105 brake disc pull (update: now a hideous squeal!)

acuna_read
acuna_read Posts: 36
edited July 2020 in Workshop
I have built up an older steel Genesis equilibrium disc with 105 5800 components but Hope RX4 post mount calipers with IS adapters. I have managed to set up the brakes correctly and all works well most of the time apart from when I grab the front brake rapidly the disc/wheel noticeably pulls to the left. The discs are tektro (160mm) on second hand Mavic Aksiums (6 bolt). I've checked the wheels and they seem ok but could this need spoke tightening, wheel truing is my mechanical downfall.

Is this something I've done wrong with the set up, can it be dialed out?

Thanks for any help.

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,325
    Is it QR, thru axle or what? I'm wondering whether the wheel doesn't sit correctly...
    left the forum March 2023
  • acuna_read
    acuna_read Posts: 36
    Its QR, I'll have a look at the wheel in more detail and try to see.
  • pilot_pete
    pilot_pete Posts: 2,120
    Can be an issue with quick releases and disc brakes. Need to be really tight. Make sure you have the correct end caps on the hubs too...

    PP
  • ugo.santalucia
    ugo.santalucia Posts: 28,325
    Yes, normal QR skewers never worked well on my Ridley disc, I had to use Shimano ones, which clamp with more force
    left the forum March 2023
  • pilot_pete
    pilot_pete Posts: 2,120
    edited June 2020
    I fitted DT Swiss RWS thru bolts which are excellent. Just needed to change end caps on the Hope Hubs, the clamping force is exceptional compared to normal quick releases in dropouts with disk brakes fitted. For those who have not seen them, they are the second skewer the guys demos in this video -

    https://youtu.be/A2m-hBzli9w

    PP
  • acuna_read
    acuna_read Posts: 36
    Had a bit of a play and tightened the skewer up a fair bit which has helped considerably, thanks. Think there may still be a bit of a pull on the wheel though.
    pilot_pete said:

    I fitted DT Swiss RWS thru bolts which are excellent.PP

    Will have a look into these as well.

    Thanks for all the help.

  • acuna_read
    acuna_read Posts: 36
    So this has now progressed and turned into a really obnoxious squeal from both front and back brakes.

    The bike sat for 2-3 weeks due to using my other road bike but I am now back to commuting 8 miles each way in/out of London. However the squeal is embarrassing and has slightly reduced braking performance. The pads were glazed so I cleaned both the pads and discs with isopropyl, I then sanded the pads down with some 280 grit paper on a flat surface and cleaned again with isopropyl. Still squeals.

    I am running Hope RX4 calipers and had Tektro rotors on 6 bolt mavic aksiums. However I tried this with Shimano SM-RT66 rotors as well as hope floating rotors, same result. I can see no evidence of fluid leaking past seals onto pads/discs either. I have even done the old silicone copper on the back of the pads which I'm sure doesn't really do anything but was worth a go. I have checked all alignment and both wheels and discs are fine.

    I know the next port of call is the pads but does anyone have any other advice that may help?

    Thanks in advance.
  • lesfirth
    lesfirth Posts: 1,382
    You have done exactly what i would have done except - remove discs and give them a rub with 280 or maybe 400 grit paper all over the braking surface. Now you have had them squealing you will have to give the pads a rub again.
    A bit of copperslip on the back of the pad and on the edges where they slide in the calipers helps stop the pad vibrating , That is what is causing the squeal. It is standard practice in the car trade.
  • prcody
    prcody Posts: 67
    Have you tightened up the hoses and checked the olives in the hoses? I had this before and it was a dodgy olive that I replaced and tightened up. I also used a blow torch to burn the oil out of the pads as I was getting sick of contaminating every set of replacement pads I had due to the faulty olive.
  • acuna_read
    acuna_read Posts: 36
    edited August 2020
    Hi, I managed to get the squeak sorted and did check all of these but thanks for the advice.

    Sadly the bike got stolen on Tuesday so any further squeaking issues will be some thieving p**cks problem.
  • ballysmate
    ballysmate Posts: 15,996
    Shame you got the squeal sorted before it got nicked. Could have helped trace the thieving twat.

    What was the cause in the end?
  • acuna_read
    acuna_read Posts: 36
    Not sure as I changed many things at once. I cleaned all braking surfaces again + rubbed down discs with some emery paper. I also changed the front pads to sintered and put copper slip on the backing plates of all pads. Checked all connections as suggested above as well but they seemed fine.

    Stolen bike info here in case anyone sees anything for sale online. https://forum.bikeradar.com/discussion/13112607/genesis-equilibrium#latest

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