ordered some new brakes hoses from Crown and was going to buy some brake fluid but could not remember which fluid to buy, dot 3, 4,? I was about to pic up some dot 3 but noticed it was synthetic. I thought synthetic was bad for our trucks? Can some one reccomend the right brake fluid?

thanks

Gilbert

 

Brake fluid is brake fluid. 3 , 4 , or 5.1 doesn't matter. plain generic DOT 3 is well within spec

 

I use dot 4 in just about everything now. Stay away from silicone based dot 5.
Here's a compatibility chart. And a link full of info.
What is the Difference between DOT 4 and DOT 5.1 Brake Fluid? | Epic Bleed Solutions

 

Thanks, guys

 

Auto Zone also has a Super Dot 4 which raises the boiling point. Only reason I noticed it is that is what the wife's Mercedes requires.

 

My old company used to make and private label most of all the brake fluid provided by US suppliers. It's gone away now, but the plant manager used to say that Ford's DOT 4 was the best formulation out there, they didn't supply it.

All the USA designed vehicles today are designed and tested around 3 year contaminated DOT 3 against fluid boil, initially on dynos but the final vehicle prove out is going down Townes Pass under a specific procedure. Cooling guys used to go up, brake guys going down.

Ford was real hyper about brake fluid boil on the '99 P131 design due to historical problems with the OBS. If you look at the rotor design they went to a post vane construction rather then a standard straight or directional curves vane design from TRW. The redesign for 2005+ went back to a straight vane as the SDs run really cool compared to there vehicles.

Akebono was charged with making sure the calipers also ran cool. Everyone has switched over to phenolic Pistons to address the fluid boil issue, but there were other details done. The pistons were capped with stainless to ensure integrity with contact to elevated temps. There was a stainless steel heat shield applied between the inner brake pad assembly and the pistons to act as a thermal break. This went away later in production.

The brakes pads supplied by Federal-Mogul utilized an underlayer between the friction material and steelbacks that was thermally insulating. This was carried over to the '05+ design level despite a change in friction formulations.

Since the rear calipers don't see the cooling air that front calipers do, on the back of the rear calipers you find Akebono added cooling fins, not unlike those of an air cooled motorcycle engine. These were determined as not needed with the '05+ redesign with TRW calipers, again these trucks run cool brakewise.

So the '99-04 system got real hyper, and by '05 Ford calmed down.

DOT 3 works fine in these trucks. If you tow heavy often, or get aggressive in the mountains, DOT 4 is not a bad choice anyway to give an extra margin. Brakes in the past were designed around a trucks GVW consideration, with little consideration about trailers. The thinking being a trailer should be handling its own. We know that's not always true, it's the operator who can alter the balance and things can get dicey when trailer brakes aren't maintained. Plus IMO disc and drum brakes are never a good combination. But trailering is now being considered more in brake design.

DOT 4 gives a higher boiling point initially, but degrades more rapidly then DOT 3, so with a changeover it becomes important to be fastidious on brake fluid changes if you want to maintain that threshold. Otherwise with moisture absorption in a few years they both end up at the same boiling point.

 

"DOT 4 gives a higher boiling point initially, but degrades more rapidly then DOT 3, so with a changeover it becomes important to be fastidious on brake fluid changes if you want to maintain that threshold. Otherwise with moisture absorption in a few years they both end up at the same boiling point." Quoted from Jack.


That's probably why Mercedes requires a brake flush every two years or 20,000 miles during the vehicles B service.

 

Yep, the European based vehicles tend to be more DOT 4 and routine maintenance based. The guys from our euro group (Ferodo and Jurid) always talked with a different service view then we had with the USA manufacturers. It was confounding to them that the US got away from scheduled brake fluid changes.

 

They should go back to them. I know people that will argue all day that brake fluid is good for the life of the vehicle or until a major component has failed. Some of them on this and the 6.7 forum.

 

There are articles in popular publications that stand on both sides which really makes it difficult. The industry design work as I noted earlier has been to make it as safe as possible, with frankly, internal discussions of how to get out of legal catch 22s. Like many aspects, brake fluid chemistry is not a static science and there have been advancements in corrosion resistance more so then in the water/fluid boil side of it. Hoses have been improved from a moisture seal aspect, but all you have to do is see if the brake fluid has turned dark to see that is not an absolute.

The other problem that we don't test for is the corrosion protection, which breaks down in 6-7 years and if tested shows an increase in dissolved copper or other metals, and changes in pH.

But the easiest way to just get around all this is changing the brake fluid. Which can be done reasonably well if you're educated to do it without entraining air in the ABS unit, something where SAE committees do not have a lot of confidence in the public.

Another automotive aspect that ain't rocket science.

 

I would think sucking the old fluid out of the res and putting more in would be ok sure there is some left in the line but should come out when bleeding after a brake change.

 

Brake fluid is cheap. Flushing is easy. If done on a regular basis you can avoid changing the more expensive parts. Even better than the cost, in my opinion, is the peace of mind knowing that the system is operating as designed and my family and others on the road are that much safer. Buy a 70,000 dollar truck and worry about saving 20 bucks that is a safety item. Your choice, your truck. I've made mine.

 

What more expensive parts would you have to change eventually when only changing fluid during pad changes?

 

Calipers for one. Some vehicles, my 05 for example, made it ten years on the first set of brakes. After 4 years I did a flush and the fluid coming out looked like rust. I do believe that doing the fluid every 3 years will lengthen the life of items such as calipers and master cylinders. I'm no engineer but I'm also not blind. Rusty looking fluid equals crap in the braking system.

 

I use MOTUL brake fluid (DOT 5.1) why?, mainly because I switched to Hawk LTS pads coming from EBC Yellow Stuff which from my viewpoint, was too much like running "train brakes". Not your everday daily driver pads. There was LOTS of life in them but couldn't handle the constant squealing. These pads were tough as they get.

I like what Hawk Green LTS pads offer but afraid of experiencing another brake fade incident/failure while loaded coming down Loveland Pass having glazed OEM rotors and pads.

So I compromised having experienced Heavy Duty pad media (EBC Yellow stuff) in exchange for the average driving empty experience Hawk LTS Green pads offer. However in exceptional situations as noted above, I felt better using a higher temp fluid to actuate the calipers using this particular Light Duty Brake Media. If that makes any sense?