Differential change

[1shemp]

The van was struggling a little pulling the new camper up some hills.I'm having the gears changed from 3.73 to 4.30.Probably cost me some gas mileage.

 

[bullfrog]

How did you come up with what to use? What series van is it? Were you running oversized tires? Did you lock out overdrive? Did you weigh the trailer? What is the tow capacity of the vehicle? A gear change is the last resort usually as there may be several other items that should be considered like suspension and brakes. That is over 1/2 a point of ratio. Most heavy duty vans are 4.10 ratios I believe. Not only will your fuel mileage be affected but your top speed will be reduced as well in most cases.

 

[highdesertranger]

yeah bullfrog I saw this when it was first posted and I suspect the 4.30 number.

also everything "struggles a little" pulling hills doesn't matter what it is.

highdesertranger

 

[bullfrog]

It would have to struggle a lot for me to do a gear change. I really feel most people are trying to pull too much with two little although I see huge boats show up on the launch ramp everyday after traveling several hundreds of miles on both interstates and 2 lane mountain roads. I guess modern engines have more power combined with choice of gears in transmissions to be able too tow these loads but surely wear would destroy the drivetrains after 5 years or so. Maybe all these people can afford to buy a new truck every 5 years or so? I70 in Utah has an 80 MPH speed limit and unless you want to take several days to avoid using it you will be cussed by the truckers doing 65 MPH or faster. With my vehicles being geared at 4.10 and running stock sized tires even with overdrive I don’t like doing much over 60 MPH. Most vehicles with 4.56 ratios won’t do 55 MPH unless larger diameter tires are installed or the engine is turning too fast.

 

[nature lover]

I had a friend who had a post WWII military surplus willies. That thing was geared so low that you could almost get out of it and walk past the thing on the flat roads it had a top speed of 40 to 45 mph. When you came to Hill was still 40 to 45 miles an hour I don’t know how they had them geared but it was the same speed no matter what the terrain. I wish I had been smart enough to buy one back then and kept it going. Right after Korea those things were selling for Less then $100. Of course buying them at big government auctions you never knew exactly what the vehicle would be like when you got it. Some people bought two or three in order to build One good one. Can you imagine what one would be worth now? Oh and in keeping with the original thread they could tow an amazing amount of weight. We pulled some major stumps out of the ground with that thing.

 

[Pleasant Travels]

Yep, when it comes to climbing (off road or otherwise) gearing is king. I had a Suzuki Samurai with a dinky 1.3 liter motor, but it had a reduction gear transfer case of 6:1. That damned thing would climb a wall if it could get traction. It was unstoppable getting over obstacles and such. But it also had a top speed of 60mph when I had the tachometer pegged, due to the tall gears I had in the differential to compensate for the larger tires. Despite the 1.3 liter displacement, that pig only got 15mpg because it was wrapping that thing up in rpms just to get anywhere.

 

[tripper]

Just put it in a lower gear, give it half throttle and go up the hill slowly.  I have had two really underpowered rigs, a 225 slant  6 65 Dodge truck with a truck camper and a 69 Class A Dodge RV with a 318.  Both had no problems towing a car behind them too. I just put it in 2nd or even first gear, get in slow lane put on hazards, give it half throttle (don't overrev the engine) and let it poke up the hill with some good tunes playing on the 8 track. Traveled all over with both rigs no problem, just do like the truckers do with heavy loads, people can pass.

My old 65 Dodge (still have it) drove many years all over country no problem with mountains, towed trailers with it too, just went up in 1st and 2nd gear.
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[nature lover]

Itripper - you still have an eight track? Now there’s a blast from the past.

 

[user 37446]

Slant 6 and the 318 - great motors. Same with 300-6 Ford and GM's 292-6 truck motor. They all had relatively little HP but made great torque.

 

[bullfrog]

And more main bearings than V8s.

 

[user 423]

Roller cams in the later 318's,too.

 

[Freelander]

I watched a 292 Chevy at the DragStrip make a 9 sec run. I was impressed!!

 

[gsfish]

I like the way the six sounds. The slant six was made in an aluminum block version too. Keep your magnet handy when you see a slant 6 in a scrap yard

Guy

 

[Freelander]

If you run a split header those 6 cylinders have a sound all their own.