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Old 09-11-2010, 08:12 AM   #1
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Question Axle ratio???

My Jeep GC has an axle ratio of 3.55:1. I was checking out the manual last night (never opened it in 5 years!), and noted that for class III (GTW 5000 lbs max) the 'requirement' is an axle ratio of 3.73:1. When we purchased the vehicle, we weren't towing at the time so we did not get the towing package which would have included this axle ratio.

How big of a deal is this? It doesn't 'seem' much bigger but what do I know about axles and axle ratios. From what I can gather, it seems having a lower axle ratio would decrease the amount I can tow but it doesn't seem it would decrease by a significant amount.

What's the impact of having 3.55 instead of 3.73?

We mostly tow in the flat midwest (IL, WI, MI, etc.). At least, for now...

Thx,
Deena
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Old 09-11-2010, 08:27 AM   #2
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First, we need to clear up the semantics. A "lower" gear ratio is generally considered to be a higher numeric number - the 3.73 is a lower gear than the 3.55. A "taller" gear ratio is a lower number numerically. Don't know if you ever had a 21 speed bike, but think of the rear sprocket as your transmission with 5 speeds or whatever and the front sprocket as the "rear gear" - except you dont get to change it on the GC like you do on the bike. The bigger sprocket is harder to pedal - the 3.55 is a bigger sprocket than a 3.73 is.

If you don't have the towing package, you probably don't want to tow a TT, regardless of the gear ratio (you probably don't have trans oil cooler, heavy duty alternator, etc.).

The lower gearing will make it much easier on your transmission while towing - the engine power is not the issue here. I am towing with 3.31 gears in an F150 (8,100# tow limit - I am pulling about 4k) with no problems at all.

I am sure most here will tell you to stick with the mfg. reccomendations, I don't think I would tow a TT (maybe a pop up) without the tow package.
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Old 09-11-2010, 08:51 AM   #3
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Thanks for the explanation about the axle ratios! Makes sense now...

The tow package for Jeep GC included trans oil cooler, the 3.73 axle ratio, a receiver and plug adapter. The only thing I'm missing is the 3.73 axle ratio. We added the trans cooler, receiver and wiring...

I've read elsewhere that axle ratios below about 3.3 should consider limited towing and that 3.5 to 4 is adequate. Opinions?

I can have the vehicle re-geared, just wasn't sure it was worth it given the size of our TT.

Thanks!
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Old 09-11-2010, 09:53 AM   #4
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Deena, We have a 2005 Jeep Liberty with the tow package, it is rated for 5000lbs. I only tow a 20' bass boat with ours but at 3700lbs it is about the same weight if not more than the Jeep. I have to tell you I don't like the way it tows. Luckily we don't have to use the Jeep to tow very far usually only to launch when we are out camping. I intend on getting something like an F150 next year so we can tow longer distances if need be.

I have never liked Jeeps of any sort for towing. They just aren't a good stable platform for it, usually being short wheelbase and narrow which doesn't give a good stance for it. Also, SUVs always come from the factory with soft suspensions and "car" tires that are meant for a smooth ride but aren't well suited for towing.

Regearing your Jeep would likely run around $900 per axle for new gearsets and installation. I would recomend finding a good used F150 instead of, as we say in the Jeep world, "throwing good money after bad".

As others have stated you would be fine with a small pop up but for larger trailers I wouldn't be using your GC for it.
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Old 09-11-2010, 10:20 AM   #5
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Axle ratio has everything to do with performance and little to do with towing capacity. Your 3.55 rear ended Jeep will pull the same load, just not be very happy doing it. While not an ideal gear ratio for towing, a small tent trailer or Aliner would be fine. Just keep a close eye on your actual weights and do not try to overload it.
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Old 09-11-2010, 10:35 AM   #6
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Well, we towed the TT last weekend, short trip, about 2.5 hours and it seemed to do okay. Didn't have any overheating issues, in fact I was surprised because the temp was the same as it runs without the TT attached. We're taking the TT to get weighed today, it still falls within the allowable limit for the TV but of it sounds like another TV would be ideal. We'll probably use is 1-2 more times this year before putting it in storage until the spring and don't really plan on any long trips. It's mostly flat land out here.

My husband is getting rid of his car next year so we'll probably pick up something a little more suitable rather than regearing the GC. Suggestions? We need seating for 4 and an area in the back for the dog. Envoy maybe? Should I always be going for an 8-cyl? What else do we look for?
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Old 09-11-2010, 10:47 AM   #7
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We need to know the GVWR of your travel trailer to be able to give you any meaningful answer, other than get an F-350 with a Diesel You are in a good position as you already have your travel trailer and need to choose a suitable tow vehicle. If you give us the GVWR of the TT (Not the UVW, it is always safe to assume that you will be at or close to the GVWR as weight accumulates over time in a TT) and the number of people which will travel in the TV, then I am sure members will start giving you recommendations. if you could also include the length of your TT, even better the make and model of it, it will help everyone to come up with suggestions.


I am guessing that you prefer a capable SUV to a pickup truck ? And I will risk saying, no 6 cylinders please .....
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Old 09-11-2010, 11:14 AM   #8
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The trailer GVWR is 4800 lbs. and it's 18' in length. It's a 2010 Dutchmen Sport 716fd.

4 people (2 adults, 2 kids), 1 dog in the TV.

Would definitely prefer a capable SUV rather than a pickup, we can confine the dog in the back.
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Old 09-11-2010, 12:29 PM   #9
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The trailer GVWR is 4800 lbs. and it's 18' in length. It's a 2010 Dutchmen Sport 716fd.

4 people (2 adults, 2 kids), 1 dog in the TV.

Would definitely prefer a capable SUV rather than a pickup, we can confine the dog in the back.
Sounds like a Chevy Suburban or GMC Yukon (same vehicle) 1500 would fit the bill for what you currently have. However, might I suggest you would be happier with the 2500 series (3/4 ton chassis). If you decide you want a larger camper at a later date you would be good to go without buying another tow vehicle.
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Old 09-11-2010, 12:32 PM   #10
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X2 what Herk said. RVs are a strange thing, I can almost guarantee you will be upsizing in the furture (as most of us have ) so plan ahead and go bigger on the TV right now.
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Old 09-11-2010, 01:27 PM   #11
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a Tahoe will return near the same fuel econom as ann Envoy and be far better as a tow vehicle.
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Old 09-11-2010, 04:07 PM   #12
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Well, we towed the TT last weekend, short trip, about 2.5 hours and it seemed to do okay. Didn't have any overheating issues, in fact I was surprised because the temp was the same as it runs without the TT attached.
Should I always be going for an 8-cyl? What else do we look for?
when you talk about temp, are you talking about the engine temp or the tranny temp? you didn't say if a tranny temp gauge was installed with the trans cooler.
if you are talking about the dash temp gauge, that's not the tranny's temp. that's the engine's oil temp.
the tranny could be waaayyy hotter while pulling.
if you don't have the tranny temp gauge, you need to get one if you continue to pull with that Jeep.

and yes, i'd look at one of the newer generation v-8. my v-8 Avalanche gets about the same gas mileage as v-6 trucks. the newer GM and Dodge v-8 engines have a v-4 feature that allows them to get highway mpg of 20 or better.
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Old 09-11-2010, 05:24 PM   #13
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Be careful factory gauges can be misleading. Even though you have a "real looking" gauge, they can still be nothing more than an idiot light and not be truly proportional as you might think. This is the case with many of the Ford products believe it or not.

Tire size will change the effective gear ratio as well. Going to a taller tire is like going to a steeper gear.
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Old 09-12-2010, 09:51 PM   #14
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We have a jeep with 4:56 gears in it. pulling is not a problem for a boat or pop up off road. But highway I think about the tail wagging the dog. That short wheel base can get you back to off road where you want to or not!
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Old 09-12-2010, 10:09 PM   #15
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You got very good advice on above posts, You WILL be upgrading if you are like any of us A 2500 based Suburban/Yukon or an excursion will serve you well.

One word of caution, we are not responsible for the gas mileage you will be getting

After the last upgrade, befor every trip I carefully calculate how much the fuel will cost to get there and to return, and then decide if I can afford to make the trip.
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Old 09-12-2010, 11:07 PM   #16
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the newer GM and Dodge v-8 engines have a v-4 feature that allows them to get highway mpg of 20 or better.
I don't have any experience w/ the "displacement on demand" engines, but would it be safe to say the engine only reverts to the V4 mode when the load on it is light?
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Old 09-13-2010, 12:27 AM   #17
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A little off topic but I can tell you for a fact that the gauges on my F150 are "managed". I have a ScanGaugeII so I know this is true. They are, in fact, mostly just another form of idiot light. Apparently they got too much consumer concern from people who don't understand their oil pressure is lower at idle than on the highway!! So now we get dumbed down "gauges".
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Old 09-13-2010, 09:36 AM   #18
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There is alot to look at with gear ratios. They also determine the max tow weight of the vehicle. For example an 08 Ram 2500 Hemi Megacab with 4:10 gears has a max trailer weight of 10,400 and the same truck with 3:73's is 8,400. It is not that the truck is any less capable, it is what the manufacturer deems a safe margin for stuff like the tranny as less gear equals more work for the tranny. And get in an accident with a vehicle that has a trailer that has exceeded the ratings for the TV and you may be in a whole other kettle of fish as to insurance coverage etc.
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Old 09-13-2010, 10:10 AM   #19
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I had a rental Sierra with the 4/8 cylinder management feature for two weeks. The moment I touched the gas pedal to accelerate with nothing in tow, no passengers, it immediately switched to 8 cylinder mode. I am usually very light on the gas pedal and experimented a lot to make it stay in 4 cyl mode, but it would just switch to 8 cyl mode the moment I touched the gas pedal. The only times it reported 4 cyl mode was if I was going downhill with my foot off the gas pedal, or coasting to a stop light again with my foot off the gas pedal. Other than that it was always in 8 cylinder mode. I would not count on that feature much to save gas, just my opinion based on the truck I drove.

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I don't have any experience w/ the "displacement on demand" engines, but would it be safe to say the engine only reverts to the V4 mode when the load on it is light?
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Old 09-13-2010, 10:20 AM   #20
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Wow, thanks everyone for all of the advice!

Now you have just added more fuel to the fire, as my husband has been wanting to replace his 'regular' car with something much larger for some time now. I was originally going to get rid of the GC, and replace it. But now he wants to keep the GC and replace HIS car! :-) Oh, and now he wants to make sure it's 'something we can grow with'. What does that mean? I tell you what it means - he KNOWS he is going to want a larger trailer. hahahha, everyone was right!

Our intent was actually to wait until next year and get a truck and trailer at the same time. When we went to the RV dealer we just wanted to look around to get an idea of the features we wanted for next year. We didn't want to buy anything. However, the deal we got on this 2010 closeout was just too good to pass up, it had everything we wanted (including being 'small', that was one of my requirements) so we bought it... figured we wouldn't really use it much until next year anyway since it's probably going to be snowing in a few weeks (I just jinxed everyone in the Chicago area btw - sorry!).

So we are looking at a Suburban or Yukon. I think his preference would be a truck (meaning, an open bed the back) and then we would get a cap for the bed for the dog. But for right now the priority is finding an adequate storage location for the winter.

Is it ok to store it outside? Will it get damaged at all, the winters are pretty harsh here.

Deena
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