Fox 38 Fork With Magura 220mm Rotor Help

[Chris525uk]

Hi guys,

just looking for some help as it looks like i have been provided with bad knowledge.

so i have a magura MT7 stock set up on fox 38 forks 203mm rotors. I wanted to upgrade to 220mm. I was told to get the QM46 adapter. But this doesnt seem to work the rotor will push the Calliper out to far for me to screw the QM46 mount to the fork…

so any ideas what adapter i need? Or is this even possible?

added some photos for reference. You can see im way off from getting this to fit. (Thats with the 220mm on btw)

 

[VWsurfbum]

They're rear ones by the look of it, you need the offset ones.

 

[johnf0246]

Hi guys,

just looking for some help as it looks like i have been provided with bad knowledge.

so i have a magura MT7 stock set up on fox 38 forks 203mm rotors. I wanted to upgrade to 220mm. I was told to get the QM46 adapter. But this doesnt seem to work the rotor will push the Calliper out to far for me to screw the QM46 mount to the fork…

so any ideas what adapter i need? Or is this even possible?

added some photos for reference. You can see im way off from getting this to fit. (Thats with the 220mm on btw)

View attachment 62597

View attachment 62598

View attachment 62599

View attachment 62600

Chris:

If you don’t need to use any adapter to use a 180 mm rotor on that fork I believe you need a Magura QM45 adapter which allows you to adapt the 180 mount to 220 mm. The adapters you have don’t do that.

 

[Chris525uk]

Thank you all. Looks like the shop gave me the wrong one then. I will try QM45.

 

[Chris525uk]

@johnf0246 i bought that adapter looks like it will be the correct one.

however the original bolts dont fit. Would you know which ones i need? The ones that are supplied (smaller ones in the photo) fit into the fork which is fine… but my original ones that were in the adapter are to long… can you recommend a bolt size?

 

[johnf0246]

@johnf0246 i bought that adapter looks like it will be the correct one.

however the original bolts dont fit. Would you know which ones i need? The ones that are supplied (smaller ones in the photo) fit into the fork which is fine… but my original ones that were in the adapter are to long… can you recommend a bolt size?

View attachment 63150

View attachment 63151

Chris the bolt size that would work is 2 mm longer than the short bolts. If the long bolts thread all the way through the treaded part in your picture, you could find someone with a hacksaw and cut them one millimeter shorter than the part you screw the brake caliper on to.

 

[Chris525uk]

Chris the bolt size that would work is 2 mm longer than the short bolts. If the long bolts thread all the way through the treaded part in your picture, you could find someone with a hacksaw and cut them one millimeter shorter than the part you screw the brake caliper on to.

I don’t suppose you know the name of this type of bolt so i can search for them?

im starting to think this 220mm disk really isnt worth it haha

 

[johnf0246]

I don’t suppose you know the name of this type of bolt so i can search for them?

im starting to think this 220mm disk really isnt worth it haha

Mountain bike brake caliper bolt.

 

[Chris525uk]

Mountain bike brake caliper bolt.

did google that. Lots of options came up. Hahaha no worries thanks for your help il just go to my local bike shop and see if they got any.

cheers

 

[johnf0246]

did google that. Lots of options came up. Hahaha no worries thanks for your help il just go to my local bike shop and see if they got any.

cheers

Chris if they don’t got any I would change shops. Any good hardware store would also have them. ?

John

 

[Gyre]

You need M6 x ## where "##" is the length in mm that you want. Pick up fitting washers while you're at it or use bolts with integrated washers.

 

[johnf0246]

You need M6 x ## where "##" is the length in mm that you want. Pick up fitting washers while you're at it or use bolts with integrated washers.

Gyre you make a good point about using washers on the brake caliper. Using the special brake caliper washers would probably mean the current bolts Chris has would work.

 

[Chris525uk]

@Gyre @johnf0246

Thank you both! I now have the bolts and its fitted to the bike!

1 last question though i was bedding the new pads and rotor and noticed a knocking noise when coming to a stop… i can only describe it as a woodpecker pecking at a tree haha. Is this a normal sound from the bigger rotor do you know? The performance is spot on and is noticeable improvement and i can only imagine with more bedding in when i hit the trails they will get even better… but if the knocking isn't normal i guess i should do something about that before i get onto the trails :/

 

[VWsurfbum]

Pads are sitting too low down and are hitting/rubbing on the black part of the disc, you may need a 1-2mm washer under the caaliper.

 

[Chris525uk]

Pads are sitting too low down and are hitting/rubbing on the black part of the disc, you may need a 1-2mm washer under the caaliper.

Hi. Just check and they are clear from the black part from the disk… also checked the wear on the disk and its the same as the original rear rotor. So thats all good

 

[Gyre]

A little bit of warbling seems normal, but knocking might be a little bit of contact between the pins that fix the aluminum and steel parts with some part of the caliper or pads.

 

[johnf0246]

@Gyre @johnf0246

Thank you both! I now have the bolts and its fitted to the bike!

1 last question though i was bedding the new pads and rotor and noticed a knocking noise when coming to a stop… i can only describe it as a woodpecker pecking at a tree haha. Is this a normal sound from the bigger rotor do you know? The performance is spot on and is noticeable improvement and i can only imagine with more bedding in when i hit the trails they will get even better… but if the knocking isn't normal i guess i should do something about that before i get onto the trails :/

View attachment 63337

Chris when you have the front wheel elevated and spin it, does it spin without ANY NOISE? Could the 180 to 220 adapter be on backwards?

 

[Chris525uk]

Chris when you have the front wheel elevated and spin it, does it spin without ANY NOISE? Could the 180 to 220 adapter be on backwards?

only slight noice as the pads are slightly touching the rotor but with some wear and use im sure it will free up a bit…

adaptor is 100% correct can only go on one way with the arrow stating “UP” im going to go out on it tonight and see if it beds in more. Il probably go over the bars or something now lolll

 

[Chris525uk]

@johnf0246 after my ride it didn’t go away. Put in my old pads and that solved the problem. So looks like an issue with the new pads.

thanks again for all your help

 

[DOGBOY333!]

@johnf0246 after my ride it didn’t go away. Put in my old pads and that solved the problem. So looks like an issue with the new pads.

thanks again for all your help

Hi mate, did you use QM 45 on the front and the back?
I'm looking to go with 220mm rotors front and rear so your advice would be great.