Lost my nuts (and bolts) driveshaft

[OriginalOwner]

+1 kbmb02 ......  rubber turning a nut ??   I dunno ........

 

Cheers,

 

Carl

  

[Dudeland]

The bolts are all in one direction, I will take a look to see if I find arrows and report back. The locknut seems nice and tight. I got some new nylock nuts and washers.  They are 8.8 not 10.9 strength.  I can't see this a being an issue, as the sheering force is applied to the bolt, not the nut.  I will also loctite them, this way if they let go, I know that there is something more going on than meets the eye. 

 

 

 

 

[TobyB]

I had a thought about this- it's more related to 4- bolt flanges, but it might apply here, too.

 

The guibo's bonded around sheet metal sleeves, which are then compressed by the relatively small area

of the flanges.  If the guibo's a cheap piece of crap, it'll compress a bit, and let the bolts work loose.

I've overtorqued a 4- bolt enough to bend the sheet metal (I was butch back then) and realized you CAN overdo it.

 

As to bolt direction, meh- I never bothered, never had a problem.

As to the arrows, I do make sure they point to flange ears.  There's

some string science going on inside there, and why mess with success?

 

t

 

[manimal]

On 7/6/2017 at 4:59 PM, OriginalOwner said:

+1 kbmb02 ......  rubber turning a nut ??   I dunno ........

 

Cheers,

 

Carl

  

Although it may seem strange, it's entirely possible. Bicycles commonly have the left crank arm fall off if the bolt compressing it to the tapered flange isn't extremely tight and checked occasionally. When pedaling the crank arm can twist or flex a tiny amount and eventually back out the bolt. They're M8 bolts and I frequently tighten them to 80ft/lb or more and re-torque after a few rides. The one I haven't figured out is why square taper cranks with a "square" interface vs a "diamond"(rotated 45 deg, same actual taper) seem to come loose more frequently. 

 

[jgerock]

Don't think there are any arrows on the 8-bolt giubos that use the 4-bolt flange. Here is the old one I removed from my tii.  I was quite surprised how bad it was.

The 6-bolt giubo from febi/Bilstein comes with these instructions

Note the arrows on these 6-bolt giubos (febi brand on the right, MTC brand on the left)

[Dudeland]

I checked carefully and I didn't see any arrows.  I "added more tightening" to the bolts and put Nyloc nuts on the ones I can get at, I will do the rest today when I change the oil.  The test drive was fine. 

 

M

[OriginalOwner]

manimal,

 

Very Interesting about that bicycle crank arm failure mode .......

 

That 80 ft-lb number really caught my eye because it seems that is way beyond what would strip the threads of an M8 bolt, so in my curiosity I did some Google'ing ......

----  the lower left of this chart recommends 20 ft-lbs for an M8 .....

--------   https://www.imperialsupplies.com/pdf/A_FastenerTorqueCharts.pdf

----  this chart shows 377 in-lb (31 ft-lb) 

--------   http://www.cncexpo.com/MetricBoltTorque.aspx

 

I'm definitely learning something about bolted joints.

 

Cheers,

 

Carl

 

Edited July 8, 2017 by OriginalOwner

[zinz]

Are the bolts long enough? Is there enough thread for the nyloc nut to actually do its job? Thread should protrude the nut a couple threads...

[02tom]

34 minutes ago, zinz said:

Are the bolts long enough? Is there enough thread for the nyloc nut to actually do its job? Thread should protrude the nut a couple threads...

In addition to these concerns, I would caution against using the nyloc nuts from your local hardware store if you can't confirm the hardness.  Apologies if the nylock nuts aren't from you local hardware store, they just look like they could be and I've even bought all metal M10 locknuts from Ace Hardware that were not the right hardness only to be disappointed when the treads easily stripped out.

 

  The 10.9 bolt should have a 10.9 all metal lock nut (07129964672 per realoem.com) which BMW recommends being replaced after removal - but I think it's overkill if you know the history of the hardware.  If the hardware is original to the car, I would definitely replace the bolts and nuts as I had to do the first time I did a 5 speed conversion.  It's not worth risking tearing up the tail end of the transmission housing.  I've also had rear trailing arms loosen up due to reusing old bolts and locking nuts, just not worth the risk - in my opinion for what its worth

 

[Dudeland]

Yup they are long enough.  The hardness of the nuts is 8.8, not 10.9. I am doing a lot of short runs, nothing at highway speed to shake things out.  I will keep an eye on them and check them weekly until i can sort out why they are backing out.