LR4 brakes soft/hard

[gsxr]

I believe standard DOT4 and DOT4-LV are both glycol ether and borate esters based. I believe the LV version has a minimum 10°C higher wet boil point (155C std, 165C LV) while the dry boil point is minimum 20C higher (230C std, 250C LV). Note those are DOT minimum requirements and many high-performance brake fluids will have much higher boil points.

I wonder how many people replace the brake fluid every 3 years (or 45kmi) as specified in the manual? And, that is reduced to 2 years / 30kmi for severe service...

 

[Stuart Barnes]

I believe standard DOT4 and DOT4-LV are both glycol ether and borate esters based. I believe the LV version has a minimum 10°C higher wet boil point (155C std, 165C LV) while the dry boil point is minimum 20C higher (230C std, 250C LV). Note those are DOT minimum requirements and many high-performance brake fluids will have much higher boil points.

I wonder how many people replace the brake fluid every 3 years (or 45kmi) as specified in the manual? And, that is reduced to 2 years / 30kmi for severe service...

I guarantee the previous owner to me didn’t. I have a brake bleed receipt from pep boys.

so it’s on the list pretty soon.

as far a severe service goes, that’s pretty much the maintenance schedule I’m using. The poor thing is in la traffic on the school run and at least 2 out of 4 weekends on some sort of dirt trail exploring.

Stu.

 

[ktm525]

I have found brake fluid deterioration is also correlated to the relative humidity the vehicle lives in. Brake fluid loves water. Here it is very dry and I swap brake fluid maybe every 5 years and it never looks all that bad.

 

[sceh]

Right. I did the one-man method as in the video I posted. Engine running. The pedal was pretty hard starting at the rear offside brake - very odd feeling. I pushed hard but could not feel proper movement as though fluid was being pushed through. I did that brake and then switched to the other rear brake and it felt better - as though when I pressed there was fluid flowing. Did the other rear again and then the fronts. I then tried the car on the driveway, braked and nearly went thought the windscreen! Sharp and hard and brilliant!!
I suspect the first brake had the ****** still a bit tight but in any event it worked perfectly and the brakes are now superb.
I found no leaks so still wonder how the brakes were soft and had air somewhere though.
Indeed you do need to pump the brakes 28 times for the rear and 10 for the fronts. Th rear has very little movement unlike the fronts

 

[ryanjl]

Bumping this thread. So what is currently the recommended brake fluid?

Going though this thread (and other threads it links), turns up the possibility of this:

https://www.amazon.com/gp/product/B009SNFBV8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

or perhaps this:

DOT 4 LV Brake Fluid (1 Liter) - Pentosin 1224116

DOT 4 LV Brake Fluid (1 Liter) - Pentosin 1224116

www.fcpeuro.com

But i'm not sure.

 

[gsxr]

I used the Pentosin LV (Low Viscosity) you linked above, and had no issues. I believe the Ate SL.6 is equivalent. Either one should be fine. The Ate fluid is substantially cheaper. At the time I think I ordered Ate but the vendor (RM European) was out of stock, and sent Pentosin LV at no extra charge.

I used a pressure bleeder, and would recommend buying one if not already in your arsenal.

 

[ryanjl]

I previously had my brakes bled at the dealer. Going to do it myself this time. How much fluid would it take? Two 1-liter bottles?

 

[gsxr]

I previously had my brakes bled at the dealer. Going to do it myself this time. How much fluid would it take? Two 1-liter bottles?

If you are careful, 1 liter is enough. But, have 2 liters on hand just in case. I bought 2 but was able to complete the flush with only 1 liter.

I used the Motive catch bottle, and marked it in cc's/mL so I can tell how much I've flushed from each caliper. I forget if the FSM says how much to extract but in general, 80-120ml at each caliper should be adequate.

 

[avslash]

I would get two to be safe.

I just bled mine after replacing master cylinder, and it took over a liter, but there was obviously a lot of air in the MC.