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Discussion Starter · #1 ·
Hello, first of all sorry for my English, I am from Spain.
I have read the excellent guide about the Hope brakes overhaul by SteveUK and I decided to do the maintenance. I have a question that, maybe, you can answer.
I did a complete overhaul to clean deeply my brakes (Mono Mini Pro), but when I opened the cap of the reservoir, after draining the brakes, I found one little piece of aluminiun loosen inside the reservoir. In the other brake this piece is welded. You can see the piece I refer in the picture number 11 of SteveUK's "Hope Mini/Mono/Moto Lever Overhaul" guide.
Do you know what is the role of this piece? I am going to reassembly the brake without this piece, do you think it will work properly?
Thank you.
 

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The piece that you're referring to is the deflector plate. It's not welded in, but rather it's pressed into place using what might be called an interference fit.

Based on the name of the part, I'll take a semi-educated guess as to what its purpose may be. The friction of the braking process produces heat which can cause the brake fluid to expand as it in turn is heated. The reservoir in the MC of open system brakes (like the Mini) is to allow the brake fluid to expand without affecting the performance of the brake (ithe fluid can expand into the reservoir rather than preventing the pistons from properly retracting). This heating occurs at a time when the lever is pulled and the fluid in the reservoir is isolated from the rest of the fluid in the system. The longer the brake has been applied and the more the fluid has been heated, the more the fluid will expand. When the lever is released the heated fluid in the system will then be allowed to expand into the reservoir. Should this happen too quickly, as it may do after an extending period of braking, the fluid in the reservoir may force its way past the seal/diaphragm and out of the system. If fluid is forced out, it's almost certain that air will then be pulled in. Even if it doesn't go as far as requiring that the system needs to be bled of air, it would mean that the fluid in the reservoir will deteriorate* pretty quickly, thus reducing the overall performance of the brake. It would appear to me that the deflector plate is there to slow the heated fluid as it is reintroduced to the reservoir.

*DOT fluid within a brake system will thicken over time as a result of air drawn in past the seals in the caliper and lever. It might usually take 2 to 4 years for this to cause a notable reduction in brake performance, the first signs of which are pistons which are slower than normal to retract.

I'd suggest that you 'phone/email Hope do get clarification on this.
 

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Discussion Starter · #3 ·
:eekster: :eekster: :eekster: :eekster: :eekster: :eekster: :eekster: :eekster:

Excellent explanation, a master class about brake perfomance.
I emailed Hope but there's no answer yet. I am in a hurry, so I will take the risk and reassembly the brakes without that piece. I hope it is not as important as I thought, and I hope too that the brakes work well.
Thank you.
 

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You could just press the deflector back in, carefully, using a small screwdriver or similar. If it came out of its own accord it shouldn't be too difficult to refit.

For integrity of information, would you please post up any information that Hope gives you regarding the plate? I'd be interested to know if my guess is a good one...
 

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Discussion Starter · #5 ·
SteveUK said:
You could just press the deflector back in, carefully, using a small screwdriver or similar. If it came out of its own accord it shouldn't be too difficult to refit.

For integrity of information, would you please post up any information that Hope gives you regarding the plate? I'd be interested to know if my guess is a good one...
Sure, I will post what they tell me.
Now I have tried to put the deflector back in the reservoir, but it gets out when I flip the MC, it seems that the inside of the reservoir, where the deflector fits, is worn. Maybe could I cut a piece of alluminium with similar size and try to put it back?
 

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Ahh, if it won't go back in then I wouldn't worry about it, unless Hope tell you that it's vital to the brake's performance. If my theory is correct, then the deflector is only really important if you're in the habit of heating the brake up. Who knows how long the deflector has been loose in the MC, but it obviously hasn't affected the brake's performance so far. If you are the original owner of the brake, I would guess that Hope will warranty the lever for you if needs be.
 

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Discussion Starter · #7 ·
SteveUK said:
For integrity of information, would you please post up any information that Hope gives you regarding the plate? I'd be interested to know if my guess is a good one...
Hello, this is what Hope told me:

"The small metal piece is a deflector plate. It stops bubbles from being pushed into the master cylinder. It isn't welded in position, just pushed to a tight fit. If it has come away it just re align it and push it back in place, but don't run it without t. "

Cheers.
 
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