Home » Public Forums » GMCnet » Re: [GMCnet] Rear Brake Shoes
| Re: [GMCnet] Rear Brake Shoes [message #245531] |
Fri, 28 March 2014 13:04  |
KB
Messages: 1262
Registered: September 2009
Karma: 0
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> Seriously, during my 3 weeks with Manny last summer, and the week he was
> here in the Fall, I tried to understand his point about downshifting. The
> best I was ever able to understand it, the front band is his primary
> concern. That is nothing more than a strap of steel, lined with friction
> material, wrapped around a drum. The front servo piston tightens that band
> during Super and Lo operation specifically to provide engine braking. The
> band itself is somewhat fragile, compared to most of the transmission, is
> subject to wear during engagement, and is anchored to the transmission case
> in what could be a more substantial manner.
Hey Ken, not long after your visit I posed the following question to him:
"You have a coach sitting, stopped, at the top of a steep hill.
You put said coach into Super or Low (ie, not Drive) and coast
down the hill, WITHOUT changing gear at all while moving. Is this still bad?"
His response (to paraphrase) was "yes, it's bad. The tranny will TRY to
hold back the coach, but it's too heavy. Use your brakes, that's what they're for."
I think that is consistent with your understanding of the bands, and I don't think I'm misquoting.
Karen
1973 23'
1975 26'
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] Rear Brake Shoes [message #245562 is a reply to message #245544] |
Fri, 28 March 2014 16:43  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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| Gary Berry wrote on Fri, 28 March 2014 14:15 |
I was at Manny's yesterday and asked him about this thread and his thoughts on the downshifting problem. He told me to not downshift at anything over 45 mph and to use the dickens out of the brakes to control my downhill speed.
...
we both have experienced complete loss of drum brakes coming down the Grapevine in CA.
...
--
Gary and Diana Berry
73 CL Stretch in WA
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| KB wrote on Fri, 28 March 2014 13:04 |
Hey Ken, not long after your visit I posed the following question to him:
"You have a coach sitting, stopped, at the top of a steep hill.
You put said coach into Super or Low (ie, not Drive) and coast
down the hill, WITHOUT changing gear at all while moving. Is this still bad?"
His response (to paraphrase) was "yes, it's bad. The tranny will TRY to hold back the coach, but it's too heavy. Use your brakes, that's what they're for."
I think that is consistent with your understanding of the bands, and I don't think I'm misquoting.
Karen
1973 23'
1975 26'
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I won't dispute that the GMC is heavy. And I don't know more than Manny.
HOWEVER, there is an engine on one end of the transmission. That will moderate a great deal of stress. The engine only offers a certain amount of resistance, and if there is more torque than what it can hold against, it will rev faster and faster.
On a long slope where you are going to cook your brakes in "D", slow down to 35 or less and shift into "S". If the engine starts to rev too fast, apply the brakes to reduce engine speed. When slowed, release the brakes so they can cool. Repeat as necessary until you get to the bottom, or your brakes fail, or the transmission fails, or the engine blows.
As you can see from Gary's post about Manny losing brakes on a long steep and curving road, shifting into "S" has its place.
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| Re: [GMCnet] Rear Brake Shoes [message #245563 is a reply to message #245531] |
Fri, 28 March 2014 16:56 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Senior Member |
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Somebody once stated a rule of thumb:
"Never go down a hill faster then you can drive up it"
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] Rear Brake Shoes [message #245571 is a reply to message #245544] |
Fri, 28 March 2014 18:13 |
corleyw
Messages: 130
Registered: June 2007
Location: Battle Ground, WA
Karma: 0
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| Gary Berry wrote on Fri, 28 March 2014 11:15 |
I was at Manny's yesterday and asked him about this thread and his thoughts
on the downshifting problem. He told me to not downshift at anything over
45 mph and to use the dickens out of the brakes to control my downhill
speed. He and I are both really glad that we have disc brakes all around
after we both have experienced complete loss of drum brakes coming down the
Grapevine in CA. I finally understand the EBL/transmission issue.
--
Gary and Diana Berry
73 CL Stretch in WA
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Since you now understand the EBL issue, pray tell, are DFCO engined coaches supposed to downshift or not, according to Manny? You did not tell us what he said ABOUT THAT.
(Sorry to return to posting after Les said I should shut up and go away, but I really do want to know what Manny is telling the world.
Corley
'76 Glenbrook
29 other vehicles
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| Re: [GMCnet] Rear Brake Shoes [message #245596 is a reply to message #245587] |
Fri, 28 March 2014 20:55 |
jhb1
Messages: 303
Registered: February 2004
Karma: 0
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Decel Fuel Cut Off
| Gary Berry wrote on Fri, 28 March 2014 21:06 |
Hey Corley;
Just like rallymaster I don't know what a bDFCO engine is but the EBL
thing has all ready been talked about and explained by RobM and I just
didn't understand it. Another thing is that I don't think I have done
anything to you to warrant being yelled at. However, I sure hope you find
your answer to this DFCO thing.
Gary Berry
73 CL Stretch
Currently in CA.
On Fri, Mar 28, 2014 at 4:13 PM, Corley Wooldridge <corley@corleyw.com>wrote:
>
>
> Since you now understand the EBL issue, pray tell, are DFCO engined
> coaches supposed to downshift or not, according to Manny? You did not tell
> us what he said ABOUT THAT.
>
> --
> Corley
>
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John H. Bell
77 Royale; QuadBag,Manny OneTon,Honda EV4010, FITech
Montreal Qc.
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| Re: [GMCnet] Rear Brake Shoes [message #245600 is a reply to message #245587] |
Fri, 28 March 2014 21:42 |
corleyw
Messages: 130
Registered: June 2007
Location: Battle Ground, WA
Karma: 0
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Senior Member |
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| Gary Berry wrote on Fri, 28 March 2014 17:06 |
Hey Corley;
Just like rallymaster I don't know what a DFCO engine is but the EBL
thing has all ready been talked about and explained by RobM and I just
didn't understand it. Another thing is that I don't think I have done
anything to you to warrant being yelled at. However, I sure hope you find
your answer to this DFCO thing.
Gary Berry
73 CL Stretch
Currently in CA.
On Fri, Mar 28, 2014 at 4:13 PM, Corley Wooldridge <corley@corleyw.com>wrote:
>
>
> Since you now understand the EBL issue, pray tell, are DFCO engined
> coaches supposed to downshift or not, according to Manny? You did not tell
> us what he said ABOUT THAT.
>
> --
> Corley
>
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Gary,
I've spelled out what DFCO is several times now, others have as well. It is basically stopping all fuel flow when the throttle is let up, and the engine speed is still higher than idle.
EBL can be setup to provide DFCO (deceleration fuel cutoff). You said the EBL thing has been covered, but it has not been covered. Rob said he thought Manny told him not to downshift an EBL/DFCO engined coach, and since that can be very BAD advice, it needs to be clarified. (Personally, I doubt that is what Manny said, he seems smarter than that.) You did not clarify it, but you said you did, which makes others then jump on the Stupid Corley band wagon.
I apologize if I seemed abrupt, it's just that I've repeatedly asked about this, explained it, and had people give an answer that does not apply nor fit the question, just as you did, one that has nothing to do with DFCO, and in some cases tell me I don't know what I'm talking about. In fact Les told me to shut up and go away, implying, albeit in a nice way, that I'm too ignorant to even ask the question. This whole idea of people giving an answer when one doesn't read and understand what I asked is getting to me I guess... Maybe I do need to just go away! Anyway, please accept my apologies.
Corley
'76 Glenbrook
29 other vehicles
[Updated on: Fri, 28 March 2014 21:47] Report message to a moderator |
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| Re: [GMCnet] Rear Brake Shoes [message #245612 is a reply to message #245600] |
Fri, 28 March 2014 22:20 |
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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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Corley,
I thought I made it abundantly clear that I DID NOT UNDERSTAND WHAT MANNY WAS SAYING!
Here's a link to Manny's website call him up and get the story from him.
That way you can argue with him.
http://www.mannystransmission.biz/
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Corley Wooldridge
Gary,
I've spelled out what DFCO is several times now, others have as well. It is basically stopping all fuel flow when the throttle is
let up, and the engine speed is still higher than idle.
EBL can be setup to provide DFCO (deceleration fuel cutoff). You said the EBL thing has been covered, but it has not been covered.
Rob said he thought Manny told him not to downshift an EBL/DFCO engined coach, and since that can be very BAD advice, it needs to be
clarified. (Personally, I doubt that is what Manny said, he seems smarter than that.) You did not clarify it, but you said you did,
which makes others then jump on the Stupid Corley band wagon.
I apologize if I seemed abrupt, it's just that I've repeatedly asked about this, explained it, and had people give an answer that
does not apply nor fit the question as you did, one that has nothing to do with DFCO, and in some cases tell me I don't know what
I'm talking about. In fact Les told me to shut up and go away, implying, albeit in a nice way, that I'm ignorant. This whole idea
of people giving an answer when one doesn't read and understand what I asked is getting to me I guess... Maybe I do need to just go
away! Anyway, please accept my apologies.
--
Corley
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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] Rear Brake Shoes [message #245613 is a reply to message #245600] |
Fri, 28 March 2014 22:26 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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I'm not going to get into an absurd argument with anyone about it, but the
FACT is that Manny DOES recommend against using engine braking with DFCO
implemented. That is his privilege and as an expert on this transmission,
he is justified in making such recommendations. It is NOT a
"bad" recommendation. It's technical advice based on personal knowledge
and experience which should be applied as such. It is not a recommendation
that anyone put them self into a precarious situation. He cannot judge
whether everyone has a bad master cylinder, worn brake linings, or any of
the myriad possible mechanical faults, any more than he can determine
whether they have highly effective brakes capable of being abused down the
steepest extant grade with a grossly overloaded vehicle -- that's the
individual driver's responsibility.
What IS "bad" is putting ONESELF (and others) in an out-of-control
situation, regardless of anyone else's actions. If your brakes are not
adequate for your driving habits, you should change the brakes or the
habits -- including, if necessary, violating recommendations which are
intended to protect your equipment. Manny says engine braking is bad for
the TH-425. Only the driver can decide whether that's to influence his
driving habits. There ARE other ways of safely descending ANY grade. Try
a maximum of 30 mph for a maximum of 100 yards between 1 hour stops, if
necessary.
Each and every one of use SHOULD be responsible for our own actions, NOT
seek to blame anyone else if we ACT stupidly (regardless of our
intelligence -- or lack thereof).
'Nuff said.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL
www.gmcwipersetc.com
On Fri, Mar 28, 2014 at 9:42 PM, Corley Wooldridge wrote:
...
> Rob said he thought Manny told him not to downshift an EBL/DFCO enginedcoach, and since that can be very BAD advice, it needs to be clarified.
> (Personally, I doubt that is what Manny said, he seems smarter than that.)
> You did not clarify it, but you said you did, which makes others then jump
> on the Stupid Corley band wagon.
>
> I apologize if I seemed abrupt, it's just that I've repeatedly asked about
> this, explained it, and had people give an answer that does not apply nor
> fit the question as you did, one that has nothing to do with DFCO, and in
> some cases tell me I don't know what I'm talking about. In fact Les told
> me to shut up and go away, implying, albeit in a nice way, that I'm
> ignorant. This whole idea of people giving an answer when one doesn't read
> and understand what I asked is getting to me I guess... Maybe I do need to
> just go away! Anyway, please accept my apologies.
>
> --
> Corley
> '76 Glenbrook
> 29 other vehicles
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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