Can someone experienced in auto-x or track days advise on changing out to higher wet and dry boiling point brake fluid? I am a little confused as to which fluid would be the best for our cars? The manual states replacement with a DOT 3 fluid, what about synthetics and true race fluids? anyone have experience with this yet? I am looking to get the most out of my stock system. I would like to upgrade to SS lines, better fluid, and eventually better pads. Help.

 

...is by replacing the OEM brake fluid with a good DOT 4 synthetic. Although I have used Motul (pricey, but good), Autocraft (known in racing circles) and various other high performance fluids, my current favorite is Valvoline SynPower DOT 4 fluid.

Bled and replaced the brake fluid in my Brembos and am pleased with the results so far.

 

What is the downside to replacing with a DOT 4 istead of DOT 3 as the manual states?

 

...as far as I know. DOT 4 meets higher standards than DOT 3- lasts longer works better, etc. It does cost a few pennies more, but you could check with your dealer if you have any warranty questions on the use of DOT 4 vs. DOT3.

 

I've tried several different fluids and Motul 600 Racing fluid is the best I've found.

Try Mammoth Motorsports:

http://www.mammothmotorsports.com/pr...3&pagenumber=4

 

dk & neg:
Do you keep this racing fluid in for good, or just around track days/autox ? Not trying to make this complicated, I just read on one racing board that some synthetic fluids are meant to be changed very often. I am wondering if this is the case with all higher temp fluids? Thanks.

 

It is just fine for the street too, so there is no reason to use it for the track only. Both of the cars I've used Motul in were daily driven autox cars. My personal opinion is that the pedal feel was much more firm with the Motul than with other fluids (street or high temp).

BTW, high temp fluid is an absolute must for nearly any street car that is taken to the track especially with a 3200lb car like the Z. Finding out that your fluid has boiled as you apply the brakes going into turn one at the end of a straight is not a happy experience.

 

I agree with negcamber on the brake fluid for street vs. track. One note on the Motul: it is a dark blue color as it comes fresh out of the can. This made it difficult to tell when it has absorbed water or become contaminated.

In contrast, Valvoline Synpower brake fluid is a clear color and becames darker as it absorbs water. It is also more commercially available than Motul, cheaper and quite effective.

 

I read that the 300ZX TT brake seals would be damaged by silicone brake fluid. Don't know if this is true for the 350Z. Also, are these other synthetic brake fluids (e.g., Valvoline Synpower) silicone?

 

...by silicone! All OEM brake fluids (incuding Nissan) are silicone-based and the 350Z is no exception.

Are you certain this 'rumour' about the Z32 is a confirmed fact?

 

I think you mean the other way around. Almost all manufacturers specify a DOT 3 or DOT 4 brake fluid, which is polyalkylene glycol ether based. DOT 5 fluid is silicone based.

The owners manual for the 350z says "add genuine Nissan Brake Fluid or equivalent DOT 3 fluid up to the MAX line" (p. B-14) and "Do not add synthetic brake fluid. The use of improper fluids can damage the brake system and affect the vehicle's stopping ability." (p. B-13). I don't have access to a 300ZX manual, but I would be very surprised if it turned out to specify a DOT 5 fluid.

Although I wouldn't say the following sources are infallable, they all pretty much agree that silicone-based fluid is not commonly used on street or race applications for several important reasons:

http://www.shotimes.com/brakes/part5.html
http://www.rpmnet.com/techart/fluid.shtml
http://www.240sx.org/faq/articles/brake_fluid.htm

A quote from the first site to highlight the reason why:

Silicone brake fluids are not hygroscopic, and tend to retain their dry boiling points for very long periods of time. For this reason, silicones are favored by owners and restorers of classic and antique cars, as there is minimal danger that seldom-used and possibly irreplaceable brake components will be lost to corrosion.

Silicone will cause natural rubber to swell, even when it's compounded with synthetics. The seals in modern brake systems are no longer 100% natural rubber, but blends of natural rubber and synthetics like nitrile. Glycol fluids will also tend to swell blended rubber seals, but to a much smaller degree then silicone. Swollen seals may leak, or cause caliper pistons to bind, resulting in brake drag.

Silicone has several other properties that make it less then desirable for street or track use. When forced thru small orifices under high pressure, like the solenoid valves in an antilock brake system, it tends to foam, generating bubbles. Bubbles in brake fluid make for spongy brakes. Silicone also tends to become slightly compressible at temperatures near its boiling point, which makes it generally inappropriate for racing.

To get the maximum benefit from silicone, the entire brake system MUST be flushed of old glycol fluid. A brake system cannot be completely flushed using the bleeder fittings, as they are purposely at spots in the system to allow air to be bled, you simply can't get all the old fluid out by bleeding. The best way to completely flush a brake system is to dismantle and overhaul it, cleaning everything with alcohol, and then coating all the parts with the new fluid as they are re-assembled. Going to this much hassle just doesn't justify changing to silicone.

You can go ahead an put it a DOT 5 fluid if you want, but I think it would be huge and expensive mistake. For track use, a I have used both Motul 600 and ATE Super Blue in my Celica w/o trouble. There are other good brake fluids out there that are less expensive, but I didn't want to change my brake fluid every few weeks, and these seemed to have a pretty good wet and dry boilding point. Just my $0.02.

 

dkmura, or anyone else who's done it:

Is it hard to change the fluid and bleed the brakes? I've heard its tricky because of the ABS and the fact that there are two bleed valves per caliper on the Brembos.

Is it a two-person job, or can you do it by yourself? If so, how?

When I hit the brake pedal it goes down about halfway, but if I lift and push it again, it's firmer. Is that normal, or does the system need to be bled?

 

Do you understand this to mean that Nissan would consider replacing DOT 3 with a synthetic to be violating the warranty? Or are they simply saying don't mix in synthetic with the stuff that came with the car?

How can you tell if a brake fluid is synthetic? For instance, is ATE Super Blue synthetic? The can doesn't say so.

 

Is it hard to change the fluid and bleed the brakes? I've heard its tricky because of the ABS and the fact that there are two bleed valves per caliper on the Brembos.

It's not hard to bleed brakes and there is only one external bleeder on the Brembos.

Is it a two-person job, or can you do it by yourself? If so, how?

It does require two people, although I always get my wife to help me (she is well-trained)! There are one-man systems out there, but I've never used one!

When I hit the brake pedal it goes down about halfway, but if I lift and push it again, it's firmer. Is that normal, or does the system need to be bled?
Sounds like it needs to be bled- there's air in there that is being compressed.
__________________
--James
Lemans Sunset Track

 

Thanks for the discussion, I ended up buying ss stoptech lines & Motul rbf 600 from street sports in KY. I have my first track days coming up in mid-Feb at VIR, I feel better about giving my brakes any advantage I can.

 

Anything you've ever wanted to know about the subject!
http://www.rx7club.com/forum/showthr...eel+brakelines

maybe it's not the greatest idea!?!

 

After reading that long post regarding the SS braided brake lines, that's enough to scare the crap out of anyone. It does make a lot of sense as well.

Think I will still with the factory lines.

 

That article scared the crap out of me also! I'm sticking with the stock lines until further data comes out.