4.30 vs 3.71 ratio
#17
09-26-2017, 09:28 AM
Cargo Master
#18
09-26-2017, 10:15 AM
I had a similar experience buying my truck. The salesman knew nothing about trucks so he had no reaction to the 4.30 gears requirement. What was interesting was their finance department guy balked and asked me if I was sure and that 3.73 gears would be much better. He was also informed it was a deal breaker.
After much searching they actually located a special order truck that had been delivered but not accepted by the customer because he backed out. Loaded up Lariat with 4.30 gears and Camper/FX4 package. I couldn't believe my luck.
Also, while I understand the "lock out 6th gear" thought it really only applies when someone wants to compare going down the highway in the highest gear between 3.73 and 4.30. It doesn't compare all the gears shifted before then so it is kind of a moot exercise for someone interested in towing.
GF
After much searching they actually located a special order truck that had been delivered but not accepted by the customer because he backed out. Loaded up Lariat with 4.30 gears and Camper/FX4 package. I couldn't believe my luck.
Also, while I understand the "lock out 6th gear" thought it really only applies when someone wants to compare going down the highway in the highest gear between 3.73 and 4.30. It doesn't compare all the gears shifted before then so it is kind of a moot exercise for someone interested in towing.
GF
#19
09-26-2017, 10:52 AM
I had a similar experience buying my truck. The salesman knew nothing about trucks so he had no reaction to the 4.30 gears requirement. What was interesting was their finance department guy balked and asked me if I was sure and that 3.73 gears would be much better. He was also informed it was a deal breaker.
After much searching they actually located a special order truck that had been delivered but not accepted by the customer because he backed out. Loaded up Lariat with 4.30 gears and Camper/FX4 package. I couldn't believe my luck.
Also, while I understand the "lock out 6th gear" thought it really only applies when someone wants to compare going down the highway in the highest gear between 3.73 and 4.30. It doesn't compare all the gears shifted before then so it is kind of a moot exercise for someone interested in towing.
GF
After much searching they actually located a special order truck that had been delivered but not accepted by the customer because he backed out. Loaded up Lariat with 4.30 gears and Camper/FX4 package. I couldn't believe my luck.
Also, while I understand the "lock out 6th gear" thought it really only applies when someone wants to compare going down the highway in the highest gear between 3.73 and 4.30. It doesn't compare all the gears shifted before then so it is kind of a moot exercise for someone interested in towing.
GF
Steve
#20
09-26-2017, 11:15 AM
Originally Posted by dnewton3
Ehhhhhh ...... sort of yes, but not really. It's not just first gear that is effected. Given that the 6.2L engine develops an average torque of 390 ft-lb across it's power-band, the scenario you suggest would result in the 3.73/5th gearing actually giving a slight edge over the 4.30/6th gearing. So, I agree that you will find a "sweet spot" where the gearing will be effectively similar.
But that ignores the topic of how much gearing effectively allows one to "hold" a road speed, especially under load. May folks who tow (especially those who tow heavy loads) want to be able to maintain momentum uphill.
The 4.30 gearing returns a smaller spread of wheel rpm for every engine rpm.
Taller diff gears (lower numerically) offer a broader range of wheel speed per tranny gear, but give up a slight bit of force generation via lower torque multiplication.
Shorter diff gears (higher numerically) offer a greater wheel force generation effect for any tranny gear selected, at the expense of wheel speed.
So, when towing at or near GCWR limits, greater diff reduction gearing offers more ability to "hold" any given gear going uphill, whereas taller gears will cause a downshifts sooner, and more often.
For the OP, I would highly recommend the 4.30 gears for his stated intent of use.
But that ignores the topic of how much gearing effectively allows one to "hold" a road speed, especially under load. May folks who tow (especially those who tow heavy loads) want to be able to maintain momentum uphill.
The 4.30 gearing returns a smaller spread of wheel rpm for every engine rpm.
Taller diff gears (lower numerically) offer a broader range of wheel speed per tranny gear, but give up a slight bit of force generation via lower torque multiplication.
Shorter diff gears (higher numerically) offer a greater wheel force generation effect for any tranny gear selected, at the expense of wheel speed.
So, when towing at or near GCWR limits, greater diff reduction gearing offers more ability to "hold" any given gear going uphill, whereas taller gears will cause a downshifts sooner, and more often.
For the OP, I would highly recommend the 4.30 gears for his stated intent of use.
#21
09-26-2017, 11:34 AM
RV_Tech,
Sorry if I'm unclear so let me see if I can use wordiness to fix it.
The OP is trying to decide between 3.73 and 4.30 gears. If he were only interested in knowing what RPM's would be for 4.30 gears at highway speed then he could lock out 6th in a 3.73 and get the same feel. This is really the only time the two are comparable (a single gear, 5th, at HWY speed.) That's because the effective gear ratios become the same given trans gear X final drive.
When the comparison falls apart is in the very first gear. 1st gear in 3.73 and 1st gear in 4.30 trucks will not have equal mechanical advantage so you cannot compare the two trucks off the line (nor in subsequent gears until final drive in 4.30 becomes somewhat equal to 3.73 in 5th gear.)
4.30 gears will pull with greater advantage from 1-5.
4.30 gears will pull similarly in 6th gear to 3.73 in 5th gear.
I agree that pulling a load and locking out 6th gear (or even 5th) is nice no matter the final gear ratio because you reduce downshifts by one and you increase RPM and mechanical advantage.
Ron94150,
You're good brother. You had a good explanation but I think we were all starting to talk past each other. This is where videos and pointy/talky help.
GF
Sorry if I'm unclear so let me see if I can use wordiness to fix it.
The OP is trying to decide between 3.73 and 4.30 gears. If he were only interested in knowing what RPM's would be for 4.30 gears at highway speed then he could lock out 6th in a 3.73 and get the same feel. This is really the only time the two are comparable (a single gear, 5th, at HWY speed.) That's because the effective gear ratios become the same given trans gear X final drive.
When the comparison falls apart is in the very first gear. 1st gear in 3.73 and 1st gear in 4.30 trucks will not have equal mechanical advantage so you cannot compare the two trucks off the line (nor in subsequent gears until final drive in 4.30 becomes somewhat equal to 3.73 in 5th gear.)
4.30 gears will pull with greater advantage from 1-5.
4.30 gears will pull similarly in 6th gear to 3.73 in 5th gear.
I agree that pulling a load and locking out 6th gear (or even 5th) is nice no matter the final gear ratio because you reduce downshifts by one and you increase RPM and mechanical advantage.
Ron94150,
You're good brother. You had a good explanation but I think we were all starting to talk past each other. This is where videos and pointy/talky help.
GF
#22
09-26-2017, 12:00 PM
RV_Tech,
Sorry if I'm unclear so let me see if I can use wordiness to fix it.
The OP is trying to decide between 3.73 and 4.30 gears. If he were only interested in knowing what RPM's would be for 4.30 gears at highway speed then he could lock out 6th in a 3.73 and get the same feel. This is really the only time the two are comparable (a single gear, 5th, at HWY speed.) That's because the effective gear ratios become the same given trans gear X final drive.
When the comparison falls apart is in the very first gear. 1st gear in 3.73 and 1st gear in 4.30 trucks will not have equal mechanical advantage so you cannot compare the two trucks off the line (nor in subsequent gears until final drive in 4.30 becomes somewhat equal to 3.73 in 5th gear.)
4.30 gears will pull with greater advantage from 1-5.
4.30 gears will pull similarly in 6th gear to 3.73 in 5th gear.
I agree that pulling a load and locking out 6th gear (or even 5th) is nice no matter the final gear ratio because you reduce downshifts by one and you increase RPM and mechanical advantage.
Ron94150,
You're good brother. You had a good explanation but I think we were all starting to talk past each other. This is where videos and pointy/talky help.
GF
Sorry if I'm unclear so let me see if I can use wordiness to fix it.
The OP is trying to decide between 3.73 and 4.30 gears. If he were only interested in knowing what RPM's would be for 4.30 gears at highway speed then he could lock out 6th in a 3.73 and get the same feel. This is really the only time the two are comparable (a single gear, 5th, at HWY speed.) That's because the effective gear ratios become the same given trans gear X final drive.
When the comparison falls apart is in the very first gear. 1st gear in 3.73 and 1st gear in 4.30 trucks will not have equal mechanical advantage so you cannot compare the two trucks off the line (nor in subsequent gears until final drive in 4.30 becomes somewhat equal to 3.73 in 5th gear.)
4.30 gears will pull with greater advantage from 1-5.
4.30 gears will pull similarly in 6th gear to 3.73 in 5th gear.
I agree that pulling a load and locking out 6th gear (or even 5th) is nice no matter the final gear ratio because you reduce downshifts by one and you increase RPM and mechanical advantage.
Ron94150,
You're good brother. You had a good explanation but I think we were all starting to talk past each other. This is where videos and pointy/talky help.
GF
Steve
#23
09-26-2017, 12:08 PM
Fleet Mechanic
#24
09-26-2017, 12:41 PM
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#25
09-26-2017, 12:58 PM
I need to keep strong and hold out and do a proper 2018 order! But this truck was packaged perfectly today...... 
#26
09-26-2017, 12:59 PM
#27
09-26-2017, 01:14 PM
The reason I keep commenting about the importance of where a truck is used is it really does make a difference. Last week we hauled out slide-in camper down to the Smokies to camp for a few days. For us that is a shot down I81 and I40. We were in 6th almost the entire run going 70 mph.
I understand fully what folks are saying about the difference, but there can be a good many times when there really is not a difference for an average driver doing average things. It's not really a debate. It is just asking yourself how am I going to use my truck and where. The majority of trucks I see are running empty the majority of the time.
Just my two cents worth.
Steve
I understand fully what folks are saying about the difference, but there can be a good many times when there really is not a difference for an average driver doing average things. It's not really a debate. It is just asking yourself how am I going to use my truck and where. The majority of trucks I see are running empty the majority of the time.
Just my two cents worth.
Steve
#28
09-26-2017, 02:03 PM
Cargo Master
#29
09-26-2017, 02:09 PM
RV,
you hit the nail on the head. Lots of folks can get by with less equipment. I think a lot of fellas focus too much on what the truck CAN DO before asking themselves what they NEED IT TO DO.
Now my tuck spends more time towing than anything else but you are right that there sure are a lot of empty trucks running down the road or that have light loads versus there capability.
You were in my old stomping grounds the other day. That 81 and 40 stretch I am very familiar with. My dad used to run the 417 truck stop down that way before you get to the exit for Gatlinburg/Sevierville/Pigeon Forge.
GF
you hit the nail on the head. Lots of folks can get by with less equipment. I think a lot of fellas focus too much on what the truck CAN DO before asking themselves what they NEED IT TO DO.
Now my tuck spends more time towing than anything else but you are right that there sure are a lot of empty trucks running down the road or that have light loads versus there capability.
You were in my old stomping grounds the other day. That 81 and 40 stretch I am very familiar with. My dad used to run the 417 truck stop down that way before you get to the exit for Gatlinburg/Sevierville/Pigeon Forge.
GF
