Bus Weight, Axle Distribution PD4107-565

[TrentAiken]

Does anyone have knowledge of the original bus weight and axle weight distributions on a GM PD4107?

[RJ]

Trent -

GMC never published any of that information until the FMVSS went into effect in 1976 or 1977.  Once the Feds required it, then GM placed a sticker on the "A" pillar next to the gasper with GVWR plus GWR for each axle info printed on it.

However - GM coaches did have to comply with axle weight limits previously enacted, primarily by the Fed Bridge regulations, which are, in typical bureaucratic fashion, an incomprehensible maze.  Suffice to say, after wading thru the muck, your coach was built to these limits:

Front Axle = 12,000 lbs (37.5%)
Rear Axle = 20,000 lbs (62.5%)
Total = 32,000 lbs

(I'm surprised Ralph Nader didn't do an expose on a GM pusher bus, as those percentages are almost identical to the Chevy Corvair's weight distribution!  And we all know what happened to that little car after his book came out. . .)

If you're asking because of concerns you're going to be overweight, most 35' GM conversions cross the scales in the 25-26K range, leaving you around 6K for "stuff."

FWIW & HTH. . .

[TomC]

I have a AMGeneral transit bus that is much like other transits. The gvw axle ratings are 13,000lbs front and 23,000lbs rear. The bus weighed 28,000lbs empty and when done with everything in, filled up weighs 31,000lbs-10,500lbs front, 20,500lbs rear. Still 5,000lbs shy of the GVW rating. Good Luck, TomC

[TrentAiken]

RJ,
Thank your thank you!  I am looking at tires (remotely away from the bus) and needed the weights and ratios.  At 46 the corvair was before my time but being a fan of older as opposed to newer cars, yeah it was a interesting tale.  Though I still like the corvair.

Again, Thanks!

[RJ]

I am looking at tires (remotely away from the bus) and needed the weights and ratios.

Trent -

When looking at tires for you coach, remember this magic number: 495.

That's the number of tire revolutions per mile that GMC designed the powertrain around.

If you buy tires that turn MORE than 495, your fuel mileage will suffer, you'll loose speed in each gear, but you'll have slightly (very slightly) better pulling power on grades.

If you buy tires that turn LESS than 495, you'll have the opposite effect.

Any tire dealer will have the revs/mile info in their data book.

Just remember the magic number: 495.

FWIW & HTH. . .

[uncle ned]

For a gm owner RJ"S info is the most important thing ever..

talking from experience.

Huggy has 11r24.5 tallest tires that i could find.

One of the best mods so far.

Doubles my fuel mileage or was it triple just depends on how full of it I am today.

uncle ned