I have a 5spd with 3.55's in the rear along with 33 inch tires. I was wondering if anyone has 4:10's with the same or simaler tires and what they were running for rpms at differnt speeds. Maybe 70, 40, and 25 mph's.

Im thinking about doing the swap as im sure i will have a done of torque but i am afraid of killing my highway performance. I drive mostly city everyday but the miles are 70/30 highway to city. I tow trailers some of the time on teh highway and she dogs on hills. But i am just afraid that i will lose MPG's and hte longevity of my truck due to a higher rpm on the highway.

What is the thoughts of everyone on here?

I would really love to hear from some people tha have the 5spd.

 

I went from 3.55's to 4.10's and it was the best thing for the truck. It really helps out in the city, and it takes a lot of wear off the clutch too. I can pretty much just drop the clutch in 1st and it won't stall, which makes it great for lots of stop and go driving (just stay in 1st and let go of the clutch at idle speed).

My Dakota has 3.92's from the factory, with a 4.7l V8, and it's got 108k on it and it has no problems. So engine wear and tear is probably minimal.

Actually, from what I've read, by keeping the RPMs a little higher, it might extend the engine life... instead of ******* it at low RPMs which is harsh on the connecting rods of the engine.

What is really cool is that I can scale hills in my truck and stay in 5th, without it bogging down. Not to mention when I tow trailers, that I don't even feel that a trailer is EVER behind me.

 

Thats what im looking for. My truck stock was a dog on hills sometime i would even be down in 3rd on some of the passes in montana. THen i put the edge in and that helped a ton. But still not where i want and when i tow its even worse. Im just worried cuase if i dont have atrailer im always doing 75-80 on the highway. Kinda worried about longevity. The tranny and clutch are brand spankin new. Not a rebuild either. Ford direct with a centerforce.

How much would i be looking at for the swap? I have a 4x4 so i would have to do them both..... I konw the parts are cheap but i think the service is what is so expensive?

 

If you go from 3.55's to 4.10's, your RPM's in each gear will be 15% higher at the same speeds with the same tire size. If it's 3000 RPM now, it will become 3450 RPM.

 

Thanks. That puts some light on what to expect.