Magura MT7 mod to reduce lever throw. Part 2 of ???

Thanks for following along if anyone is still with this series of threads i’ve posted.

Based on previous assumptions being correct in
Part 0
and
Part 1

Magura radial master cylinders don’t have any complex linkage/servowave/swinglink driven piston.

Its just a hammer/’pointy end’ on the (removeable) lever blade which swings in on the pivot and pushes against the flat top of the (mechanically seperate) master cylinder piston in order to push it down into the lever body.

So in order to have the piston sat further into its travel to begin with (to reduce lever throw before bite-point, being mindful of the potential issues with compensator port discussed in part 1) could I simply add a thin shim on the flat piston surface? effectively a long winded ‘bite point adjustment’ feature?

Can anyone see any reason why that shouldn’t work?

Regarding pad/ rotor clearance (always assuming perfectly flat rotors). I remember seeing a table somewhere that listed the pad rotor clearances for different braking systems but cant find it anywhere now.

I think Magura had 0.3mm pad clearance. Do you engineering types think its possible to reliably run slightly less clearance?
I could get less clearance by using a thinner rotor between the caliper for the ‘fix’ (eg shimano standard 1.8mm rotor instead of my fitted 2.0mm Magura Storm HC rotor) and using a feeler gauge to reduce the gap further, then putting the caliper with reduced gap back on to my 2.0mm rotor. effectively moving each caliper piston consistently 0.1mm closer to the rotor.

Or will there just be too much warp in the Storm HC rotors during use to make that small a gap feasible?

The point of all this is I’m exploring to see if its possible to have the brake levers closer to the bar but engaging quicker and giving maximum braking before levers hit handlebar. My Magura MT7’s already have so much lever throw and even with longest adjusted reach they easily pull to the bar (brand new but on way to Magura for warranty inspection becasue of this), so tp get closer to the bar, if I reduce the reach as is, I’ll be getting even less braking as the master piston will be travelling even less distance to push the fluid to actuate the slave pistons.

Why bother with the shim when your first objective is to move the levers closer to the bars anyway. Just work on that

And keep the threads together. One of the mods is going to wake up this morning and start closing the others as otherwise it all gets a bit ‘noisy’

I’m not familiar with your lever design, but there should be a circlip or other retainer that holds the piston inside the cylinder. By adding a shim between the piston and retainer, you will reduce the dead stroke. However, you absolutely do not want to have the port to the reservoir blocked, so you need to shim it until it’s blocked, then back it off a mm or so.

Putting a shim between the lever and piston will just move the lever outwards, it won’t change the dead stroke.

The best you can do with calipers is to strip them and make sure the pistons are lubed, then fit nice new rotors. Trying to manually change the clearance is pointless because the pads will wear and you’ll get a wandering bite point.

Why bother with the shim

The reach adjust only moves the lever blade closer to the bar, nothing else changes inside the master cylinder. When I leave the lever as far out as possible so full lever travel is available, the lever can still be pulled right down to the handlebar where the maximum braking force is. So if I only use ‘reach adjust’ to bring the lever closer (reduce lever travel by half for example) but the piston is still in its original position then it only gets pushed half way in and not fully in, so result is much less force being transmitted at the caliper.

Thanks for the videos paton.

Even after multiple bleeds and using the BAT adjustment as shown by Jude Monica in that first video you linked, the rear lever still has too much lever throw and free-stroke. and that’s why I’ve sent my MT7’s off to Magura to be checked out. The front brake is operating fine though with less lever travel up to the bite-point.

Lever travel up to bite-point shouldn’t be affected by longer or shorter hose so the front and rear in theory shouldn’t be so vastly different as the system isn’t under high enough pressure at that stage to cause the hose to expand significantly.

So the reason I’m interested in trying to investigate this modding option is if Magura send them back saying there is nothing wrong and its all operating within spec. I will end up with a rear brake that has almost 60% longer lever travel to reach bite-point than the front brake.

I’m probably going to get bummed with a frozen neighbours dog after this but..

I have just achieved what you have described with my bike brakes.

Assume a perfect bleed, everything as it should be.
The span adjuster works fine but putting the lever closer where I want it still has the same free travel before the bite point. No alternative lever blade with a bite adjuster was available.

I have jerry rigged my own bite point adjuster and it is working fine, no food through a straw or visit to dentists.

I was very careful to look in the M/c to watch that both ports were still open prior to squeezing the lever. I’m happy with the results and took a lot of care and time before actually riding, finding the point where after application, it wouldn’t release etc.

It can work but work on the solution. If another lever with a bite adjuster is a simple swap, this may be the way to go.

Also this is currently a thought experiment. I do understand that if I ever tried to attempt anything like this it would invalidate my warranty.

I’m seeking advice and info now in case of the worst case scenario where Magura cannot/will not fix this issue and say that this is just the acceptable range of operation for this brake and I have to learn to live with it.

@rickmeister
I knew there had to be someone out there trying the same thing, lol. Which brakes did you try it on? And what were mechanics of your solution?

I came across an article somewhere about the Outbraker Booster thats what got me thinking about a fix.

The problem I see with that device is that all it seems to do is just adding a secondary adjustable fluid reservoir within the hydraulic line itself. So when you turn its dial and reduce the volume of the secpndary reservoir you are pushing more fluid back down into the system again.

But then what’s stopping that fluid from just flowing straight back up through the compensator port in your brakes master cylinder straight back into your brake lever body’s reservoir? Nothing, unless you pull the lever slightly to close the port or you have stuffed your main reservoir full, in which case there is no more room for thermal expansion.

No alternative lever blade with a bite adjuster was available.

You can’t build a bite-point adjuster into the lever blade.

The lever throw before bite point is determined by the gap between the pads and the disc and ratio of lever movement to pad movement. The distance between the pads and the disc is determined by the rollback of the caliper piston seals (nothing in the lever, or the pad ‘spring’)

Shimano have a cam operated link that means the relationship between lever and pads is non linear, ie the pads move more at the start of the lever pull than at the end.

Put Shimano levers on your magura calipers and get the best of both worlds. It gets rid of the plasticy crap that magura builds their levers with and it gets you a brake that works and has more power than Shimano Saint.

To be fair, the MT5 levers were rubbish on my maguras, but I’ve not seen the MT7s so they might be less plasticy.

But Shigura works a treat

What Neb said.

“Bite point” is set at the caliper end.

Shimano free stroke adjustment is in effect changing when the cam kicks in, it does move the piston, but it’s doing it to move the actuator just moving the piston alone wont work, the calliper seals will still roll back the same amount, and the excess fluid will go into the reservoir. If it has an effect it probably means there was air getting into the master cylinder and trapped between the reservoir port and the piston, move the piston down the barrel and that bubble is more likley to go into the resevoir.

SRAM adjust bite point by moving the whole cylinder, hope do it by adjusting the distance between the lever and the actuator on the piston.

“Bite point” is set at the caliper end

Also determined by how far the piston has to move to close off the transfer port to the reservoir.

Indeed, although I’m curious why you’d design a brake where that wasn’t already minimal?

thanks @Hols

…Trying to manually change the clearance is pointless because the pads will wear and you’ll get a wandering bite point…

That was a super important point I didn’t fully think through the consequences of.

I wrote incorrectly before. When I talk about adjusting bitepoint. Really I am referring to 2 things. Reducing dead-stroke (which theoretically is achievable at the lever side) and then reducing pad-gap-stroke, which can only be achieved at the piston/pad end but with a caveat…

@Neb
I totally understand that ‘bite-point’ itself is a mechanical function of gap between slave piston and rotor and the properties of the slave piston seals, how much it lets the piston extend and retract and how much extension of the piston beyond the seal is required before it slips through to assumes a new more outward seated position to self-adjust for pad wear.

I had to think it through but that last bit made realise its worthless manually reducing the pad-rotor clearance because it cant stay constant.

As the pads wear the gap will grow, until the pads thickness is reduced enough that the piston gets ‘slid’ further out through the seal to ‘take up the slack’ and that will recreate the default system designed gap

Which I see now is directly controlled by how much lateral movement is designed into the seal around the slave piston, so to do with seals material property (shape, thickness etc) and how its seated in the caliper.

SOOOOOOOO then does that mean that EVERY brake that has a ‘Bite Point Adjuster’ feature is just doing so by reducing dead-stroke?

There’s not a lot you can do bar making them as close to 100% oil as possible and bleeding any air out. It’s a hydraulic system, the lever pull is compressing the oil, to then operate the pistons at their designed pressure, unless you can increase the pressure applied to the pistons with less movement of the plunger it’s not going to do anything, and you can’t increase the area of the plunger, or decrease the area of the piston, or increase the oil pressure, basically not a lot you can do.

I too have MT7s, the rear is never as good as the front, but it’s got a longer hose so bleeding without being able to pressurise the system isn’t going to be as efficient as the front, the trapped air is always going to be harder to push out due to this.

@argee –

With your MT7’s, aside from the difference in feel which I appreciate is to be expected with the longer rear hose, do you also find that there is a significant difference in how much you have to pull the lever before the pads hit the rotor on each side.

Yeah, but as per previous, the rear is always going to be slightly slower, so require a little more pull to get the same effect.

If you’re worried about this, there’s always the shigura modification!

The Shigura is biding its time waiting for the right opportunity!

These MT7’s are brand new retail units. Doesn’t sit well with me to spend all that money and then end up swapping them out straight away for Shimano levers at a further additional cost.
But the minute a tree or the ground takes its anger out on and breaks the MT7’s, I’ll pony up for some Saint Levers for them.

Reverse bleed will help reduce air in the system as well. Push fluid in at caliper end as air rises so should move quicker and easier to lever.

I’ve had similar issues with various brakes over the last few years. Love shimano for feel and power, but random bite point got tedious after a while.

Swapped to magura trail brakes, which are great, but cheap plastic levers and long lever throw wasn’t ideal.

Then reading this got me thinking that I have plenty of shimano xt servowave levers with dodgy calipers, and excellent magura calipers with dodgy levers, so tried the shigura bodge yesterday.

Wow! I have everything I want out of a brake now. Short lever throw with great feel, fantastic power and super easy to bleed. Haven’t tried them properly off road yet, but round the local park they felt spot on.

Fingers crossed for the long term!

…so tried the shigura bodge…

What saddens me about this(my) entire thread is that after spending all this money and effort on brand new Magura and then resigning ourselves to the fact of needing to swap back to Shimano levers.

Begs the question (for those looking for new brake setups, not implying for those who are happy with older setups) why didn’t we just go with the new Shimano 4 pots in the first place? If we are accepting the fact that we will be swapping out levers as they develop problems, ie throwing more money at the problem, whether you are shimano or magura user?

New Shimano 4 pots (2x16mm and 2x18mm pistons) compared to the Magura MT’s(4x17mm pistons) are within 0.3% of each other in terms of relative hydraulic leverage all other things being equal (seeing as we are going back to using shimano levers)

so where’s the advantage of the Magura caliper anymore?

And shimanos newer servowave shape and differing sized pistons seems to offer better modulation and progressivity than their previous iterations.

and at least with Shimano calipers if seals and pistons fail we can just cannibalise a cheap £30 Deore caliper for its parts if I wanted to keep the XT/Saint/Zee branding on the outside. Cheapest Magura 4-pot caliper is around £80 plus

This is the best case of buyers remorse I have had in ages, lol.

I’m not just whinging for the sake of whinging, I’m also genuinely putting this out there for others in a similar position looking at all the factors to help them make their future decisions.

I wasn’t anticipating on encountering the ongoing issues I have had with my brand new Maguras, through my experiences I’ve resigned myself to ‘shigura’ing’ when the time comes.

In hindsight if I had known I would need to resort to Shigura I would have just bought brand new XT 8120’s.

BUT I do actually love the look of the forged MT7 calipers and I kinda find the radial master cylinders growing on me design wise. Along with the opportunity to personalise the ‘7-shaped’ sticker on top and even 3d custom print the caliper eyelet thingamajiggies, not that i’ve done that but its a little bit of fun if you are that way inclined

uploaded by user Smiley88 on mtb-news.de forum

and I know there are thousands and thousands of very satisfied happy Magura users who aren’t here complaining. So they have made the right choice for themselves and are reaping the rewards of that choice. Maybe when I get my units back from Magura there is every possibility I will be entirely happy with the levers and they remain consistent for me. I would like nothing more than to be happy about the way the Maguras work.

This is NOT a Magura bashing thread. They are a good company with clearly a lot of experience and history behind them and their products are great and have a lot of thought put into their design that I wont comprehend.

ALSO Chris @Magura Bikeparts UK is awesome and always so helpful. This thread is simply my right to explore my personal preferences through the knowledge and assistance of other like minded individuals.

Begs the question (for those looking for new brake setups, not implying for those who are happy with older setups) why didn’t we just go with the new Shimano 4 pots in the first place?

Because you might not like the bite point on your maguras but at least its in the same place all the time and the seals aren’t made of sugar paper?

Bought some Mt5’s for the wifes bike (which is also my spare bike) a couple of weeks ago, I’m actually quite impressed with them, the power is good, modulation good. The lever bodies are a bit plasticky but they seem to get the job done.

I cut the hoses down as they were way too long, after this the rear didnt need bleeding, but the front must have got air in, and the lever throw was quite long. I gave them a quick bleed using a bodged bleed kit from some old shimano brakes that I had lying around, and they were fine. Very easy to bleed actually, I just pushed oil through from the lever end.

Op – I suspect that magura will fix the issue with your brake and then they’ll be fine.

…bite point…same place all the time…….seals….made of sugar paper?

Just out of curiosity, Ive never had Shimanos that did the wandering bite point thing. Is there an average time of useage you get out of them before they get posessed? Or is it just a random lottery?

A new deore caliper at 30 quid seems like a non-horrendous price to get four spare donor seals and pistons (2 large + 2 small)to keep you going for another 2 years at least if seal failure is likely a yearly thing and they dont all implode at once.

The old 2 pot ceramic shimano pistons that used to get chipped, I swapped out for the Hope HBSP235 pistons (they were a smidge taller so need to be careful) their surface was a lot smoother than the shimano ceramic so I imagine would be less stressful on the seal, which obviously weren’t the hope seals because those are for DOT fluid