I'd be contacting the news agencies to see of they wanted to do a story.
And, your insurance company. I'm sure they don't want you driving a flamethrower.
And have them meet you at the dealer's parking lot...if they won't allow
then out on the street in front of their dealership
Start it up and let it do it's thing...
Might make the national news...
Air bags, or any auxiliary springs in PARALLEL will change the spring rate curve
and travel curve. In series, the lower rated will do the work until it compresses
to match the lowest rating of the bigger spring
In parallel and aired up a small bit...it will take some load off of the leaf
Then both of these springs will be in a lower rate (poundage) portion of their
Meaning they will ride a bit softer until they compress into a higher rate portion
of their curve
Here are some torque/HP curves for GM's 6.0L 2010 and 2012 for their
express Savana vans...SUV's should have a bit more but close for discussion
This is for the Sierra Pickup and should be very close to the SUV version
So we finally took a long trip with our new rig, which performed better than expected. Coming from a diesel tow rig to a gas tow rig was a bit of a culture shock; the high revving 6.0L does the job but it is a little unnerving sometimes! I don't have a choice unless I could afford a Duraburb conversion (which at this time I can't)
I do know that I could benefit from better gearing to help the Suburban out.
And before anyone suggests it, NO, going down to factory sized tires is not an option. We do too much trail riding which I need the bigger tires (33" for better clearance.
Normal OEM tire dia used to be 30" and with the larger dia wheels, some
are 31" to 32"...or more
With the 30" OEM dia, going to a 33" will have a diff gear ratio reduction
of about 10% less torque multiplication
Reference the above curves and see how that 10% factors the torque
multiplication to the drive axle...then factor the tire dia difference
Better to find the tire rev's per mile, as that is a more accurate
My question is this, is there a mechanical difference i.e. more or less work/HP used, if the engine is having to turn at a given RPM for a certain speed in one gear vs another?
Example: 2700RPM in 5th gear (0.85:1 OD) vs turning the same RPM in 4th gear (1.15:1) at the same wheel speed (65mph). I'm not sure how to phrase this or explain it, but I'm wondering if the engine is having to work as hard if it is in a higher transmission gear vs a lower gear?
Yes, the engine is working harder, as the torque multiplication is less in OD. By the difference in gear ratio
I found that the Suburban will cruise at about 65 mph at about ~2000 RPM fairly well, but I also know that the power curve for the 6.0L climbs throughout the RPM range. It make more HP at higher RPMs. So I know that it will cruise better with less downshifting at higher RPM. I'm just trying to find that optimal combo.
I'm thinking that if I can get the cruise RPM to about ~2300 in 5th gear at 65 mph would be great. That puts the 4th downshift to ~3150 or so and it climbs well like that! 4.10 seems to be what'll put me there. That would even allow me to tow some in 6th gear too at about 1800-1900 RPM.
That is what the "Tow/Haul" function is for and assume your Sub has it, right?
Tow/Haul will change the computer look up tables for shifting. It is
married with the torque management system
Help in answering my initial question will give me some insight to select the right rear end gear for my combo.
I'm basically debating on whether or not going from 3.73 to a 4.10 is good or if 4.56 is THAT much better. Especially given that we do drive the Suburban on road trips without the trailer, I'm considering the 4.10s as a good intermediate.
Look at my sig...ordered 4.1's for my Sub. Yours has the double OD,
so better situation than mine...
Wasn't in hopes of someone stating the laws of physics on this
topic...but now gotta state some facts
All friction braking has the friction material rub against something much
That then has the friction material become sacrificial to that harder
material...meaning more of the friction material will be abraded off than
the harder material...in this case, the cast iron rotor or drum
There is kinetic energy in the moving vehicle/trailer and in order to
slow/stop that moving mass....that energy is converted to HEAT by the
friction material rubbing against the cast iron
Braking will ALWAYS create heat and braking down from a higher speed
will have HIGHER temps...each time...
Maybe best to link an older thread talking about this...
Trailer Brakes - How hot is TOO hot?
Do a search on brake pad MAXIMUM temperature or working temperature....that is
the temperature before it transitions to 'fade'...really getting so hot the
friction material out-gasses (smokes) to float the material off the cast iron
Below are the working temperatures for the friction material itself and the
cast iron temps will be a 'bit' less...but not much less and dependent on how
well they reject the heat
OEM/stock/mud-hen friction material's maximum WORKING temperature is around 280*C (536*F)
HD friction material's maximum WORKING temperature is around 400*C (752*F)
Performance friction material's maximum WORKING temperature is around 500*C (932*F)
For reference...to fry a T-Bone to medium-rare, the internal temp should be 125*F
Also note that there is a minimum working temperature...below that and
the braking will NOT be very good
So any of the above maximum working temperature will fry your fingers or even
have flesh stick to the cast iron brake material...
Careful of internet forum info...not all are accurate...suspect mine too and
do your own research. I've had mine actually bellow visible smoke...my 2 seater
on a track day, my Silverado and even my Suburban...
Here is a picture of a test run and note that the rotor is glowing...
Do a search here and other internet forums/sites...RAM IBC has an issue
reported and filed with The NHSTA
Trailer brakes 'should' have the ability to skid the tires...but also
well known/documented is that the trailer OEMs 'mostly' do NOT put in
the highest rated braking systems out there...and many disagree with
me on that based on their experience...but experience with OEM trailer
Turtle...again spot on and one of the biggest goals in setting up any trailer...
One goal is to have the trailer level at its highest pointing and IMHO prefer/recommend
pointing slightly down
There are several other goals too. Enough tongue weight, TV ratings, etc, etc, etc.
And the majority of those overloaded and at the hairy edge of their
ratings to over will just be okay during the good days out there...their
issue will be when Mr Murphy crosses their path...like what happened to this OP...
Many say it only happens to the 'other guy'...well this OP is that
Semi-floaters has a failure situation that is dangerous not just to
those in that vehicle, but to others around them...have seen one come
off and fly a couple lanes over to the shoulder. Lucky there was no
vehicle in the way...
Weights? Its all ablout weights. How loaded or overloaded is your rear end? Loading to the max or over weights will eventually lead to failures of lots of parts. What did the old oil look like? Water in it? There will always be more to this story for sure.
I agree about the weights, but there are a lot of people on this site that think nothing of overloading and think that as long as their TV pulls it they are good to go!
Turtle & GMW are spot on and agree with them
The OEMs all have dialed in the handling behavior of all of their vehicles...even TV's...
Meaning it steers neutral, over-steer, under-steer both empty through GVWR
For a sports car...neutral to over-steer is desired for 'good' to 'expert'
drivers. For the general drivers...an under-steer tendency is the
general goal for most all OEMs
Why 911's of old had the reputation of leaving the road tail first and
why Nadar was/is so wrong for the Corvair...for the general driver out
there...it is the wrong setup...as GM semi-copied the VW/Porsche rear
By placing a weight on the tail, that upsets that dialed in behavior/handling...especially
during an emergency maneuver
Am older than most here and remember the old WD systems and the rule of thumb of
even drop. The amount of weight to do so is different front and rear because of
the different suspension spring rates front to rear
That translates to keeping the OEM dialed in steering geometry and handling,
which includes how the tires are mushed into the pavement via that flat spot
That flat spot changes during the dynamics of an emergency maneuver and that then
has several other things affecting that tire. Like the suspension components and
For towing, IMHO, under-steering is the desired handling...not overly so...just
the tendency to do so.
Over-steer is the worst thing for towing and leads to a potential jack-knife situation
Bottom line: follow YOUR TV's manual instructions, as today has so many differing
OEM/suspension setups that there is no one size fits all...therefore be careful
of advisors who advise out of context to 'YOUR' vehicle
To the OP...for about $200 bucks and about an hours labor, change out
the OEM receiver for a higher rated one
Of course...they know you are stuck...and most act like this...
If a used diff/gear set/carrier...it should already be broken in...if NEW, then
take it REALLY easy leaving town...suggest driving around without the trailer to
break in the gear set
Assume that this half ton has a semi-floater like most half ton's do
The bearing out at the end of the axle by the wheels should not have
tossed debris that far into the diff pumpkin...normally, but not impossible
Most likely the carrier bears went, if it was bearings...
The gear set when it fails will toss flakes of gear facing into the
lube. That will take out the carrier bearings
When over loaded, gear's fail in two ways
#1 is that the face will work harden and 'potato chip' (flake) pieces
to leave a rough surface...that will make a whining noise. Those flakes
will destroy the carrier bearing.
It will heat up before it flakes off and some times smoke to flame out
the vent tube
This failure takes a bit of time and/or mileage and typically tells
by whining or some other noise. Some have described it as whirling
#2 is that the gear tooth/teeth will snap or chip. This is an instant
failure of the whole pumpkin. This is not common, but it happens and
the ones I've eyeballed were street/track racers popping the clutch or
Not weak per say, but low RGAWR as are all of the lowest class TVs have
Next higher class TV will have a higher RGAWR, as will the next higher
Example is that most half ton TV's has a RGAWR in the +4,000 lb range
Next higher class TV will have a RGAWR in the 6,000 lb range or higher
Next higher class TV will have a RGAWR in the 7,000 lb range or higher,
previous era had 1 ton TV's with a 6,000 RGAWR
Betcha your load on the TV's rear axle is higher than you think...or
maybe your rear axle had a problem/defect
Here is my 1996 GMT400 Suburban's torque to the drive axles:
7.4L's torque 410 ft/lbs at 1,800 RPM x 2.48 1st gear x 2.72 transfer case x 4.1 diff
410 x 2.48 = 1,016.8 ft/lbs at the tranny output shaft
1,016 x 2.72 = 2,765.7 ft/lbs at the transfer case output shafts
2,765.7 x 4.1 = 11,339.4 ft/lbs at the diff output shafts (front and rear)
4L80E ratios, 1st to 4th (OD)
2.48 1.48 1.00 0.75 2.07
NP241 transfer case ratio
Diff ratio (both front and rear)
Enough to break things in a hurry if I put my foot into the throttle
pedal, but I'll not do so because of my decades off roading...seening
folks break things out there in the boonies...heck even out at Pismo
with loosey-goosey sand...
In 2wd you might not get there without the fronts clawing/pulling along
with the rear...so might give it a bit more throttle...to break
something back there...
With today's much higher torques...MUCH MORE EASILY break things and
even faster than ever before...hoping the vehicle computers know that
it is in 4x4 LOW....
Home now and not using an Ipad...so can post better pic's...and laughable
when folks say they will 'watch it'...this and other stuff happens
in a flash...
Personally have seen/helped buddies and strangers out there with broken/twisted drive shafts and axles
No longer offer to pull them out, offer to give them ride out till they get cell coverage...seen one to many who blamed someone for bending their bumper after they helped them...
One buddy carries two spare axles...yes, he has a full floater
Search "4x4 broken twisted drive shaft axle"
Here Is one from a quick search...
Me too...but...many will only look at the lowest class TV AND only
(seemingly to me) want to have something 'rated just enough'...
Why only advise with metrics for anyone asking/reading/lurking to
figure it out themselves...
Lost is that all things designed are NOT for the good days when a riding
lawn mower 'can tow it'...but...for the worst day out there when
Mr Murphy crosses your path...either you have the right sized/rated
spot on...or not...no time to go back to the store for better/bigger/etc...nor
time to resetup the whole thing...
Lot of technical advice. One practical piece of advice I learned the hard way. Buy more truck than you need. Buying your first camper is like buying your first house, you make mistakes and things you think aren't important, really are. So you end up trading up.
Also I've been on the side of not having a big enough pickup and it's irritating. I hated towing, but now that i have the right setup, towing is a breeze.
So while yes, most vehicles will pull what you need, get a reliable pickup. Your price range, you should be able to find an early 2000s gas 3/4 from any of the big 3. Or mid to late 2000s you can get a V8 half ton. The advantage to the half ton is unloaded fuel mileage is way better.
Two are very different by design and construction
Radial:Has lower rolling resistanceHigher usage mileageRuns coolerContact patch to pavement is more consistent throughout its duties(does NOT pull off the pavement as easily)Current standard for most all vehiclesSidewall plys have the woven threads 90* to the pavement (radial to the axis of rotation)Higher slip angle to a bias-ply (on higher aspect ratio...as the aspect ratio lowers...the slip angle is reduced
The old standard tireHigher capacity, all things equalStiffer sidewallSidewall Plys are at an angle to the pavement and axis of rotationGenerates more heat than radialHigher rolling resistanceAt higher cornering speeds, pulls tread contact patch off pavement during it's duties
'Most' ST (speciality trailer) tires are bias-ply and am seeing a few nowadays
As stated....DO NOT mix radial and bias-ply tires on the same axle is the normal
recommendation and add to not mix them on any vehicle
Using your numbers...repeat that you need/should actually weigh your
TV fully loaded ready to go, axle by axle, in order to figure the
true MTWR for your TV
comments in red embedded below
Lots (and lots) of info to go thru here, thanks.
Assuming the following TV:
2007 Dodge Ram 1500 Quad Cab ST, 4.7LV8, 2WD, 5spd Automatic
- GVWR = 6700 this is one of the 'light' rated half tons
- GCWR = 11500
- Curb = 5024 this is the stripper model and most do NOT own
the stripper model...if it has AC...it is NOT at curb...if it has power
door locks/windows/seats/etc...it is NOT at curb, etc...it will weigh
more than the curb weight. If the driver weighs more than 150 lbs, then
add that weight to the TV...then add the people/pets/luggage/etc
Note that if you add the 'curb' of 5,024 + the MTWR of 6,350
it will equal closely to the GCWR of 11,500
5,024 + 6,350 = 11,374
Dodge says I can safely tow 6350.
this is normally derived from the 'curb' or 'stripper model'
So the simple math above says your TV must weigh in very closely to
the curb of 5,024 in order to be rated to tow 6,350
If it weighs more than 5,024...then each pound over 5,024...must be
subtracted, pound for pound, from the MTWR of 6,350
Why recommend loading up and actually weighing your TV axle by
Assuming the following TT:
Starcraft AR One 17RD
- Dry weight = 2865
- GVWR = 3500
This means I can load 635 of gear, propane, etc, in the TT, right?
Some include the spare tire...others do NOT
Some include the battery...others do NOT
Etc...then add the propane, clothing, lawn chairs, bikes, food, fire
wood, water, toolbox, etc, etc
Weight adds up FAST...
As long as I don't have more than ~3000 in gear in the TV, I'm good, right?
Now get that trailer tongue weight and it will be based on the 'dry'
weight. Okay, they are all done that way and indicates the percentage
of the actual weight when loaded
That weight goes onto the TV's rear axle
Check your state, as the trailer weight dictates whether it will need
trailer brakes or not
Welcome to the forum and to the world of Towing an RV !!!
Glad to hear you are researching before jumping in...too many jump in
and then find that they have the wrong setup and/or marginal setup
First, decide if you believe in the OEM's ratings system and numbers
If not, then academic and do whatever you wish, but note that the OEMs
are now off the warranty hook (if any left) and liability hook
If yes, research, read up and gather info to do the simple math to
figure. The best is to actually weigh the whole setup fully loaded
ready to go RV'ing. Weigh it axle by axle
Comments embedded in red below
Wife and I are longtime tent-campers trying to upgrade to a travel trailer. We're looking at something in the 15-17' range (such as Starcraft AR-One, R-Pod, etc.) weighing under 3,000.
Since my current vehicle (Ford Fiesta) wont tow *anything* I know I need to get a truck capable of safely towing a camper. I've tried to do my homework, but I'm going crazy...GVWR...GCW...axle rating...tongue weight...gear ratio...transmission coolers...
GVWR.....Gross Vehicle Weight Rating...AKA max rated weight on the pavement
This applies to any DOT approved/registered vehicle...including the trailer
Derived from a 'curb' TV weight and the MTWR (Max Tow Weight Rating)
for the largest trailer this TV is rated to tow. "Curb" is the stripper
model TV with NO options, except for the 'tow option' and one 150LB driver
GCWR....Gross Combined Weight Rating...both TV and trailer
GAWR....Gross Axle Weight Rating...there are two, Front and Rear that
the axle is rated for. Most times the front and rear added together do
NOT equal the GVWR and is something we outside of the OEM design team
will never know how they derived their GVWR
MTWR....Max Tow Weight Rating...is the largest trailer a 'curb' weight
TV is rated to tow. Too many think of this rating in an absolute term.
Meaning that if their TV is loaded up to it's GVWR before hooking up,
their TV is rated for that....NOT SO, if loaded to their GVWR there is
NO MORE RATING for the tongue & hitch weight
I've seen plenty of trucks in my price range ($10K) that I *think* will work (F150, Excusion, Silverado 1500, Yukon) but I've been unable to make an exact determination. The sellers sometimes have no idea what gear ratio the truck has. Or if the installed hitch is a "load distributing" hitch. Etc.
Suggest using their GVWR's to reference between them. Example is that
you are comparing 'half ton' to '3/4 ton' and that a Silverado can be
either a 'half ton' or a '3/4 ton'. Ditto a Yukon, there are two of them
An Excursion was never sold in a 'half ton' model
Ford (other too) has over 12 F150 (half ton) models. IIRC, ranging
from low 6,000 lbs to just under 8,000 lbs...they used to have an 8,1000
lb GVWR F150
Most all of a TV's have their loaded weight placed on their rear axle
Just look at their side views and that most will have the rear edge
of the drivers door near dead center. Loading is most always behind
the drivers seat
'Half ton' TVs generally have a rear GAWR in the 4,000 lb range. Next
higher class TVs generally have a rear GAWR in the 6,000 lb range. That
approx 2,000 higher ratings provides for larger tongue weight and loaded
stuff in/on the TV
Buying used has the potential that the previous owner(s) changed out
the diff gears. Below is a method to figure that out.
Just checking the option label and/or the tag on the diff only tells
you what that vehicle left the factory with
The part bolted to the TV's rear for towing is the 'receiver' that
has a square tube (some call it the receiver pin box) that holds the
'shank'/'draw bar', which holds the ball or WD Hitch
The part on the trailer that goes on the ball is the coupler (if you
already know this, then it is for the lurker newbies)
With the small size trailer we're looking at, can I safely assume that nearly any full-size vehicle with a V8 will work? Is there anywhere online that I can simply plug in a vehicle VIN and get a "you can safely tow XXXXX" determination?
The link provided is a good source, but best if from the OEM
Roll the vehicle so that one wheel valve stem is straight down.
Tape length of string on the drive shaft pointing straight down
Roll the vehicle one rotation so that the valve stem is again straight
Count the full number of string wraps on the drive shaft. That is the
first full number of the diff ratio. If 3 full wraps, then it is 3.X ratio
The fraction of string wrap is the second part of the diff ratio. So
if about 3/4 of a wrap/turn, the diff ratio is 3.73
Remove the string
Suggest should'a included: "All other things being equal"...as so many folks take
things as an absolute
There are many, many other variables
From technology to frictional losses and many of them factor each other to either
cancel out or multiply those losses
Hybrid and all electric will some day over take/replace ICE's, but technology is
not there yet. Mainly for the power storage (AKA battery). Saline is looking very
good, but they are not ready for vehicles just yet...too big
Next gen hybrid will NOT have an alternator...nor starter...the electric half
of the hybrid will be all that and more...
On why diesel is more efficient than a gasser...the main reason is that on a gasser,
it is throttled...the most efficient throttle position on a gasser is WOT...and
diesel's are WOT all the time...then factor in more BTU's per gallon and then
of course diesel has higher MPG's
Plus diesel's have much higher compression ratio's...therefore higher PSI on the
Also lost is the duty cycle rating of all of these in discussion. Even
hybrid or all electric. There is a guy in San Louse Ca who gets over
200 MPG with his Prius and key is the extra wet/lead-acid batteries and
the custom controller he built
Know...guessing...what Turtle is getting at...is that these hugmongo HP's/torque
numbers are more for acceleration and ability to go faster up hill than ever before
That once up to speed (from slow poke to racer) and at steady speed...the HP
required to maintain that speed is way below the new ICE's max ratings...
Good write up Turtle and know most are clueless of what you said...as most are
only interested in either the marketing HP number and/or acceleration rates (or
seat of their pants acceleration)
Lost on what you said is that it takes X HP to move the same weight/frontal area/etc
at Y speed no matter what type of ICE you have
Or that diesel has more energy per gallon than does gasoline, so it appears to
have better MPG...lost is that it not comparing apples to apples
Or that the most efficient ICE is a 2 cycle diesel at about 50%...which means
approx 50% of the energy is lost...not delivered to the pavement...meaning that
there is more head room to get better efficiency (more MPG)
Oh, forgot to touch on the dealer saying, IIRC, to check the filter/etc for 'metal filings'...
Not going to find much from pre-ignition/knock damage, as it will be chunks or
bits of metal that will sink to the bottom of the oil pan
Filings are smaller and lighter that will, most times, flow with the oil.
Generally, filings are from rotational issues. Like a bearing going bad