Gears and towing

[Halstem1]

I need some opinions on gearing as it relates to towing. I have seen some responses from people that have towed but not a thread specific to it.

my current setup is a ‘19 JLUR 3.6L auto on 37” BFG KO2 with stock 4.10 gears. I purchased a small travel trailer. It weighs approximately 2650 empty and just weighed at 3100 fully loaded without water.

First time I towed it I noticed I was spending a lot of time in 5th and 6th gear which for me looking at re-gearing. Based on most opinions, recommendations and tire size, 4.88 or 5.13 would be best paired. 5.13 is strongly recommended by most if I ignore the trailer.

this last weekend I towed the trailer another 1200 miles and paid more attention to gear selection and speed. I also utilized the manual function of the auto transmission. For all comparison purposes I tried to maintain 70 MPH. This speed was most comfortable with traffic and wind.

Most consistently the Jeep stayed in 6th gear which has a 4.10 overall ratio and would run 2600 RPM. If relatively flat with tail wind, I could put manually in 7th which has an overall ratio of 3.44 and maintain speed at approximately 2250 RPM. Any excess with or significant grade and it would not maintain speed. Any head wind or cross wind above 20 MPH would require constant use of 5th gear (overall ratio 5.29) at 3200 RPM. Also rolling hills would require constant downshifting to 5th to climb hills.

my first question relates to overall ratios. If 2 gears have the same overall ratio with different ring and pinion ratios, to they have the same pulling effect? For example, the overall ratio of 7th gear with 4.10 R&P has an overall of 3.44. If you regear to 5.13 R&P, your overall 8th gear is now 3.44, so the same relative ratio. If I cannot currently maintain 7th, would it be assumed I would not maintain 8th if regeared to 5.13?

Relatedly, if I consistently utilized 5th and 6th gear now, should I plan on gears that allow optimal use of 6th and 7th later? For example, if the Jeep regularly stayed in 6th gear (4.10 overall ratio) would a 7th gear with a similar overall ratio be best? The 4.88 R&P has an overall 7th gear of 4.10 where the 5.13 R&P has a 7th gear of 4.31 which would run an even higher RPM at the same speed.

Also, if the overall ratios are the same or have the same effect, is it even worth regearing? Whether I’m in 6th or 7th is all relative if I’m at the same RPM and the same speed. My ideal scenario would be to reduce my downshifting but also maintain a comfortable RPM. Maybe that’s just not possible with towing and high RPMs is just a product of the 3.6.

Am I overthinking it and I should just regear and not worry about it? If I ignored the trailer completely, I would most likely regear to 4.88 just to improve daily drivability. I’m purposely keep the rig light. I’m most likely staying with 37’s. I don’t think it drives horrible now. Because of where I live I get to off-road about 4 times a year. The rest of the time I want my same reliable daily driver.

thanks.

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[ChattVol]

I need some opinions on gearing as it relates to towing. I have seen some responses from people that have towed but not a thread specific to it.

my current setup is a ‘19 JLUR 3.6L auto on 37” BFG KO2 with stock 4.10 gears. I purchased a small travel trailer. It weighs approximately 2650 empty and just weighed at 3100 fully loaded without water.

First time I towed it I noticed I was spending a lot of time in 5th and 6th gear which for me looking at re-gearing. Based on most opinions, recommendations and tire size, 4.88 or 5.13 would be best paired. 5.13 is strongly recommended by most if I ignore the trailer.

this last weekend I towed the trailer another 1200 miles and paid more attention to gear selection and speed. I also utilized the manual function of the auto transmission. For all comparison purposes I tried to maintain 70 MPH. This speed was most comfortable with traffic and wind.

Most consistently the Jeep stayed in 6th gear which has a 4.10 overall ratio and would run 2600 RPM. If relatively flat with tail wind, I could put manually in 7th which has an overall ratio of 3.44 and maintain speed at approximately 2250 RPM. Any excess with or significant grade and it would not maintain speed. Any head wind or cross wind above 20 MPH would require constant use of 5th gear (overall ratio 5.29) at 3200 RPM. Also rolling hills would require constant downshifting to 5th to climb hills.

my first question relates to overall ratios. If 2 gears have the same overall ratio with different ring and pinion ratios, to they have the same pulling effect? For example, the overall ratio of 7th gear with 4.10 R&P has an overall of 3.44. If you regear to 5.13 R&P, your overall 8th gear is now 3.44, so the same relative ratio. If I cannot currently maintain 7th, would it be assumed I would not maintain 8th if regeared to 5.13?

Relatedly, if I consistently utilized 5th and 6th gear now, should I plan on gears that allow optimal use of 6th and 7th later? For example, if the Jeep regularly stayed in 6th gear (4.10 overall ratio) would a 7th gear with a similar overall ratio be best? The 4.88 R&P has an overall 7th gear of 4.10 where the 5.13 R&P has a 7th gear of 4.31 which would run an even higher RPM at the same speed.

Also, if the overall ratios are the same or have the same effect, is it even worth regearing? Whether I’m in 6th or 7th is all relative if I’m at the same RPM and the same speed. My ideal scenario would be to reduce my downshifting but also maintain a comfortable RPM. Maybe that’s just not possible with towing and high RPMs is just a product of the 3.6.

Am I overthinking it and I should just regear and not worry about it? If I ignored the trailer completely, I would most likely regear to 4.88 just to improve daily drivability. I’m purposely keep the rig light. I’m most likely staying with 37’s. I don’t think it drives horrible now. Because of where I live I get to off-road about 4 times a year. The rest of the time I want my same reliable daily driver.

thanks.

If you only offroad 4 times a year, arent going to go bigger than 37" tires, its your daily driver and you care about efficiency....4.88 would make sense. I'd go 5.13 for towing 3100 lbs if you want it to stay in 8th longer on the hwy and like having a little more power....especially in windy conditions. Bear in mind, 5.13 only runs 150rpm higher than 4.88....so not a big difference. Essentially, its the difference between cruising the hwy at 70mph with 4.88's at 2200 rpm or 2350 rpm with 5.13's.

 

[Halstem1]

If you only offroad 4 times a year, arent going to go bigger than 37" tires, its your daily driver and you care about efficiency....4.88 would make sense. I'd go 5.13 for towing 3100 lbs if you want it to stay in 8th longer on the hwy and like having a little more power....especially in windy conditions. Bear in mind, 5.13 only runs 150rpm higher than 4.88....so not a big difference. Essentially, its the difference between cruising the hwy at 70mph with 4.88's at 2200 rpm or 2350 rpm with 5.13's.

Thanks for the reply. That's great feedback and helpful. Quick follow up question.... does the extra 150 RPM apply across all gears? or just 8th gear? I don't mind the higher if I'm in 8th gear. Like you said, its basically 2350 at 70. but if pulling the trailer, I'm likely going to stay in 6th and 7th (90% of the time), now I'm talking 2800 and 3300 rpm. As opposed to 2600 and 3100. Or does that pulling power make up for it so you spend less time in that gear? I guess I'm not sure if I'd ever see 8th gear towing. And without the trailer, I think 4.88 makes sense, like you said.

 

[ChattVol]

Thanks for the reply. That's great feedback and helpful. Quick follow up question.... does the extra 150 RPM apply across all gears? or just 8th gear? I don't mind the higher if I'm in 8th gear. Like you said, its basically 2350 at 70. but if pulling the trailer, I'm likely going to stay in 6th and 7th (90% of the time), now I'm talking 2800 and 3300 rpm. As opposed to 2600 and 3100. Or does that pulling power make up for it so you spend less time in that gear? I guess I'm not sure if I'd ever see 8th gear towing. And without the trailer, I think 4.88 makes sense, like you said.

You will have more power throughout the 8 gears with 5.13. Give this a watch..

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