IS Adapter help

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IS Adapter help
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Posted: Sep 20, 2020 at 8:10 Quote
Hi guys,
New to the forum and to an extent MTB altogether!
Having some issues with brakes on my bike. It's an old Iron Horse warrior 1.x
The rear hydraulic calliper had a seized piston so I swapped it to a Shimano Deore m6100. Got it on and bled today and seems to be working somewhat okay but I didn't swap the adapter over, and looking at the wear on the pads and disc, only about half of the pad is actually contacting the disc. Brake is slipping and not working amazingly well. Looks to me like the new calliper is too high.
Having a bit of a nightmare with the adapter lingo, are all 160mm post mount adapters the same or do I need a specific one for the new brake? Cheers

Posted: Sep 20, 2020 at 19:54 Quote
Some photos would probably show the problem straight away instead of having to ask questions about the setup.

What was the old brake with a seized piston an Avid?

If yes, did you attach the Shimano brake the same way as the old brake?

If yes, Shimano brakes do not use spherical washers and they should be removed.

Posted: Sep 21, 2020 at 1:43 Quote
As mentioned pics would really help. In general best to buy Shimano adaptors for Shimano brakes. Do you have Post mounts or I.S. mounts? Post mount front, I.S. rear?

Both post mount and I.S. mount types of Shimano adaptors are sized to fit their size rotors 160mm, 180mm and 203mm.

Some other brands have slightly different rotor diameter sizes which can put caliper in the wrong position in relation to rotors as you describe (e.g. Sram 200mm rotor with 203mm Shimano adaptor.)

Adaptors simply being fitted upside down or the wrong way around is another possibility. As mentioned again, Shimano brakes don't require aluminium cup/cone washers to be fitted underneath the caliper mount points like Avid set ups do for example.

Maybe one of these could explain the issue?

Posted: Sep 21, 2020 at 5:05 Quote
The old brake was a Tektro Auriga, and I’ve just mounted the new Shimano to the old adapter. As you can see in the photo the outside of the disc is the only part actually making contact, and I pulled the pads and only the bottom parts are marked. Should all be compatible as far as I can tell so I’m guessing it’s the adapter?

Posted: Sep 21, 2020 at 5:17 Quote
Look in the gap on top of the caliper and see where the outer edge of the rotor is in relation to the outer edge of the pads.

How old is the rotor and what's it's thickness, Shimano says 1.5mm is the minimum thickness of the rotor.

If that old adapter was the correct size for the rotor, it should be the correct size for the new caliper.

Posted: Sep 21, 2020 at 5:40 Quote
I’ve just pulled the pads and there’s a lip cut in at the top (doesn’t come across too well on camera) about 1/4 down.

Rotor is about 8 years old but the bike hasn’t had much use, measures around 2mm.

Posted: Sep 21, 2020 at 6:50 Quote
You have fitted it properly looking at the pic so there's is no reason for the Shimano brake not to fit properly on that adaptor just like the original Tektro caliper with the same rotor.

Is there any markings showing the type number on the adaptor itself to double check with this Tektro chart?

Posted: Sep 21, 2020 at 7:10 Quote
It's marked as A_F180/R160

Can't see a number referring to any of those but it looks a lot like A3 to me which would make sense

Posted: Sep 21, 2020 at 7:51 Quote
This looks like it confirms it's the A3.

Posted: Sep 21, 2020 at 8:26 Quote
Yeah looks like it! Would a shimano one make any difference? Can’t work out what else it could be

Posted: Sep 21, 2020 at 9:11 Quote
It's a weird one Pal. With the markings F180/R160 suggests its a +20mm adaptor.

Looking at the pics of the pad track on the rotor it looks like your caliper is out by 10mm, worth measuring it to confirm.

I would say the I.S. mounts are native 160mm instead of 140mm, putting the caliper position at 180mm, possibly because your bike is older?

If so the solution would be borrow/buy and fit a 180mm rotor on the rear providing you have enough chainstay and seatstay frame clearance.

Posted: Sep 21, 2020 at 10:24 Quote
Has the top and bottom of the pad been chamfered?

Posted: Sep 21, 2020 at 11:02 Quote
I half know someone at a local bike shop so I might have to take it there and see if they’ll let me try a few different sized discs.

The bottom of the pad was chamfered but the top is actually a lip that sticks out rather than in, the photo angle is a bit misleading sorry! The edge of the disc is contacting where the top line is

Posted: Sep 21, 2020 at 11:21 Quote
Hard to tell but looking at the pic it seems like the previous brake was in the same position too. Below the rotor wear line looks like it's not had any previous wear from the Tektro brakes and pads. Have you still got them to check for the same step in the pad material?

Posted: Sep 21, 2020 at 11:53 Quote
I think it just looks like that as it’s been sat for quite a while without being used, there wasn’t a lip on the old pads and they were worn all over. It worked fine previously but one of the pistons seized and the reservoir seal had gone so was letting air in, hence the change!

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