Gear ratios for 3 speed tranny?

[JMiller81]

I have been reading the page for a while now and I keep seeing people running 4.56 gears with 35" tires. Every mechanic I have talked to in town and have told me I am nuts if I run more than a 4.11 with 35" tires. My question is what kind of actual accurate rpm's are you guys turning running 4.56 gears? Use 65mph as your guideline. The reason I say actual rpm is I have checked my factory tach and it is 300+ rpms off of actual engine rpm. This was verfied with a timing light that could read engine rpm. This truck has to be driven on the street and I don't want to be turning 3000+ rpms driving on the street.

Thanks. :wacko:

 

[Yardape]

I have been reading the page for a while now and I keep seeing people running 4.56 gears with 35" tires. Every mechanic I have talked to in town and have told me I am nuts if I run more than a 4.11 with 35" tires. My question is what kind of actual accurate rpm's are you guys turning running 4.56 gears? Use 65mph as your guideline. The reason I say actual rpm is I have checked my factory tach and it is 300+ rpms off of actual engine rpm. This was verfied with a timing light that could read engine rpm. This truck has to be driven on the street and I don't want to be turning 3000+ rpms driving on the street.

Thanks. :wacko:

If you only have a three speed and you do highway driving then 4.11's will work good. Any performance mods you do whether its drag racing or offroading take sacrifice in one way or another. If you want your truck to perform off road, than yes its going to be a bear on the street. Mechanics tend to try and look out for your best interests as to what is logical. There is nothing logical on my truck, when its finished I will adapt to it, if it cant go on a 1000 mile trip to the mudbogs then I will trailer it. 4.56's are a good ratio for offroading with 35's but still liveable on the road. I plan on going with 4.88's and 38 inch tires. It will be driven on the street but its not going to be the family grocery getter. I have 33's on my F-250 and 4.10 gears. I never noticed any power difference from stock to the 33's. So 35's should be alright as well.

 

[Justshootme84]

Yeah, I concur with YA. I think with a C-6, 35" tires and 4.56 gears with spools that I had before the 1-ton swap, the rpm's at 65 were around 3000. That's screaming down the highway, and about as revved-up as i would ever get the 351W H.O. motor. With that said, I use the Bronco for 90%+ offroad, and very little road use. 4.10's would work, too, if you do more on-road driving than off. IF you do the math, the 4.56's put your engine closer to the stock powerband, and I think you get a bit better performance offroad than the 4.10's. One last thing to consider. IF you ever plan to run a 36 or a 37 inch tire, the 4.56's will be good to go. IF you go to 4.10's now, you may not be happy with that ratio and the taller tires. It's really a small difference in most cases with the C-6 and a V-8. Where I've noticed more power loss from tall tires is with the 300I-6 or the OD trannies. JSM84