how much Hp needed for 42's?

[panamacj5]

ok so its confirmed, gears are 4.56, dana 60 with trac loc and detroit locker on the 14bolt, my tranny came from a bronco, Dana 300 stock ...will it be enough to clean those 42´s ?

 

[tarry99]

ok so its confirmed, gears are 4.56, dana 60 with trac loc and detroit locker on the 14bolt, my tranny came from a bronco, Dana 300 stock ...will it be enough to clean those 42´s ?

NOPE! I would doubt it with a 302 V8............T-19 I assume has the 4.0 or 5.0 low gear? Not enough pure power or mechanical advantage with those gears for such a large tire.................will it work? Sure, will it be under powered I think so.

 

[derf]

I don't know. It's going to depend on the engine. That combination isn't far off for a Jeep that sees highway use. But I suspect that you're going to hate trying to crawl with it.

Try installing them as-is and see how you like it. Then you can plan on what gears you want to upgrade to once it's rolling.

 

[jasonmark1993]

I don't know. It's going to depend on the engine. That combination isn't far off for a Jeep that sees highway use. But I suspect that you're going to hate trying to crawl with it.

Try installing them as-is and see how you like it. Then you can plan on what gears you want to upgrade to once it's rolling.

I agree. Or maybe just run a little smaller tire. 38s on a Jeep are HUGE.

 

[panamacj5]

i believe its the 5.0 low gear, the 302 has a 3.4 inch crank kit with .30 pistons increasing displacement up to 357 cubic inches, i guess i will use the 4.56 see how it works and then regear when i have the money ...any more input will be apreciated

 

[panamacj5]

I don't know. It's going to depend on the engine. That combination isn't far off for a Jeep that sees highway use. But I suspect that you're going to hate trying to crawl with it.

the jeep wont be doing any rock crawling

 

[panamacj5]

I agree. Or maybe just run a little smaller tire. 38s on a Jeep are HUGE.

thats the tire i wanted to run but i was adviced to go bigger because of the axles that will be swapping in (dana60 /14 bolt)

 

[tarry99]

thats the tire i wanted to run but i was adviced to go bigger because of the axles that will be swapping in (dana60 /14 bolt)

No Rock crawling............Maybe a daily driver? Maybe in the Mud? But, If you put it in the mud with those gears it well really be underpowered You could change the gear set in the Transfer Case to a 4.0..........that would help. In either case have fun!

 

[panamacj5]

No Rock crawling............Maybe a daily driver? Maybe in the Mud? But, If you put it in the mud with those gears it well really be underpowered You could change the gear set in the Transfer Case to a 4.0..........that would help. In either case have fun!

Here in Panama is mostly muddy trails and hills

 

[jasonmark1993]

thats the tire i wanted to run but i was adviced to go bigger because of the axles that will be swapping in (dana60 /14 bolt)

Im guessing someone suggested that because of the over all bulk of those axles and the larger tire will give you more clearance.

I know guys that get around just fine with a 60 and 34s. They aren't that big.

I think you would be much happier dropping down to a 38. Personally, I'll never run a tire that big on my CJ. Everyone thinks my 33s are 35s.

 

[Incommando]

A true 38" tire works well with that combo especially if you shave the rear dif housing on the 14 bolt. You can go as simple as using a angle grinder to cut the lip off of the bottom (you will see what I mean), you can do as I did and order this GM 14 Bolt High Clearance Shave Cover to shave even more off of the 14bolt, or you can go crazy and cut the rear so much you have to turn down the ring gear and weld the diff housing shut.

I know plenty of folks who run the D60/14bolt axle combo with 37"-40" tires and with a little work they are no issue at all.

For a lot of mud I do think you will be under powered. You definitely need wheel speed as you know and I don't know if you are going to have enough. 42" tires on steel wheels especially are very heavy and take a ton of power to spin.

 

[justinfonder]

i think the moral of this thread is that its not how much hp, its what gearing for the hp that you have. we know that a 100 hp stock AMC 258 i6 / 4.2l can turn 35s all day long with the right gearing, and then get you home at 60 mph. the OP is probably pushing around 250hp (and i think thats a VERY low estimate out of a stroked sbf). which just so happens to be a pretty torquey motor as well. i've built a few of these for some street/strip cars

 

[derf]

i believe its the 5.0 low gear, the 302 has a 3.4 inch crank kit with .30 pistons increasing displacement up to 357 cubic inches, i guess i will use the 4.56 see how it works and then regear when i have the money ...any more input will be apreciated

Yeah, it won't cost anything to try those tires and gears together. If you like how they work you can keep them. It will only cost money if you decide to change them.

Thing about mud is that you really want good wheel speed. You don't want to have your axle gears so short that you can't get the tires up to speed to sling mud.

A lot of the performance will center around how the engine is built. Where does the engine make torque? If it's in the low RPM bands you should be fine or at least close enough. A 5:1 first gear isn't the best for rock crawling but that's not what you're doing. That first gear may be exactly what you need for 4.56 gears. Give it a try and see how they work and then you can adjust from there.