Dumb question about how to best use my transmission - #1

[TJMexico]

I’ll be posting some questions over the next few days about how to best use my transmission and transfer case on the roads I run. I’m really trying to do right by La Negrita, so if folks will bear with me, I’d like to drop a few questions about best practices for the 42RLE in my road conditions. As have said, all of my 4wd vehicles have had manual trannies, so this is my first automatic in these kinds of conditions. It’s a different beast. I don't run rough roads on weekends for fun. This is my job. I do mission work up in the big mountains here in Southern Sonora. I make long trips over bad roads to get to the villages where I visit, teach, and serve the communities. I need to keep this gal running as well and as long as I can.

BTW, I run a 2005 X model, all stock, including stock 4.0l and the 42RLE, but a 3” lift.

One of my biggest concerns is how high I should let my engine rev on these roads, specifically - for this thread - on downhill runs.

Some of the downhill stretches are long and very rough (rocks, gullies, blind curves). The curves are dangerous as you often can’t see vehicles coming from the other direction, so I do not like to let her run free because of that and just the fact that it’d beat up the vehicle. (Last trip, I nearly got hit head-on by some jerk in an Unlimited model came around a blind uphill curve like a bat out of hell, fishtailing all over the place. I was heading downhill in low gear and he’d have nailed me had I been going a bit faster.) I also want to save my brakes. I have seen folks heat up and crystallize brake pads on these roads.

So, on these long, rough downhill stretches I’ll either run in 2wd or 4hi and drop her down into 2nd or 1st gear and let the engine rev. If it’s really steep and/or rough and/or curvy, I’ll drop into low range and shift from 1 to 2 to D as road conditions need. Sometimes, if I hit a smooth or flat spot and want to go faster but know I’ll be needing to go back into low range soon, I’ll even turn on O/D for a short distance.

My question is, How high is it safe to let the engine rev before I shift up into the next gear? I’ve let it get up to about 2,500rpm and she seems to be screaming, so I’ll up-shift, but sometimes I’d be more comfortable speed-wise leaving it there. I just am not sure about how high I can let the engine rev for an extended period. How would going above 2500rpm affect the transmission, transfer case and engine? How high can I safely go?

And as to using 4lo, I wouldn’t think that there’d be a problem with running it in 4lo for extended periods in that situation, using it to hold the vehicle back speed-wise. Am I correct? Seems like that tactic would be best for the engine and the transmission.

Also, if I need to downshift, is it best to brake and slow down, then downshift as opposed to just dropping down into a lower gear. Seems that would be easier on the transmission.

These are probably some pretty basic question for some of you fellows, but y’all help a brother out as I am learning to tailor my driving style to what is gonna treat my li’l Negrita best.

 

[ColoJeep]

I’ll be posting some questions over the next few days about how to best use my transmission and transfer case on the roads I run. I’m really trying to do right by La Negrita, so if folks will bear with me, I’d like to drop a few questions about best practices for the 42RLE in my road conditions. As have said, all of my 4wd vehicles have had manual trannies, so this is my first automatic in these kinds of conditions. It’s a different beast. I don't run rough roads on weekends for fun. This is my job. I do mission work up in the big mountains here in Southern Sonora. I make long trips over bad roads to get to the villages where I visit, teach, and serve the communities. I need to keep this gal running as well and as long as I can.

BTW, I run a 2005 X model, all stock, including stock 4.0l and the 42RLE, but a 3” lift.

One of my biggest concerns is how high I should let my engine rev on these roads, specifically - for this thread - on downhill runs.

Some of the downhill stretches are long and very rough (rocks, gullies, blind curves). The curves are dangerous as you often can’t see vehicles coming from the other direction, so I do not like to let her run free because of that and just the fact that it’d beat up the vehicle. (Last trip, I nearly got hit head-on by some jerk in an Unlimited model came around a blind uphill curve like a bat out of hell, fishtailing all over the place. I was heading downhill in low gear and he’d have nailed me had I been going a bit faster.)

So, on these long, rough downhill stretches I’ll either run in 2wd or 4hi and drop her down into 2nd or 1st gear and let the engine rev. If it’s really steep and/or rough and/or curvy, I’ll drop into low range and shift form 1 to 2 to D as road conditions need. Sometimes, if I hit a smooth or flat spot and want to go faster but know I’ll be needing to go back into low range soon, I’ll even turn on O/D for a short distance.

My question is, How high is it safe to let the engine rev before I shift up into the next gear? I’ve let it get up to about 2,500rpm and she seems to be screaming, so I’ll up-shift, but sometimes I’d be more comfortable speed-wise leaving it there. I just am not sure about how high I can let the engine rev for an extended period. How would going above 2500rpm affect the transmission, transfer case and engine? How high can I safely go?

And as to using 4lo, I wouldn’t think that there’d be a problem with running it in 4lo for extended periods in that situation, using it to hold the vehicle back speed-wise. Am I correct? Seems like that tactic would be best for the engine and the transmission.

These are probably some pretty basic question for some of you fellows, but y’all help a brother out as I am learning to tailor my driving style to what is gonna treat my li’l Negrita best.

Honestly I have ran mine at 3600 r.p.m. on downhill runs in Colorado on my daily commute . No issues since 2008. What you are doing is fine .

 

[TJMexico]

Honestly I have ran mine at 3600 r.p.m. on downhill runs in Colorado on my daily commute . No issues since 2008. What you are doing is fine .

Thanks.

Is there any difference or considerations regarding using 4lo as opposed to 4hi on these bad downhills? (I'm working on getting that tranny pan with the temp sensor as soon as I can.)

 

[ColoJeep]

Thanks.

Is there any difference or considerations regarding using 4lo as opposed to 4hi on these bad downhills? (I'm working on getting that tranny pan with the temp sensor as soon as I can.)

I say use the range that gives you the best control and keeps you off the brakes . Sometimes 4lo is too slow for the road , but mountain roads are not like driving in town , on flat asphalt like most folks do.

 

[Rickyd]

I’ll be posting some questions over the next few days about how to best use my transmission and transfer case on the roads I run. I’m really trying to do right by La Negrita, so if folks will bear with me, I’d like to drop a few questions about best practices for the 42RLE in my road conditions. As have said, all of my 4wd vehicles have had manual trannies, so this is my first automatic in these kinds of conditions. It’s a different beast. I don't run rough roads on weekends for fun. This is my job. I do mission work up in the big mountains here in Southern Sonora. I make long trips over bad roads to get to the villages where I visit, teach, and serve the communities. I need to keep this gal running as well and as long as I can.

BTW, I run a 2005 X model, all stock, including stock 4.0l and the 42RLE, but a 3” lift.

One of my biggest concerns is how high I should let my engine rev on these roads, specifically - for this thread - on downhill runs.

Some of the downhill stretches are long and very rough (rocks, gullies, blind curves). The curves are dangerous as you often can’t see vehicles coming from the other direction, so I do not like to let her run free because of that and just the fact that it’d beat up the vehicle. (Last trip, I nearly got hit head-on by some jerk in an Unlimited model came around a blind uphill curve like a bat out of hell, fishtailing all over the place. I was heading downhill in low gear and he’d have nailed me had I been going a bit faster.) I also want to save my brakes. I have seen folks heat up and crystallize brake pads on these roads.

So, on these long, rough downhill stretches I’ll either run in 2wd or 4hi and drop her down into 2nd or 1st gear and let the engine rev. If it’s really steep and/or rough and/or curvy, I’ll drop into low range and shift from 1 to 2 to D as road conditions need. Sometimes, if I hit a smooth or flat spot and want to go faster but know I’ll be needing to go back into low range soon, I’ll even turn on O/D for a short distance.

My question is, How high is it safe to let the engine rev before I shift up into the next gear? I’ve let it get up to about 2,500rpm and she seems to be screaming, so I’ll up-shift, but sometimes I’d be more comfortable speed-wise leaving it there. I just am not sure about how high I can let the engine rev for an extended period. How would going above 2500rpm affect the transmission, transfer case and engine? How high can I safely go?

And as to using 4lo, I wouldn’t think that there’d be a problem with running it in 4lo for extended periods in that situation, using it to hold the vehicle back speed-wise. Am I correct? Seems like that tactic would be best for the engine and the transmission.

Also, if I need to downshift, is it best to brake and slow down, then downshift as opposed to just dropping down into a lower gear. Seems that would be easier on the transmission.

These are probably some pretty basic question for some of you fellows, but y’all help a brother out as I am learning to tailor my driving style to what is gonna treat my li’l Negrita best.

Your redline is 5200 rpm. that is your safe limit for compression braking. Compression braking is much easier on an engine than when under power,you don't see thousands of psi from explosions in the cylinders. Many tj's came with a non overdrive auto that had them sitting at 3000 rpm continuously. The little v6 in my 3/4 ton van sees almost 7000rpm(it's redline) on compression braking at times.

Yes,slowing down before downshifting is always better.

I wouldn't use overdrive with low range. That is extremely fast speeds for the planetary gears. I'd rather use 1st gear hi range.

 

[TJMexico]

I wouldn't use overdrive with low range. That is extremely fast speeds for the planetary gears. I'd rather use 1st gear hi range.

Thanks. Helpful.

Regarding that comment, what about running 2nd and 3rd in low range for extended periods of time. That engine braking is the main reason I'd do this on the downhill stretches.

 

[JMT]

I’ll be posting some questions over the next few days about how to best use my transmission and transfer case on the roads I run. I’m really trying to do right by La Negrita, so if folks will bear with me, I’d like to drop a few questions about best practices for the 42RLE in my road conditions. As have said, all of my 4wd vehicles have had manual trannies, so this is my first automatic in these kinds of conditions. It’s a different beast. I don't run rough roads on weekends for fun. This is my job. I do mission work up in the big mountains here in Southern Sonora. I make long trips over bad roads to get to the villages where I visit, teach, and serve the communities. I need to keep this gal running as well and as long as I can.

BTW, I run a 2005 X model, all stock, including stock 4.0l and the 42RLE, but a 3” lift.

One of my biggest concerns is how high I should let my engine rev on these roads, specifically - for this thread - on downhill runs.

Some of the downhill stretches are long and very rough (rocks, gullies, blind curves). The curves are dangerous as you often can’t see vehicles coming from the other direction, so I do not like to let her run free because of that and just the fact that it’d beat up the vehicle. (Last trip, I nearly got hit head-on by some jerk in an Unlimited model came around a blind uphill curve like a bat out of hell, fishtailing all over the place. I was heading downhill in low gear and he’d have nailed me had I been going a bit faster.) I also want to save my brakes. I have seen folks heat up and crystallize brake pads on these roads.

So, on these long, rough downhill stretches I’ll either run in 2wd or 4hi and drop her down into 2nd or 1st gear and let the engine rev. If it’s really steep and/or rough and/or curvy, I’ll drop into low range and shift from 1 to 2 to D as road conditions need. Sometimes, if I hit a smooth or flat spot and want to go faster but know I’ll be needing to go back into low range soon, I’ll even turn on O/D for a short distance.

My question is, How high is it safe to let the engine rev before I shift up into the next gear? I’ve let it get up to about 2,500rpm and she seems to be screaming, so I’ll up-shift, but sometimes I’d be more comfortable speed-wise leaving it there. I just am not sure about how high I can let the engine rev for an extended period. How would going above 2500rpm affect the transmission, transfer case and engine? How high can I safely go?

And as to using 4lo, I wouldn’t think that there’d be a problem with running it in 4lo for extended periods in that situation, using it to hold the vehicle back speed-wise. Am I correct? Seems like that tactic would be best for the engine and the transmission.

Also, if I need to downshift, is it best to brake and slow down, then downshift as opposed to just dropping down into a lower gear. Seems that would be easier on the transmission.

These are probably some pretty basic question for some of you fellows, but y’all help a brother out as I am learning to tailor my driving style to what is gonna treat my li’l Negrita best.

2500 rpm isn’t even in the power band. The bigger concern is how hot is the transmission getting. You need a temperature gauge with the sender in the pan. You don’t want your Transmission pan temps getting over 230F. If they are you need a cooler. The 42rle runs hot, ridiculously hot, so in your climate running it like you describe I have no doubt it’s getting too hot. Heat kills transmissions.

 

[Rickyd]

Thanks. Helpful.

Regarding that comment, what about running 2nd and 3rd in low range for extended periods of time. That engine braking is the main reason I'd do this on the downhill stretches.

The bigger concern is how hot is the transmission getting.

Downhill probably isn't going to heat up your transmission but jmt is right. I'd let transmission temp dictate how you use it for the most part. Not brake pad life so long as you don't smoke the brakes and lose stopping ability. Brakes are much cheaper

 

[JMT]

Downhill probably isn't going to heat up your transmission but jmt is right. I'd let transmission temp dictate how you use it for the most part. Not brake pad life so long as you don't smoke the brakes and lose stopping ability. Brakes are much cheaper

I assumed he’s going uphill before downhill but perhaps didn’t consider that to be a problem. I’ll just ask here, @TJMexico, are you also driving up long stretches of road? That’s when I’ve had my 42rle start getting hot.

 

[Rickyd]

I assumed he’s going uphill before downhill but perhaps didn’t consider that to be a problem. I’ll just ask here, @TJMexico, are you also driving up long stretches of road? That’s when I’ve had my 42rle start getting hot.

That is why i included part of your post to answer his question to me. Thank you for the mind blowing observation, lol

 

[TJMexico]

I assumed he’s going uphill before downhill but perhaps didn’t consider that to be a problem. I’ll just ask here, @TJMexico, are you also driving up long stretches of road? That’s when I’ve had my 42rle start getting hot.

Actually, that's where I had my first problems. I did a post about that exact issue awhile back. You can see that thread here:

https://wranglertjforum.com/threads/transmission-overheating-need-some-advice.86611/

First time I made that big climb, I definitely overheated the transmission, to the point it scared me. I desperately need to get that temp sensor installed. Will have to figure out how to get the pan down here. I can't find a shop there that will promise me that they'll do silver solder.

Heavy duty transmission cooler is on the short list. We're heading into winter so ambient temps will be a lot lower next few months. I plan to get another fluid change in the next couple of months. (Want to get nutserts first as I have a skid plate bolt that won't grab.) Had fluid and filter changed recently, want to do it again as only half of the fluid gets changed out. Will do that then.
———————————————————————————
ETA: Looking at transmission coolers. I can get the HAYDEN TRANSAVER PLUS-COOLER OC-1679 EXTRA HEAVY DUTY transmission cooler for about $150usd shipped to me here in Mexico. Says it's rated FOR PICK UP TRUCKS AND VANS GROSS WEIGHT UP TO 30,000 LBS, CLASS "A" MOTOR HOMES, LARGE TRAVEL TRAILERS, 5TH WHEELS, HEAVY DUTY TOWING UP TO 10,000 LBS. DIMENSIONS ARE 11"X 11 5/8"X 3/4".

Another option would be a Hayden 689 Universal Add-On. It's about the same size, measuring 11.6" x 11" x 0.75" This one is cheaper, at just over $100usd.

I'm also seeing Tru-cool "Low Pressure Drop" coolers.

Anybody have experience with these? Educated recommendations?

At any price, these things are cheaper than a transmission rebuild.

 

[Gilaguy23]

I cant answer this for you but someone here can. The max recommended speed/gear in 4lo? I have read concerns of the planetary and to high of rpm's. This would be something like being in 3rd, rolling down hill going fairly fast. I'm pretty OCD myself and always keep speeds in 4lo way down, if not its back to 4 hi which is kind of PITA shifting frequently. At any rate, yes, do what you can to save breaking power. Having nothing left when trying to slow or stop isnt fun.

 

[mrblaine]

Actually, that's where I had my first problems. I did a post about that exact issue awhile back. You can see that thread here:

https://wranglertjforum.com/threads/transmission-overheating-need-some-advice.86611/

First time I made that big climb, I definitely overheated the transmission, to the point it scared me. I desperately need to get that temp sensor installed. Will have to figure out how to get the pan down here. I can't find a shop there that will promise me that they'll do silver solder.

It doesn't need to be silver brazed. I do silver brazing because it is easy, fast, and I'm good at it. It can be Tig welded, Mig welded, normal brazing rod, or high temp refrigeration silver brazed. I also told you how to get stuff down there, I asked him, he said it would not be a problem.

Heavy duty transmission cooler is on the short list. We're heading into winter so ambient temps will be a lot lower next few months. I plan to get another fluid change in the next couple of months. (Want to get nutserts first as I have a skid plate bolt that won't grab.) Had fluid and filter changed recently, want to do it again as only half of the fluid gets changed out. Will do that then.
———————————————————————————
ETA: Looking at transmission coolers. I can get the HAYDEN TRANSAVER PLUS-COOLER OC-1679 EXTRA HEAVY DUTY transmission cooler for about $150usd shipped to me here in Mexico. Says it's rated FOR PICK UP TRUCKS AND VANS GROSS WEIGHT UP TO 30,000 LBS, CLASS "A" MOTOR HOMES, LARGE TRAVEL TRAILERS, 5TH WHEELS, HEAVY DUTY TOWING UP TO 10,000 LBS. DIMENSIONS ARE 11"X 11 5/8"X 3/4".

Another option would be a Hayden 689 Universal Add-On. It's about the same size, measuring 11.6" x 11" x 0.75" This one is cheaper, at just over $100usd.

I'm also seeing Tru-cool "Low Pressure Drop" coolers.

Anybody have experience with these? Educated recommendations?

At any price, these things are cheaper than a transmission rebuild.

We have some very educated recommendations. We use the Setrab, it works for problem areas when you need a cooler that works better than most. But, I also have several samples of other coolers you can have for the cost of shipping including one of the Tru-cool LPD versions that I acquired to see what fit.

I also have some stellar brake pads that I seriously doubt you will overheat.

 

[lumberjacklloyd]

2500 rpm isn’t even in the power band.

Here I am again to disagree with the group think on this board. You aren't close to lugging this engine at 2500 rpm and is well into the bell curve of the 4.0

@TJMexico , no problem running up to 3500 consistently as needed, but at some point 3750-redline becomes unnecessary unless terrain doesn't warrant a shift. As others said, just watch out for harsh down shifts.

 

[JMT]

Here I am again to disagree with the group think on this board. You aren't close to lugging this engine at 2500 rpm and is well into the bell curve of the 4.0

@TJMexico , no problem running up to 3500 consistently as needed, but at some point 3750-redline becomes unnecessary unless terrain doesn't warrant a shift. As others said, just watch out for harsh down shifts.

Define not in the power band. When I say not in the power band I mean if there’s an uphill section you can’t hold your speed without downshifting. In my experience (not group think) I have to have 2800+ rpm to hold speed.

I didn’t say 2500 rpm was lugging. Here I am again having to tell woman brain thinkers to stop reading between the lines and making assumptions.

 

[lumberjacklloyd]

and is well into the bell curve of the 4.0

Define not in the power band. When I say not in the power band I mean if there’s an uphill section you can’t hold your speed without downshifting. In my experience (not group think) I have to have 2800+ rpm to hold speed.

I didn’t say 2500 rpm was lugging. Here I am again having to tell woman brain thinkers to stop reading between the lines and making assumptions.

Can't have a conversation without making insults? Weak

 

[JMT]

Can't have a conversation without making insults? Weak

You started it with the assumption of “group think” which implies “can’t think for self.”

Now you’re doing it again with “weak.”

 

[NashvilleTJ]

Can't have a conversation without making insults? Weak

That…is quite ironic.

 

[TJMexico]

Come on, folks. All I wanted to do here is discuss the best way to drive my Jeep on really bad roads without burning up the transmission or the engine. Be nice to one another. It really ain't that hard.