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Tranny stress from gears?

9

92jeeper

NAXJA Forum User
Location
Orlando
Alright guys, i got a question for ya'll. I have stock gears in my axles, Chrysler 8.25 in the rear and Dana 30 up front. I am running 35's. My question is, i towed a little pop up trailer from my house to my office, (7 minutes away at 45 mph) and, when i got to the office, i could smell the tranny hot. What can I do to fix that? I am adding a tranmision cooler this week, but, would regearing also help that? I do know it will help get my torque back up. The reason I ask is, i will be towing a single slot trailer for my street bike and, want to make sure I can tow it without frying my tranny. So, any help is greatly appreciated.

Tylor
 
Tranny cooler for certain. Yes, gears will also help. Like ... at least 4.56, which I think is as far as you can go with an 8.25 axle, otherwise for 35s I'd say go with 4.88 gears.
 
It's my DD so, 4.88's are out of the question, cause, it'll spend some time on the highway, with the trailer on it. So, 4.56's are the ticket for me. I'm gonna go ahead and throw lockers on the beast while it's apart. hehe. So, tranny cooler, gears, and lockers are in stall for this or next month. Thank you sir for your insight. ***grasshopper bows***


Tylor
 
You know, it is okay for your Jeep to run in th 2500-3000 range on the highway and around town.

You'll regret it if you dont go low enough on your gearing.

Fergie
 
Not if you wanna keep decent gas mileage. It's a DD and play toy in FL. It's no rock buggy so, i don't think i need the 4.88's. 4.56's should be plenty for me. Especially if I add the locker! It's gonna be like a new rig! Either way, i'm expecting both sides to come out on which gearing to chose. I plan on driving 45 minutes either way to the beach and 2 hours down south to where i'm gonna be moving to. So, i don't want to run the rpm's that high. But, if i am to switch it to just a toy and mud truck i'll regear lower, but, 4.56's are the gear of choice for my application.

Tylor
 
Your reasoning behind not wanting high RPMs is bogus.

The engine was designed to run in its powerband. It doesnt have feeling, so use it like it is supposed to be used.

Decent gas mileage? You're talking about decent gas mileage with 35s and stock gears!

And you are right, both sides will come out, but only one side is correct, the other side "works".

Do what ya want.

Fergie
 
Hey dude, Fergie is right. Do a little search around and you will find a thread that has been beat to death about what is the best gear combo. You said that you have an auto tranny right? From what I remember, 4.88 was the ratio of choice for a 4.0 motor, auto trans and 33's... yeah I said 33's. I personally run 33's, auto tanny and 4.88's locked front and rear. I am maybe pushing 2500 rpm's at 75 in O/D, and if it wasn't for my roof rack, swampers and carrying a lot of crap around, my mileage would be decent, but it aint that bad. I know I am relatively new to posting here, but I searched for a while before I bought gears, so trust me, you will find a buttload of info on this if you just look. Oh yeah, mine is a DD too.

Matt
 
Yeah, if you can do 4.88's (might not be able to with the 8.25", which makes this whole thing moot), go that route with 35's. I'm running 4.56's and 35's and wish I had 4.88's. I put aboot 45-50 [highway] miles a day on my rig. Going with 4.88's over 4.56's should be good for 250-500 more rpm on the highway, which would get my power up a bit.

You'd definitely want the lower gears for towing too. Here's what I used to tow with my rig, and back then I was *really* wishing I'd had 4.88's...

DSC01742.jpg


Anyway, 4.56's will be fine with 35's, but 4.88's will be better. ;)
 
92jeeper said:
Not if you wanna keep decent gas mileage. It's a DD and play toy in FL. It's no rock buggy so, i don't think i need the 4.88's. 4.56's should be plenty for me. Especially if I add the locker! It's gonna be like a new rig! Either way, i'm expecting both sides to come out on which gearing to chose. I plan on driving 45 minutes either way to the beach and 2 hours down south to where i'm gonna be moving to. So, i don't want to run the rpm's that high. But, if i am to switch it to just a toy and mud truck i'll regear lower, but, 4.56's are the gear of choice for my application.

Tylor
Click to expand...
4.56 is the gear of choice because that's as far as you can go with the 8.25 axle, not because it's the best choice. With 35" tires, 4.88 would be the better choice if they were available, even for street use, and especially if you plan to tow. 35" tires with 4.88 gears works out to 2673 RPM at 75 MPH according to the calculator on Randy's Ring & Pinion web site. (Less RPM if you use 35" ... I assumed a tire diameter of 34.5"). That puts you right on the sweet spot for the torque curve of the engine.

With 4.56s you'll be at 2498 RPM at 75 MPH. At 60 MPH you'll only be turning 1998 RPM, which is equivalent to or slightly slower than stock gearing and stock tires with an automatic. That's in overdrive. Not terrible, but those tires have a lot of inertia.

Remember not to use overdrive when towing.
 
wow guys! Sorry! I didn't realize i posted I am on 35's! I am running 33's. I was wondering, "Why is everyone telling me about 35's?" Hehe. sorry, But, 4.88's wont go with a chrysler will they?, 4.56's with 33's and a chrysler 8.25 axle is what i'm gonna be runnin. Sorry for the confusion. So, does 4.56 sound better with 33's? Sorry again

tylor
 
Jeepin Jason said:
Yeah, if you can do 4.88's (might not be able to with the 8.25", which makes this whole thing moot), go that route with 35's. I'm running 4.56's and 35's and wish I had 4.88's. I put aboot 45-50 [highway] miles a day on my rig. Going with 4.88's over 4.56's should be good for 250-500 more rpm on the highway, which would get my power up a bit.

You'd definitely want the lower gears for towing too. Here's what I used to tow with my rig, and back then I was *really* wishing I'd had 4.88's...

DSC01742.jpg


Anyway, 4.56's will be fine with 35's, but 4.88's will be better. ;)
Click to expand...
Man, that black on red looks great! :laugh3:
 
Do what you want, but you should gear as low as you can with 33's or 35's. Since the lowest gear for a 8.25 is 4.56, go with that. If you had a hp30/44 combo then 4.88 gears. If you had 44's f/r then 5.13 or so. I'm going with 5.38/5.43 in my hp44/9" because that is the lowest U can go in the hp44 and I'm planning on running 37's or maybe 35" mtrs. With the overdrive, you can gear low to get power back. With a 33'+ tire, there is alot of forces at work to get your tires moving so you need to gear for it. I had 4.56 gears and 35's and wish I had lower, with my hp44/9" I'm getting those gears I always wanted. I'm also adding a klune v 4:1 to get the gearing I want for the trail too. :laugh3:
Troy
 
Big Red said:
I'm going with 5.38/5.43 ...and I'm planning on running 37's or maybe 35" mtrs. ... I'm also adding a klune v 4:1 to get the gearing I want for the trail too.
Troy
Click to expand...

I consider the Klune to be a complete and utter waste of time and money. first, you won't need more gearing with low diff gears and an auto tranny. second, even if you want more gearing (unlikely) all you would want is a 4:1, get a Teralow. third, you would likely kill a np231 with a 4.0 and 4:1 reduction in front of it. fourth, you would need new driveshafts, possibly a 2 piece up front.
 
Jason, pulling that camper didn't stress the tranny too much? Do you have the transmission cooler? Cause, like I said, I pulled a little pop up, much smaller than yours, and, after 7 minutes at 45mph, the tranny stunk.

Tylor
 
92jeeper said:
Jason, pulling that camper didn't stress the tranny too much? Do you have the transmission cooler? Cause, like I said, I pulled a little pop up, much smaller than yours, and, after 7 minutes at 45mph, the tranny stunk.

Tylor
Click to expand...

Nah, tranny was fine. It got "hot" at times, but nothing I really worried about. I've got a factory Mopar tranny cooler and B&M temp gauge.

Your biggest problem was towing with 33's and stock gears, that's why your tranny got stressed/hot. A tranny cooler could certainly help, but it's no substitute for having the right gears.
 
i'm installing the tranny cooler next week, and, gears are my next purchase. And, if I can get through to my connections, i'll try and get some lockers in too :laugh3:

Tylor
 
fyi even without pulling something it is gonna be pretty hard on your tranny with 33's and 3.55s.
 
92jeeper said:
It's my DD so, 4.88's are out of the question, cause, it'll spend some time on the highway, with the trailer on it. So, 4.56's are the ticket for me. I'm gonna go ahead and throw lockers on the beast while it's apart. hehe. So, tranny cooler, gears, and lockers are in stall for this or next month. Thank you sir for your insight. ***grasshopper bows***


Tylor
Click to expand...

With the 8.25 4.56 is the lowest you can go. However 4.88's would have been a better choice even with a DD I run 4.88's and 33's on my DD and am alot happier than 4.56's. Great for towing as well.
 
i have 33's and stock gearing now is this going to wear out my transmission within quicly. i plan on going to 4.88 or lower when i swap my axles out but i dont want to put money into the 30/35. How low can you gear a D60?
 
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