The older Barths didn't have a GCWR, just a just a GVWR. How would one estimate the GCWR? Lets say that the GVWR is 16000#. Then lets say you weigh your coach by itself with driver and passenger and normal loads and you're close to 16000# And you have a 5000# hitch. We tow a dolly/car behind our 85 Regal that has a GVWR of 16000#. The car and the dolly together weigh about 3500# The 454 doesn't seem to mind it's back there but we haven't climbed any mountains since we got the dolly.
Jim

Jim this is from the 1995 GM Motorhome Guide (BTW there is a 97 version on the BM CD) My scanner isn't getting it that well but I think you can read it?

Reading the chart and the notes below, it appears that the limiting factor is the transmission, ie 19,000 lbs GCWR limit.

This is why I don't want anything but a VERY light toad... with the tag axle and overall coach length, I have little weight to spare.

I suspect your gear vendor gives you some leeway here since you can split gears. I'd like one but I'm not sure it would make enough difference to justify the cost.

56.) GCWR: gross Carry Weight Rating

I looked on my data tag this morning and it actually says GVWR is 14500#. So with the toad at 3500#, that would bring me up to 18000#. I'll call Gear Vendors tomorrow to see what they say.
Thanks
Jim

quote:

The rear-end gearing will also play into this picture. Higher rear-end gear equals more stress on the transmission and lower rear-end gear equals less stress on the transmission. Lower rear-end gears will generally result in less miles per gallon though.

Actually, it's the reverse - higher gear ratios result in less stress on the drivetrain, and higher driveshaft RPM for a given speed.

quote:

Originally posted by Rusty:


Actually, it's the reverse - higher gear ratios result in less stress on the drivetrain, and higher driveshaft RPM for a given speed.

This is where it usually gets confusing for most. What both Kevin and Rusty are saying is true.

When "higher rear-end gear" statement is used WITHOUT the word "ratio" included then the actual numerical ratio is lower resulting in a "higher speed" per given input RPM. Lower rear-end gear would indicate a higher numerical resulting in a lower speed per given input RPM.

When I was setting up BMW track cars, I had to be very careful with my statements about rear gearing. I usually state "rear-end gear ratio" so it is very clear.

I've usually encountered the term "Taller" for lower ratios and "Shorter" for higher. Neither really makes sense...but they're used.

Torque multiplication. Higher ratios multiply torque more.

Actually, it doesn't.

I was going to comment earlier but I wasn't sure how to explain properly.

There are indeed a lot of semantic traps in the torque/ratio discussion. Gear sets transfer "power" which is torque times rpm. Power in must equal power out (minus friction losses) so where torque is high, rpm is low and vice versa.

Sooo, as you found, torque and load depends on which side (input vs output) of the gear set you are looking at and ratios, rpm, etc. On top of that the "tall/low ratio" vs "low gear/high ratio" thing comes in.

I try to stay with ratios...

high ratios (4.56:1) mean input side will spin faster, generate lower output rpm but higher torque. (These are sometimes referred to as "low" gears because the vehicle speed is lower, pulling torque is actually higher)

Low ratios (3.73:1) mean input spins slower, higher output rpm but lower torque. (Again the confusion, these are sometimes referred to as "high, or highway, or even tall" gears because vehicle speed is faster)

good luck.

I have talked to Gear Vendors and they have said that as long as I keep the combined weight under 20000#,there should be no problem. This is based on a P32, TH400 with Gear Vendors. My GVWR is 14500, so that give me 5500# to play with. Heck, I could probably flat tow a small SUV. Expands the possibilities for a dingy.

quote:

Originally posted by Kevin:
GREAT Jim, but on second thought... You an Tere want a Diesel Pusher, Right?

Clarification: Jim wants to buy a diesel pusher. I don't want to sell our 454 gas puller.
Tere

quote:

I don't want to sell our 454 gas puller.
Tere

.
..........rootin' fer yuh, Tere

Stand your ground Tere .

Let's see-- 'His and Hers'

We know who works on hers, who is going to work on his?