B21 said:
Joycey said:
GuidoK said:Joycey said:
I know you have to remove them, I've had my quaife apart more than once. But if they're fine they're fine. Easy to inspect.
So imho this is more on a decision basis.
What also is a problem with replacing bearings, is that there is a chance you have to reshim your diff.
That is done with the 2 large C clips on the end. These are specific thicknesses (laser etched on them), but these shims are not something you can just buy. Different thicknesses have to be sources from scrap diffs afaik, so there is definately a downside to replacing bearings.
So playing with different thicknesses you can both align the gears to set backlash, and if necessairy remove lateral bearing play.
These different thicknesses of C clips are also necessairy if the width of the diff is out of spec, so measuring the width (at the bearing mating contact points) with a micrometer is good practice.
Here you can see some C clips with the different thickness I'm talking about:
One here is 3,80mm and the other one 3,74mm (so 0,06mm difference) so these tolerances are all pretty tight. So these different thickness rings are of course also used to compensate for tolerances in the casing (so tolerances in casing, bearings, diff width and alignment of crown/pinion)
So taken all of this into account, my opinion is that if your bearings are OK and you don't have ridiculous mileage on your car, it's maybe best not to swap them. Especially if you don't have a scala of micrometers and indicator dials and of course some ink.
GuidoK said:Apparently there is a kit now on the market with different thickness circlips.
Not cheap though
https://www.ebay.co.uk/itm/263582689780
The installment guide from Bird's auto states: "The friction torque of the pinion
bearings, the backlash and tooth contact pattern will not
have to be adjusted again provided the circlips and
bearing races are reinstalled in their original positions,"
With changing bearings the bold section is not happening, so that's why if you don't have to change bearings, it's better not to. Especially taper rollerbearings vary in width.
When fitting new bearings or other parts that can effect the preload, it has to be assembled without crownwheel (so the pinion doesnt rotate) and preload has to be adjusted and measured with a rotational torque measuring device (don't know what it's proper name is) at 50revs/min.
So this is pretty specialized stuff. This is not listed in TIS anymore for the e85/e46 as those diffs are deemed by BMW not servideable anymore, but you can find such settings and procedures with older models that also used the 188 diff. Obviously those don't have the circlip system (but used proper bolt flanges and shims) but if you look through that you can find the info and understand the procedure.
Just like the pinion bearing, the axle bearings have to be under a preload, otherwise wear is extremely accelerated on bearings and gears (they are obviously under a great forces when the car drives). The preload and thus the rotational torque even has to be set differently according to what brand bearings (FAG/SKF/Timken/Koyo) you use..
So that preload you don't measure with a normal torque wrench (that clicks) but it has to be measured as drag torque. Those tooles are pretty much made from unobtanium but I measure it with a spring scale set at a certain distance and recalculate torque that way.
Joycey said:Little update chaps, yesterday I was at Brands Hatch. I was also at Brands ealier this year with the open diff, I can confirm the LSD unit makes a huge difference on track more noticable in and exiting the corners along with the high speed cornering. I've covered around 500+ miles with 100 of them on track, So far so good with this Blackline unit this seems very good value for money.
autosport said:Joycey said:Little update chaps, yesterday I was at Brands Hatch. I was also at Brands ealier this year with the open diff, I can confirm the LSD unit makes a huge difference on track more noticable in and exiting the corners along with the high speed cornering. I've covered around 500+ miles with 100 of them on track, So far so good with this Blackline unit this seems very good value for money.
Awesome, am just installing at the moment, What Diff oil did you use (Weight and spec), Matt Lewis racing is just advising any good quoality oil but isn't providing a weigh or recomendation for Synthetic, semi synthetic, mineral etc..... thanks
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