I have been learning alot about the gears in my truck and need to make a change. Right now I have 3:55 open rear end. I would possible like to go to the 3:73 ls rear end and curious if anyone has any idea what kind of gain I will see. My prob is that I am running 33" bfg a/t's on the truck and it is kinda sluggish off the line, not kinda, it is!!!! I have done alot to gain some back by adding the K&N kit, throttle body spacer, hypertech, cover(to reduce drag) and its not what I want. I need to make changes. I would like reccomendations from anyone who actually knows what they are talking about!!!! Thanks in advance.

 

Bob,
Thanks for the info on the 4x4 engaging on my 98.

I'm afraid I'm not much help with your gear question, but I still think 3:55-3:73 seems too small a change. Consider 4:10's. Hopefully someone else can shed more light on your question.

Here's a push to the top .

~Jim

 

3.55 to 3.73 is a waste of effort and money. None of those other mods will compensate for the 33's. Yes, you need gears, but you need the proper ones. You will need 4.10's to even be close to factory overall performance. Personally, I would increase performance by installing even lower gears (higher numerically). Do you have the 8.8" or the 9.75" rear end? The 8.8" offers a 4.30, but the 9.75" jumps right up to 4.56.

 

max, thanks for the help with the gears. I do have the 8.8 rear end. I was thinking 4:10 gears but at the same time I do travel the freeway a lot and for long distances. I am not trying to build a race truck just one that I will be happy with. 4:30 gears what kind of gain will I get you think. I am also running an open rear end which I am not sure is the best thing for that. Please advise if you know.

Thanks again

 

You're Welcome ! The 4.10s will bump you up about 300rpms at 70mph and the 4.30s will add another 100rpms. There won't be a drastic difference between the two. The overdrive is wonderful for highway cruising. I beat my 2000 F-150 all over the highway with 4.10s and 29" tires. It cruised at about 200rpms higher than the 4.30s would in your truck. To make it simple, the 4.10s will return you to factory performance and have a SLIGHT improvement in highway mpg, over the 4.30s. The 4.30s would give a bit more oomph towing, hauling, hauling *** off the line, or offroading.

 

thanks max, now I'm off on the hunt for gears. I think I will go with the 4:30 ratio. If I'm gonna spend the money I only wanna do it once.

Thanks for your help.

 

Not a problem ! Good luck !