Thread: 101 Front brakes retaining pressure

Sorry about the pic, I love my Canon SLR.
I hear what you are saying about the reservoirs and I will look at it one day, bit lazy myself at times.
Have not taken the individual hoses off yet.

Whats the go with the silicone fluid? I have heard it does not compress as much as normal fluid. Also that you need to flush the system before putting it in

Peter

Originally Posted by PeterP

Whats the go with the silicone fluid? I have heard it does not compress as much as normal fluid. Also that you need to flush the system before putting it in

Peter

I will let Ron answer all that as he is the expert .

Garry

Experts can get online fault finding wrong.......
I now use in all of my vehicles Russel brand silicone brake fluid.
It is dot 5 rated, by that doesnt mean much these days as better quality normal brake fluid can now be dot 5.
The main reason I use it is because silicone is very slightly thicker and more viscous and it lubricates the seals like oil does.(normal brake fluid has little lubrication effects)
It makes the brake components last longer.
Normal brake fluid is hydrostopic....meaning it adsorbs water and a moisture which is suppose to be safer and the brake fluid usually turns from a blue to a brown colour when it is no good any more and has assorbed to much moisture and must be bleeded out.
I find if you bleed the brake system every 2 years like you are suspose too, the silicone fluid has no issuses.
I find no wheel cylinder corrosion and longer lasting rubbers.
Silicone brake fluid and normal brake fluid can be mixed with no ill effects, but why would you want to.
I just open up the brake bleeders one by one until the fluid changes colour and you then know you have the silicone fluid right though the system.
Another advantage is if it leaks or you spill it there is no effects on paint work.
The disadvantage is trying to find the silicone fluid as no one stocks it and then it is expensive.
There are alot of old stories about silicone fliud........in practice using Russel brand silicone fluid none of them have been true.

Just about ready to put back together with all new rubber hoses.


Previously when I have done a few braking tests the back wheels always locked up so I have pulled the apportioning valve off. It was not seized and I managed to get all the 'O'rings and seals from the local brake shop.

While trying to establish how it works and if I could test it I started to realise it has probably been plumbed incorrectly.
The line from the front was connected to the left hand connection and the line to the axle jump hose was on the right connection as per pic.
Page 70.25.23 of the service manual shows it the other way round and the arrows seem a very good clue its wrong.
The pipes do not appear to be bent in anyway though.
I have never played with one of these before so I ask, am I seeing this correctly?

Thanks Peter

Originally Posted by PeterP

From email archive - You will not find any on the open market, so don't even look if any people have them they are hanging on to them the same with the vacuum servo unit part number # AAU1277 these are now obsolete same deal none on the open market. DON'T OPERATE THE SERVO UNIT WITHOUT ANY BRAKE FLIUD IN THE SYSTEM AS YOU WILL CRACK THE BRAKALITE INNER'S IN THE SERVO, THUS CAUSING GROWN MAN TO CRY. YOU HAVE BEEN WARNED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!. You can get a 110 replacement servo unit but there is extra parts required and work. Its not straight forward, this is your only option again you have been warned.

If it is not advisable to operate this servo without break fluid, how is one meant to bleed the brakes after replacement of the master cylinder?

Originally Posted by Mick_Marsh

If it is not advisable to operate this servo without break fluid, how is one meant to bleed the brakes after replacement of the master cylinder?

Gravity, vac bleeder, pressure bleeder, prelubricate the MC and fill it.

Lots of choices...

Be careful with your choice of brake fluids. Dot 3,4,5 5.1 are not all the same.


Dot # is rarely available any more so skipping that the others are available in synthetic and non synthetic flavors AND they are not always interchangable with a butter consitency goop being the end result. It turns out that this was the nail in the coffin for fozzys brakes with a clot of it holding the fast fill open (single line brakes) so no brake pressure for me with the pedal on the floor as quick as you like. In hind site I should have pulled it down and fixed it when it happened instead of slating him off the road for rebuild.

The brake pedal was solid when I got it. I had the master cylinder reco'd because it was dribbling. I suspect the booster is stuffed as well as it hisses when the brakes are applied.
I am using PBR Gold Dot DOT4 brake fluid. Would that be ok or have I made a mistake?

Normal dot 4 is not a mistake.
I have always bled the brakes normally by pumping the pedal and never had a problem.
I find the brakes on my 101 bleed well and I dont know why people have so much trouble bleeding them.
The only problem I have found is the fluid transfer from one reservior to the other and the silicon brake fluid fixed that for a very long time and then the fitting of a general purpose Quad ring in the master cylinder during a normal overhaul instead of the one supplied in the overhaul kit.
The 101 will gravity bleed with time too.
Brake shoe adjustments must be carried out regularly on the front brakes if you want a good pedal as the front shoes wear quickly.