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Wed Dec 18, 2013 9:44 am

I have searched and clearly brake issues have been beaten to death here.

I've found on my new to me 67 that a couple of front wheel cylinders are toast and the run out on the drums is done so I have opted to replace all of it. My question is simple......what brake fluid do you all recommend?

TIA..

Wed Dec 18, 2013 10:11 am

Wed Dec 18, 2013 12:39 pm

All DOT 4 approved brake fluids will work for your 67 and will surpass all requirements that were originally set when the bus was new. The main culprit with brake fluids/brake components is that people do not change the fluid often enough. All brake fluid is hygroscopic, meaning it absorbs water from the atmosphere. If not flushed at regular intervals (typically every two years), that water will rust the components, pit the cylinders and cause leaks as you've discovered. When brakes are used often and under severe conditions, the fluid heats up and the water absorption increases--that's why track racers typically change their fluid after every event. Your bus will not have that kind of punishment, but the fluid is still subject to water accumulation. Go with any DOT 4 approved fluid and you will be fine.

Wed Dec 18, 2013 12:48 pm

Does it matter if it is synthetic? Everything in the local pep boys and whatnot is synthetic.

Wed Dec 18, 2013 12:54 pm

Synthetic is good. It means that if there is a drop of DOT 3 fluid in the system somewhere, it will not have a nasty reaction to the new DOT 4 fluid. Mixing non-synthetic brake fluids is not recommended because different oil-based fluids sometimes combine to make tarry gunk.

Wed Dec 18, 2013 1:28 pm

NVNATIVE wrote: Does it matter if it is synthetic? Everything in the local pep boys and whatnot is synthetic.

All brake fluid is synthetic in that it is not dino-oil based. DOT 3 and 4 fluids are glycol based and can be mixed without problem. DOT 5 fluid is silicon based and is not compatible with 3 and 5. Your system will be fine with any brand of DOT approved 3 or 4.

Wed Dec 18, 2013 3:39 pm

10-4....

Thanks Gentlemen....and Ladies if there were any :oops:

Wed Dec 18, 2013 4:36 pm

any thoughts on using dot 5 silicone fluid?

i have heard quite a few people mention they liked it

i am going to be starting fresh with a project i am working on ; new lines, cylinders, hoses etc. and am thinking of using the silicone stuff, opinions?

Wed Dec 18, 2013 6:04 pm

StockNazi wrote: any thoughts on using dot 5 silicone fluid?

i have heard quite a few people mention they liked it

i am going to be starting fresh with a project i am working on ; new lines, cylinders, hoses etc. and am thinking of using the silicone stuff, opinions?

As long as your new project will get all new parts (not just cleaned or bled), as you listed, you will avoid the biggest pitfall--contamination from reaction with glycol based fluids.

That being said, silicon behaves a bit differently than glycol fluid. For one thing, silicon does not absorb moisture which leads to rust and corrosion (the best part of using this fluid) but it does absorb air. That is not the same as having an air bubble in the system but it does cause a more spongy feel to the brake pedal than glycol fluid. This should not have any real negative effect in everyday driving where modulating the brake pedal to make a high speed turn would be necessary--certainly not in a bus :) . You likely may not notice any difference in pedal feel in a bus, but the fluid is up to three times more compressible than glycol and thus, open to a softer feel.

This absorption of air and the higher viscosity of silicon also means that filling and bleeding has to be done with care to avoid air in the system. The thicker fluid means a longer time to fill and a power bleeder or a vacuum bleeder is preferred to avoid bubbles. If you use the pedal system, you have to be careful to use long, slow strokes rather than pumping.

Other than the above, a totally new system with new silicon fluid should last for years without any danger of corrosion, and will not boil under hard, extreme braking (like you're going to be doing that in your splitty :wink: .) Ordinarily, I wouldn't recommend the change over due to the expense and the lack of real need for high performance fluid in a bus, but since you're going to change out the system anyway I say, why not?

Wed Dec 18, 2013 7:00 pm

I'm running silicone fluid in my '66 Notchback without any problems. The pedal is firm and it bled nicely It was recommended by Jim Adney after the rebuilding of my calipers. My system was very clean prior to its use (mostly all new components). Here is the link to an article written by Jim regarding the use of silicone fluid. I believe he is on this site...I don't know if the pros and cons are similar for buses.

http://www.aircoolednut.com/erkson/ttt/silicone.htm

jaransonT3 wrote: email him at [email protected].

Wed Dec 18, 2013 7:53 pm

Every time I have put prestone or other common brake fluid in my VW's they always started leaking and the master cylinder usually went out too. But have found Castrol to be fine! I have heard it has to do with the the rubber German cars use is a natural rubber and won't hold up to US brand brake fluids.

Avoid: :(

Works Fine: :D

Wed Dec 18, 2013 8:33 pm

Danwvw wrote: Every time I have put prestone or other common brake fluid in my VW's they always started leaking and the master cylinder usually went out too. But have found Castrol to be fine! I have heard it has to do with the the rubber German cars use is a natural rubber and won't hold up to US brand brake fluids.

Avoid: :(

Works Fine: :D

Castrol has changed the label of the GT LMA brake fluid. It is now in a black bottle and simply called synthetic DOT 4. It is the same fluid, I talked to someone at Castrol to make sure (Castrol GT LMA is the specified fluid for early Land Rovers, which I also drive)

Wed Dec 18, 2013 8:37 pm

RPGreg2600 wrote: Danwvw wrote: Every time I have put prestone or other common brake fluid in my VW's they always started leaking and the master cylinder usually went out too. But have found Castrol to be fine! I have heard it has to do with the the rubber German cars use is a natural rubber and won't hold up to US brand brake fluids.

Avoid: :(

Works Fine: :D

Castrol has changed the label of the GT LMA brake fluid. It is now in a black bottle and simply called synthetic DOT 4. It is the same fluid, I talked to someone at Castrol to make sure (Castrol GT LMA is the specified fluid for early Land Rovers, which I also drive) anyone else had problems with us spec dot 3 or 4 fluid causing leaks?

Thu Dec 19, 2013 2:00 am

I switched to silicon DOT 5 many years ago ...never looked back.

Thu Dec 19, 2013 6:34 pm

Does anyone have experience with the valvoline product? It says dot 3 and dot 4 on the bottle. I've been to three parts places and none of the,m have castrol brand. All of them have valvoline and the above Preston's avoid one.

Thu Dec 19, 2013 7:32 pm

Dot 4 has a higher boiling point and is better for disc brakes. It absorbs water faster than Dot 3. For all drum system Dot 3 is fine. All just my opinion. Try to bleed Dot 3 or 4 every couple years and it seems to stay fine.

Thu Dec 19, 2013 8:00 pm

NVNATIVE wrote: Does anyone have experience with the valvoline product? It says dot 3 and dot 4 on the bottle. I've been to three parts places and none of the,m have castrol brand. All of them have valvoline and the above Preston's avoid one.

Looks like there are some other vendors selling through Amazon where it can be purchased for half the price of Amazon...Shipping is usually fast too. Just an option to consider.

http://www.amazon.com/Castrol-GT-LMA-Brake-Fluid/d...rake+fluid

Tue Dec 31, 2013 8:14 pm

delx23 wrote: I switched to silicon DOT 5 many years ago ...never looked back.

Ditto...going to DOT 5 has solved the leaky wheel cylinders that seem to be a problem here in Canada, typically when putting vehicle back on road after winter storage (especially with non-german brake components)

Drain old fluid, flush brake lines with alcohol and blow out with compressed air; install new german seals, or even better: get NOS german master & wheel cylinders to replace the Brazilian (or worse, Indian ones) like I did,
fill with DOT 5, bleed and enjoy a great brake system.

No need for expensive and troublesome disc-brake conversion etc as long as you don't mind the periodic brake adjustments (I grease the steering components, check/grease the wheel bearings and do a tire rotation at the same time)

IMHO:

Silicone brake fluid with original brake components is the only way to go!!

Wed Jan 01, 2014 9:23 am

Ditto for us on the silicon brake fluid. Switched over ten years ago in our buses and have no rust issues and cylinder leaks since. Plus have not done the yearly take apart and inspect each slave cylinder since.

With standard brake fluid was taking brake cylinders apart every late Spring to clean out any rust and flush out all the old brake fluid. Even then had about one or two cylinders fail every other year.

Found that taking brake system apart at the wheel cylinders, and letting them and the lines dry out for three weeks or more rids the system of the old standard brake fluid by evaporation so the new silicon brake fluid does not react badly with the old rubber seals.