Brake Fluid Type dot4 synthetic or dot 5

[DButler]

I have currently put a twin turbo setup on my car and my down pipe is nearly touching my master cylinder at one point and then it gets away from it. With it being so close at the end of the master cylinder I am worried about brake fluid overheating. I am looking for suggestions on what some of you would do of have done. I was going to run a dot 5 fluid but they are silicone based and I have read that they are not really that good. It said it will cause you to have a spongy pedal. I have looked at going with a synthetic based dot4. Any suggestions. Thanks

[silver69camaro]

I would run a higher-end Wilwood fluid with a higher boiling point. Make sure the DP is well wrapped.

[DButler]

Any special wrap you recommend or just regular header wrap?

[Apogee]

I'd suggest running a DOT 5.1, non-silicone base fluid. The fluid Matt suggested above meets the 5.1 temperature requirements, similar to DOT5 silicone but without the downside.

Can you swap your master cylinder to something with a smaller body? There's not a lot you can do with header wrap or heat shields if there isn't any room to install them.

Tobin
KORE3

[DButler]

Yeah I am running the smallest booster possible with a late model style master cylinder. The master cylinder is like a 95 camaro mastercylinder.
I talked to Wilwood and they suggested EXP 600. I just dont want this to cause my brakes to malfunction. How hot do you think the down pipe will get with wrap and without if I can mangage to get it on there?

[DButler]

By the wya the car is a 67 Camaro, so you will know how far the master cylinder sticks out.

[Yoda4561]

Dot 5 silicone fluid is a big fat no, the only advantage is that it doesn't eat paint, so if it's just a trailered showcar it'll work great. Use a good DOT4 or DOT 5.1 fluid for any serious driving. DOT3, DOT4, and DOT 5.1 are cross compatible. The best DOT4 synthetics have specs exceeding the minimum for 5.1, ATE Type 200 is a popular choice for its high wet/dry boiling points and reasonable price. The Motul 600 and Brembo LCF600 have higher dry boiling points, pretty much the highest your're going to get, so if those don't work then you'll need to find other solutions.

[DButler]

Ok thanks. I was going to order Wilwoods, but I am trying to carry my car to the dyno saturday and tune it, but I have to finish brakes. Looks like I may just be waiting. Do you think synthetic Dot4 would work probably?

[silver69camaro]

I'd consider switching to manual brakes, which should move it away from the DP.

[silver69camaro]

Do you think synthetic Dot4 would work probably?

It will be just fine. Just keep an eye on it.

[DButler]

I really appreciate your help...if I which over to manual brakes what master cylinder do you recommend? A tandem Wilwood? I am running an 8" booster with a late model Camaro mastercylinder. Do you think I will notice a difference whiching over to a Wilwood Tandem thats manual?

[Skip Fix]

FWIW My TA has had silicone DOT 5 in it for almost 20 years and NO spongy pedal and has been HARD street driven,autocrossed with road race slicks for years, and pulled me down from 128 mph 1/4 miles with never a bad pedal feel.

[DButler]

I had a guy tell me yesterday he runs it in lots of sports cars and have for years just fine. I have heard good and bad things about it. I called Wilwood and they said stay away from it unless its a trailered hotrod. I dont know if they where saying this to sell me their product or what I think they offer a silicone based brake fluid as well. I guess I am goning to try synthetic dot 4 and if it doesn't work I will go a different route. May which to manual brakes.

[T_Raven]

From what I understand, just general info to put out there, DOT 5 doesn't absorb water therefore any moisture in it will be able to boil and that's why the pedal feels spongy. That's why brake fluid is designed to absorb water, to avoid a spongy pedal.

[Skip Fix]

I can tell you for sure mine isn't a trailered hot rod! Keeping a good sealed system and there should be little water in the lines or calipers.

[silver69camaro]

I really appreciate your help...if I which over to manual brakes what master cylinder do you recommend? A tandem Wilwood? I am running an 8" booster with a late model Camaro mastercylinder. Do you think I will notice a difference whiching over to a Wilwood Tandem thats manual?

Any tadem MC at about 7/8" to 1" should work OK, depending on your calipers, pedal ratio, etc. You'll notice the difference, it will take about 50-80lbs of pedal effort for a hard stop. Some like it, some don't. It sounds like it would give you the room you need.

If it were me, I'd run the car real hard and get it nice and hot, then stick a thermometer of some sort into the MC resevoir. If it's near the boiling point listed on the bottle, it's too hot.

[DButler]

Thats what I am going to do because I really want ot keep power brakes. if it doesn't work right then I will which to manual. I appreciate your help and I will let you know how it does.

[TnBlkC230WZ]

I'd suggest running a DOT 5.1, non-silicone base fluid. The fluid Matt suggested above meets the 5.1 temperature requirements, similar to DOT5 silicone but without the downside.

Can you swap your master cylinder to something with a smaller body? There's not a lot you can do with header wrap or heat shields if there isn't any room to install them.

Tobin
KORE3

X2. Also called DOT 4+. It can be hard to find in the parts stores but but Mercedes and BMW stock it as standard replacement fluid.

[DButler]

I have decided to go with manual brake setup. The mastercylinder is just too close for my likings. Running 4 wheel disc what bore size should i go with?

[a67]

I have decided to go with manual brake setup. The mastercylinder is just too close for my likings. Running 4 wheel disc what bore size should i go with?

What is the effective piston area of the front calipers?

Bob.

[DButler]

Its just stock style single piston right now, but I soon will be going with big brakes in front or switching over to the D52 wilwood calipers. Car is a 67 Camaro.

[TnBlkC230WZ]

With the single pistion calipers all around, I run a 71 Corvette master cylinder. I believe it is a 1-1/8 bore. Works great and a rebuilt unit is about $20 at most parts stores.

[DButler]

I was thinking 1 1/8" is what I need. I am gonna go with the Wilwood tandem polished one though. I am either going to go with their replacement 2 piston calipers or I might just go ahead and go with the 13" 4 piston setup. Will this master cylinder still work with these setups?

[wicked68]

I was thinking 1 1/8" is what I need. I am gonna go with the Wilwood tandem polished one though. I am either going to go with their replacement 2 piston calipers or I might just go ahead and go with the 13" 4 piston setup. Will this master cylinder still work with these setups?


1 7/8 will be your best bet.

[Apogee]

1 7/8 will be your best bet.

That has to be a typo.

Tobin
KORE3

[a67]

Its just stock style single piston right now, but I soon will be going with big brakes in front or switching over to the D52 wilwood calipers. Car is a 67 Camaro.

A 1" bore M/C will provide close to the same line pressure (but lower) as the stock 1-1/8" bore M/C with a booster. The D52 calipers, which I am assuming since you mentioned 'stock type single piston', are what is in use. They have lots of piston area for lots of clamping.

Combined with good pads (> FF) you will be happy with the results. Just be sure to bed the pads in before passing judgment.

If you want to go with an off the shelf semi-metallic pad (FF), I would drop down on the M/C bore size. Such as a 15/16" bore.

You have since mentioned other brake set ups. Really need to do the foot work on caliper piston area and rotor diameter. It is worth the time to figure some of this using Excel prior to purchase.

Bob.

[68zz502fi]

I have currently put a twin turbo setup on my car and my down pipe is nearly touching my master cylinder at one point and then it gets away from it. With it being so close at the end of the master cylinder I am worried about brake fluid overheating. I am looking for suggestions on what some of you would do of have done. I was going to run a dot 5 fluid but they are silicone based and I have read that they are not really that good. It said it will cause you to have a spongy pedal. I have looked at going with a synthetic based dot4. Any suggestions. Thanks


this excerpt is from a motorcycle site but still applies to any motor vehicles using DOT 5 and silicone brake fluid in general;

D.O.T. 5, a silicone fluid having a higher temperature rating, emerged, initially to meet the higher boiling point requirements of racing use. (Race car brake systems include oil-cooler-like heat exchangers and ceramic pads.) Silicone fluid was able to withstand the most heat of any brake fluid, so it earned a reputation as a racing brake fluid. However, silicone brake fluid has properties very different from glycol fluid, and has its own pros and cons. On the advantage side, silicone fluid will not harm paint or plastic, and does not aggressively attract additional moisture as glycol fluid does. On the disadvantage side however, silicone fluid aerates easily. Harley-Davison, one of the sole current OEM users of silicone fluid, warns buyers to let the fluid sit at least an hour before using it. The trip home in the saddlebag is enough to aerate silicone brake fluid until it looks like a freshly poured soft drink. Silicone fluid is also slightly more compressible than glycol fluid, does not change color to tip the user to its moisture content, and worst of all, neither accepts or disperses moisture, making systems using it more corrosion prone, and requiring much more frequent fluid changes. Silicone brake fluid also lacks glycol fluid's naturally occuring lubricity, making it incompatible with the mechanical valving in some antilock braking systems.

I would not run D.O.T. 5

do you have room to insulate the pipe and or the brake line? you could possibly have the O.D. of the brake line treated with a high performance coating, something like a metallic-ceramic or other hi-tech coating. their are companies out there that have industrial / aerospace coatings available with excelent heat mitigation properties and do this on a small scale. this might be worth looking into.

as I remember it can be expensive,but it is an option.

[Skip Fix]

Probabaly get tarred and feathered for this BUT. I may not be an engineer but I disagree with a couple of those statements. Silicone fluid is pretty lubricating. Put a drop between your fingers and a drop of regular fluid. On my hands the silicone is pretty slick the glycol absorbs into my skin. Since glycol absorbs water very well that is why brake system components get rust, and why you need to flush it routinely. Try breaking loose a bleeder screw on an older car that has had glycol sitting there for years. I can pop the bleeders loose on my calipers with the silicone fluid quite easily.

Now is incompatible with ABS I can not make a comment.

[DButler]

Wilwood recommends me to use the hole on my brake pedal that is 6:1 ratio and they recommended a 1" bore.

[a67]

Wilwood recommends me to use the hole on my brake pedal that is 6:1 ratio and they recommended a 1" bore.

Absolutely correct about the upper hole. I've measured a '67 Firebird brake pedal and the upper hole, for manual brakes, provides a 6.3 to 1 ratio. The power brake hole provides a 3.6:1 ratio.

The upper (manual) hole also provides the correct push rod angle. So that it pushes straight into the M/C.

Use some good pads, Wilwood offers them for the D52 caliper. And you will be happy with the brakes.

Bob.

[68zz502fi]

Probabaly get tarred and feathered for this BUT. I may not be an engineer but I disagree with a couple of those statements. Silicone fluid is pretty lubricating. Put a drop between your fingers and a drop of regular fluid. On my hands the silicone is pretty slick the glycol absorbs into my skin. Since glycol absorbs water very well that is why brake system components get rust, and why you need to flush it routinely. Try breaking loose a bleeder screw on an older car that has had glycol sitting there for years. I can pop the bleeders loose on my calipers with the silicone fluid quite easily.

Now is incompatible with ABS I can not make a comment.


hey thats fine,were all free to form our own opinions and do what we want. I just think the cons out weigh the pros with silicone fluid.

here are a few reasons why I choose NOT to use it.



I preffer not to have a spongy brake pedal

It doesn't absorb water, so any water already in the system accu-mulates in the lowest point of the system and stays there, causing rust.

Additives in the fluid can vaporize at comparatively moderate temperature, increasing the spongy feel.

Silicone fluids expand significantly when hot.

Silicone fluid is functionally incompatible with systems that have held glycol-based fluids for any length of time, requiring flushing and seal replacement (there are counter opinions on this, which state that the modern silicone formulations are in fact compatible with only a flushing, rather than a complete reseal). The actual DOT specification requires chemical compatibility, so as far as that goes, the two fluids won't cause reactions if used in the same system, but they certainly won't mix, either.

It's pretty much incompatible with anti-lock brakes because the silicone fluids tend to be more viscous, which can cause problems with the timing of the pulses that are intended to work with the thinner glycol-base fluid. This sometimes leads to damage of the ABS valving. The rapid pulsing necessary to anti-lock functions tend to cavitate the fluid, as the tiny bubbles collapse and coalesce into larger ones, and then collapse and reform into smaller ones. This tends to counteract the ABS effect and can diminish the actual effective braking. This condition also heats the fluid and can lead to even more sponginess and possible damage to the ABS controller. Thirdly, silicone brake fluid tends to foam when expressed from a small orifice under pressure, reducing its hydraulic effectiveness greatly.

[Skip Fix]

When I used it we had a fresh system so no residual glycol based fluid. I know I've read lots about the "spongy pedal" and was worried about it also but have yet to experience it. So I understand reluctance to use it since that has been stated about it. I had another member her PM me that he hasn't experienced it either. But then alot of folks say they didn't inprove their braking adding the TA rear discs in place of drums also. FWIW I've had the car since new so I drove it with new factory brakes for 70,000 miles for 10 years before it got the rear discs and the silicone fluid. Since then mainly driving to and from autocrosses and drag races. And you can stuff 4 road race slicks in a TA and swap them at the track:) Maybe I've been lucky with both the fluid and disc system,only had to replace one ratchet caliper for a problem.

Most of the rebuilt calipers I've seen have some light grease on the O ring/boots that sure feels slick like silicone based grease also. The rust in glycol based seems to accumlate everywhere that I have seen, bleeders , in the MC, on the calipers and MC if some leaked during bleeding.

My new system on the drag car is getting DOT 4, since it's easier to find in a pinch at O reilley.

[wicked68]

That has to be a typo.

Tobin
KORE3


HA - lol - yeah - sorry I typed 1 inch and remembered I switched to a 7/8 for better feel and forgot to delete the 1 off.

that would be kind of stiff with that big of a piston. Maybe they make one for a caterpiller tractor.

[TnBlkC230WZ]

If you are staying with the D52 calipers, the EBC Yellow Stuff pads are amazing and they are very easy to bed. They work as good cold as the do hot and they work very good hot.

[silver69camaro]

A note on glycol fluids and rust - you MUST flush your fluid about every one to two years to avoid this. No system is 100% sealed, water will always find it way in somehow.