Dot 3 vs Dot 5 brake fluid
Thread Starter
Racer
Joined: Jun 2002
Posts: 401
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From: Parrish FL
Dot 3 vs Dot 5 brake fluid
I went to Willow Springs Streets last Dec. Boiled the fluid half way through the first run. Everyone said I needed to switch to Dot 5 fluid for the higher boiling point. Well I look in my shop manual ('92) and it say "DO NOT USE DOT 5 FLUID". What's the deal? Anybody know?
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: Dot 3 vs Dot 5 brake fluid (jstkrsn)
DOT5 is not compatible with ABS systems. The ABS pump can cause fluid cavitation(bubbles) and ABS will not work properly.
Lots of good DOT3 and 4 fluids available that will withstand the higher brake temps encountered in track events. It's always a good idea to bleed brakes before a track day. I do a flush once a year.
Lots of good DOT3 and 4 fluids available that will withstand the higher brake temps encountered in track events. It's always a good idea to bleed brakes before a track day. I do a flush once a year.
Drifting
Joined: Mar 2002
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From: Waterford MI
Re: Dot 3 vs Dot 5 brake fluid (knp)
FWIW... I just picked up a training manual on the Bosch ABS and ASR systems, DOT 5 fluid WILL damage the controllers for the ABS and ASR units. They are not repairable, they are to be replaced when damaged/ malfunctioning. Use only DOT 3 fluid. I can't remember what the difference is in DOT 4 to DOT3 so I cannot say if it could be used.
:cheers:
:cheers:
Le Mans Master
Joined: Dec 1999
Posts: 8,540
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From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Dot 3 vs Dot 5 brake fluid (knp)
Is there some reason some people use the DOT5?
There are plenty of DOT3/4 fluids that will perform as good or better than DOT5 fluid. DOT 5 fluid is usually purple.
ATE Super Blue / Gold is excellent fluid. Ford HP DOT3 is also very good, and inexpensive. Buy brake fluid that comes in a sealed metal can only.
Pete
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Burning Brakes
Joined: Aug 2001
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From: Westminster MD
Re: Dot 3 vs Dot 5 brake fluid (knp)
Thanks. I wasn't planning on using DOT5, just curious why some do. :cheers:
- It doesn't absorb water. Water is what makes the internal parts corrode and degrade
- it doesn't destroy paint like normal DOT3/4 fluid (yes, brake fluid is an EXCELLENT paint remover...)
As such, it gets uses in the show cars a lot - the extreme concours trailer queens that don't really get driven much (if any) and would otherwise require mainteance to keep water from building up. And they risk a possibly MEGAbucks paint job every time that cap comes of the resevoir.
For a sports car that's actually driven :steering: stick with a good high-temp DOT3/4 fluid like others have recommended. And change it every couple of years (or sooner depending on how you use the car).
Le Mans Master
Joined: Dec 1999
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From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Dot 3 vs Dot 5 brake fluid (TravisD)
Two reasons that I've heard for using the DOT 5 are:
- It doesn't absorb water. Water is what makes the internal parts corrode and degrade
- It doesn't absorb water. Water is what makes the internal parts corrode and degrade
All brake systems allow moisture in, it is a product of the plastics used in the MC and brake lines. Teflon flexible lines (SS) help, but I haven't seen a metal MC in years.
Two years tops on DOT3/4; Six months tops on DOT5 (and never in abs cars).
- it doesn't destroy paint like normal DOT3/4 fluid (yes, brake fluid is an EXCELLENT paint remover...)
As such, it gets uses in the show cars a lot - the extreme concours trailer queens that don't really get driven much (if any) and would otherwise require mainteance to keep water from building up. And they risk a possibly MEGAbucks paint job every time that cap comes of the resevoir.
Actually they should use DOT3/4 and change every two years. The main reason is paint damage and lack of information. My buddy killed his brake system on his body off restored C3 taking this advice. You can't prevent water from entering the system, DOT3/4 will absorb it and prevent corrosion, while DOT5 will allow it to puddle. Both require maintance, DOT5 more IMO.
Pete
Thread Starter
Racer
Joined: Jun 2002
Posts: 401
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From: Parrish FL
Re: Dot 3 vs Dot 5 brake fluid (jstkrsn)
Thanks for the reply, I'll be looking for some Dot 3/4. I'm upgrading to 13" in the front, steel brake lines, and I want to flush it all out and put in new fluid.
Jim
:seeya
Jim
:seeya
Le Mans Master
Joined: Nov 2002
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From: Corvette valley Georgia
St. Jude Donor '06
Re: Dot 3 vs Dot 5 brake fluid (jstkrsn)
Dot 5 also has a better brake feel, but is has a affinity for air and once it is aerated is next to impossible to bleed out. We used this on road race motorcycles to great success. but if the book says not to use it, then don't
Instructor
Joined: Sep 2002
Posts: 159
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From: Denver CO
Re: Dot 3 vs Dot 5 brake fluid (grapeknutz)
My freind uses dot 5 in his track-only car. But this doesn't have ABS. Works good if you are changing the fluid alot.
I have been using the DOT 3 Performance Friction Z fluid lately. It has a dry boiling point a few degrees lower than the MOTUL or other high performance fluid, but I have not had any brake fade problems with it yet. The local speed shop campaigns a C5 vette in the speedvision cup and they run the Performance Friction Z fluid. They claim it works better for them than the Castrol SRF ($75 per quart).
-Ken
I have been using the DOT 3 Performance Friction Z fluid lately. It has a dry boiling point a few degrees lower than the MOTUL or other high performance fluid, but I have not had any brake fade problems with it yet. The local speed shop campaigns a C5 vette in the speedvision cup and they run the Performance Friction Z fluid. They claim it works better for them than the Castrol SRF ($75 per quart).
-Ken
Pro
Joined: May 2000
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From: Etowah, Tennessee
Re: Dot 3 vs Dot 5 brake fluid (grapeknutz)
DOT 5 is super on bikes, that is all I would ever use in my Boss Hoss, but beware...never..NEVER mix DOT5 with any other type. It does not mix, and you will end up replacing the complate brake system. And I mean the master cylinder, calipers, lines and everything! A friend of mine with a Boss Hoss thought he would bleed the brakes, and he did. He went to Auto Zone, bought some regular DOT4 brake fluid, bled the rear brake caliper, added the DOT4...in a few miles, there were no brakes at all. Upon disassembly, there was a "gunk" build-up on everything. Ruined...(and a rear chromed billet Wilwood dual caliper like on our Bosses means $650.00, chromed billet master cylinder is $225.00, chrome line was $45.00). Needless to say...he NEVER mixes the fluids now. Please don't ever mix them, it is a baaaad scene. :chevy
On the other hand, the DOT5 is a SUPER fluid, but never in an ABS system, and a 7oz. bottle costs nearly $10.00. (You don't waste it) :yesnod:
[Modified by Mrcorvette91, 11:48 PM 3/6/2003]
On the other hand, the DOT5 is a SUPER fluid, but never in an ABS system, and a 7oz. bottle costs nearly $10.00. (You don't waste it) :yesnod:
[Modified by Mrcorvette91, 11:48 PM 3/6/2003]
Melting Slicks
Joined: Apr 2001
Posts: 2,119
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From: Ca.
Re: Dot 3 vs Dot 5 brake fluid (TravisD)
- it doesn't destroy paint like normal DOT3/4 fluid (yes, brake fluid is an EXCELLENT paint remover...)
[/QUOTE]
And don't hold the caliper in your lap as you take it apart........I found that dot 3 is also an excellent scrotal skin remover.....
[/QUOTE]
And don't hold the caliper in your lap as you take it apart........I found that dot 3 is also an excellent scrotal skin remover.....
Drifting
Joined: Mar 2002
Posts: 1,254
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From: Waterford MI
Re: Dot 3 vs Dot 5 brake fluid (drive it)
And don't hold the caliper in your lap as you take it apart........I found that dot 3 is also an excellent scrotal skin remover.....
6th Gear
Joined: Mar 2003
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From: San Francisco CA
Re: Dot 3 vs Dot 5 brake fluid (jstkrsn)
Did someone need brake fluid? :smash:
For you guys who track your vette's, I had an extra shipment of Castrol SRF racing brake fluid. $55 / 1 Liter. Call or email me to order. Thanks.
For those who dont know about SRF. Its currently the best fluid you can buy. NASCAR uses it. It has the highest WET boiling point. The wet boiling point is much higher than its closest competitor which is Motul 600. It will not boil on you at a track day. Retails for $79/Liter. At this price of $55 per full liter, it isnt that much more expensive than Motul or AP Racing fluid which is sold in half liter bottles.
It is OK for street use as long as you replace it every 18 months...
Danny
Garage1
415-864-6660
For you guys who track your vette's, I had an extra shipment of Castrol SRF racing brake fluid. $55 / 1 Liter. Call or email me to order. Thanks.
For those who dont know about SRF. Its currently the best fluid you can buy. NASCAR uses it. It has the highest WET boiling point. The wet boiling point is much higher than its closest competitor which is Motul 600. It will not boil on you at a track day. Retails for $79/Liter. At this price of $55 per full liter, it isnt that much more expensive than Motul or AP Racing fluid which is sold in half liter bottles.
It is OK for street use as long as you replace it every 18 months...
Danny
Garage1
415-864-6660
