ABS and DOT 5.1 Silicone fluid

[snow patrol]

Dear All,

I have read that there are issue's with the ABS system on the NSX if the cars are stored and not used regularly I was wondering if this could be reduced by using DOT 5.1 Silicon brake fluid, or are there any issue's with this on the NSX?

If the fluid is drained and replaced with new DOT 5.1 silicone fluid, will the ABS modulator also need to be bleed?

All comments welcome.

[Hagasan]

Hi, just for clarification DOT 5.1 is not silicon based brake fluid. 5.1 is glycol based and therefore compatible with DOT 3 & DOT 4, so is therefore suitable for use in the NSX.

DOT 5 is silicon based and I don't believe suitable with the seals etc in the NSX braking system

Hope this helps,

Gary

[TheSebringOne]

If you don't drive your car much, stamp on the ABS each time you go out to stop the pump seizing, preferably in a straight line! HTH

[Kaz-kzukNA1]

Hi, snow patrol.

ABS on NSX was modified several times since the original one. Looking at the other post of yours regarding the 'ABS system' and as you are using the word 'modulator', I presume that you have an earlier model of NSX.

If this is the case, then please note that the brake fluid used for the ABS system and the one used for the main Brake system (brake master cylinder) are completely separated. So, replacing the brake fluid on the main brake system doesn't require the bleeding of ABS.

By the way, regardless of how often you drive the car, I would strongly recommend to replace the brake fluid at least once a year and have your caliper serviced at least once in 2 years. For earlier model of ABS, I would recommend to bleed the ABS once a year or once in 2 years at least.

If you only use your car mainly for street usage, then I would like to suggest using DOT 4 and spend any extra money for the regular fluid change.

Regards,
Kaz

[Senninha]

If you don't drive your car much..........

He needs to buy one first rather than worry about which fluid to use....

[snowman01]

I just purchased a bottle of Silicone Brake Fluid for my own NSX, so will let you know if there are any problems in the near future. I do not expect any problems with the NSX type brake system. The fluid is compatible with most systems seals utilising the old fashion Brake Fluids (Dot 3 etc) It is not compatible with mineral oil systems. I have used the fluid on both a SAAB 900 and an Audi 90 in the past without doing any more than draining, refilling and bleeding the systems. I owned both cars for several years and never had any problems. The biggest advantage of the Silicone Fluid as far as I can see, is that it does not absorb water like ordinary fluid and should therefore help in preventing corrosion in your brake system. Also, it will never need replacing like conventional fluid and has a higher boiling point. Just a bit odf advice, it does not strip paint like ordinary brake fluid, but I work in aviation and have come across problems of silicone grease getting into the surface of magnesium/aluminium and no matter what cleaner was tried, it could not be totally removed! When it came to painting the item the paint would not cover the silicone contaminated area and just kept shrinking away.
Regards
Snowman01

[markc]

Snowman,

As Gary (Hagasan) said, there is a fundamental differance between DOT 5 (Silicon based) and DOT 5.1 (Glycol based) brake fluids and the following rules apply...

You MUST NOT mix Silicon and Glycol fluids.
Silicon brake fluid is primarily designed for military vehicles and also classic/show cars.
Silicon fluid is highly compressable and will give you a very soft/spongy pedal feel.
Silicon fluid does not lubricate in the same way as Glycol fluid and is therefore not suitable for ABS systems.
Silicon fluid does not absorb water BUT water ingress will therefore "pool" in the braking system and potentially rust more quickly than a Glycol filled system.
You should not put silicon brake fluid in your NSX or indeed any road car.
You can mix DOT 3, DOT 4, and DOT 5.1 (all Glycol based fluids) as you please.

I suspect that when you say DOT5 you mean DOT5.1 but please check again and confirm that this is infact what you have used in the past.

Everyone else... DO NOT put silicon (DOT 5) brake fluid in your NSX braking system!!!

Regular brake fluid changes i.e. annually for normal road use or prior to any and every trackday will be of far greater benefit than using expensive brake fluids for longer periods. A decent DOT 4 fluid will do the NSX just fine

Cheers

Mark