I wanted to warn those of you who are replacing or have replaced a flex disc recently with one not made by Febi/BMW. I completed by manual swap 4 months ago. I replaced all wear components with new, mostly OEM BMW or OEM supplier parts. The one exception was the flex disc. I bought an Doorman flex disc from Rockauto. Admittedly, I should've compared the part with the good-condition BMW part I pulled off the car (130k miles). I didn't and I installed the flex disc following the directional arrows on the unit. Fast forward 4 months and 5,000 miles, and I went under the car to inspect everything. I was shocked to notice significant cracks in the disc. My first thought, was that I had installed the arrows backwards, meaning that the thinner (compression) portion was taking the tensile loads. Turns out, I had installed according to the arrows, but my intuition about the crack propagation turned out to be correct. The arrows on the Doorman part are OPPOSITE the arrows on the BMW part. If you install the Doorman part "correctly" it will fail. I made sure the part number I received was the same as I ordered. I have some photos of the original BMW flex disc (left) next to the Doorman (right).
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Clearly, the relation of the arrows to the thinner and thicker portion are different. BMW disc is on top. If you rotate the disc, then you can clearly see the arrows line up.
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Yeah. Looks bogus.
TBH while officially the guibo does have a 'direction', I don't think it's 'direction' that is most important really. The arrows aren't 'front/back' directional, they point to where the bolts go for each yoke, but, that's of course depending on it being oriented a specific way. Because of the alternating nature of the holes vs the yokes etc. you could absolutely install it backwards fine, as long as you get the pairings right. For each pair of holes for each 'thick' section, you want the tranny on the 'leading' hole and the driveshaft on the trailing hole... As long as you did that flipped the stresses should be the same I think.
But that's all academic, agreed the markings are clearly reversed on the cheapo Dorman part.
2003 M3CicM6 TiAg
2002 540iT Sport Vortech S/C 6MT LSD TiAg
2008 Audi A3 2.0T DSG (the daily beater)
2014 BMW X1 xDrive28i (wifemobile)
Former:
1985 MB Euro graymarket 300SL
1995.5 Audi S6 Avant (utility/winter billetturbobattlewagen)
Another quirk about guibo installation is that you're not supposed to tighten the nut/bolt head that rests on the guibo. You only tighten the nut/bolt head that rests on the steel DS or trans flange. Tightening the nut/bolt head on the guibo puts torsion into the metal sleeve, which in turn puts stresses in the rubber. With photo's showing every other guibo bolt sleeve cracked, I wonder if this is the real cause of the failure.
^this
98 540i 6, 525 whp, 120 mph 1/4, V3 Si S/C'er @16 psi, W/A I/C, Water/Meth, Supersprint Headers, HJS Cats, 3" Custom Exhaust, UUC Twin Disc, Wavetrac LSD, GC Coil Overs, Monoball TA, AEM FP, Aeromotive FPR, AEM Failsafe AFR/Boost, Style 65's w/275's, M5 Steering Box, Eibach Sways, M3 Shifter, Evans Coolant, 85 Deg Stat, PWM Fan, 10" Subs, B.A. speakers, Grom Aux/BT, Still Rolling as my DD!
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