Jump to content
SAU Community

Recommended Posts

I want to do a complete replacement of my brake fluid but i have some questions for the experts;

1. Do i just pump it all through with the pedal after replacing the fluid in the resevoir?

2. How will i know when all the old stuff is out (and how much will i need for R32 GTR)?

3. Does the ABS unit need any attention?

4. Is it ok to use high temperature fluid (Motul 600) in a car that does the occasional track day but is mostly street driven?

Cheers,

Kot

What I've been told:

I want to do a complete replacement of my brake fluid but i have some questions for the experts;

1. Do i just pump it all through with the pedal after replacing the fluid in the resevoir?

DO NOT pump it through. Jack the car up on all four corners. Simply open the bleed nipples and let the fluid drain under gravity
2. How will i know when all the old stuff is out (and how much will i need for R32 GTR)?
When the fluid stops flowing, top up the reservoir, and let the new fluid flow through under gravity. Helps if you use different coloured fluid, otherwise you have to basically guess. Close off all the nipples, then do the normal brake bleed method.
3. Does the ABS unit need any attention?
Nothing out of the ordinary.
4. Is it ok to use high temperature fluid (Motul 600) in a car that does the occasional track day but is mostly street driven?
The temperature resistance of the brake fluid can't be too high, ie high temp fluid is better than lesser temp fluid.

If you simply pump the pedal you will suck air back in as you release it.

The only way to pump fluid through is in this sequence:

1) open bleed nipple

2) push pedal 2/3 of the way to the floor (NOT all the way you can root your master cylinder seals if you do)

3) hold pedal at that point

4) close bleed nipple

5) release pedal

repeat. obviously you need 1 person working the pedal and 1 person opening and closing the bleed nipple.

a simple gravity bleed is much simpler you just jack the car up evenly, whack a bleed hose on and open the nipple, then wait until you see new brake fluid (you'd want it to be different colour to the old stuff).

start from the corner furthest away from the master cylinder (ie the rear left) then the next closest (rear right) then left front then right front last.

I would always do a gravity bleed unless there was a reason why that didn't work, or i was in a hurry and had extra help available.

Edited by Kinks

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
    • Nah, that is hella wrong. If I do a simple linear between 150°C (0.407v) and 50°C (2.98v) I get the formula Temperature = -38.8651*voltage + 165.8181 It is perfectly correct at 50 and 150, but it is as much as 20° out in the region of 110°C, because the actual data is significantly non-linear there. It is no more than 4° out down at the lowest temperatures, but is is seriously shit almost everywhere. I cannot believe that the instruction is to do a 2 point linear fit. I would say the method I used previously would have to be better.
×
×
  • Create New...