.
[Top Image: Andrew Everett]
