98 Mounty 3.73's -> 4.10's -> 3.73's

[Hokie]

Maybe I'm glutton for punishment...

When I bought the Mounty I swapped its axles with my old '99 Sport, regearing it to 4.10s. I built this truck figuring I would go to 285's (33's) and have since decided that I wasn't going that big. I ran it like this for about 8-9 months with 265/75R16 tires (32's) and decided that 4.10's were too low for 32's and the 4406'd V8 torque.

So this weekend we (me and ProjectAviator) swapped rear axles. We would've swapped both axles, but his vacuum disconnect front axle won't work with my V8 oil pan.

We were wrenching at a pretty good clip.. We had both trucks back on their feet in less than 3.5 hours.

Tonight I swapped the front axle by myself. I went ahead and replaced the front brake pads while I was at it.

I pulled the old axle, installed the new axle and did a brake job in ~2.5 hours

I drove to Denver on Saturday with the 3.73 rear axle and got 18 MPG. I haven't seen that in this truck in almost a year.

 

[MountaineerGreen]

So it is confirmed the CAD won't work with no lift? If so, how close was it to fitting?

 

[Hokie]

So it is confirmed the CAD won't work with no lift? If so, how close was it to fitting?

Didn't try... so no its not officially confirmed

I installed a low mileage (85k) 3.73 front axle from Jaime's (410Fortune's) rolled '96 Explorer.

I didn't want to mess with trying to do the swap if the fit was questionable.

 

[MountaineerGreen]

Well, non the less, its nice to see an Explorer/Mountaineer wrenching party.

 

[Hokie]

Well, non the less, its nice to see an Explorer/Mountaineer wrenching party.

Ha, yeah... my neighbors now think I'm crazy though

 

[CDW6212R]

Come on over here, I have plans to do my trucks soon. I'm rebuilding a 3.73 spare front unit for my Mountaineer. Then I'm going to swap it out, rebuild the other, and (for my 99)install it and a spare 3.73 rear I had from buying for axles. I think I want to get away from the 4.10's I have now, I don't like 9mpg on my route and upper teens commuting. I should end up with a set of 4.10 housings with 105k or so on them. Regards,

 

[askingxforxit]

answered my question...

I was thinking of swapping my stock 3.73 LS to the 4.10 LS when I get 32's. Now that I know from this thread that it kills gas mileage I think i'll leave the 3.73.

Thanks for the thread guys and good job on the swaps!!!

 

[Hokie]

I was thinking of swapping my stock 3.73 LS to the 4.10 LS when I get 32's. Now that I know from this thread that it kills gas mileage I think i'll leave the 3.73.

Thanks for the thread guys and good job on the swaps!!!

If you have a V6, then swapping to the 4.10's would be a good idea. If you have a V8, then swapping to 4.10's for 32" tires is not necessary

 

[askingxforxit]

If you have a V6, then swapping to the 4.10's would be a good idea. If you have a V8, then swapping to 4.10's for 32" tires is not necessary

Oh I see, that makes sense. Then i'll do it! thanks again!

 

[CDW6212R]

Well it's all in the usage. People who drive tons of highway miles like Al do much better with 3.55's. A truck with gig heavy tires that runs around slow a lot needs much bigger gears, like the 4.10's or 4.30's etc. I have had past experience with a same type vehicle and did better with 3.73's, so I'm wanting to try those again.

 

[99SportX]

Interesting. I have the stock 4.10's in my V8 swapped sport with stock 30" tires, and the gas mileage isn't anything special. It hauls though. lol I still have both 3.73 axles and may swap back to those because as we all know fuel isn't cheap, and this thing is a daily driver, not a race car.

I think I may start making some adjustments for better fuel economy.

 

[askingxforxit]

Interesting. I have the stock 4.10's in my V8 swapped sport with stock 30" tires, and the gas mileage isn't anything special. It hauls though. lol I still have both 3.73 axles and may swap back to those because as we all know fuel isn't cheap, and this thing is a daily driver, not a race car.

I think I may start making some adjustments for better fuel economy.

Well as of now it's my DD, about 55 fwy miles a day. I guess I'll wait and see how the reprogramming goes with a few other mods. I'm just worried that when I got off-roading the 3.73's and 32's, it will not be enough for getting over obstacles or going through decent mud pits.