Gears

darren paget

New member
Oct 28, 1998
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I don't see any problem with 65 mph at around 3000 rpm. Every RV I have
owned has always had 4.11's. By the time you load it all down most of us
are overweight any ways. I agree, there is a sense of security, knowing
you can go up steep hills in a single bound, or being able to tow medium
sized vehicles or equipment trailers with hardly an effort. You may not
be faster than a speeding locomotive, but if you are in that much of a
hurry, fly. I talked with Jim Kanomata the other day and liked what he
had to say. I was waiting for him to come out with his 3.7 ratio and now
all that is left to do is to come up with a spare $1300.00 US. I may
back track a little and opt for the 3.55 he sells but living in the
mountains may entice me to go to the 3.7's.
I know that, at some point, I am going to be towing a vehicle and the
3.7 will give me the extra torque I may need to pull it in the
mountains. If you drive 5 - 8% grades the 3.7 would be my choice. I
would also like more information on gearing down on the downhill grades.
I was always proud of the fact that I hardly ever had to use my brakes
in the hills. It is a lot easier on all of your equipment and your
nerves. I remember reading that you should not do this with the 455. Is
this true? Why? Is there a way to make it possible? As long as the oil
pressure and vacuum are up does it really matter? All input would be
greatly appreciated. Myths gratefully declined. Darren

- --

Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
 
Don't know. I always got 10 to 12 mpg with a 4.11 and that is what I am getting
with the GM at 3.07 + oversize tires. 4% larger. Darren

> Hi Darren. I am really getting myself emerged in the GMC Culture with hopes
> of picking up a solid coach at a good deal. How do the gear ratios affect
> fuel economy. I am waiting for our weather to improve so I can call you up
> and come see your machine.
>
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com

- --

Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
 
That is what I always do, also. On this group in the recent past someone was
making a statement similar to... Number ? cylinder gets starved for oil if you
down shift and let the engine do the braking. I had never heard of this before
that and wondered why. If this is true, could the person who said it let me know
if this is accurate or not and why?
That's where I got from Emery. Anybody have archives listed by subject who
could easily check? Darren

>
> this true? >>
>
> Darren -- where did you read this?
>
> I have been downshifting to second for years when I drive on steep downgrades
> and have had no problems, even when doing 65 mph in second. If i know there
> is a long steep downgrade ahead, I slow to about 45 and put it into second.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

- --

Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
 
Lots of information. I agree with all of it. I have always used the
engine to do most or all of the braking for me on long downhill grades.
I was never worried about oil starvation before but the post that came
out got me thinking. If the starvation is true, is there a way around
it? Still have to do some checking in the archives. Thanks for the info
Emery. Good stuff. Darren

- --

Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
 
Ok. I don't have to worry. The 455 is not any different than any other
engine, basically. I will treat as I have others. Thank you all for the
responses. Darren

- --

Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com
 
Emory,
I'm sure you have a lot more miles in the mountains than I do but in my
twice a year visits to places like Yellowstone, Taos etc. I shift down just
like you and maybe even to 1st gear if there are some 25 MPH corners or 8%+
grades. If that's going to damage my 455 then I'll just have to repair as
needed. My brakes aren't good enough to go it alone. I've got 100k on the
Pickle (named by a trucker in Colorado)
with the OEM trannie and gears with no problems. The engine had an overhaul
at 70k for a strange sound in the valve train. The cam had over half an
inch end play because it wasn't put together right at the factory. There
was no wear on the bearings and we put it back together with standard
bearings. I don't think my driving habits hurt it. Sorry Darren, this may
be sounding like a myth, but I hope the first myth is about the engine
braking.
Bob McLaughlin

- -----Original Message-----
From: owner-gmcmotorhome
[mailto:owner-gmcmotorhome]On Behalf Of
EMERYSTORA
Sent: Sunday, January 16, 2000 12:31 PM
To: gmcmotorhome
Subject: Re: GMC: Gears

>

Darren -- where did you read this?

I have been downshifting to second for years when I drive on steep
downgrades
and have had no problems, even when doing 65 mph in second. If i know there
is a long steep downgrade ahead, I slow to about 45 and put it into second.

Emery Stora
77 Kingsley
Santa Fe, NM
 
>this true? >>

>Not only another myth to be taken out but you must downshift. Use the
tranny to keep your downhill speed in check. The brakes won't last to the
bottom of the next hill if you don't. I don't think you can hurt it as it
must have a limiter built in somehow. My Mondello oild restrictors keep
the oil in the engine where it is needed when downshifting at hi revs.

I think!.

David Lee Greenberg
GMC Motorhome Registry
200 MacFarlane Drive
Delray Beach, FL 33483-6829
www.gmcss.com/registry.htm
 
Can't say much about most of your questions.. as to shifting down. When I
first got my coach, I made a trip of just 200 miles when going down a steep
hill I downshifted and started hearing a ping,, the ping got louder and
then the real loud pinging could be heard. Lost #7 they said and that was
because of oil starvation. Don't know much about what that meant except a
new engine. Then I asked when it was done if I should downshift. The
answer was "yes" and I do and I have not lost the engine ... that is my
story and I will stick to it.

Darren Paget wrote:erves. I remember reading that you should not do this
with the 455. Is

> Why? Is there a way to make it possible? As long as the oil
> pressure and vacuum are up does it really matter? All input would be
> greatly appreciated. Myths gratefully declined. Darren
>
> --
>
> Darren Paget
> 76 Experimental
> Another Fab Day
> http://www.TZEplus.com