4.10 to 3.54 ratio swap

[JJump]

Thanks to all who have answered my previous posts-this forum is great!



I'm interested in changing my axle ratio from 4. 10 to 3. 54. I came across a set of 3. 54 gears in the TDR classified stating the following...



"Came off of 1996 Dodge Diesel 2500 series. Automatic two wheel drive. Changed at 16,000 miles. Like new. Changed because I went to 410 for pulling 5th wheel trailer "



1) Will these gears fit my '93 D 350 (Dana 70?) LSD rear axle? Does this ratio change require a different carrier?



2) How do you change the cal for the speedo? Do you change the speedo gear in the transmission, or can it be done with a software (?) change in the electronic control unit?



Thanks in advance for your response-appreciate your time!



J. Jump

St Louis

 

[dpuckett]

Not sure if it will fit from a 2nd gen auto, but I do know that the 4. 10 and 3. 54 have the same carrier. For the speedo, find a speedometer shop and they can tell you what you need to do to find the ratio you need; or a 4x4 shop may be able to point you in the right direction. There is a little adapter that comes out of the transmission that the speed sensor connects to. There are 3 or 4 gears in there, and thus, you can get just about any ratio you need. I have the little box form a 3. 54 truck, but it needs a new driven(?) shaft on the transmission side- it broke, and getting a new one made at a speedo shop was cheaper than getting this one rebuilt.



Daniel

 

[sparks57]

I'm pretty sure they would fit. From what I remember, the autos had the same axles as our trucks. If it came off a stick, I think they wouldn't fit. The stick 2nd gens had the bigger axles.

 

[y-knot]

This must be a sad, sad day. Every truck I have has between a 4:10-and a 5:12 You couldn't give me a truck with 3:54's

 

[sparks57]

They are nice for pulling, because they drop the gears down and tighten them up... but for a normal diesel rig they aren't necessary because diesels have such a strong low end. Gas trucks need the lower gears because low end on a gas engine sucks.



The only reason I would ever get a diesel with lower than 3. 54 gears is if I was only pulling trailers with it or putting big tires on it.

 

[cerberusiam]

Jjump, on a 2x4 all you have to change is the speedo gear in the output shaft of the trans. The gear holder has an offset depending on the number of teeth the gear has. Rotate it to the area marked for the number of teeth. It generally runs about 2. 5 mph per tooth for adjustments. If the gears are from a Dana 70 they will fit, however, the 2nd gens switched to American Axles and an 80 series rear end some time. You need to check and see where the change over was made.

 

[MMiller]

The 3gens switched to american axles. All the 1st and 2nd came with dana axles. As said above some second gens came with dana 70's and some with dana 80's. Need to find out if it came from a dana 70 or 80. If it came from a 70 it should fit.



I have been looking for a ring and pinion too. My 93 just tore up its rear ring and pinion. Three of the pinion teeth were torn right off of the pinion. Thought about picking up a used set or another dana 70 but I am going to install new. I torque on the poor rear end too much to risk a used set. Found ring a pinion 3. 54 for $295 with pinion bearings+$36 for carrier bearings. Just trying to decide whether I will pay someone to install, of lay out in my cold driveway and do it myself.



I wouldn't change to a 4. 10 in my 93 for nothin, just seem to be too many revs down the road with 4. 10. Mite put some 4. 10's in my 90 when I step up to 39"+tires, But it will be an offroad truck too, not a pavement pounder!



Michael