The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 06-20-2009, 01:27 PM   #1
louder50
Registered User
 
Join Date: Jun 2009
Location: Central Michigan
Posts: 47
DOT 5 in an 84??

I have a completley new brake system from the master cyl, new lines, valves, calipers and drums. I am ready to bleed the system. Is there any reason not to run DOT 5 brake fluid? I like the idea of the extended life you get with it. Is it safe in older style systems like on my 84?
louder50 is offline   Reply With Quote
Old 06-20-2009, 02:12 PM   #2
GM72K10
Next!
 
GM72K10's Avatar
 
Join Date: Jan 2003
Location: Eastern Pa.
Posts: 2,479
Re: DOT 5 in an 84??

the military CUCVs 1983-1987,(K30s and K5s) run Dot 5 in their brake systems . . .
__________________
86 K30 CUCV M1028A1
86 K30 CUCV M1028a2 dually
86 K30 C&C 6.2 4:56s, 4M, 11,000 gvw, ex fire truck, now lowboy dump
More square bodies and CUCVs than I care to admit to
2020 Silverado K3500HD Work truck
GM72K10 is offline   Reply With Quote
Old 06-20-2009, 08:23 PM   #3
silvereagle07
Registered User
 
silvereagle07's Avatar
 
Join Date: Sep 2008
Location: Bailey, NC
Posts: 2,462
Re: DOT 5 in an 84??

I bleed older vehicles with Dot 4 all the time and haven't seen any problems yet. I'm sure Dot 5 would be the same. It should have a label on the bottle to let you know if it's compatible.
__________________
Jeramy

'84 GMC project truck
'85 Chevy 4X4 SOLD
'07 Chevy Trailblazer SS

5th Annual SHPHC Car/Truck Show Pics
http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT
silvereagle07 is offline   Reply With Quote
Old 06-20-2009, 09:26 PM   #4
willett
Another Day, Another Dollar
 
willett's Avatar
 
Join Date: Nov 2008
Location: North Vancouver, BC
Posts: 1,316
Re: DOT 5 in an 84??

don't do it man.

dot 5.1 o.k, but dot 5 has a tendency to eat seals in certian brake systems.
it might work, but i'd rather stay on the safe side and use 3, 4, or 5.1.
__________________
-78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box

"its hip to be square"
willett is offline   Reply With Quote
Old 06-20-2009, 10:26 PM   #5
tvblazer78
Low & Fast!
 
tvblazer78's Avatar
 
Join Date: Jan 2007
Location: Knoxville, TN
Posts: 3,110
Re: DOT 5 in an 84??

Ya what they said, it's very good!
tvblazer78 is offline   Reply With Quote
Old 06-21-2009, 07:23 AM   #6
James McClure
One shot, one kill.
 
Join Date: Dec 2007
Location: Saratoga Springs NY
Posts: 859
Re: DOT 5 in an 84??

I have been using DOT5 exclusively in all my vehicles from a 69 Chevelle up to and including my 84K 20 with great results. What you must do though is make absolutely sure the system is "clean"! No DOT3 left over anyplace. Rebuild or replace the MC, calipers and cylinders, flush lines with alcohol, or replace with stainless like I did and use the DOT5. Make sure you tag the MC so if you get oil changes at a shop they don't touch the MC and add DOT3. Also DOT5 will not attack the paint and works real good in locks. jim
__________________
1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.
James McClure is offline   Reply With Quote
Old 06-21-2009, 09:51 AM   #7
LONGHAIR
just can't cover up my redneck
 
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
Re: DOT 5 in an 84??

Quote:
Originally Posted by louder50 View Post
I Is there any reason not to run DOT 5 brake fluid? I like the idea of the extended life you get with it.
First of all, James McClure is absolutely right, they do NOT mix well at all. You must be sure that every part of the system is new or rebuilt and completely clean.

Second, where did you get the idea that DOT5 fluid has a longer life? From what I understand, the opposite is actually the case. DOT5 fluids are "silicone" based and as such will withstand higher temperatures, not do they absorb water from the air like "glycol" based fluids (DOT3 & 4). But there are trade-offs (negatives) By not absorbing the water in the system, it is free to corrode the steel parts. This factor alone means that is requires more frequent fluid changes, not less.


willett is mostly on track. DOT5.1 is really the best way to go. It is a glycol based fluid that meets DOT5 heat requirements. It's not that the DOT5 will hurt the seals, but that it allows the moisture to rust the steel parts.

Personally I use DOT5 in my motorcycles because of "paint" issues. Having one master cylinder hanging out over my gas tank and another bolted to the side of a color-matched frame makes it worth it to me. It has mostly aluminum parts and all braided lines, so I don't really have corrosion worries.

In a car/truck I would stick with DOT4 or the newer DOT5.1 if you feel the need.
__________________
You can review the site's rules here.



Quote:
Originally Posted by Longhorn Man View Post
As for reading directions...
The directions are nothing but another man's opinion.
Learn from the mistakes of others, you won't live long enough to make them all yourself...

Bad planning on your part does not necessarily constitute an instant emergency on my part....

The great thing about being a pessimist is that you are either pleasantly surprised or right.
LONGHAIR is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 04:39 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com