Product Review Shimano XT M8020 4 piston caliper only kit.

EsPeGe

Likes Bikes and Dirt
Item: Shimano XT M8020 4 piston brake caliper only kit.
Purchased From: MTB Direct
Purchase Price (approx): $139 each end
Usage: Stopping, fast.

Pros - Look the balls, ridiculous stopping power, less finger/arm pump due not having to death grip so hard, modulation feels really good.

Cons - This is why I'm posting the review, the caliper only kit DOES NOT come with a banjo bolt and despite the caliper being "backwards compatible with M8000 levers" you can't use the old banjo bolt from the XT M8000 calipers. This is F$%KING stupid and I'm stuffed if I know why Shimano don't stock the correct banjo bolt with the kit when they know it will be paired with the old levers (which is why you are buying the caliper only!!!!) and therefore you won't have it. So if you decide you want these you need to order the Saint/Zee Banjo bolt and o-rings Shimano part number Y-8H0 98010 which cost me $10 for the pair. End rant here.

The correct banjo bolt (M8020/Saint/Zee)


The old M8000 banjo bolt, big difference.


Comments: Firstly these are the first 4 piston brakes I've used, ever. So a lot of what I say, I assume could be applied to all 4 piston brakes, eg less force required to slow down and therefore less arm pump, better modulation and of course much better stopping power.

They were easy to fit and bleed and took no more time than the M8000's they replaced. I tested them at Thredbo and was blown away. They stop sooo much faster but I never felt like I would go over the front, they always felt nicely modulated. There isn't much more I can say. They work really damn well.

I've read that they both are and aren't just rebadged Saint/Zee calipers on different forums etc but from what I can see if they aren't the same they are bloody close. They use the same pads and the aforementioned AWOL banjo bolt.

Pictures/Videos:



 

Dales Cannon

lightbrain about 4pm
Staff member
I did not realise that the 8000s had that weird looking bolt. Just checked mine and yep. The correct one looks tge same as the 810 Saint.

Thanks for the heads up.

Gotta get me one of these for the front of the Bronson.
 

Oddjob

Merry fucking Xmas to you assholes
What I don't get is the why? If they use the same pads as the Saints/Zees, why not just get the Zee calipers which are cheaper? It also raises the question of what Shimano will do with the next generatikn of Saint.

Sent from my SM-G900I using Tapatalk
 

Dales Cannon

lightbrain about 4pm
Staff member
What I don't get is the why? If they use the same pads as the Saints/Zees, why not just get the Zee calipers which are cheaper? It also raises the question of what Shimano will do with the next generatikn of Saint.

Sent from my SM-G900I using Tapatalk
6 pots!
 

EsPeGe

Likes Bikes and Dirt
What I don't get is the why? If they use the same pads as the Saints/Zees, why not just get the Zee calipers which are cheaper? It also raises the question of what Shimano will do with the next generatikn of Saint.

Sent from my SM-G900I using Tapatalk
Two reasons. Firstly at the time I purchased most places were out of stock of caliper only Zee kits. I could’ve got some off eBay but I’m pretty wary of buying there. The second and possibly more important reason would be that the XT’s match all my other XT groupset. For the difference in price which isn’t much I’d rather it all be the same.
 

stirk

Burner
Wouldn't the m8020 master cylinder push more fluid to cater for larger piston volume of 4 pot caliper?

No doubt the m8000 master cylinder would work but not be optimal.
 

Dales Cannon

lightbrain about 4pm
Staff member
I have run M810 Saints with XT levers on the Muru for years without issue, no shortage of fluid or excessive lever movement. I ordered an XT 4 pot for the pointy end of the Bronson so I will see how that goes with M9000 levers.
 

EsPeGe

Likes Bikes and Dirt
Wouldn't the m8020 master cylinder push more fluid to cater for larger piston volume of 4 pot caliper?

No doubt the m8000 master cylinder would work but not be optimal.
Good question. I might be wrong but I suspect the lever that comes with the M8020 kit is the M8000 lever. I can’t see any difference although I’ve not looked too closely.

Performance wise if you are correct then the M8020 levers must be really good because if the M8000 levers aren’t optimal they certainly feels pretty damn close.
 

stirk

Burner
Based on interweb intel the 2 pot calipers have a piston surface area only 20% smaller than the 4 pots. If the master cylinder are the same diameter and leverage ratio then it's not much of a difference. 80/20 rule, she'll be right!

I can't comment on the fluid dynamics but it seems to work just fine. From an engineering perspective you'd make a larger master cylinder to factor in the larger volume displacement of the bigger calipers.

Or would a smaller diameter master cylinder with a larger leverage ratio be better?
 
Last edited:

Dales Cannon

lightbrain about 4pm
Staff member
Based on interweb intel the 2 pot calipers have a piston surface area only 20% smaller than the 4 pots. If the master cylinder are the same diameter and leverage ratio then it's not much of a difference. 80/20 rule, she'll be right!

I can't comment on the fluid dynamics but it seems to work just fine. From an engineering perspective you'd make a larger master cylinder to factor in the larger volume displacement of the bigger calipers.

Or would a smaller diameter master cylinder with a larger leverage ratio be better?
Not necessarily. Smaller diameter with longer stroke is easier pull. Suck it and see. As I said no issue with 800s and 810s. Let you know next week as long as I can find my spare banjo bolt...
 

Dales Cannon

lightbrain about 4pm
Staff member
4 pots is partly about pad area but also because the pistons are different diameters it creates a progressive feel.
 

Dales Cannon

lightbrain about 4pm
Staff member
Mine arrived today so I will fit it tonight! Found my old extra Saint Banjo bolt while digging out the rotors for a Mexican.

Have to say it looks very nice.
 

The Duckmeister

Has a juicy midrange
Good question. I might be wrong but I suspect the lever that comes with the M8020 kit is the M8000 lever. I can’t see any difference although I’ve not looked too closely.
It is indeed the same M8000 lever. Running through Shimano Techdocs reveals that there is no such beast as a M8020 lever.
 

Dales Cannon

lightbrain about 4pm
Staff member
Fitted mine and after a brief panic found the Shimano brake fluid amongst the rest of the brake fluid in the shed. Lever movement looks to be the same as the XT at the rear which is odd unless the 4 pots don't retract as far away from the disc. Anyway while bedding the pads I reckon there is a bee's dick of air still in the caliper so I will let it sit overnight and rebleed tomorrow. Then I will measure lever movement.

After bedding the pads initial bite is a little stronger but comparing front and rear is problematic. Feels good with just one finger!
 

Oddjob

Merry fucking Xmas to you assholes
Fitted mine and after a brief panic found the Shimano brake fluid amongst the rest of the brake fluid in the shed. Lever movement looks to be the same as the XT at the rear which is odd unless the 4 pots don't retract as far away from the disc. Anyway while bedding the pads I reckon there is a bee's dick of air still in the caliper so I will let it sit overnight and rebleed tomorrow. Then I will measure lever movement.

After bedding the pads initial bite is a little stronger but comparing front and rear is problematic. Feels good with just one finger!
You will probably find that the difference will only become apparent when you're really hauling to a stop. The 2 pots will just seem to run out of braking force no matter how hard you pull on the levers whereas the 4 pots will actually have reserves of braking force.

Sent from my SM-G900I using Tapatalk
 

Dales Cannon

lightbrain about 4pm
Staff member
Finished off the bleed after the old rubber band trick overnight. Feels nice but really the way I ride the XTs would be enough...
 
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