OVERSPEEDING-TRUCK & ENGINE

joel gopan · Post by **joel gopan** » Sun Jan 29, 2006 10:17 pm

The GMC Factory had a concern about drivers overspeeding the engines and trucks. I will quote the Bulletin from the factory.

Reports have been received relating serrious engine failures which were directly caused by excessive speeds being used while trucks were decending hills. Such willful disregard of good driving practices invariably leads to excessive operation costs. The importance of restraining speed of vehicle and speed of engine while descending grades cannot be over emphasized, and in this connection, attention should be called to the instruction plate in driver's cab entitled "Maximum Permissible road Speeds in the Following Gear Positions". This plate clearly states maximum speed in each gear ratio of transmission or transfer case.

In addition to this instruction plate, the GMC Maintenance Manual gives additional operating instructions which should be adhered to. To drivers who may still be in doubt as to how to properly drive vehicles ascending grades, we can give no better general reccommendation than that contained in our Maintenance Manual which reads as follows: " In general, it is advisable to use the same transmission speed going down hill as would be required to climb the same hill". Hold the vehicle speed not to exceed maximum shown on the caution plate for the particular gear combination used.

SPECIAL INSTRUCTIONS ON DESCENDING HILLS

1. Keep vehicle under control at all times.
2. It is desireable to reduce speed of with the brakes several times during the descent of a hill.
3. Remember the possibility of over-speeding when truck is loaded and more caution is required.
4.Do not use a lower gear ratiothan would be required to ascend the same hill.
5.Do not allow the vehicle to exceed the maximum permissable speed for the gear ratio selected. See "road speed caution plate".

Consider, for example, a typical 6X6 where the maximum permissable road speed in "high low" (transfer case in high--transmission in low) is 6 M.P.H. would cause engine to operate faster than its governed speed of 2750 R.P.M.

The above was taken from a 1943 General Motors Service Bulletin to all GMC Service Command Service Managers and Representatives.

Joel

armydriver · Post by **armydriver** » Mon Jan 30, 2006 9:09 am

Well I have never been faced with going too fast in my truck. I did get her up to fifty one time going down a hill and it scared me and the truck.

Normally 35-40 MPH is our speed, regardless of what the other people are doing.

42cckw · Post by **42cckw** » Mon Jan 30, 2006 10:49 am

IT HAS BEEN FROM MY OBSERVATION THAT MY TRUCK LOVES 35MPH ,SHE WILL DO IT ALL DAY LONG AND NO COMPLAINTS. SHE WILL GO FASTER BUT NOT AS QUIET AND AS SMOOTLY AS SHE GOES AT 35MPH. GOING DOWN THE ROAD AT THAT SPEED SHE WILL START FORMING A LINE OF TRAFFIC BEHIND ME

BUT I HAVE FOUND MOST PEOPLE WILL GIVE A TOOT, A WAVE, AND A THUMBS UP AS THEY PASS BY, AFTER ALL THESE YEARS AND HARD WORK SUPPLYING OUR BOYS WITH WHAT IT TOOK TO DEFEAT THE AXIS OF EVIL I THINK SHE HAS EARNED HER RESPECT AND PLACE OF HONOR ON THE ROAD

COME SPRING I THINK I'LL ASK THE CCKW MASTER JOEL TO TAKE HER FOR A SPIN AND GIVE HER THE DOCTORS EXAM I HOPE SHE PASSES. IN THE MEAN TIME TILL SPRING AS JOEL WOULD SAY SHE'S GETTING HER BEAUTY SLEEP

JIM 42CCKW

Minnie · Post by **Minnie** » Fri Feb 03, 2006 2:12 pm

My experience is also that 35mph makes the engine purr and keeping gasoline, consumptions within a normal and acceptable level.

Minnie wants to go faster than the safe and nice 35-40mph driving
(She'll do up to against 55 on a god day i'f she wants - but i dont't let her...)
Keeping the revs down prolong the life of your engine, keeping oil temp down. And I have also noticed that high speed driving (45mph) makes her start to consume oil..

Regards

Sturla