| [GMCnet] Correct/preferred brake fluid for GMC [message #79954] |
Fri, 09 April 2010 21:37  |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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I have seen some notes regarding brake fluid for our buggies.
The manual says DOT Type 3, but I seem to remember that some
have stated use of DOT Type 4. Are these compatible? Is
DOT 4 worth any extra cost?
My brake problems with "Money Pit" continue and it seems now
that I have probably lost some fluid. I suppose that this
could be a result of some air in the lines having been displaced
and level in the master cylinder dropping accordingly. This is
a problem I discovered when moving the coach from in front of
our house to a storage facility about 1/2 mile away.
I received a full set of brake shoes from Jim K's place today
and will need to find a competent technician to pull the drums,
have them trued, and put the whole bit back together.
* Mac Macdonald *
* Oklahoma City *
** "Money Pit" **
* '76 ex - P.B. *
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| Re: [GMCnet] Correct/preferred brake fluid for GMC [message #79958 is a reply to message #79954] |
Fri, 09 April 2010 22:39  |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Senior Member |
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Both should be compatable. Several people have commented on using ATE or Ford Truck Heavy Duty brake fluid. We used to use the Ford product in race cars back in the 70s since it had a very high boiling point (but was also changed very frequently).
I put silicone DOT5 fluid in my coach, since it spends most of its time just sitting there. I did replace the master cylinder, distribution valve, etc. before filling it (I still have to find out if it will work out well).
If you keep it changed appropriately, any DOT4 fluid should work just fine.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Correct/preferred brake fluid for GMC [message #79962 is a reply to message #79958] |
Fri, 09 April 2010 23:50 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
Below is a link to an article about Dot 4 brake fluids.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=33086
Below is a link to the ATE Brake Fluid website:
http://tinyurl.com/q2xtm
http://www.ate-na.com/generator/www/us/en/ate/ate/themes/20_ate_brake_produc
ts/50_brake_fluid/bf_info_us.html
ATE Brake fluid has very high dry and wet boiling temps.
ATE absorbs water at a slow rate; ATE states it can be left in your system
"up to three years."
If you're interested in using ATE Dot 4 brake fluid and you can't find it
locally you can get it here:
http://www.tirerack.com/brakes/accessoryDetail.jsp?ID=21
Note that it says the Super Blue is not DOT approved for Florida. This is
strange as I bought 3 liters of Super Blue and 3 liters of Type 200 from a
hot rod VW shop in Orlando!
and Type 200:
http://www.tirerack.com/brakes/accessoryDetail.jsp?ID=22
As you can see it costs $12.00 per liter.
It took one liter to refill a completely dry brake system on Double Trouble.
Double Trouble has Cadillac front calipers, Cadillac middle calipers, and
OEM rear wheel cylinders.
Dot 5 silicone brake fluid has a higher dry and wet boiling point than Dot
4.
The down side to Dot 5 Silicone brake fluid is that it is hydrophobic. If
water does get into the brake lines it stays in "slugs" and can freeze and
plug the lines.
If you do decide to convert from Dot 3/4 to Dot 5 it is VERY important to
get ALL the Dot 3/4 out of the system as Dot 3/4 and Dot 5 are NOT
COMPATIBLE.
People who have converted from Dot 3/4 to Dot 5 have noted they successfully
accomplished that by:
1) Blow Dot 3/4 out using compressed air - flush system with denatured
alcohol - blow alcohol out with compressed air - refill with Dot 5.
2) Blow Dot 3/4 out using compressed air - flush system with denatured
alcohol - remove, disassemble, clean, and replace all the soft goods,
reassemble, and reinstall - refill with Dot 5.
Harley-Davidson used Dot 3/4, converted to Dot 5 for a number of years, and
converted back to Dot 3/4 a couple of years ago.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Correct/preferred brake fluid for GMC [message #79977 is a reply to message #79954] |
Sat, 10 April 2010 02:50 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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DOT 3 and DOT 4 are compatible and can be used and mixed in the same system.
I strongly recommend DOT 4 because it's wet and dry boiling points are higher. Several GMC people have had problems with front brakes fading after the brake fluid boils. This is due to the wet boiling point being exceeded.
Within the DOT 4 group there are several brands that have an even higher Boiling point. ATE and Valvoline are two that come to mind. The Ford special fluid is also better than DOT 3 but it's boiling point is not as high as DOT 4. Read the label on whatever you are buying and compare the wet boiling point temperatures.
You can get Valvoline DOT 4 at AutoZone.
DO NOT USE DOT 5 unless you completely flush and rinse out all of the DOT 3 or 4 in your system first.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Correct/preferred brake fluid for GMC [message #79994 is a reply to message #79954] |
Sat, 10 April 2010 08:47 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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| k2gkk wrote on Fri, 09 April 2010 21:37 |
I received a full set of brake shoes from Jim K's place today
and will need to find a competent technician to pull the drums,
have them trued, and put the whole bit back together.
* Mac Macdonald *
|
Mac,
JMHO here...Those drums are getting scarce, so treat them like gold. IMO it is not always necessary to "have them trued". Common practice is to "turn" the drums to supposedly make them round again and to provide a surface for the new shoes to break into. IMO, often times all you are doing is removing good metal from a good drum and bringing them closer to or over Maximum diameter. ( after Max dia. they need to be replaced...an expensive venture). Unless the drums have been severely overheated, or the shoes were run down to the backing plate causing severe scoring, all you need to do is rough up the surface with 60 grit sand paper or emery cloth (being careful not to get the grit in your bearings.) You can also take a bastard file and remove the lip that generally forms at the outside edge of the drum, making install over the new shoes easier. Even minor grooving will be ok...the new shoes will then break into the old imperfections.
All of this being said, this is JMHO
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Correct/preferred brake fluid for GMC [message #79995 is a reply to message #79994] |
Sat, 10 April 2010 09:02 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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I agree here with Larry. It is NOT necessary to have the drums
"trued" unless they have been damaged. Just rough up the surface to
break up the glaze. Same for the front disk.
J.R. Wright
>
>> I received a full set of brake shoes from Jim K's place today
>> and will need to find a competent technician to pull the drums,
>> have them trued, and put the whole bit back together.
>>
>> * Mac Macdonald *
>
>
> Mac,
> JMHO here...Those drums are getting scarce, so treat them like
> gold. IMO it is not always necessary to "have them trued". Common
> practice is to "turn" the drums to supposedly make them round again
> and to provide a surface for the new shoes to break into. IMO,
> often times all you are doing is removing good metal from a good
> drum and bringing them closer to or over Maximum diameter. ( after
> Max dia. they need to be replaced...an expensive venture). Unless
> the drums have been severely overheated, or the shoes were run down
> to the backing plate causing severe scoring, all you need to do is
> rough up the surface with 60 grit sand paper or emery cloth (being
> careful not to get the grit in your bearings.) You can also take a
> bastard file and remove the lip that generally forms at the outside
> edge of the drum, making install over the new shoes easier. Even
> minor grooving will be ok...the new shoes will then break into the
> old imperfections.
>
> All of this being said, this is JMHO
> --
> Larry :)
> 78 Royale w/500 Caddy
> Menomonie, WI.
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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