SavageSunJeep
Adventurer
Lawrence said:
Since it is an auto I am thinking ??? that with the 4:88's and 33's you might be geared too low??? Possible "walking" between 1st and 2nd gear a lot??
What is your transfer case ratio in low?
Building an Expedition TJ, give me your opinions
- Thread starter Lawrence
- Start date
Since it is an auto I am thinking ??? that with the 4:88's and 33's you might be geared too low??? Possible "walking" between 1st and 2nd gear a lot??
What is your transfer case ratio in low?
SavageSunJeep
Adventurer
I think it is 2.73:1 in low range as I remember unless you have a Rubicon or Rubicon transfer case swapped in, then it is 4:1Lawrence said:
I have a discussion on my web site on the Rock Crawling Index. You might wish to read it to gain additional insight into crawl ratios.
http://www.savagesun4x4.com/rock_crawling_index_rci_dis.html
86cj
Explorer
Lawrence said:
I looked at your link to the jeepbbs Lawrence,
I have been thinking this over every time I turn the OD off and set the cruise at 2750 RPM. I run the stock 3:73 (for now) and 4spd Auto with 33" 285's.
My question to you guys is under real world loads at freeway speeds, can the trans hold the OD gear except on real steep grades when regeared?
Right now even a bridge overpass in Ohio or wind gust will cause a downshift from 4th into 2nd. My worry is if I can't pull OD gear with 4:56 or 4:88 the cruising RPM in 3rd will be 3500+ and force me into the slow lane to often.
The LJ will pull most Mtns in 3rd gear but with alot of throttle input so it works OK for now. I just don't use OD really at all, but do get 15MPG at 70 MPH.
86cj said:
First of all, the constant downshift you are experiencing is from running the 33s with 3.73s, any gear swap will help with this. Then, it depends how many mods you have to your Jeep. 4.56 gears with the 4-speed auto and 33s will put you back to stock, or thereabout. If your Jeep doesn't have too many mods (ie. not too overweight), it is fine for the most part. A lot of friends of mine are running this combo and they love it.
I have been running this same combo but with 35s (4.88 and 4-speed auto) and although I have been fairly happy with it, putting the 33s on last weekend was a real eye opener. With the 35s, the Jeep cruises very nicely, and it is almost able to hold the OD on steep grades when alone and no load. At 75 mph with the OD on, I turn about 2,300 rpms, and although it is acceptable, I personally like it closer to 2,500 as I think the Jeep runs better. Loaded with 3 people and my military trailer, I have to kick the OD off on some of the nasty grades we have here in SoCal to keep up with friends. I have taken the jeep to about 75 mph with the OD off and the rpms are still great IMO, turning around 3,250. Not once was I close to 3,500.
Now, with the 33s and the same 4.88 gear ratio, it was a different ballgame. The Jeep was much quicker and the freeway rpms with the OD on were outstanding. It gave me more power to compensate for the added weight of all the mods, and the rotational mass of those big tires. In grades where I usually turn the OD off to hold my speed, I didn’t have to with the 33s, it kept its speed nicely. So, when going on a day run with the family without the trailer, I believe it will be a great combo.
Now, when pulling the KK it will be a different story. I am able to pull it in OD for the most part, but obviously, on grades I will have to kick the OD off and that’s when the rpms jump a bit with this combo. On the other hand, anytime you have a trailer in Cali, you have to ride the 2 right lanes and go 55 mph. I also don’t want to put my family at risk, so I will be conservative. Even if I decide to cheat a little and run 60 mph with the OD off, I am looking at around 3,000 rpms, which is perfectly acceptable.
To answer your question, if you don't need all the power and you are concerned about gas mileage, I'd say go with 4.56 gears if you plan on keeping the 33s. It is a very good combo for most people. If you have a heavy vehicle and plan on towing frequently, I would go with the 4.88s. Just my opinion and I am sure others will have different views on this.
ntsqd
Heretic Car Camper
With an Auto I would suggest that a trans temp gauge be added to the mix, if not already present.
You can find on the net an argument to support any where you want to mount the temp sender. BowTie Over Drives dot com wants it in the pan of their trans', so that's where mine is placed.
You can find on the net an argument to support any where you want to mount the temp sender. BowTie Over Drives dot com wants it in the pan of their trans', so that's where mine is placed.
86cj
Explorer
Thanks for the input so quick. I was looking for a subjective opinion and you provided just that, thanks again.
The weight of your rig is a good gauge for me, you are heavier with the trailer and lighter without and also have a similar "Windprint".
My worry has more to do with the way the trans behaves than the math involved.
I feel like the 4:88 is for me, the LJ loaded is heavy. I don't mind slowing down for mountains, I just need to run 70-75 MPH regularly (the Jeep is very stable on the Hwy). If small grades or light wind make me turn the OD off it will take all my vacation time just to get out West.
I really don't mind turning the big RPM's at times, I just can't bear to set the criuse like that for the 500+ mile days we see when on the road.
(BTW it takes 3 of those days to reach Moab)
The weight of your rig is a good gauge for me, you are heavier with the trailer and lighter without and also have a similar "Windprint".
My worry has more to do with the way the trans behaves than the math involved.
I feel like the 4:88 is for me, the LJ loaded is heavy. I don't mind slowing down for mountains, I just need to run 70-75 MPH regularly (the Jeep is very stable on the Hwy). If small grades or light wind make me turn the OD off it will take all my vacation time just to get out West.
I really don't mind turning the big RPM's at times, I just can't bear to set the criuse like that for the 500+ mile days we see when on the road.
(BTW it takes 3 of those days to reach Moab)
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roadkill
Adventurer
there is a big thread over on ROF about gear selection (4.88 vs 5.13) and the auto tranny. the consensus has been that if you have the auto then 5.13s are the way to go with either 33s or 35s.
now for some first hand info. I regeared my 2006 auto Rubi Unlimited with 5.13s and I'm running 33s. I am armored up so I am not light at all. at 70 I'm pulling @ 2500 rpms if I remember correctly. its not my dd and around town I rarely hit 70. I pulled my M416 to the ranch a few weeks ago and had it loaded with a 150 quart ice chest, drinks, ice, food, and fishing poles, etc. along with the wife and son in the jeep. I have no idea of my total weight but I was not light. I had no problem cruising @ 65 but with the cruise. on a few larger hills the OD did kick out a few times. it wasn't that bad but I would have prefered it to stay in OD and keep on going. now with the cruise off I was able to keep it from downshifting but at the cost of 5-10 mph on the hills.
around town without a trailer in tow I have a lot more pep and the jeep never downshifts on overpasses or hills. if I had to do it over again I would still go with 5.13s. if I could get a deeper gear I would, that OD ratio in the 4 spd auto just plain sucks. I wish there was a way to convert the OD from the .68 or .69 (whichever one it is) to a .78 or .82, something a lot more reasonable and workable
if I had 35s I think the jeep would perform similiar to stock gears(4.10s) and 33s. its not that bad but performance is definately lacking in OD and at highway speeds
now for some first hand info. I regeared my 2006 auto Rubi Unlimited with 5.13s and I'm running 33s. I am armored up so I am not light at all. at 70 I'm pulling @ 2500 rpms if I remember correctly. its not my dd and around town I rarely hit 70. I pulled my M416 to the ranch a few weeks ago and had it loaded with a 150 quart ice chest, drinks, ice, food, and fishing poles, etc. along with the wife and son in the jeep. I have no idea of my total weight but I was not light. I had no problem cruising @ 65 but with the cruise. on a few larger hills the OD did kick out a few times. it wasn't that bad but I would have prefered it to stay in OD and keep on going. now with the cruise off I was able to keep it from downshifting but at the cost of 5-10 mph on the hills.
around town without a trailer in tow I have a lot more pep and the jeep never downshifts on overpasses or hills. if I had to do it over again I would still go with 5.13s. if I could get a deeper gear I would, that OD ratio in the 4 spd auto just plain sucks. I wish there was a way to convert the OD from the .68 or .69 (whichever one it is) to a .78 or .82, something a lot more reasonable and workable
if I had 35s I think the jeep would perform similiar to stock gears(4.10s) and 33s. its not that bad but performance is definately lacking in OD and at highway speeds
roadkill said:
I didn't read all 8 pages of the mumbo jumbo, but it seemed to me they all pretty much agreed that 5.13+35+4-speed auto was the way to go. I think so too, and it would be the same as 4.88+33+4-speed auto.
I am sure your 5.13+33 combo is fine, but I wonder if the you are sure about your rpms at 70 mph? 2,500 seems to be in line with what I had with the 33s and I would think they'd be a bit higher given your gear ratio. The only thing that would concern me with 5.13+33 would be high rpms with the OD off.
robert j. yates
Explorer
Running the 32RH 3 speed auto with 35's and 4:56 gears means I am constantly running in the low 3k range on my tach on the highway. The 4.0 is perfectly fine with running in that range from my experience of almost 10 years with my Jeep. I've done plenty of 300-500 miles/day trips and its simply not been an issue.
If that sounds like BS then I suggest that folks look to what the TJ sports used to run with the 3 speed, 30's and 3:73's...what they would find is that they were running in the same low 3k range stock from the factory so worrying about pulling 3000-3500 up a hill with your OD off is simply worrying about nothing in my experience.
Now would I like an OD transmission....sure, but thats a different discussion.
If that sounds like BS then I suggest that folks look to what the TJ sports used to run with the 3 speed, 30's and 3:73's...what they would find is that they were running in the same low 3k range stock from the factory so worrying about pulling 3000-3500 up a hill with your OD off is simply worrying about nothing in my experience.
Now would I like an OD transmission....sure, but thats a different discussion.
SavageSunJeep
Adventurer
robert j. yates said:
Glad you weighed in Robert. I knew you were running an auto and pulling a serious trailer too. :REOutArchery02:
Have you heard from Jason at Airpark Jeep here in Scottsdale? Ref your big rig requirements?
Speaking of BIG RIGS. Wife bought her bosses Caddy Escalade last week. Big engine of some kind, w/Supercharger, chipped, Volant cold air box, Borla headers and exhaust, etc etc, 22 in wheels...JEEZ. Her boss got it as a present from her hubby who is into fast movers...Aston Martin, Bentley, twin-turbo Porsche Ferrari, hopped up V8 Jeep etc...He has a "stable" of cars and they drive all of them.