Do I need a transmission cooler?

brwalkersk8

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Jul 16, 2007
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I have a 01 Dodge Ram 4X4 with a six inch lift and big *** mud Tires. I am only towing about a 2700 lb boat. The truck didn't have a tow package so I just took it over to uhaul and had them put a hitch recieverch and trailer wiring on it with a ball and dropped hitch to keep the trailer level. I was reading that I might need other crap that a tow package would normally include (transmission cooler, oil cooler, better suspension, etc...) Now I am all worried that I am going to mess up my beloved truck towing the boat. We normally have to tow the boat about 3 hours to the lake and then 3 hours back home....I live in New Mexico....the state with the lowest water to land ratio in the nation. ..Should I be worried?
 

Silvertip

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Sep 22, 2003
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Re: Do I need a transmission cooler?

External transmission coolers are good insurance and depending on the weight of the boat and trailer, are not always needed. In your case however, you added big mud tires which lowers the effective gear ratio of the truck. Now don't confuse lower ratio with lower gear as they are opposite each other. A 3.5:1 rear end gear is a lower ratio than 4.10. A 4.10 however is typically referred to as a lower gear. That said, unless you also changed the axle gearing to compensate for the increased tire diameter, the trucks towing capacity has been reduced dramatically. Even at that, the truck should handle the load just fine but do not even think about towing in overdrive. Because of the changes you made to the truck I would suggest you add an external tranny cooler. An engine oil cooler is not required nor are any suspension changes.
 

JB

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Re: Do I need a transmission cooler?

Pretty much what Silvertip said, but I think you are on (or over) the edge of your truck's towing ability even with a tranny cooler.

You didn't say what size tires you are running. 31s greatly increase the torque stresses on your drivetrain and 36s are even worse.

You also don't say what ratios you are running in the axles. If they are less than 4.10 you are in trouble. If you are running 36" tires I suggest that you go to 4.44.
 

bjcsc

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Re: Do I need a transmission cooler?

In my experience, trucks can either be setup for towing or off-roading. Seldom will the same setup do both well. It might be time for you to choose which. Mud tires seriously decrease towing ability and safety, mostly due to the sidewalls...plus a 6" lift!...be careful!
 

tashasdaddy

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Re: Do I need a transmission cooler?

if it doesn't have a cooler, put one on. better safe.
 

Silvertip

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Re: Do I need a transmission cooler?

Since we don't know what engine this truck has, we should not suggest he is well over the towing limit. For all we know he has a modified V10 in which case he definitely NOT over the towing limit. He's towing 2700#, not 8000.
 

brwalkersk8

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Re: Do I need a transmission cooler?

Thanks for all the advice. I have no idea what my gear ratio is, or where to find it. I bought the truck like this and have done nothing to it. The truck doesn't tow real well or for that matter have a lot of pick up even when not towing so I doubt the gear ratio was ever changed from stock. The tires are 315/75/16 (approximately 35's). It has a V8. Ball park what would I pay to have the gear ratio changed? I talked to a guy yesterday who would put a heavy duty tranmission cooler on for $250. Does that sound about right? Below is a picture of my truck.
 

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CATransplant

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Re: Do I need a transmission cooler?

Hmm...you are losing some pulling power with those big tires. Let me ask you: Do you do a lot of off-roading in that truck? If not, you might want to consider returning to a more standard configuration if towing is going to be important to you.

It's just a thought. You'd gain more pulling power, and the truck would be more driveable on a daily basis. If, of course, you are doing a lot of off-roading, then my suggestion wouldn't make much sense.
 

gonefishie

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Re: Do I need a transmission cooler?

Are there lots of mud in New Mexico? :rolleyes:
 

klicknative

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Re: Do I need a transmission cooler?

I'd put a tranny cooler on it just because it's working harder pulling the big tires.
 

Silvertip

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Re: Do I need a transmission cooler?

You don't want to know what it costs to change axle ratios. You need to change the ring and pinion on both the front and rear axles. Parts and labor will eat a hole in your wallet faster than a hungry rat. Tell us what your "exact" engine rpm is at "exactly" 60 mph in "third gear" (not overdrive). Measure the tire diameter "exactly" and I'll calculate the axle ratio for you. Don't bother with that if the speedometer has not been recalibrated for the big tires.
 

brwalkersk8

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Re: Do I need a transmission cooler?

When I bought the truck it had what I thought were the biggest tires that would fit on it. Then I picked up a couple nails in two different side walls down at a horse ranch. As a result I had to get new tries and just got all four replaced. These new tires, (not the ones pictured) must be a slight bit bigger as they rub and the old ones never had. I really doubt that the speedo was ever recalculated. I can say that the truck isn't so bad that the trip is unbearable. It pulls the boat no problem. I can tell the boat is back there, but I can still get her going 75 uphill pretty easily. I definately feel like it works the truck harder than I should. It doesn't feel like a sports car, but it works. I just am worried that I am going to mess up the truck towing the boat. I will get a transmission cooler put in and just drive it till the tranny goes I guess and then replace it when it needs it and so on. Thanks for everyones help
 

jeeperman

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Re: Do I need a transmission cooler?

Those tires are about 34.5" diameter and your truck looks like it has a 4 inch lift not 6 inch.
Standard original equipment tire size for your truck was 245/75-16 at 30.5" diameter.
I don't think you have increased the tire diameter enough to warrant changing axle rings and pinions. It is now more sluggish than stock but your not drag racing.

If your at all mechanically inclined, add a tranny cooler. I think it has one already plumbed from the tranny to inside the radiator. Disconnect those lines from the rad and reconnect via extentions to an external trans cooler in front of the rad.
Do not just ad another external cooler in-line with the one inside the rad.
 

jeeperman

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Re: Do I need a transmission cooler?

If you have been pulling the boat and your temp gauge stays in the same spot as driving around without the boat, your okay.
If you bypass the trans cooler in the rad, you might actually run cooler.

Oh, and put in a tranny temp gauge too so you can monitor that.
 

brwalkersk8

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Re: Do I need a transmission cooler?

I talked to the guy at mty transmission place who said he won't put in a trans temp guage. He said they are all "cheesey" and not worth the trouble and that they would leak and they won't do it bc of liability. He said that if the tranny heat up there is already a problem. Damn I don't know what to do everyone seems to have a frickin different opinion. I think the best thing is to sell the truck and buy a stock 4x4 with a tow package. I want my cake (my truck) and to eat it too(my boat). I love my truck and don't want a new truck. F***
 
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klicknative

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Re: Do I need a transmission cooler?

I think the guage is nice to have but not life or death for your tranny. I would put the cooler on and be shure to change the fluid and filter every year or 12,000 miles. That pickup realy shouldn't have any problem pulling a 2700 lb boat. Hell, I've seen Toyotas pulling boats that big. Just take it easy with it and you'll be fine. BTW, nice looking pickup, and when you do get a new one, you'll have a better idea of what you want for pulling a boat ect.
 

jeeperman

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Re: Do I need a transmission cooler?

I talked to the guy at mty transmission place who said he won't put in a trans temp guage. He said they are all "cheesey" and not worth the trouble and that they would leak and they won't do it bc of liability. He said that if the tranny heat up there is already a problem. Damn I don't know what to do everyone seems to have a frickin different opinion. I think the best thing is to sell the truck and buy a stock 4x4 with a tow package. I want my cake (my truck) and to eat it too(my boat). I love my truck and don't want a new truck. F***


It won't leak if done right. You want one designed for transmission fluid and it is not like it is a 2000psi hydraulic line.
A temp gage will tell you when your working it too hard via increased temps.

Keep your truck. If you want to gain back the pulling power it had from factory, the cheapest way would be to buy a set of stock size wheels and tires. Keep an eye on the classifieds as you can pickup a set reasonable from someone that put aftermarket wheels and tires on their new truck.

I have even bought brand new o.e.m. alum. wheels with factory fresh tires from the dealer for less then aftermarket. There is always a customer buying a brand new vehicle that wants fancier wheels and bigger tires on it before taking delivery.
 

Sherminator

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Jul 8, 2007
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Re: Do I need a transmission cooler?

your truck will pull it fine, i had a 96 with a 318 and i put a hitch on that (no towing package) and it did just fine. i just didnt have the big tires like you do, id say you are safe. maybe just keep it in D and not OD.
 

thenotsofreeboat

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Apr 20, 2007
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Re: Do I need a transmission cooler?

I have a 1800 Lbs boat and tow it with a full size blazer with 4 inch lift and 33's it handles it fine, just don't put it in OD and watch the RPMS mine are up there at 65 MPH. Next tow mobile defiantly stock as boat is new habit.
 

aggiedave98

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Jul 14, 2003
Messages
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Re: Do I need a transmission cooler?

Put my vote in for the tranny cooler. You can buy one for about $50 at summit racing (or lots of other places). HEAT kills tranny's. Definitely do this. There's no downside. VERY easy to do yourself. I would recommend the guage. The point of it is that if the temp goes up you know it and can do something to cool it off. But towing 2700lbs and not using OD, you can get away w/o the gauge.

The problem w/ changing the gear ratio is that like somebody said, since it's 4wd, you have to do front and back...

good luck.
 
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