I've got a Delite with Magura E hydraulic brakes. I am looking for suggestions on how to adjust the rear disc brake pads by very minimal amount. No matter how I attempt to adjust rear caliper bolts I end up with the rotor contacting the pads. Wondering if there is an adjustment screw on the rear calliper to dial in the pads so there is no rotor contact. A dealer assembled the bike and I am not sure if the rotor tocuhing the pads was intentional due to the weight and speed potential of the bike. Any suggestions, help or advice will be appreciated.
Help with Magura E rear brake adjustment
- Thread starter Alanzo
- Start date
AguassissiM
Well-Known Member
fooferdoggie
Well-Known Member
the works well wedge it in-between the pads and rotor then tighten them. there are cheaper version out there.
m@Robertson
Well-Known Member
- Region
- USA
Part of the benefit of the Magura brakes is the pads are self-adjusting. Once you get fitment right, you never have to touch them again until the pads wear down and need replacement. That includes pulling off a wheel and putting it back on.
The trick then is to get the fitment right. Absent some other problem - like a warped rotor - the way you do that is to adjust caliper placement. The bolt holes on the caliper itself are oval. The best way to get these perfect is to start with what @AguassissiM describes. However there are nuances on Maguras that it will help to know.
- Lift the bike somehow so the affected wheel is off the ground and can be spun by hand. this is crucial to getting the job done right.
- Loosen the caliper bolts so the caliper is only *barely* mobile when wiggling it gently with your fingertips. It should in fact still feel snug but moveable when you give it some torque from two fingers gripping it side to side.
- Spin the wheel by hand several times, engaging the brakes *gently* several times. This will ensure the caliper has migrated to where it wants to be without undue influence from jerky anomalies like slamming on the brakes with a loose caliper.
- While holding the brake lever to keep the brake engaged (bungie cord), slowly and carefully - use only your fingertips on the wrench - give each caliper bolt about 1/8 of a turn so the caliper is gently tight to the adapter
- spin the wheel. Is it spinning free now? If so again tighten one bolt at a time about 1/8 of a turn, in alternating fashion, about 2 more times.
Tightening a Magura caliper on a Magura adapter, the final tightening after caliper alignment usually suffers from two things. First, overtorqueing the bolts will shift the caliper sideways just enough to screw up your alignment. Next, fully clamping the caliper to the face of the adapter will foul it up vertically, on the plain of the rotor face to the pads. Care in tightening it up will solve this.
Once you get a feel for this with Magura brakes, it will be simple and one-step to get it right. Also once you don't have both fresh pads and rotors together, you'll have wider tolerances to play with. Sometimes to get it *just* right after the above, I loosen the caliper bolts so one is still snug in place, but the other is *barely* movable and I use my eyeballs to look down the rotor and pad gap and visually ensure there is a hair of daylight on both sides.
The trick then is to get the fitment right. Absent some other problem - like a warped rotor - the way you do that is to adjust caliper placement. The bolt holes on the caliper itself are oval. The best way to get these perfect is to start with what @AguassissiM describes. However there are nuances on Maguras that it will help to know.
- Lift the bike somehow so the affected wheel is off the ground and can be spun by hand. this is crucial to getting the job done right.
- Loosen the caliper bolts so the caliper is only *barely* mobile when wiggling it gently with your fingertips. It should in fact still feel snug but moveable when you give it some torque from two fingers gripping it side to side.
- Spin the wheel by hand several times, engaging the brakes *gently* several times. This will ensure the caliper has migrated to where it wants to be without undue influence from jerky anomalies like slamming on the brakes with a loose caliper.
- While holding the brake lever to keep the brake engaged (bungie cord), slowly and carefully - use only your fingertips on the wrench - give each caliper bolt about 1/8 of a turn so the caliper is gently tight to the adapter
- spin the wheel. Is it spinning free now? If so again tighten one bolt at a time about 1/8 of a turn, in alternating fashion, about 2 more times.
Tightening a Magura caliper on a Magura adapter, the final tightening after caliper alignment usually suffers from two things. First, overtorqueing the bolts will shift the caliper sideways just enough to screw up your alignment. Next, fully clamping the caliper to the face of the adapter will foul it up vertically, on the plain of the rotor face to the pads. Care in tightening it up will solve this.
Once you get a feel for this with Magura brakes, it will be simple and one-step to get it right. Also once you don't have both fresh pads and rotors together, you'll have wider tolerances to play with. Sometimes to get it *just* right after the above, I loosen the caliper bolts so one is still snug in place, but the other is *barely* movable and I use my eyeballs to look down the rotor and pad gap and visually ensure there is a hair of daylight on both sides.
Thanks for the replies. Wondering if the tight tolerance between the brake pads and disc rotor is the result of a bike that has not been in use. I have had the bike for over 2 years and waited an extended time before riding again. A non E bike I rode had Avid mechanicals with an adjustable dial on the caliper to fine tune the pads. Does not appear to be the same with the Magura caliper. I have tired thin plastic strips on the rotor in effort to align the caliper before tightening. I've also loosened the caliper bolts, wrapped velcro around the right brake lever and re-tightened the caliper bolts. That technique allowed the best alignment so far but I still end up with pads contacting the rotor when the wheel is spinning in a bike stand.
Wondering if Magura calipers require brake in time with wear on the pads before there is clearance between the rotor and the pad. Have other people experienced rotor pad rub on their bikes before getting time on the road? I was hoping there might be an adjustment screw or dial on the caliper to fine tune the pads.
Wondering if Magura calipers require brake in time with wear on the pads before there is clearance between the rotor and the pad. Have other people experienced rotor pad rub on their bikes before getting time on the road? I was hoping there might be an adjustment screw or dial on the caliper to fine tune the pads.
fooferdoggie
Well-Known Member
it could be a stuck piston so one side does not move as well. here on my shimano 4 pistons I took the pads out and used the lever a tiny bit to get the pistons out a bit so the pads were closer. but then I had rub and no matter what could not get it to stop. even pushing the pistons back in. I finally put in new pads and it was fine. so maybe I got one of the two pistons not in as much.
AguassissiM
Well-Known Member
m@Robertson
Well-Known Member
- Region
- USA
The Magura pistons should be self-centering. Thats part of their German-engineering allure - they are set-and-forget.
Its not uncommon for one side or the other to press the pistons in a tad further than the other side. But we are talking about a millimeter of difference by and large and the oval mount holes are well-capable of making up for this.
You can buy 0.5mm and 1.0mm Magura brake shims - fancy washers that are machined to much tighter tolerances than Ace Hardware washers. Used between the frame and brake adapter they will move the caliper inboard by the shim's width. Here's the thing though: This is an R&M, right? Not some DIY job. R&M figured out the brake tolerances when they did the specs for the bike (assuming no manufacturer's defect somewhere). Its a lot more likely you just need to do a proper one-time caliper adjustment.
FYI Magura rotors are 2.0 millimeters thick when new. Ordinary rotors are 1.8mm. BUT Magura calipers are designed specifically to use the wider spec rotor (using narrower 1.8mm rotors can over-extend the pistons and cause leakage) so there should not be a problem with the thickness. I actually use Tektro Type 17 downhill rotors with my 6 sets of MT5's on various bikes, and even with those thick 2.3mm rotors, the calipers fit. So 2.0mm Magura rotors aren't going to be the issue, and neither is fitment inside the caliper in terms of there being enough space.
AguassissiM,
Your suggestion worked!. One pad was contacting the rotor. I loosened the caliper bolts, placed a .004" piece of metal shim stock between the pad and rotor, pressed the brake lever and retightened the calliper bolts. Voila! There is no longer any caliper rub issue.
I called Magura and tech support said there was no tool or adjustment screw to change position of the pads. I tried a plastic shim which was too thick. Thin metal shim stock worked best.
Thanks!
m@Robertson,
I would have tried your suggestion if I had not used a thin gauge shim. I was wondering if others had tried different washers, rotors or caliper mounting techniques. The components on this R&M are the best of any bike I ever owned and I did not want to start messing anything up with effort to resolve the rotor rub. So I occasionally will ask rookie questions about Bikes and I do appreciate the time and effort people take to post a reply. Its all good!
AguassissiM
Well-Known Member
m@Robertson
Well-Known Member
- Region
- USA
It is! When I write stuff like this its just as much for the Next Guy who is using the Search function as it is for the situation at hand.
I can't use those brake-specific feeler gauges myself. Not enough room. But I bet a spark plug gauge could come in handy and never thought of it until now. I have one somewhere in the garage...
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