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rear end


easywind's Avatar
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10-04-03, 09:53 PM   #1  
rear end

85 Dodge B 150 van, 318, 3 speed auto. I just found a 3,400 pound caming trailer I would like to pull down to Mexico. I am going to replace the engine. I have a 294 rear and have found that a 390 ring and pinion will fit. The question is am I better off replacing the whole rear with something that has the 390 gears or just change the ring and pinion. I will most probably put new brakes, hardware and bearings in either one.
Yes Joe I know it not worth it to you.

 
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bejay's Avatar
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10-04-03, 11:21 PM   #2  
I suppose it would not matter either way but if its something you are going to be doing yourself it would likely be easier to just throw another rear end under it, a different ring and pinion is easy enough to install but if not set just right will make noise which is why installing another rear end can be easier atleast time wise.
you should also consider a different gear ratio something inbetween what you have now and a 3.90 as it will still pull loads easier but also not just get terrible gas mileage, and save some wear and tear on the engine from not turning as many rpm at highway speed.

 
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10-05-03, 01:45 AM   #3  
I agree, a 294 is too tall of a ratio for that use, but a 390 is probably going to be too low of a gear. Look for something inbetween. Swapping the whole thing would be much better, unless you have the knowledge and measuring tools to set up a rear end. There is a good bit of precise work to make these changes properly, and if they aren't done precisely you will have wear and premature failure. I don't know what gear ratios are common to chryslers, but I think I would want something in the 330 to 370 range.


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10-05-03, 03:51 AM   #4  
swap

I would swap lots more easy I would go with something like a 3:73 ratio.getting into the pumkin is somethig for a real pro with proper calipers and dial guages.

 
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10-05-03, 08:10 AM   #5  
Joe_F
With gas 2 bones a gallon in most states, this will be an expensive idea.....I have to think you're getting 15 at best with the stock setup. I would say a 3.90 would net you single digit fuel mileage.

Leave it stock and it should be fine. No need to mess with success .

My .02. I can tell you that the 3.23 in my 79 Trans Am is about as tall as you can get with A/C which would be another consideration if you are going to swap. Many A/C systems don't like high numbered ratios like that.

 
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10-05-03, 11:21 PM   #6  
You know, a lot depends on the transmission. If you have overdrive, a 390 might be alright, but if not, it will be terribly low. Especially without a lockup converter. I know you can run a 308 or lower ratio rearend behind a 700r4 GM, but if you run a 273, you won't hit overdrive until you are already speeding. It also depends on tire size. You can go to a smaller diameter tire and get a lower ratio. Taller tire for higher ratio. I never had problems with an AC system running 308 and 273 ratio rear ends.


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10-06-03, 06:52 AM   #7  
I have A/C in the van and the system is totally rebuilt. I'm not real concerned with gas mileage as I put on only 6/7,000 miles a year. What I want to be able to do is tow. Tranny is three speed. Gas mileage at the moment is 11 mpg as the camper van weighs 6,080 pounds with wife and myself. Chrysler has a 355 gear ratio which I will be looking into. I am also going to change the whole rear end as I thought that would be easier. Thanks

 
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10-06-03, 06:55 AM   #8  
Joe_F
Definitely easier to swap the whole carrier as there are specialized tools required to swap the internals in most cases.

 
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10-06-03, 06:12 PM   #9  
mike from nj
easywind, i think your overlooking something here.

a b150 van with a 318, a 2.94 rear and a three speed, in a 6000 pound van!! that's a lot already. now you want to tow another 3400 lbs!!!!

with fuel and luggage, your close to 10,000 lbs. most heavy duty pick-up trucks would struggle with that on flat land, never mind a 5% hill, you'd be lucky to crest it with the trans in first gear. i'd be surprised if it didn't overheat the engine, trans and rear.


our commuter van fleet used to have 3.55 rears (with a 360) when equipped with a 3 speed and 3.91 with an overdrive trans( 4 speed) these are 15 passenger extended wheelbase vans.

figure 4-5000lbs curb weight, plus 15X200(average)lbs. each person =3000. that's 8000lbs in a b350 or 3500 series heavy duty van with a spicer/dana-60 rear.

i think you may be slightly overloaded with your set-up with any gear selection.


my 2 cents

 
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10-07-03, 09:25 AM   #10  
Mike, thanks for the reasoned reply, thanks everyone else. This setup is basically for a one time tow. I intend to pull the trailer down to Mexico and leave it there year round. I also intend to take the flattest route going down there. If I go with the 390 rear a new motor, rebuilt trans and fully serviced cooling system do you thing I'd be able to do this on a one time basis?

 
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10-07-03, 09:32 AM   #11  
Joe_F
For the one time? Probably.

Would I personally take the chance? No way. I wouldn't be putting 10,000 lbs in a B150 with "Light duty" brakes (compared to other models which have better brakes).

 
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10-07-03, 11:30 PM   #12  
mike from nj
for a one time tow----it might be cheaper to hire a flatbed that can haul your van on top and tow the trailer in back. then you could just sleep in the van most of the way, if the driver would let you.

 
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10-09-03, 07:03 AM   #13  
Thanks Mike I think I've gone as far as I can with the van. I'm going to try to hire someone to pull the trailer down for me.

 
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