GeoffS wrote: ↑Mon Feb 08, 2021 9:59 am
This ain't good....
Swapped over Ultegra brake calipers to Dura Ace ones on the weekend. Went to tighten up the mounting bolts - the Shimano instructions call for 6-8 Nm, so set the torque wrench to 6 Nm. Did the front bolts first and thought that felt pretty tight, but as I was doing up the second bolt on the rear caliper there was a nasty cracking sound from the frame. Had a closer look and there is a hairline fracture in part of the rear stay near the bolts, and the mounting surface is visibly deformed. Damn
So I dig around a bit and find the Addict manual on Scott's website. Sure enough, under the "Front Fork Disc" there is a note "max bolt torque front and rear 5 Nm". I have looked more closely at the front and while I can't see any visible damage, the caliper rocks over as bit as it is tightened up (to the extent that the brake disc rubs against the caliper body) suggesting there is some damage in the fork also.
So I have a cracked frame - at the rear certainly, and possibly at the front also. I'm absolutely gutted. I could tolerate a slightly dodgy rear brake, but there's no way I'm riding with a possibly cracked mounting for the front brake.
Yes, my stupidity for not checking the Scott manual instead of the Shimano manual, but is there any basis for a warranty claim against Scott? I've looked carefully at the frame internally and there is no internal sleeve to support the bolt tension. As an engineer, I find that pretty appalling.
Hello,
I get a similar situation on my bike.
I changed my wheelset for "winter wheelset" where I have disk already installed.
No particular issue with rear wheel/disk.
But with the front, it's not the same story, all the time my disk is in contact with the caliper R8070 (my disk is not perfectly flate).
I also seen by screwing the caliper bolt, that the caliper slide a little bit, therfore the disk is in contact to the brake pad.
I would like to confirm that I respect the torque mentionned on the fork (6Nm), not the torque describes in the user manual (5Nm).
- Brake caliper torque.jpg (31.23 KiB) Viewed 6076 times
After several hours unmount/mount and analysis, I also seen that the piston did not come out the same length between right/left (maybe 1mm). I also used an automobile mineral oil.
Therefore, I wanted to change the existing oil to Shimano and also open the caliper to clean the pistons OR take the opportunity to buy a new Dura Ace R9170 to also save some gr.
How many gr can we save with the change ?
I assume with the new 5Nm torque, probably the caliper will keep the correct/original place, but not solve the gap of both piston.
Do you know how to open Ultegra R8070 to clean piston ?
Thank you
