Re: [DOG mailing list] BRAKE FLUID IN H36

[Michael Stockhill]

Thanks Rob

On Sun, Jun 24, 2018, 5:31 PM Rob Thompson  wrote:

> H36 Master Cylinder
> http://www.aircraftspruce.com/catalog/lgpages/cleve_mbrakecyl3.php
>
> H36 Wheels and Brakes
>
> http://www.aircraftspruce.com/catalog/lgpages/cleve_amphibian.php?recfer=7984
>
> regards
> Rob
>
> Rob Thompson
> 0429 493 828
> (Please note that my new email address is amessageto...@gmail.com)
>
> On Mon, Jun 25, 2018 at 8:48 AM, Michael Stockhill 
> wrote:
>
>> I just checked my H36/HK36 pplservice manual.  Page 59 specifies that
>> DOT3 or some equivalents are used.  They emphatically state that MIL5606 is
>> not to be used. I have always attributed this to the belief that the seals
>> and O rings in the master cylinder were incompatible with 5606. If the
>> master cylinder is a Cleveland part, I wonder if anyone has a Cleveland
>> part number. I have always thought of it as a BMW part--like the gas cap.
>>
>> Other serial number birds may have differing specifications in their
>> service manuals.
>>
>> I have no clue why Hoffman chose DOT3 fluid, but I can't imagine any such
>> manufacturer buying Cleveland brakes and then disassembling them to change
>> out O rings due to an incompatibility issue. Nor, I wonder if Cleveland
>> would make such a change on the assembly line, for certification reasons.
>>
>> My H36 arrived with automotive brake fluid. I put new tires on and
>> rebuilt the brakes, operated without any issues for about fifteen years,
>> then rebuilt the brakes a year or so back when I installed new tires. Upon
>> disassembly this was purely preventive maintenance because I hate the drill
>> of removing the wheels from the fairings.  In both instances of disassembly
>> I used MS O rings.  I saw no softening or significant deterioration after
>> years with DOT3.
>>
>> I live in a fairly dry climate, so absorption of water doesn't seem an
>> issue for either the H36 or thousands of autos here.
>>
>> My sophomoric understanding of hydraulics tells me the issue of water in
>> brake fluid is that it changes into a vaporous state at about 100 degrees
>> C.  As with brake fluid, it is not compressable in fluid state.  If the
>> brakes get hot--above that temperature and there is moisture in the slave
>> cylinders or in adjacent lines, one could have soft brakes or even
>> failure.  In comparison, corrosion may be the lesser concern.
>>
>> The fluid in the brake system does not circulate, so I wonder if it
>> wouldn't take many months of water absorption before the fluid at the slave
>> end of the system had an issue. This may be the case with most autos in the
>> states that can go decades without brake fluid replacement. It is a rare
>> spot of maintenance here (we have our foibles, including our elections.)
>> Once, when I requested brake fluid change, the shop didn't even get the
>> reason.
>>
>> Michael Stockhill
>> Polson MT
>>
>>
>> On Jun 24, 2018 3:25 PM, "Rob Thompson"  wrote:
>>
>> I just found this useful and comprehensive table of how different rubbers
>> are effected by different chemicals
>> http://mykin.com/rubber-chemical-resistance-chart-3
>> It says that Nitrile rubber is OK with glycol but as the auto brake
>> fluid absorbs water over time it must adversely effect the Nitrile O rings
>> as Nigel says. With Nigel's experience in hydraulics I would take what he
>> says as being the most practically accurate.
>> I have always bought genuine Cleveland nitrile rubber 0-rings for the the
>> H36 brake system and used the mineral oil that is recommended for them. You
>> need to pump a lot through to get the bubbles out so the mineral oil saves
>> a fair bit of cash. You can use Automatic Transmission Fluid.
>> Sounds like Glycol based fluids may be OK but on the condition that you
>> need to change them regularly if you have genuine Cleveland seals.
>> And make sure no one gets them mixed up when topping up the system!
>>
>> Rob
>>
>>
>> regards
>> Rob
>>
>> Rob Thompson
>> 0429 493 828
>> (Please note that my new email address is amessageto...@gmail.com)
>>
>> On Sun, Jun 24, 2018 at 10:05 PM, Nigel Baker > > wrote:
>>
>>> I think your right on the DOT 5 Konrad. Silicone lubricants are fine on
>>> BN seals and Silicone Grease is used to lube BN seals in food processing
>>> machinery as it is non toxic so compatible.
>>>
>>> The H36 mm does say DOT fluid but either some have been changed over at
>>> some stage eg by the Thai Airforce and others or depends on when it was
>>> built. There is a mix out there that I have seen.
>>>
>>>
>>>
>>> *Characteristics of common braking fluids*[6]
>>> [5]
>>> 
>>>
>>> *Dry boiling point *
>>>
>>> *Wet boiling point*
>>>
>>> *Viscosity limit*
>>>
>>> *Primary constituent*
>>>
>>> DOT 2
>>> 
>>>
>>> 190 °C (374 °F)
>>>
>>> 140 °C (284 °F)
>>>
>>> 

[DOG mailing list] more RE: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

[Nigel Baker]

These links spell it out very well.

Fluids are NOT interchangeable.

You can only change fluids if all the rubber components are changed to the 
correct material and the system flushed.

 

https://www.popularmechanics.com/cars/how-to/a2669/4253624/

https://www.quora.com/What-will-happen-if-you-use-brake-fluid-for-power-steering-fluid

 

Nige.

 

From: dog@lists.riverland.net.au  On Behalf Of Rob 
Thompson
Sent: Sunday, June 24, 2018 7:29 PM
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

 

Hi Michael,

So you have been running water soluble auto fluid in Cleveland brakes for 17 
years?

Interesting. I didn't think the rubber bits would go OK with a water/glycol 
based fluid.

Make sure you label the reservoir very clearly what type you are using. If 
someone adds the wrong type you will get a horrible mess!




regards

Rob

 

Rob Thompson

0429 493 828

(Please note that my new email address is amessageto...@gmail.com 
 )

 

On Sun, Jun 24, 2018 at 9:26 AM, Michael Stockhill mailto:sto...@gmail.com> > wrote:

I believe the service manual specifies  automotive type fluid, likely for the 
motorcycle type master cylinder.  No problem with Cleveland O rings in slaves 
for last 17 years.

 

Best

 

Michael Stockhill

 

 

 

 

 

On Jun 23, 2018 3:01 PM, "Rob Thompson" mailto:amessageto...@gmail.com> > wrote:

Just a reminder to everyone and Martin from K1W1 land.

The H36 uses hydraulic brake fluid. Auto fluid is water based and will wreck 
the seals and system.

 


regards

Rob

 

Rob Thompson

0429 493 828

(Please note that my new email address is amessageto...@gmail.com 
 )

 

 

AW: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

[Konrad FDU]

Hello Rob,
 
my MM for the Super Dimona specifies DOT4 as break fluid. So does TOST which
also is a Cleveland break. It is not specify DOT 5 that you might refer to
and is silicone based (not DOT5.1 which again is glycol based) .
I would not call DOT4 or DOT3 water soluble. It is hygroscopic and accepts
to accumulate the humidity from the air but water degrades performance and
boiling point. This is why break fluid is changed regularly or checked for
water.
 
regards
Konrad

  _  

Von: dog@lists.riverland.net.au [mailto:dog@lists.riverland.net.au] Im
Auftrag von Rob Thompson
Gesendet: Sonntag, 24. Juni 2018 11:59
An: dog@lists.riverland.net.au
Betreff: Re: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36


Hi Michael,

So you have been running water soluble auto fluid in Cleveland brakes for 17
years?

Interesting. I didn't think the rubber bits would go OK with a water/glycol
based fluid.

Make sure you label the reservoir very clearly what type you are using. If
someone adds the wrong type you will get a horrible mess!


regards
Rob

Rob Thompson
0429 493 828
(Please note that my new email address is amessageto...@gmail.com)

On Sun, Jun 24, 2018 at 9:26 AM, Michael Stockhill  wrote:


I believe the service manual specifies  automotive type fluid, likely for
the motorcycle type master cylinder.  No problem with Cleveland O rings in
slaves for last 17 years. 

Best


Michael Stockhill






On Jun 23, 2018 3:01 PM, "Rob Thompson"  wrote:


Just a reminder to everyone and Martin from K1W1 land.

The H36 uses hydraulic brake fluid. Auto fluid is water based and will wreck
the seals and system.

 

regards
Rob

Rob Thompson
0429 493 828
(Please note that my new email address is amessageto...@gmail.com)

RE: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

[Nigel Baker]

It depends when it was built as to whether it originally had car fluid or 
hydraulic oil.

The Cleveland brake systems come fitted with  bn seals (nitrile) and yes as Rob 
says the seal will break down with the auto product.

The G109 for instance uses auto so you have to change the seals over when you 
replace cylinders.

The advantage of mineral oil/hydraulic oil is that it doesn’t readily absorb 
moisture in contrast to auto fluid.

That advantage results in less risk of corrosion in the internals of the 
cylinders. Rob has recently had to overhaul some calipers where this was an 
issue. If the bore gets too pitted it is all over and time to buy a new one.

 

The master cylinder is not a motorcycle unit as many other manufacturers have 
adopted. It is a Cleveland with park brake valve and external reservoir. Also 
more expensive than the other type as used in Pawnee’s .

In the HK36 the slaves are Cleveland but the masters which are on both pedals 
for steering brakes are Matco mfg. That surprises me as Matco supplies the 
experimental market and I don’t think they have any certified equipment. How 
diamond does that I don’t understand but there is obviously a work round under 
EASA.

All the Matco stuff comes with BN seals fitted which is the industry norm as in 
GA mineral based hydraulic oil is the norm.

Cars often suffer long hill decent profiles that cause significant heat 
problems and the auto fluid id made to take that heat without boiling. Aircraft 
generally don’t get exposed to that problem. Schemp Hirth and others tend to 
use motorcycle master cylinders so seem to mainly use auto fluid I guess to 
avoid changing seals.

I am sticking with cheap mineral hydraulic oil. I always seem to have an 
abundance of it around the place and have dealt with brakes running on car 
fluid in both cars and gliders and not forgetting the old rarely maintained 
glider trailer and experienced significant corrosion issues many times. When I 
changed the axle in my trailer recently I went for mechanical disk brakes for 
that very reason.

Ill stick with mineral thanks.

Fly Safe.

Nige.

 

From: dog@lists.riverland.net.au  On Behalf Of Rob 
Thompson
Sent: Sunday, June 24, 2018 7:29 PM
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

 

Hi Michael,

So you have been running water soluble auto fluid in Cleveland brakes for 17 
years?

Interesting. I didn't think the rubber bits would go OK with a water/glycol 
based fluid.

Make sure you label the reservoir very clearly what type you are using. If 
someone adds the wrong type you will get a horrible mess!




regards

Rob

 

Rob Thompson

0429 493 828

(Please note that my new email address is amessageto...@gmail.com 
 )

 

On Sun, Jun 24, 2018 at 9:26 AM, Michael Stockhill mailto:sto...@gmail.com> > wrote:

I believe the service manual specifies  automotive type fluid, likely for the 
motorcycle type master cylinder.  No problem with Cleveland O rings in slaves 
for last 17 years.

 

Best

 

Michael Stockhill

 

 

 

 

 

On Jun 23, 2018 3:01 PM, "Rob Thompson" mailto:amessageto...@gmail.com> > wrote:

Just a reminder to everyone and Martin from K1W1 land.

The H36 uses hydraulic brake fluid. Auto fluid is water based and will wreck 
the seals and system.

 


regards

Rob

 

Rob Thompson

0429 493 828

(Please note that my new email address is amessageto...@gmail.com 
 )

 

 

Re: [DOG mailing list] NO AUTOMOTIVE BRAKE FLUID IN H36

[Rob Thompson]

Hi Michael,
So you have been running water soluble auto fluid in Cleveland brakes for
17 years?
Interesting. I didn't think the rubber bits would go OK with a water/glycol
based fluid.
Make sure you label the reservoir very clearly what type you are using. If
someone adds the wrong type you will get a horrible mess!

regards
Rob

Rob Thompson
0429 493 828
(Please note that my new email address is amessageto...@gmail.com)

On Sun, Jun 24, 2018 at 9:26 AM, Michael Stockhill  wrote:

> I believe the service manual specifies  automotive type fluid, likely for
> the motorcycle type master cylinder.  No problem with Cleveland O rings in
> slaves for last 17 years.
>
> Best
>
> Michael Stockhill
>
>
>
>
>
> On Jun 23, 2018 3:01 PM, "Rob Thompson"  wrote:
>
> Just a reminder to everyone and Martin from K1W1 land.
> The H36 uses hydraulic brake fluid. Auto fluid is water based and will
> wreck the seals and system.
>
>
> regards
> Rob
>
> Rob Thompson
> 0429 493 828
> (Please note that my new email address is amessageto...@gmail.com)
>
>
>

Re: [DOG mailing list] The pesky o'ring failures

[Ian Mc Phee]

Interesting read.

Recently I found a mechanical fuel pump was down on performance and another
h36 the original fuel tap was not replaced. I initially had owner buy new
Hardy fuel pump from Germany as fuel flow was well down on the 65lit per
hour. It was that stupid Truma red diamond shaped fuel tap (original owner
ignored the AD it seems) and was not rising enough and thus was restricting
fuel flow to 25lit per hr. Again it was a rubber. With the ball valve from
diamond fuel flow is up to 65 to 70 lit per hour.

So yes ALL rubbers need replacing everywhere they may be.

Also in fuel line replacement that stupid copper line connector behind
Muffler can weap.  A the later h36 have the fuel line comes from tap to
above the rhs pilots peddles and goes through fire wall in an AN bulk head
fitting. Then there is a short run to fuel pump or use Teflon braided fuel
lines.

Ian McPhee
0428847642
Box 657 Byron Bay NSW 2481

On Sat, 23 Jun 2018 8:19 pm Martyn Cook  wrote:

> Hello fellow Dimona operators
>
> Allow me to introduce myself to this group:  I operate an H36 Dimona
> built in 1983, serial number 3667, registration ZK-GPH, with about 1300
> hours on it.  I fly from Papawai which is a gliding club near
> Wellington, New Zealand, and the aim is to use the motor glider to
> accelerate aspects of glider flight training.  I always enjoy the DOG
> posts I read, especially the hints about what to look out look for . . .
> and I sense it's now time for me to contribute.
>
> I purchased this aircraft with a fresh annual, so all the fuel hoses had
> been replaced.  But when I had an empty fuel tank one day I thought I'd
> dismantle the fuel drain tap, and the O'ring lurking inside crumbled as
> I tried to flick it off the shaft.  So the rubber hoses had been
> replaced, but not ALL the rubber bits.  For all I know the O'ring might
> have dated back to 1983.  I spent a few hours that night googling how
> many general aviation flights had ended badly because the fuel had
> drained from a leaking fuel drain during flight.  Sigh.  Actually, I
> also had to replace the electric fuel pump because although it clacked
> away it was unable to lift fuel into the carburettors.  And the intake
> filter at the electric pump had some white, fibrous stuff in it,
> possibly from the previous GRP tank (it's now a metal tank).  You might
> judge that I'm paranoid about fuel (I am) and I like to check the
> c=system fully from one end to the other.
>
> But wait, there's more!  Landing on a short runway means I depend on my
> wheel brake occasionally, especially in calm conditions.  Again, the
> brake hydraulic hoses had all been replaced on schedule, but I became
> curious about the other rubber bits in the brake system? First clue was
> a binding park brake.  Second clue was very dirty brake fluid when I
> drained the left wheel calliper.  The brake master cylinder was rather
> difficult to access for removal, but inside it I found 6 O'ring seals,
> plus a lot of gunk and corrosion product.  Two of the seals were in very
> poor condition, and 2 more were well worn.  Fortunately I could figure
> out the replacement O'ring types from the Parker-Cleveland catalogue
> ("master cylinder - push type with parking brake") because measuring
> distorted O'rings is a tricky business.  My next job is to pull the
> slave cylinders apart and clean these thoroughly before reassembling
> everything. And new O'ring seals.  And use automotive brake fluid.
>
> Lesson for me is to attend to entire systems, not just the big bits or
> the bits that are easy to get at.
>
> With kind regards
>
> Martyn Cook
> Pukerua Bay, New Zealand
>
>
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