Home » Public Forums » GMCnet » GMC killers- Steep-Long Grades
| GMC killers- Steep-Long Grades [message #94435] |
Tue, 03 August 2010 09:12  |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Any one have a source for info about Hi-way grades?
I have read many posts from people complaining about the Grapevine on I-5 in So. Cal. I have driven that hill dozens of times in the last 40 years; Driven it numerous times in 4 different GMC's in the past 8 years.
The highway sign says that the first lift up from Castiac is 6 miles at 6%.
I would like to compare that to the following hills that I've taken GMC's over.
Ca-58 Bakersfield to Tehachapi
Mex-1 north west of Santa Rosalia, Baja Ca.
Tex-170 between Presidio and Latijas. "The Big Hill" in Big Bend State Park. Where we had a near death experience when the GMC engine quit.
US-95 North out of Lewiston, Idaho. This one seems the steepest and longest. Pulled it in Wayne's coach (Royale 403/3.70 last Friday- 2nd gear 25 to 30mph. No problem. Just slow and go. Beautiful view of the Clearwater/Snake River Vallys from the top.
Any info on grades and or your hill stories will be appreciated.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: GMC killers- Steep-Long Grades [message #94439 is a reply to message #94435] |
Tue, 03 August 2010 09:46  |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
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| gbarrow wrote on Tue, 03 August 2010 07:12 |
Any one have a source for info about Hi-way grades?
US-95 North out of Lewiston, Idaho. This one seems the steepest and longest. Pulled it in Wayne's coach (Royale 403/3.70 last Friday- 2nd gear 25 to 30mph. No problem. Just slow and go. Beautiful view of the Clearwater/Snake River Vallys from the top.
Any info on grades and or your hill stories will be appreciated.
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The Lewiston Grade is mostly 6% with a short section at 7%. That is near the bottom. It is 8 miles long. Your speed and gear sounds about right for that grade. There are motorhome fires on the "hill" though, about one each season. The rigs are usually a total loss by the time any help gets there. On the downhill side, there are several good truck escape ramps which are "free" to use (that is no penalty from the state to use them). But having your rig towed out of them is costly. A couple of years ago one truck got going too fast, went through the Jersey blocks, crossed the incoming highway 12, and wound up in the Idaho State Police office building. No one was hurt, a major miracle.
The WhiteBird grade, also on US 95 south of Grangeville ID it 8 to 10 miles long, and a constant 6% with a short section near the bottom at 8%. It is the toughest grade in this area on a major road. We have several worse ones on secondary roads. I cracked a piston in an Audi on that grade one 100 degree day, but have no real proof that it had anything to do with the problem. Never had any signs of detonation or overheating, just lost some power and it ran rougher when idling. Minimal escape ramps on the White Bird grade, and nasty curves at the bottom.
Rob Allen
former owner of '76 x-PB
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| Re: GMC killers- Steep-Long Grades [message #94452 is a reply to message #94437] |
Tue, 03 August 2010 11:06 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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This seems like info that a good GPS should have.
Or at least found online somewhere.
Anyone have ideas?
| mcolie wrote on Tue, 03 August 2010 07:33 |
| gbarrow wrote on Tue, 03 August 2010 10:12 |
Any one have a source for info about Hi-way grades?
I have read many posts from people complaining about the Grapevine on I-5 in So. Cal. I have driven that hill dozens of times in the last 40 years; Driven it numerous times in 4 different GMC's in the past 8 years.
The highway sign says that the first lift up from Castiac is 6 miles at 6%.
I would like to compare that to the following hills that I've taken GMC's over.
Ca-58 Bakersfield to Tehachapi
Mex-1 north west of Santa Rosalia, Baja Ca.
Tex-170 between Presidio and Latijas. "The Big Hill" in Big Bend State Park. Where we had a near death experience when the GMC engine quit.
US-95 North out of Lewiston, Idaho. This one seems the steepest and longest. Pulled it in Wayne's coach (Royale 403/3.70 last Friday- 2nd gear 25 to 30mph. No problem. Just slow and go. Beautiful view of the Clearwater/Snake River Vallys from the top.
Any info on grades and or your hill stories will be appreciated.
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Gene,
Did you know about the Mountain Directory books??
<http://www.mountaindirectory.com/>
They print and east and a west version.
If you want to hold one and thumb through it, they are usually on the bookshelf at Camping World. I don't own one (they seem to have ignored both Michigan and Ohio).
Matt
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Bukzin
1977 Palm Beach
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94456 is a reply to message #94437] |
Tue, 03 August 2010 11:19 |
comcast
Messages: 604
Registered: August 2009
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Doesn't particularly have to be confined to Steep ones. Long, not
readily apparent, grades can do you in as well. So, here's the story
on the Black Hole as it was coming home from NH.
Crossed the bridge from Cincy into KY via interstate and encountered a
grade hardly recognizable as such. Speed came down progressively,
foot on the floor and then BANG!!!!!! The ole deaf guy couldn't hear
the strain but had no problem hearing the BANG!!!! Did I mention, it
was a LOUD BANG!!!!
Blew a piston head clean off. New engine installed months later
Moral to the story, two things. One, get a tach right now if you
don't have one. Damn the cost, get one that's cheaper than a new
engine and don't let the RPM's drop below 2500-2700 even if you go to
a lower gear manually. I thought I was in a lower gear, it's on the
floor so should be in second gear, right? Nope, tang that operates
the kickdown switch was bent out of shape and useless. Thanks, Ken B
for that knowledge. Second, test your kickdown switch and if not
operable, bend it back in shape. If you need instructions on doing
that, ask the net.
Roger Black
77 Birchaven
Burns, Tn
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| vac pump sources [message #94465 is a reply to message #94464] |
Tue, 03 August 2010 12:04 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
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OK Gene,
Looks like its time to put a crow-bar in my wallet
and purchase a vac pump to replace my dead one.
(is it worth fixing?)
If I have to get a new one, where would you suggest?
Thanks
Bukzin
1977 Palm Beach
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94477 is a reply to message #94456] |
Tue, 03 August 2010 14:02 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| comcast wrote on Tue, 03 August 2010 11:19 |
Doesn't particularly have to be confined to Steep ones. Long, not
readily apparent, grades can do you in as well. So, here's the story
on the Black Hole as it was coming home from NH.
Crossed the bridge from Cincy into KY via interstate and encountered a
grade hardly recognizable as such. Speed came down progressively,
foot on the floor and then BANG!!!!!! The ole deaf guy couldn't hear
the strain but had no problem hearing the BANG!!!! Did I mention, it
was a LOUD BANG!!!!
Blew a piston head clean off. New engine installed months later
Moral to the story, two things. One, get a tach right now if you
don't have one. Damn the cost, get one that's cheaper than a new
engine and don't let the RPM's drop below 2500-2700 even if you go to
a lower gear manually. I thought I was in a lower gear, it's on the
floor so should be in second gear, right? Nope, tang that operates
the kickdown switch was bent out of shape and useless. Thanks, Ken B
for that knowledge. Second, test your kickdown switch and if not
operable, bend it back in shape. If you need instructions on doing
that, ask the net.
Roger Black
77 Birchaven
Burns, Tn
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Yours is one of many that I have found out of adjustment and it is an easy two minute fix.
The cruise control can also accelerate trying to make up for up hill climbs. Without the switch operational it is possible unknowingly get into the same high load - low RPM situation.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Tue, 03 August 2010 14:03] Report message to a moderator |
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94478 is a reply to message #94456] |
Tue, 03 August 2010 14:07 |
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hnielsen2
Messages: 1434
Registered: February 2004
Location: Alpine CA
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Eastern and mid-west states never a problem.
We have pulled some good ones in the western states.
Denver west bound on I-70 up to the Eisenhower Tunnel, Albuquerque up to
Denver, North and South on US 395 Eastern Sierras around Bishop Ca, Tioga
Pass in to Yosemite, Grape Vine I-5 North and South, US 101 out Ventura in
to L A and the engine killer if you don't keep the RPM up south bound I-15
out of Vegas.
As Roger said look at your Tack KEEP the RPM up around 2500-2700 and also
install a vacuum gauge and drive by them.
Love our Tack-Vac Gauge.
Thank You
26' Canyon Lands
Not Quite Stock.
Howard
Alpine Ca
----- Original Message -----
From: "Roger Black" <r1black@comcast.net>
To: <gmclist@temp.gmcnet.org>
Sent: Tuesday, August 03, 2010 9:19 AM
Subject: Re: [GMCnet] GMC killers- Steep-Long Grades
> Doesn't particularly have to be confined to Steep ones. Long, not
> readily apparent, grades can do you in as well. So, here's the story
> on the Black Hole as it was coming home from NH.
>
> Crossed the bridge from Cincy into KY via interstate and encountered a
> grade hardly recognizable as such. Speed came down progressively,
> foot on the floor and then BANG!!!!!! The ole deaf guy couldn't hear
> the strain but had no problem hearing the BANG!!!! Did I mention, it
> was a LOUD BANG!!!!
>
> Blew a piston head clean off. New engine installed months later
>
> Moral to the story, two things. One, get a tach right now if you
> don't have one. Damn the cost, get one that's cheaper than a new
> engine and don't let the RPM's drop below 2500-2700 even if you go to
> a lower gear manually. I thought I was in a lower gear, it's on the
> floor so should be in second gear, right? Nope, tang that operates
> the kickdown switch was bent out of shape and useless. Thanks, Ken B
> for that knowledge. Second, test your kickdown switch and if not
> operable, bend it back in shape. If you need instructions on doing
> that, ask the net.
>
> Roger Black
> 77 Birchaven
> Burns, Tn
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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All is well with my Lord
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94484 is a reply to message #94461] |
Tue, 03 August 2010 15:20 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Several factors come into play at wide open throttle. If there is sufficient
load on the gearing that you cannot gain in rpm, probably you should be in a
lower gear with less throttle opening. When the RPM's go down, you have less
water being pumped through the cooling system, less oil being cycled through
the engine and oil cooler, combine this with a huge increase in thermal
stress on the piston tops, rings, rods, bearings, exhaust valves etc., etc.
Often times detonation creeps in like a camel head under the tent, and all
hell breaks loose. Big dollars in repairs are sure to follow. Shift her down
and let he rev up.
Jim Hupy
Salem, Or
78 Royale 403 ( happy to rev up, hates to lug.)
On Tue, Aug 3, 2010 at 9:40 AM, MICHAEL FOSTER <mfoster356@yahoo.com> wrote:
>
>
> I don't understand Roger's statement "don't let the RPM's drop below
> 2500-2700 even if you go to a lower gear manually".
>
> I can understand overrevving is bad but what is the danger in low rev's?
>
> Michael
> _______________________________________________
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| Re: GMC killers- Steep-Long Grades [message #94492 is a reply to message #94435] |
Tue, 03 August 2010 16:15 |
Luvn737s
Messages: 1106
Registered: June 2007
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Watch how much you load in your coach and never tow anything up a hill. I would think those two things should keep you out of most trouble.
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94499 is a reply to message #94461] |
Tue, 03 August 2010 16:56 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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On Tue, Aug 3, 2010 at 12:40 PM, MICHAEL FOSTER <mfoster356@yahoo.com>wrote:
>
> I don't understand Roger's statement "don't let the RPM's drop below
> 2500-2700 even if you go to a lower gear manually".
>
> I can understand overrevving is bad but what is the danger in low rev's?
>
Remember that the oil pump is only turning at half the RPMs of the
crankshaft.
At lower RPMs, you are having to apply more torque--force on the piston
heads and the connecting rods (and the bearings). At higher RPMs, you are
applying less force more frequently, and with a better supply of oil.
Ride a bicycle up a steep hill in a high gear, versus riding it in a lower
gear, and your knees will explain it to you.
I keep my engine at 2000 RPMs when applying lots of power. I do not depend
on the kick down to do so on a long hill. I downshift manually. That has the
added benefit of maintaining a higher pressure on the bands in the
transmission.
On my semiannual climb up to Flagpole knob, the roughness of the road
prevents going fast enough to maintain 2000 RPMs. But that roughness also
prevents applying full power. On the paved bit before the jeep trail,
though, I am in L by the time I get to the top, with the engine still able
to accelerate from the middle 2000's.
Rick "not scared to downshift" Denney
--
'73 230 "Jaws"
Northern Virginia
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| Re: GMC killers- Steep-Long Grades [message #94501 is a reply to message #94435] |
Tue, 03 August 2010 17:26 |
Luvn737s
Messages: 1106
Registered: June 2007
Karma: 2
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Of course, you gotta be careful on the upshift that you don't slip through N and head into R (which in this case stands for Rebuild your transmission)
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
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| Re: [GMCnet] GMC killers- Steep-Long Grades [message #94509 is a reply to message #94499] |
Tue, 03 August 2010 18:16 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| Richard Denney wrote on Tue, 03 August 2010 16:56 |
On Tue, Aug 3, 2010 at 12:40 PM, MICHAEL FOSTER <mfoster356@yahoo.com>wrote:
>
> I don't understand Roger's statement "don't let the RPM's drop below
> 2500-2700 even if you go to a lower gear manually".
>
> I can understand overrevving is bad but what is the danger in low rev's?
>
Remember that the oil pump is only turning at half the RPMs of the
crankshaft.
At lower RPMs, you are having to apply more torque--force on the piston
heads and the connecting rods (and the bearings). At higher RPMs, you are
applying less force more frequently, and with a better supply of oil.
Ride a bicycle up a steep hill in a high gear, versus riding it in a lower
gear, and your knees will explain it to you.
I keep my engine at 2000 RPMs when applying lots of power. I do not depend
on the kick down to do so on a long hill. I downshift manually. That has the
added benefit of maintaining a higher pressure on the bands in the
transmission.
On my semiannual climb up to Flagpole knob, the roughness of the road
prevents going fast enough to maintain 2000 RPMs. But that roughness also
prevents applying full power. On the paved bit before the jeep trail,
though, I am in L by the time I get to the top, with the engine still able
to accelerate from the middle 2000's.
Rick "not scared to downshift" Denney
--
'73 230 "Jaws"
Northern Virginia
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my kick down switch doesn't work and i want to keep it that way. i don't want it to kick down with the cruise control and over rev the engine. my F150 used to do that pulling my Airstream. not a good idea.
i love the tach/vac and drive by it.
Fred V
'77 Royale RB 455
P'cola, Fl
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