Shimano brake calliper tuning

Discuss light weight issues concerning mountain bikes & parts.

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TheRookie
Posts: 910
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Just swapping out the old Avids on my MTB for some Shimano, both to reduce weight and improve brake control (the Avids are very on/off!)

So I have M775 XT levers, at the front a Saint M800 (Identical to M765XT) calliper direct mounted to my PM forks and at the rear an XTR M965 IS mounted calliper.

I also have the XTR M965 front mount calliper, but by the time I add an adaptor it would be heavier than the M800 so I'm looking to see what I can use off it to 'improve' the M800.

Pads I got with the M965's are not XTR so no lighter, I have swapped the pad retaining pin (saving 2g) but wondered if anyone has any experience of the pistons and screw in plug, is it worth trying to take them out the XTR calliper and putting in the M800, I've not come across anyone who has stripped a Shimano calliper as everyone just considers them a black box!

Or should I just sell it and use that to fund some alloy backed pads?
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

TheRookie
Posts: 910
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

So no-one any thoughts/comments, no-one stripped down calipers at all?
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

by Weenie


thisisnotaspoon
Posts: 95
Joined: Thu Aug 30, 2012 8:42 pm

by thisisnotaspoon

I had some of the previous itteration XTR callipers connected to similar vintage XT levers (XTR was DC only). One of the calliper seals blew in the rear so I sold them for spares (less than the cost of the goodridge hoses and alloy connectors!), the guy said he was going to strip them and put some cheeper calliper pistons in as they were all the same size.

I suspect you'll find 2 things, the pistons if they are interchangeable will be the same, they're plastic so not something they can make cheeper/heavier, they'd have to invest in new moulds to make the heavier pistons, costing them money! Mostly shimano brakes have been the same through XT/LX/SLX/Saint/Zee with changed colour schemes and very few uniquie parts.

My other tuppence would be;
a) alloy backed pads are lighter, but also consumable so you have to keep paying for those few grames every wet ride.
b) if brakes work, leave them. Worse thing to happen if a tuned mech gives up is a mullered mech, most likely on a climb where your goign slowly, brakes on the other hand tend to be the opposite!

Are you sure they're lighter than avids? I'm sure my elixirs were almost 100g/end lighter than my XT's. I swaped after one too many brake failiures not for weight.

TheRookie
Posts: 910
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

OK, thanks for that, the M800 combo is lighter than the Avids by a total of 41g, although I think the M775 lever is a fraction heavier than the M765, at the rear the M965 caliper will save the weight of the adapter and extra bolts as well so anticpate a total saving of circa 100g, also the rear XTR may be able to use my alligator disc without it howling like a banshee (stiffer mounting) which wil save more weight, I had to take it off with the Juicy's as it made night rides unsociable!
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

TheRookie
Posts: 910
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Just to close this one out....
I ended up using the XT M775 levers and the Saint M800 front caliper (PM mount direct to my forks) and the XTR M965 rear caliper (IS mount direct to the frame).

The M775 lever is 14g heavier than the Saint M800 (identical to an M765 XT except for paint and logo and the front set complete was the same weight as my daughters M765 to the nearest gram) although I saved 2g a lever off that with shorter/smaller headed retaining screws for the lever axle covers, I also saved 2g off the Saint caliper by using the XTR pad retaining pin from the front XTR (1g instead of 3g for the Saint/XT pin) I sold on (attached to the M800 lever).

Weight wise what I now have has saved 123g's versus the Avid Juicy 5's I had before, although 42g of that was in the longer bolts and CPS washers (7g each end) and the IS to PM adaptor at the rear with extra bolts (28g) needed for mounting the Avid calipers.

I'm currently running steel backed pads (came with the XTR calipers - not originals), 'Uberbike' aluminium backed can shave 22g off the bike.
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

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