Dura ace 7800 crank question

[tuscanyswe]

I somehow damaged a part of the crank when dissembling the crankset.

On the leftside arm theres a black rectangular washer that fits inside the arm inbetween the fixing bolts. This washer has a metal pin in it that im assuming corresponds with the hole in the spindle of the crank. What exactly does it do? The pin has broken and fallen out of the washer. Can i still install this crank as per usually and ride it with np?

Thanks for info!

[dave thompson]

I somehow damaged a part of the crank when dissembling the crankset.

On the leftside arm theres a black rectangular washer that fits inside the arm inbetween the fixing bolts. This washer has a metal pin in it that im assuming corresponds with the hole in the spindle of the crank. What exactly does it do? The pin has broken and fallen out of the washer. Can i still install this crank as per usually and ride it with np?

Thanks for info!
That 'washer' is a stopper plate (see item #7 here: http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/FC/EV-FC-6600-2365E_v1_m56577569830621034.pdf) designed to keep the crankarm from walking off the spindle if the crankarm pinch bolts aren't tightened to spec or if they come loose. Personally, I'd order a new stopper and until it came I would ride very carefully after checking the pinch bolts every day.

See "Installation of front chainwheel") here: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Ultegra/SI_1G30E_001/SI_1G30E_001_En_v1_m56577569830616000.pdf

[erolorhun]

Hm, interesting. Good to know. Bought a second hand 7800 crank from eBay and where wondering what that washer does. Guess i better not skip it when I install the crank

[tuscanyswe]

Thank you Dave!

I will buy one and use the cranks with caution meanwhile.

Cheers
Björn

[kramnnim]

Hmm, the 7800 crankset I bought from someone here on the forums did not include this washer. (or the crank bolt, but that's another story...) I didn't know it was supposed to be there, my XT cranks don't have them, either. Anyway, I used the 7800 cranks without the washer for several thousand miles without any issues...

[dave thompson]

Hmm, the 7800 crankset I bought from someone here on the forums did not include this washer. (or the crank bolt, but that's another story...) I didn't know it was supposed to be there, my XT cranks don't have them, either. Anyway, I used the 7800 cranks without the washer for several thousand miles without any issues...
IIRC, there were issues of some of the first outboard bottom bracket non-driveside crank arms becoming loose/coming off because they weren't sufficiently torqued, so Shimano devised the 'washer' thingy along with a divot in the splines of the connecting tube to prevent this from happening without warning. If you remove the NDS crank arm and there's no 'divot', you have an earlier set of cranks. If there is a 'divot' in the splines of the tube, you can buy and install the washer/stop plate.

[kramnnim]

Ah, okay. So on the newer cranks with the washer and divot...do you have to remove the two bolts entirely in order to get the washer/pin out of the divot so the arm will slide off?

[dave thompson]

Ah, okay. So on the newer cranks with the washer and divot...do you have to remove the two bolts entirely in order to get the washer/pin out of the divot so the arm will slide off?
No, if you loosen the bolts the washer will pivot on the rear bolt away from the divot, protruding slightly, as shown in the image of the washer in the TechDoc regarding the "installation of the front chainwheel here: http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Ultegra/SI_1G30E_001/SI_1G30E_001_En_v1_m56577569830616000.pdf

[oldpotatoe]

I somehow damaged a part of the crank when dissembling the crankset.

On the leftside arm theres a black rectangular washer that fits inside the arm inbetween the fixing bolts. This washer has a metal pin in it that im assuming corresponds with the hole in the spindle of the crank. What exactly does it do? The pin has broken and fallen out of the washer. Can i still install this crank as per usually and ride it with np?

Thanks for info!

Yes just use a torque wrench...9-13 newton meters I think.

[SpeedyChix]

I've had cranks both w/ and w/o the plate but no issues. Perhaps lucky things stayed on? Though a torque wrench sees frequent use here.

[oldpotatoe]

I've had cranks both w/ and w/o the plate but no issues. Perhaps lucky things stayed on? Though a torque wrench sees frequent use here.

That little plastic thing won't mean the cranks will stay on or not. Proper torque means they stay on.

[SpeedyChix]

That little plastic thing won't mean the cranks will stay on or not. Proper torque means they stay on.

Cool, good to go then.