Mogman
What man as done, man can do, what never has,maybe
I have a thwaites dumper that will have mineral brake fluid but I want to put a master cylinder that has had DOT 5 in will I need to replace the seals and if I do will I need special ones?
D
DaveDCB
Well-known member
After a brief skim all that jumps out at me is don’t mix dot5 whatever you do…. But that’s not really what your asking…
I guess if you strip the cylinder and clean it out it will be fine?
www.valvoline.com
I guess if you strip the cylinder and clean it out it will be fine?
Vehicle Maintenance: Brake Fluid DOT 3, DOT 4, DOT 5.1, and DOT 5 - Valvoline™ Global Europe - EN
Brake fluid selection is a particularly important task of vehicle maintenance. Different types of brake fluids match the requirements of specific braking systems. The most common ones used today are DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluids. Are all brake fluids the same? If not, what is the...
www.valvoline.com
Bri963
Well-known member
Not that simple. The seals are different for DOT 4 and 5. You might find the seals will swell.
Canal Navvy
Well-known member
Axle end gives the problems, seals swell and brakes drag (at least they did on the Ford derived axles 
)
)
Mogman
What man as done, man can do, what never has,maybe
Bugger
where would you get seals that are DOT5 compatible that clearly come from a DOT4 system
Canal Navvy
Well-known member
I wonder if silicon fluid would work 
Gecko
Well-known member
Most (but not all) DOT5 is silicon
www.valvoline.com
@Mogman - do you want to use a DOT fluid or a mineral oil?
Vehicle Maintenance: Brake Fluid DOT 3, DOT 4, DOT 5.1, and DOT 5 - Valvoline™ Global Europe - EN
Brake fluid selection is a particularly important task of vehicle maintenance. Different types of brake fluids match the requirements of specific braking systems. The most common ones used today are DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluids. Are all brake fluids the same? If not, what is the...
www.valvoline.com
@Mogman - do you want to use a DOT fluid or a mineral oil?
Mogman
What man as done, man can do, what never has,maybe
Yes got a project in my head where I need to fit DOT master cylinder to the dumper that will have mineral oil in the axle brakesMost (but not all) DOT5 is silicon
Vehicle Maintenance: Brake Fluid DOT 3, DOT 4, DOT 5.1, and DOT 5 - Valvoline™ Global Europe - EN
Brake fluid selection is a particularly important task of vehicle maintenance. Different types of brake fluids match the requirements of specific braking systems. The most common ones used today are DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluids. Are all brake fluids the same? If not, what is the...
@Mogman - do you want to use a DOT fluid or a mineral oil
Canal Navvy
Well-known member
I can't imagine that machine makers went to the effort of having special seals in the master cylinder and then fitted a cap that says "use dot 4".
My guess is that mineral oil would be fine , the problems we all remember were when people obeyed the instructions on the lid and brake fluid ended up in a mineral oil only axle brake system
My guess is that mineral oil would be fine , the problems we all remember were when people obeyed the instructions on the lid and brake fluid ended up in a mineral oil only axle brake system
Mick-the-fitter
It’s what I do!
Is it worth taking the two axles to just change the seals, why can’t you get a replacement master cylinder, and use 32hv oil in the system!
Mick-the-fitter
It’s what I do!
Does it say girling on the cap under where the paper cover should be, that says use mineral oil only!
Mick-the-fitter
It’s what I do!
What’s the Mach number or size of dumper and age?
D
DaveDCB
Well-known member
Dot5 is silicone based, thus the seals cannot be silicone or they react and break down. Probably anything that uses dot4/5.1 etc has silicone somewhere in the seals thus meaning you can’t use dot5I can't imagine that machine makers went to the effort of having special seals in the master cylinder and then fitted a cap that says "use dot 4".
My guess is that mineral oil would be fine , the problems we all remember were when people obeyed the instructions on the lid and brake fluid ended up in a mineral oil only axle brake system
So maybe given that ramble you’d be fine using a dot5 cylinder with any other type of fluid?
Bri963
Well-known member
Not one to guess about. In the dim and distant when I was over in Africa, we had the wrong fluid put in a Land Cruiser and within 10 miles the seals in the calipers had swelled and jammed the brakes on. Can’t remember which way round we got it wrong unfortunately.I can't imagine that machine makers went to the effort of having special seals in the master cylinder and then fitted a cap that says "use dot 4".
My guess is that mineral oil would be fine , the problems we all remember were when people obeyed the instructions on the lid and brake fluid ended up in a mineral oil only axle brake system
Shovelhands
Well-known member
It’s going to be much less hassle filling a master cylinder with the correct mineral oil for the axles and finding out the master cylinder doesn’t like, than it is the other way round.
Mogman
What man as done, man can do, what never has,maybe
I will have a look tomorrow
it’s not a major problem
(think there may well be bigger things to get around) but just want to know which way to go about itjust as a teaser
this is the next ‘big‘ project Going to mount this cab
onto this dumper
wish me luck
Bri963
Well-known member
Should be quite easy to fit on the front end.
Mick-the-fitter
It’s what I do!
Reshape the hydraulic and fuel tanks, or chop a bit out of the door glass!
Mogman
What man as done, man can do, what never has,maybe
Yea mounting is the easy bit
but i want the cab to tilt like this one does and be rubber mountedit’s the outher bits
as I’m not just cutting the floor out of the cab and plonking it onto what is on the dumper
, I want to use the steering from the cab and as it was hydro static it needs a clutch peddle fitting tooFooter block 1