So I looked up my VIN number at the Dodge dealership, to see what all it has on it, because I'm planning multiple categories of restoration work on it starting soon. And sure enough, my post-VIN check parts search has revealed what looks increasingly like an anomalie as far as what my truck has, versus what all the options supposedly were. SO here's the story for tonight's controversy;

My vehicle is a 1998 Dodge Dakota Sport 4x4, with the following equipment-- first, the stuff that appears to be normal for this year/make/model according to my research thus far;

4-speed automatic 42RE transmission, with lock-up torque converter

3.9-Liter V6 Magnum

Shift-on-the-fly 231 transfer case with 175mm front axle

Chrysler 8.52 rear axle with anti-spin differential...

BUT, mentioning the differential is where things started to get frustratingly weird for me;

My VIN number also indicates that my truck's Chrysler 8.25 rear axle has a 3.92 ratio differential inside! And so far, the closest that I can find any historical reference to is I think a 3.77 or somewhere around there? I have found no reference to a 3.92 ratio being an available option for the Chrysler 8.25 rear axle of the 1998 Dodge Dakota, and I can't seem to find a ring and pinion in that ratio for the 8.25 for sale by itself.

Oh I found an number of full 8.25 rear axle assemblies with 3.92 diffs in them for sale online for above $1500 a pop by-golly, but I can't find any references to what I would need to replace along WITH a 3.92 ring and pinion JUST BY ITSELF inside an 8.25 Chrysler rear axle (like the size of lock-up thingie it's supposed to be housed in that I would need, and that would also fit the 8.25 axle for example).

So um, did some past owner of my vehicle basically frankenstein-f**k my vehicle's rear end at some point with a gear ratio that ain't supposed to be in there or what??

Because I have no intention of replacing it with say, a 4-10 ratio, and flushing down the toilet what gas mileage I already do manage to get out of this truck. I also don't want to go to an even lesser ratio than the 3.92 that's in the @$$ end of this truck, because I still want it to have whatever balance it has between gas mileage and at least marginal weight toting & mild off-roading manliness such at it is.

Who among ye hath the answer to this confounding riddle of strangety and unmatched weirdness?? Not even my contemplating this on the tree of woe has yielded me any answers thus far!

Thank you

 

So far as I know, the 3.92 was an optional ratio..... If that is what is actually in there, then its a good compromise between power and offroadability, vs gas mileage. Is the tag still on the rear axle? if it's there, it should list the gear ratio on it.

 

It has no tag on it.

Anyway though, if 3.92 was an option for the 8.25 rear axle, do you have any idea why I can't find a 3.92 ring & pinion that says it's made for the 8.25 axle, without buying the entirely completed axle assembly for almost 2 grand?

 

They are out there, but, fun to find. I found a kit on Vivid racing.... gears, bearings, seals, etc, but, it's 900 bucks...

Do you need new gears?

 

I don't know yet. I haven't yet unbolted the cover plate off the pumpkin in the middle of the axle. But it's been massively leaking fluid the whole probably 3 years or so that I've owned the vehicle, and the speedometer stopped working a year and a half ago, even though I replaced the speed sensors both on the rear axle and on the transmission.

This is of course without counting the plethora of other things wrong with this truck, that I bought for 1000 bucks and have been restoring things on ever since. lol

I like this truck for what it can and will be once I'm done with everything though. For example:

The day I bought it, you had to be accelerating to keep the motor running at all, otherwise it stalled at idle.

So when I finally got it home at the risk of a speeding ticket from every light just to keep the truck alive, the first thing I did was replace the spark coil, plug wires and plugs with all racing grade. Then I added one of those throttlebody spacers with twisty barrel rifling grooves inside the air holes. So for a long time, I had a hard time keeping this truck UNDER the speed limit with how manly the engine became.

But sure enough, a year later I finally discovered a bad catalytic under the truck, and had that replaced with a federal one (I was in Cali for that, is why). And ever since then, the truck ran like crap. Well yesterday I discovered that the exhaust manifolds have been missing some bots for the last 2 years and I never knew.

I'm convinced the mechanic removed some bolts hoping to create a fake problem to ensure repeat business from me, in the form possibly of going to get exhaust work done. I know some mechanics are sheisty like that.

So now my current categories of restoration on this truck are doing all the gaskets and replacing those exhaust manifold bolts, and then rear axle fluid leak (and I'm hoping that ONLY a fluid leak is what's going on there).

 

Keep in mind that exhaust bolts on Dakota's are pretty notorious for just deleting themselves. If they were factory bolts I would bet on that. If the leak is coming from the axle ends do the bearings as well. Usually the axle seals pop out when the bearings start to get play.

 

Throttle body spacer does absolutely nothing on a port-injected engine. Replacing the ignition parts so the engine actually fired the cylinders properly is likely what you were feeling.

Pull the rear drive shaft, wiggle the pinion, see if it moves at all. How does it feel when you turn it? Gears are pretty durable, and will take a fair bit of abuse.... if it ain't makin' any rude noises, they are likely fine. Need to fix that leak though.

 

The leak in the rear axle is coming ONLY from the cover plate on the center-pumpkin, not the ends. It's not the wheel bearings I'm therefore concerned with, as they actually have always turned smooth as far as I've been able to tell.

I am however concerned with any possible issues solely with the gear box and it's raging fluid leak (and therefore by extension, any possible secondary problems inside that such a leak may lead to).

The engine is a fuel-injected one. I just swapped out the Idle Air Control Valve at the back of the throttle body, and it's now idling a lot smoother than it has in years.

I'm fully aware this was never the only thing on my engine that needed fixing, but it seems that with every next thing I swap out & replace, I finally cure that one more ingredient to the great soup of problems my truck's engine has.

I also bought exhaust manifold gaskets and a set of 8 bolts today, and I'll be searching out youtube vids on how to swap out the old for the new on my year/make/model engine so I can try to do it myself tomorrow. Or, and I'm leaning toward this instead, going to the nearest auto shop in town to see if they'll do it for me for less than two boldily appendages, using the new replacement bolts & gaskets I bought from O'Reilley's today.

So, tomorrow here goes nothing...

 

Ah, cool. Then pull the cover, clean it up good, and look for holes. Clean the inside well, and have a look at the gears. Pay attention to any chunkies that come out.... if any.

 

As for the exhaust manifold bolt issue, I bought 2 sets of four bolts today, all the same kind;

Napa looked up the exhaust header bolts for my 1998 Dodge Dakota Sport w/ 3.9-liter V6 Magnum, and showed that a set has only 4 bolts per, when there are 8 bolt holes on each of my exhaust headers.

Does this mean my headers use that setup where it mounts with 4 conventional hex bolts and 4 of those stud bolts, or are you just supposed to buy 2 sets of all-conventional hex bolts to fully seal the headers onto the sides of the engine block?

If the latter is the case, you'd think they'd sell the full set of 8 bolts instead of selling them by the 4-pack.