Engine/Transmission (1998.5 - 2002) Cost of Diff. ratio change?

[EricBu12]

As some of you know, I am getting bigger and bigger on my RV and now I have A 2nd utility trailer for a sand rail. .



I have the 6 speed manual and 3:54 rear. . it is sorta hard to get moving from a stop light in first. gear Vendors is out because they don't have an underdrive for 1st.



So how much would it cost to change to 4:10? Am I right in assuming I have to do the front as well for 4x4? I have a 2wd low kit for manuvering the trailer but the 1st gear starts from a light are slow.



TIA

Eric

 

[Nate]

Roughly $600 in parts and whatever in labor... . another $600 on the low side

 

[CumminsDoofus]

If it's a Dana 80, It will require a carrier change,... . 3. 54 and 3. 73 fit on the same carrier,... ... 4. 10, 4. 30 and so on fit on a different ring gear carrier ( offset for thickness of gear).



I Think!

 

[rweis]

I went from 3. 54 to 4. 10 without having to change the carrier. I did because of a spun bearing, but if the DC preload would have been right at the beginning I would not of had to.



Basically the decision you are looking at is the difference in the diameters of the 3. 54 pinion and the 4. 10 pinion. The 3. 54 pinion is about . 40 bigger in diameter than the 4. 10 pinion. There are 2 choices:



1. Get the 4. 10 carrier which moves the surface the ring gear is mounted on closer to the pinion so they mesh correctly.



2. Get a "thick" 4. 10 ring gear / pinion set that mounts onto the 3. 54 carrier. What happens here is the 3. 54 carrier, the "thick" ring gear which is about . 40 thicker body material than the standard 4. 10 ring gear, ie it moves the ring gear gear teeth towards the pinion.



There are two schools of thought:



1. With the "correct" ring gear mounted closer to the centerline of the pinion you will get better torque with less stress.



2. With the "thick" ring gear the ring gear meshes correctly but the mounting surface of the ring gear is further away from the centerline of the pinion and generates more stress to the gear / carrier mating surface.



I had the thick ring gear, then found out that the carrier had to be replaced because of bad factory preload, so I would wait until you got inside of the differential BEFORE I made the final decision of the ring gear (if you can).



Bob Weis

 

[EricBu12]

Assuming the preload is good, would the thicker gear be stronger? and and would it cause any damage to the bearings in the long run with heavy towing?. . how much is the difference with getting the correct carrier and gear to getting a thick gear?. . is it worth it? (gambling?)



I assume it would be OK to do only the rear first as long as I don't use 4x4 til I get the front done. I said I have the 2wd low kit to keep the front undone... . So maybe $300 or so in parts for the rear? + labor?

 

[y-knot]

Eric,

If your going to change the gear ratio do it right and get both gear sets installed. It's absolutely stupid to do one and not the other with a 4WD. What happens the first time you pull your rig off the road and get stuck in the sand? Which is very easy to do. You got money for the big rig, sand car and so forth, so you should have the money to do the gear change right the first time, if not save until you do.



p. s. With you running such a small gear, moving up to a 4. 11 will be like picking up 200 new HP.

 

[Nate]

I would just get the 4. 10 carrier.



Or you could always put a locker or limited slip in at the same time







Yeah you could re-gear just the rear axle and then do the front later. I would pull the front driveshaft so no one puts it in 4wd though.

 

[EricBu12]

Guess I will get the carrier and both at once...



Anybody know where in salt lake city is the best? or good price for the service?



there is a place called Six States where I had my 5600 rebuilt. . don't remember if they do diffs. though

 

[GCULP]

unless the cable works from somewhere else, don't forget to have the speedometer re-calibrated.

 

[DCreed]

wont he need two carriers? can i have ur old ones?

 

[Nate]

6 States does do diffs, but they are a bit on the expensive side. I would look for a reputable 4 wheel drive shop. I know there are tons in Utah considering Moab is not far away Do stay away from 4 Wheel Parts!
For the gears, I would pick Dana or Yukon. Get a master install kit that's got good bearings (Timken, SKF, etc).

Spedometer doesn't need to be recal'd. It goes off the carrier's speed, which is relative to the rotation of the tires, not the rotation of the driveshaft.

DCreed... only the D80 needs a new carrier.

D60 is 4. 10 and down.

 

[AKAMAC]

Eric,

One of my co-workers has a 99 with ~60k that wants 3. 55. His is a 3500, what is yours. Mike

 

[EricBu12]

Mine is a 2500... . that acts like a 4500... lol



whoever said (forgot) that wants my old carrier, you got it when I do it. . let you know. .



thanks for the advice on the gears and bearings. . gonna need good stuff with what I'm towin'...

 

[EricBu12]

Thanks for all the advice guys but I think I am going to hold off the gear swap as I am not going to be towing very much this year because my vacation time is going to be used up on Honeymoon in Hawaii... . just a couple trips to local deserts for this year... maybe after tax time next year I'll do it. . got a lot on my plate too at home (other projects). .



guy who wanted my carrier, if you still want it when I do it then (08), Ill keep your PM to let you know.



Eric

 

[Silver_Ram]

Eric,



Call Eric at Six States Driveline Shop in SLC. I can vouch for his reputation. The price will be dependant on mileage, new bearings all the way through, etc... He changed my truck from 3. 54 to 4. 10. He has a good crew & will treat you good.



I had to recalibrate my speedo after the gear swap, I also have 35" tires.



Troy

 

[Nate]

I'm not sure. I went from 3. 55 to 4. 10. The speedo was spot on before (going by my GPS) and it was spot on after. I never touched anything and I neither did the guy that I dropped the truck off to.

 

[rweis]

Troy,



Did you recal your speedo because of the gear swap? or because of the tire size change?



Tire size I can understand, the speedo diff rpm sensor should still be ok just because of the gear swap however.



Bob Weis

 

[MTatsch]

i want to go from the 3. 54 to 3. 73 what am i looking at there as far as price and all of well everything goes i dont get along with rear ends that well

 

[SnoKing]

That is a lot of money to spend on a small gear change 3. 54 to 3. 73! Is it a 2 by 4? SNOKING

 

[Silver_Ram]

rweis,



I did the gear swap first - I had 33" tires at the time & according to radar speed boards I was off 5 to 5 mph.



When I added the 35" tires I was actually off 11 mph. I had heard the same thing about the speedo readings not supposed to change, but mine did.



I have access to a drb scan tool & recalibrated to within 10%. If I ever get spare time I will play with the drb some more & see if I can get it closer.