Tim Ray
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« on: 28 June, 2013, 10:11:01 AM » |
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About to change the brake fluid on my Series 2 and have a couple of questions. I am told Dot 4 is suitable for my application, which is normal road use, with a few mountain passes thrown in. I read somewhere it is vital to change the fluid every 2 years. Is this still the case if you use Dot 5.1.? I understand it is better to raise the rear of the car when bleeding the brakes. How high please? Many Thanks Tim
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Richard Fridd
Permanent resident
Posts: 3483
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« Reply #1 on: 28 June, 2013, 10:39:41 AM » |
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It is important to have the rear brake bias valve in the open position, which means supporting the rear axle, rather than using the sill mounted jacking points. Richard
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Richard Nevison Fridd Happy Lancia, Happy Life
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lancialulu
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« Reply #2 on: 28 June, 2013, 11:26:07 AM » |
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As Richard said raise the back by jacking and supporting the axle.
Fluid can take a long time to get through so I rig up a way of slighlty presurising the master cylinder (c2-5psi). As the master cylinder leaks air through the electrical terminals you will get a bit of a loss but do not over presurise or you will burst the master cylinder. I set the regulator of my air compressor to 5 psi. Also you need to ensure that the master cylinder always has fluid in it as you will find air will get into your refresh.
Dot 4 is vaguely hydroscopic and Dot 5 (silicone - dont use unless you are rebuilding the brake system) is not. I am not sure about Dot 5.1. Being Hydroscopic Dot 4 will take on water and this could allow the brake calipers could boil earlier. My Merc is maintained by a guy who tests the brake fluid (Dot4) and in 6 years he has not changed the fluid.
Boiling point ranges (from Wiki) Dry boiling point Wet boiling point DOT 3 205 °C (401 °F) 140 °C (284 °F) DOT 4 230 °C (446 °F) 155 °C (311 °F) DOT 5 260 °C (500 °F) 180 °C (356 °F) DOT 5.1 260 °C (500 °F) 180 °C (356 °F)
I boiled my Dot 5 fluid on the descent of the Stelvio (the flowing west side) in a fully laden Fulvia Sport so I have also refreshed the fluid (6 years old at the time), and found nothing like any water present.... The brakes returned to normal after 15 minutes of cooling down - assuming the boiling vapour is reabsorbed?
Tim H
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Its not the winning but taking part! or is it taking apart? Lancias: 1955 Aurelia B12 1967 Fulvia 1.3HFR 1972 Fulvia 1600HF 1972 Fulvia Sport 1600 1983 HPE VX 1988 Delta 1.6GTie 1998 Zeta 21. 12v
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Tim Ray
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« Reply #3 on: 28 June, 2013, 01:12:52 PM » |
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Many thanks Tim and Richard for your response. Much appreciated. Regards Tim
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fay66
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Posts: 6223
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« Reply #4 on: 28 June, 2013, 01:16:39 PM » |
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I recently put "Fay" in for a checkover in preperation for the Knights Rally in September, I specifically asked that the brake fluid be checked with the view of changing it if necessary, It was reported as being ok with no problems, last time fluid was changed was before going to Turin in 2006. Brian 8227
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Own 1966 Fulvia 2C Berlina since 1997, back on road 11-1999.Known as "Fay" 2006 Renault Megane 1 5 Dci Sports Tourer Dedra Technical Adviser
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nistri
Megaposter
Posts: 558
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« Reply #5 on: 01 July, 2013, 06:27:56 AM » |
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Why does old brake fluid become very dark? Andrea
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Andrea Nistri
Ardea S2 Appia S2 Fulvia GTE Fulvia Sport 1.3 S Fulvia Montecarlo Fulvia Coupe 1.3 S
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lancialulu
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« Reply #6 on: 01 July, 2013, 08:37:24 AM » |
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Oxydation process?? I assume you are referring to Dot 3 or 4??
Silicone is a light purple that fades a bit over time to clear.
Tim
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Its not the winning but taking part! or is it taking apart? Lancias: 1955 Aurelia B12 1967 Fulvia 1.3HFR 1972 Fulvia 1600HF 1972 Fulvia Sport 1600 1983 HPE VX 1988 Delta 1.6GTie 1998 Zeta 21. 12v
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nistri
Megaposter
Posts: 558
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« Reply #7 on: 02 July, 2013, 06:12:23 AM » |
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Yes, I refer to Dot 3 or 4. Oxidation and moisture probably. Perhaps not enough to give fluid boiling and lack of pressure but enough to produce corrosion of the cylinder bores. BTW, I was checking over my Fulvia Montecarlo yesterday prior to an alpine event and noted that my battery is now 12.5 year old. Charge with engine off is OK. Not bad performance for a small alternator. Andrea
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Andrea Nistri
Ardea S2 Appia S2 Fulvia GTE Fulvia Sport 1.3 S Fulvia Montecarlo Fulvia Coupe 1.3 S
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DavidLaver
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Posts: 4383
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« Reply #8 on: 02 July, 2013, 08:40:35 AM » |
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As it happens I just dropped a car in for a list of bits and bobs including a brake fluid change. BMW have it down as a change every other year.
David
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David Laver, Lewisham.
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fay66
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« Reply #9 on: 02 July, 2013, 10:44:27 AM » |
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Most manufacturers have always recommend changing every two years, but I always have the fluid checked as I can't ever remembering finding it necessary to change as recommended. I'm all for safety and checking, but IMHO it's just another one of those service items that are there to add to the profits. Brian 8227
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Own 1966 Fulvia 2C Berlina since 1997, back on road 11-1999.Known as "Fay" 2006 Renault Megane 1 5 Dci Sports Tourer Dedra Technical Adviser
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lancialulu
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« Reply #10 on: 02 July, 2013, 12:54:34 PM » |
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Most manufacturers have always recommend changing every two years, but I always have the fluid checked as I can't ever remembering finding it necessary to change as recommended. I'm all for safety and checking, but IMHO it's just another one of those service items that are there to add to the profits. Brian 8227 Hear hear!!!
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Its not the winning but taking part! or is it taking apart? Lancias: 1955 Aurelia B12 1967 Fulvia 1.3HFR 1972 Fulvia 1600HF 1972 Fulvia Sport 1600 1983 HPE VX 1988 Delta 1.6GTie 1998 Zeta 21. 12v
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DavidLaver
Permanent resident
Posts: 4383
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« Reply #11 on: 02 July, 2013, 03:31:13 PM » |
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Brian - What check do they do?
David
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David Laver, Lewisham.
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lancialulu
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« Reply #12 on: 02 July, 2013, 04:02:45 PM » |
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My merc guy says he measure SG (hydrometer)...
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Its not the winning but taking part! or is it taking apart? Lancias: 1955 Aurelia B12 1967 Fulvia 1.3HFR 1972 Fulvia 1600HF 1972 Fulvia Sport 1600 1983 HPE VX 1988 Delta 1.6GTie 1998 Zeta 21. 12v
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chriswgawne
Permanent resident
Posts: 2078
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« Reply #13 on: 02 July, 2013, 04:15:12 PM » |
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As a rule I tend to change the brake fluid in our cars roughly every 4/5 years or so - primarily because the fluid has darkened. To me, a darker fluid = contamination = shortened seal life and corroded wheel cylinders. I have never had brake fluid which has boiled. On my race car, I change the fluid every 2 years because the front brakes do get very very hot and it is part of my regular pre-season checklist. I have never used silicone fluid by the way as someone told me once that changing from Dot 4 to silicone would result in problems with seals although the change could be made the other way without any problems. Is this true? Chris
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Chris Gawne Mobile: 07778 216552
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