Hi All!

I just bought my first Dodge, a 98 B3500 converted to a Class B fully self-contained motorhome by the Xplorer company. It has a 360, automatic overdrive trans, 4.10 gears with limited slip. It has 33,000 miles on it, and gets 13.5 MPG on flat roads at 60 mph with the cruise on.

The rear gears growl and howl, especially when slowing from 20 mph to a stop. I have gear and/or bearing problems. Since the thing's gotta come apart, I'm interested in changing the 4.10's to 3.55's, to try to get some better mileage out of it. It's going to be used for camping, maybe light towing of 1500 pounds, but definitely driven cross-country on very long trips out of state. Last year, I drove 6427 miles in 4 weeks from San Diego to Detroit and back. That's the kind of miles this thing will see, and the terrain will be mostly flat.

Is the swap from 4.10 to 3.55 straightforward with a 9.25 rearend and LSD? I read in another post that the speedo pulse comes off the diff carrier, not the trans???? Is that the case in the 98 B3500 van?

I'm getting quotes ranging from "about $800" from a general car/RV shop to over $1400 from a specialized rearend shop. Can/will my local dealer perform this swap?

Thanks for your help!

Gerard
Ramona, Ca

 

If the rear end is not a DANA but the 9.25 the gears between the 1500, 2500, and 3500 appear to be the same, except spyders
The axle housing ends and drive hubs are different. light to heavy
Go to a self service junkyard and get the whole rear end .
Should be around 150. from drum to drum. You could get lucky and find a good one. Tear it apart prior to purchase.
Or invest some time into learning how to install a ring and pinion.
Summit racing has new gear sets with install kit for less than $300.
Local shop says it will take about 3 hrs at $85. per hour.

 

Morning, I have owned 5 1ton dodge vans, all my rear ends howled some worse than others. After driving about 350K miles between them all with no breakdowns or problems, I would not be concerned about the sound.

Should you put those 3.55s in your van likely will become very sluggish as that conversion can not be light (lbs) and I doubt you will gain any MPG.

Best of luck with whatever you do.

 

33k miles seems awfully early to be having rear end issues, especially with the low gear ratio. However you never really know how the previous owner used/abused it so I suppose anything is possible.

I think that given the vehicle weight and the extra stress from the rotating weight and diameter of those oversized dual tires you are going to ruin any acceleration you currently enjoy. I would also guess you will be lucky if you can ever use OD again after going to 3.55's, so your milage will be worse not better. Even with that Magnum 360 your rpms arent going to be high enough to keep you in the correct point in the torque curve. You could probably get away with 3.9s if you aren't loading a ton of extra gear in that thing and never tow.

 

Congratulations Gerard, you got one of the finest B conversion vans ever made. My wife and I bought our 2000 Xplorer two years ago, and it has turned out fantastic. Ours had 72,000 miles on it when we bought it, and we've put on another 20,000. Had to put in a rebuilt transmission on our first trip, but other than that it has been great. I believe you van as dualies just as mine does. You might want to check the separation between your tires. Mine is only about 1/8 of an inch at its closest point. Some tire people think that could cause problems. However I've checked three other XLT's, and they all have the same separation, some even touching. And no problems. We've done a number of modifications on ours. If you're interested, let me know. BTW there is an Xplorer forum on Yahoo groups.
Cheers.....Vince

 

There are a few holes in this scenario for me....

I don't have anywhere paved to jack this thing up and work on it. It won't fit into my garage! The homeowner's association would have something to say if I did this job in my driveway.

Buying used rearends is a crapshoot at best. You said it yourself...I might get lucky. They likely have even more miles, sometimes, they're bent, and any one will need a full set of bearings anyway, so I have gained nothing.

I don't have any way to get something so large home, even if I could find one.

I do not like working on integral rearends. To change the pinion depth, you need to press the bearing off, add/subtract shims, then press on again. Everything has to be done underneath the vehicle. I don't have a pinion depth checker, and would use it only once.

I have had bad luck setting up gears...I'm not good at it. Sometimes, being a good mechanic is knowing your limitations, and hiring an expert to do things you're not good at.

Thank you for the reply!

Gerard

 

Hi Vince!

Thanks for the tips!

I tried to join that Yahoo club, and the moderator is AWOL. Are you a member? Can you get the moderator's attention to approve me?

I need a third seat behind the driver...anyone there have a spare?

Thanks!

Gerard

 

Hi Gerald,
It took at least two weeks for me to get approved once I applied. The moderator is frequently out of town and out of touch. I'm sure you'll get approved once he returns. That said, I will post a message on the forum that hopefully will get his attention. As for the third seat, what is your picture showing if not the third seat? Are you looking for a different one?

 

Hi! Thanks for the reply!

I wish there was a tachometer in this thing...

The loaded radius of the rear tires is 14.5 inches, so we'll assume a 29 inch tire. According to a handy-dandy online RPM calculator, it's turning 1967 RPM now with the 4.10's at 60 mph.

If I switch to 3.55, the RPM drops to 1703 at 60 MPH.

The way I drive it, it shifts from 1st to 2nd at 8 mph, and still has plenty of acceleration. With the current 4.10's, it's in 4th-Lockup at 45 mph, or 1475 RPM, according to the calculator. With 3.55's, it should hit 4th-Lockup at 52 mph.

The only real concern is 0-10 mph on an incline. Is there enough power at converter stall to get the thing to move? That will be the big unknown.

I intend to drive a LOT of flats...if you look closely at the U.S., most of the country is flat. Even the hills are half up and half down, so power in the hills at speed is not a concern.

The other thing for me is this big question: If I spend all this money rebuilding it with 4.10's, I will ALWAYS wonder what my gas mileage would have been with 3.55's. I'm willing to take a chance, because the payoff is big for me. On a 6000 mile trip (I did this last year, San Diego to Detroit and back), the cost differential between 13.5 mpg and 15 mpg at $3.50 per gallon is $201.

With the huge rear overhang, towing capacity is limited to 3500 pounds. I don't intend to tow very much, if at all.

But this is all theoretical at this point. In the rocket biz, we had a saying: "One test is worth a thousand theories."

Has anyone ever made the change from 4.10 to 3.55?

Gerard

 

Ok, I'll be more patient with the moderator...

That seat is just an example...mine is missing. My interior is green, if I get so lucky to have a choice in colors. 1 in 3 chance--green, blue, tan!

If you want to post a photo anywhere, here is the URL of that photo to use as an example:

http://bob2000.com/vanseatb.jpg

Thank you!

Gerard