Need a tune after regear?

[Kim]

This site is such a great wealth of info, and I appreciate all the hard work that everyone who contributed to that cause put into it!

Ok, I'm getting ready to do an axle swap on my '01 Ranger 3.0 5speed manual 2WD Edge (sometime this summer/fall) so I'm getting everything I'm gonna need for that project beforehand, including info. Since I'm swapping out the 3.73 open 7.5 for an LSD 8.8, I'm also contemplating changing from the stock 3.73 ratio to the 4.10 ratio before installing the axle. I've compared the RPM differences between those two choices, and I'm happy with the results shown with 4.10s.

My question is "Will I need a tune after changing gear ratio from 3.73 to 4.10?" I understand the relationship between the tone ring and the speedo, and that the ratio change by itself won't affect the speedo...what I'm not sure of is if/how the PCM will react to that change. Will it freak out and throw codes if it thinks the drivetrain is "malfunctioning" or will the difference be not enough for the PCM to care?

 

[ericbphoto]

PCM will never know. Adopt a "don't ask. Don't tell" policy with your pcm.

Seriously. The engine and it's computer will be happy. Great move for a 3.0l.

 

[franklin2]

How will it not affect the speedometer readout? Your engine and driveline will turn faster to go the same ground speed as the 3.73 gears. It may affect when the injectors turn back on when decelerating. And transmission shift points, since the computer is in control of that. But I would think all these differences would be small.

What would be curious is if you tried to buy a new computer for your truck. If they want to know your final drive ratio, then the computers must be programmed different. If it's the same computer, probably nothing to worry about.

 

[ericbphoto]

I'm not sure what year the switch was made. But at some point, the speed sensing was moved from the transmission or transfer case output to the differential ring gear where yhe rear sensor is for abs. The ring gear will turn at the same speed as the tires regardless of gear ratio. So changing ratio has no effect on it. Only tire circumference/diameter changes will make a difference.

 

[racsan]

A 3.0 especially will benefit from a change to 4.10’s , my 2.3 came with 3.45’s and rolling a 4.10 under it was the best thing for it, took some time with a speedometer cable gear assortment to find the right tooth count gear for the speedometer to be accurate (mines a ‘94) but its dialed in now. A 4.30 ratio would be even better for a 3.0 but Im not sure if that ratio is still available, dont see it very much. 4.56 does but thats a bit too low to go unless your putting big tires on it.

 

[Kim]

Then 4.10s it shall be.
Thanks!

 

[don4331]

I'm not sure what year the switch was made. But at some point, the speed sensing was moved from the transmission or transfer case output to the differential ring gear where the rear sensor is for abs. The ring gear will turn at the same speed as the tires regardless of gear ratio. So changing ratio has no effect on it. Only tire circumference/diameter changes will make a difference.

Isn't @ericbphoto one of those mods who are supposed to know everything

https://www.therangerstation.com/tech/swapping-an-explorer-5-0l-in-to-a-1998-2011-ranger/, about 1/6th of the way down talks about PATS and other important stuff like VVS. Only '98-00 had VSS in rear axle, all the others, its in transmission/transfer case. So, while there are differences in the number of teeth on the tone ring between the axles, the OP's truck is a manual so will never know (actually, it will make ABS slight less sensitive as there are 6 more teeth rotating past per revolution).

7.5 VVS Tone Ring	102 teeth
8.8 VVS Tone Ring	108 teeth
9.75 VVS Tone Ring	120 teeth

With FORSCAN, the OP could actually correct the ratio in the PCM if he was really anal about it.

Note: The 4.10s will make the truck a lot more fun to drive, but they won't do anything for fuel economy.

 

[ericbphoto]

Isn't @ericbphoto one of those mods who are supposed to know everything

I don't know everything and I'm first to admit it. Moderators are more like referees, not know-it-alls.

 

[Kim]

I'll be sure to follow up on this once I get to working on it. Wouldn't be hard to figure out if I need to do an extra 5 minutes of work, right? lol
Thanks for all the info, btw. Super appreashed.