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Post by defender on Apr 24, 2013 19:55:43 GMT -4
I am wondering something... I realize there's more to towing than raw power, but I can't figure this one out. My friend has a '99 Grand Cherokee with a 4.0L inline 6cyl, putting out (according to Edmunds.com) 195hp and a 105.9" wheelbase and has a towing capacity of 6500lbs. My JKU has the 3.73 rear end (the one that comes with the Max Tow package), the 3.6L puts out 285hp and it has a 111" wheelbase, and yet the JKU is only rated for 3500lbs towing. On paper it seems like the JKU should have the same or more towing capacity over the Grand, or at least more than 3500lbs. What am I missing? Def
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Creepy
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Post by Creepy on Apr 25, 2013 11:52:14 GMT -4
285hp? That can't be correct. maybe at 6000rpm, just before it explodes.
Look at the torque curves for the two engines. Hp doesn't mean a whole lot for towing, if its all top end.
Does seem a huge difference tho, first time I've seen the #'s side by side. You have a good question.....?
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kilo69
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Post by kilo69 on Apr 25, 2013 12:03:24 GMT -4
My curb weight is wrong as the JKU is more. not sure why the 3500lbs towing.
So here's my 2nd opinion
Only 205hp though at 5200rpm
torque is 240 @ 4000 rpm
the 4.0L torque is 230 @ 2400 rpm HP 195 @ 4600 rpm
4.0L is a much better towing engine! (I think a better engine overall lol)
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Creepy
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Post by Creepy on Apr 25, 2013 12:08:55 GMT -4
the JKU weighs 1994lbs and has 285hp? Wow, its a rocket!
These #'s can't be right. A super light buggy is 2000lbs, most of the local ones are 3000+.
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kilo69
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Post by kilo69 on Apr 25, 2013 12:11:24 GMT -4
Yeah it was 1994kgs.. so the JK weighs more...
but engine wise see above revised comments
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Grizzly
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Post by Grizzly on Apr 25, 2013 12:18:07 GMT -4
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kilo69
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Post by kilo69 on Apr 25, 2013 13:54:42 GMT -4
Hmm I haven't been watching the JK's enough... did not know about the engine change!
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Creepy
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Post by Creepy on Apr 25, 2013 14:13:01 GMT -4
oops, I was thinking the older motor too. 3.8, 3.6......got it.
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eastcoastcam
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Post by eastcoastcam on Apr 25, 2013 15:20:53 GMT -4
OP has a 2013, with the 3.6 pentastar
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jmurphy
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Post by jmurphy on Apr 25, 2013 19:03:44 GMT -4
Towing capacity depends on a lot of factors. Engine, brakes, weight etc but also the ability of the frame to carry the stress load where the hitch assembly is mounted. Could be a calculated choice from the manufacturer that the target market won't need the higher towing capacity, so the frame can be that much lighter in some areas. Lighter should equal cheaper to manufacturer and (at least slightly) better fuel economy.
Just some thoughts. IMO the original post is not a dumb question at all.
Jonathan
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Creepy
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Post by Creepy on Apr 25, 2013 19:42:29 GMT -4
Towing capacity depends on a lot of factors. Engine, brakes, weight etc but also the ability of the frame to carry the stress load where the hitch assembly is mounted. Could be a calculated choice from the manufacturer that the target market won't need the higher towing capacity, so the frame can be that much lighter in some areas. Lighter should equal cheaper to manufacturer and (at least slightly) better fuel economy. Just some thoughts. IMO the original post is not a dumb question at all. Jonathan Nope, not dumb question! And on top of that, the Grand is unibody, JK got a nice big frame.
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Post by defender on Apr 25, 2013 20:14:17 GMT -4
According to Jeep.ca, the 3.6L Pentastar spits out 285hp. www.jeep.ca/en/wrangler/capabilityEastcoastcam is right, I have a 2013 Sahara Unlimited with the 3:73 rear end- the one that comes as part of the Max Tow package, although I got the rear end as a $100 option and will put a $200-250 Class II hitch on it myself rather than spend the $500 for Chrysler to have done it. So, while some of the posts above shed some light on why, I'm not convinced there's an answer in there. The frame seems to be a major part of the issue, but I can't help but think that a JKU frame is better (stronger) than the unibody on the Grand. Also, the curb weight on my old TJ was around 3700lbs, while my JKU is around 4200lbs. That's only 500lbs worth of a difference. I do see a difference in the 3.6L vs my old 4L though. The 4L in my old TJ rarely ever redlined while the Pentastar seems to like sitting at the high end of the tach. This really does bug me- no offense to my buddy's old Grand, but in every way my JKU has it beat, so I have to wonder why I have the lesser towing capacity. I have more power, stronger frame, bigger tires with more road contact, heavier brakes, longer wheelbase.... What am I missing? Def
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Post by bacon on Apr 26, 2013 7:15:50 GMT -4
there's always a number of factors in determining tow ratings. the engine is but one of them. One seriously weak factor for the JK is the way the hitch is attached to the rear cross member. on a ZJ, the hitch resembled something you would find on a full frame vehicle. attaching to the "framerails" of the Jeep. much more weight distribution. on a JK, the hitch is a ridiculously small unit which attaches to the center of the rear crossmember, spreading the load across about 8" of the cross member. not exactly the set up you would want to haul heavy loads.
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Big Willy
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Post by Big Willy on Apr 26, 2013 8:02:47 GMT -4
And on top of that, the Grand is unibody, JK got a nice big frame. I'm a little confused about the JK being a body on frame vehicle. Some info I read in JP Magazine (Nov 2012 issue) sounds like it could be a hybrid of sorts? Not sure really but between this article and a pic I have seen of the body stripped down it "looked" like it was a uni-body? www.jpmagazine.com/featuredvehicles/154_1211_last_real_jeep/#ixzz2RZJRtXfXLast Real Jeep How-to: TJ Wrangler From the November, 2012 issue of Jp By Pete Trasborg Photography by Pete Trasborg
Before you JK owners get your panties in a wad, we’ll explain the title. When the TJ Wrangler hit showrooms in 1996, it was the last new Jeep we’d ever see. Since 1941 Jeeps had a one-piece tub that was plunked down on the frame in the factory. Bolted to that tub was a pair of fenders, a hood, a grille, and a fold-down windshield with hinges. The JK’s body is largely built on the assembly line like a car and no longer features easily removable front fenders. Instead, the front fenders are part of the body structure.
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Post by SocialWheeler on Apr 26, 2013 8:07:51 GMT -4
JK fenders are made of popcan metal and are not part of the body structure. They bolt to the tub.
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