did allittle research the diff between 3.55 and 3.73 is only 117 RPM

 

What if I wanted to change my 3:55 to 3:73 in my 98 F150 5.4.

Could I just change the gears or get a slavage rear end and change it??

In my old 1990 Chevy with a stright axle in the front they had to be the same gear ratio.

Is this still the same with this new type front end??

Sorry not trying to Hijack your thread but seemed a good place to ask.

 

for all the work and money to change it from 3.55 to 3.73 i dont think it would be worth it, why do you want to change it?

 

I don't have a plan to change it right now.
Its more of inquirey for the later, just in case.

Did not no if you had to do anything to the front axle as well. I might want to do it if I found a disk brake rear end some where?

Thanks

 

Most folks here will say that 4.10s are the best all around ratio for our trucks. Higher ratios are more tolerable if you have oversized tires but are still succeptible to being noisy.

Bigtruck, I know from experience that online calculators are not always 100% correct. It's better to err to the lower numeric/higher ratio side for a daily driver, especially if you drive on the highway regularly.

Some gear ratios are available for the 8.8 rearend that are not for available for the 9.75 rearend. I think that 4.30 ratio is only available for the 8.8, on the heavier axle it's either 4.10 or 4.56, nothing inbetween.

Depending on which axle is in your truck you can get a complete axle or gears from the salvage yard providing that the particular ratio was offered from the factory on the same type of rearend you already have in your truck (this includes the rear ABS option too). I would think it's easier and cheaper to get the complete axle w/ the ratio already in it from factory. I honestly dont know which ratios were available for which axle but some research could easily turn up that info.

You can also switch from the 8.8 to the heavier axle but depending on which trans you have you may need the driveshaft from a truck w/ the same axle, trans, and wheelbase combo or possibly even a custom driveshaft (I dont think that 4.2 or 4.6 trucks were available w/ the 4r100 trans and 9.75 axle) .

Both front and rear axles need to be the same ratio. That's why a gear swap on a 4X4 costs twice as much as on a 2WD. Also, the front axle will need a set of reverse cut gears.

Sorry if this post is somewhat vague and longwinded but reading back through old posts and using the search function will give more definetive answers for sure.

Good luck.