โApr-20-2019 07:01 PM
โApr-23-2019 10:39 PM
Terryallan wrote:valhalla360 wrote:Terryallan wrote:
so you are saying. They should only make ONE rear gear ratio? Wonder why they still make lower gears, and rate them to tow so much more? It's a puzzle.
Not sure how you came up with that?
The 10speed means you have a gear ratio available that matches what the rig needs to what the engine produces.
With the old 3 speed transmissions, you often wound up having to drop down to a gear that was too deep, so the engine would be lightly loaded but screaming at high RPM when towing. A deeper rear-end could allow you to run in the higher gear and keep the engine better loaded at lower RPM. (This assumes you are within ratings with either rear-end...no one is suggesting towing beyond the ratings). Of course when not towing, the truck winds up running higher RPM and less efficient. And even with the deeper rear-end, it still didn't always match up well to power needs.
With the 10speed, those issues largely go away. For a given situation, the truck may pick a different gear if the rear-end is changed out but the overall gear ratio will be nearly identical.
Only reason you might need a deeper rear-end is to boost the ultimate towing capability but the discussion presumes he isn't over the tow rating and it is about drive-ability.
I just go by the rating for the different gears. and YES they make a huge difference, Especially up, and down mountains, and starting from a stop. that is one of the reason for the lower gears. Another is keeping the engine in it's power band. Still a puzzle.
If you had ever seen the difference in gear ratios as they run. you would better understand the difference, between a 3.73, and a 3.05. I see it every day. It is what I do.
โApr-23-2019 04:43 PM
valhalla360 wrote:Terryallan wrote:
so you are saying. They should only make ONE rear gear ratio? Wonder why they still make lower gears, and rate them to tow so much more? It's a puzzle.
Not sure how you came up with that?
The 10speed means you have a gear ratio available that matches what the rig needs to what the engine produces.
With the old 3 speed transmissions, you often wound up having to drop down to a gear that was too deep, so the engine would be lightly loaded but screaming at high RPM when towing. A deeper rear-end could allow you to run in the higher gear and keep the engine better loaded at lower RPM. (This assumes you are within ratings with either rear-end...no one is suggesting towing beyond the ratings). Of course when not towing, the truck winds up running higher RPM and less efficient. And even with the deeper rear-end, it still didn't always match up well to power needs.
With the 10speed, those issues largely go away. For a given situation, the truck may pick a different gear if the rear-end is changed out but the overall gear ratio will be nearly identical.
Only reason you might need a deeper rear-end is to boost the ultimate towing capability but the discussion presumes he isn't over the tow rating and it is about drive-ability.
โApr-23-2019 07:37 AM
โApr-22-2019 10:50 PM
Terryallan wrote:
so you are saying. They should only make ONE rear gear ratio? Wonder why they still make lower gears, and rate them to tow so much more? It's a puzzle.
โApr-22-2019 01:59 PM
valhalla360 wrote:Terryallan wrote:
Kind of proved my point. The lower rear gear gets you to the needed RPM for max torque.
As for the other statement about the 10 speed. Ford's engineers determined the tow capacity is always higher with the lower geared rear. No matter how many gears it has. A truck will NEVER be rated for max tow, with a 3.15 rear gear. It's in the book, and is no more than physics.
If it's rated to tow north of 7k lb, the Ford Engineers have determined, it's fine.
This is different from the old days of 3 speed transmissions where there often wasn't a good gear to match engine output, so you really needed the deep rear end if you wanted to tow much of anything otherwise you lived in 1st gear with the engine near redline if you wanted to go more than 35mph. The 10speed allows the truck to pick a gear that matches the engine output, so unless you are pushing over the tow limits, the rear end isn't a big deal.
โApr-22-2019 06:02 AM
โApr-22-2019 05:41 AM
MR MAC wrote:
I'm in no hurry, but looking at used (2016 and up) F150's, looking at eng. size and wondering what would be best a 3.5 Ecoboost or a 5.0 L V8 . to pull a 7000lb trailer (TT) I think I"m leaning towards the V8, to pull over hills in Maine.
Thanks Rob
โApr-22-2019 04:32 AM
โApr-21-2019 10:16 PM
Terryallan wrote:
Kind of proved my point. The lower rear gear gets you to the needed RPM for max torque.
As for the other statement about the 10 speed. Ford's engineers determined the tow capacity is always higher with the lower geared rear. No matter how many gears it has. A truck will NEVER be rated for max tow, with a 3.15 rear gear. It's in the book, and is no more than physics.
โApr-21-2019 06:30 PM
โApr-21-2019 05:10 PM
bartlettj wrote:
I think 8k pounds for a F150 is a bit heavy as you are going to be light on truck payload if you plan to take passengers in the cab. There's not much of a price premium on used 3/4 ton trucks unless you go diesel.
โApr-21-2019 04:24 PM
bartlettj wrote:
I think 8k pounds for a F150 is a bit heavy as you are going to be light on truck payload if you plan to take passengers in the cab. There's not much of a price premium on used 3/4 ton trucks unless you go diesel.
โApr-21-2019 03:51 PM
โApr-21-2019 11:07 AM
โApr-21-2019 10:59 AM
valhalla360 wrote:
I wouldn't get too hung up on rear-end ratios...with the newer 10speed transmissions, the truck can select an appropriate gear to convert HP to torque at the wheels.
PS: If you do want to look at torque, you need to look at the torque curve not just the peak number. A slightly bigger maximum torque doesn't prove anything if the engine can't get up to the RPM where it generates the max.