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gear ratio with 40s?

B

black dawg

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Right now I am running 4.56, and they feel a little tall, but the big block gets away with it. I am running a 465/205/gear vendor combo, and this thing does as many miles off pavement as it does on.

5.13 and 5.38 are pretty easy to get and cheap, but I will still be under 22-2300 at 65 and leaves me wondering if I should gear it a little steeper?
It will be getting a 4500/doubler/205 setup in the future, so going fast and going slow shouldn't be a problem just curios what most people run with 40s. And I don't plan on going bigger unless toyo actually does the 42 in the mt that I am hearing rumors of.
 
Yep if you are 60/70 I think you can do 7.17s but if it's a 14 bolt rear 5.38s is as low as it gets
 
Oh and if the front is a 44 or 10 bolt I wouldn't do much more than 5.38.

Even on the Dana 60/70 stuff you better know your stuff to make 6.17s last
 
ended up ordering 5.13s and wishing that I ordered 5.38....but it has a 465 and plan on a 3:1 doubler, so gearing wont be an issue anyway.

Now to find a selectable for the front.....ox with air actuator? anybody use one yet?
 
black dawg said:
ended up ordering 5.13s and wishing that I ordered 5.38....but it has a 465 and plan on a 3:1 doubler, so gearing wont be an issue anyway.

Now to find a selectable for the front.....ox with air actuator? anybody use one yet?
Click to expand...

I pretty much decided on the cable actuated one for my front axle.
 
1-ton said:
I would have to agree with that. Every time I was afraid to go big and went conservative...I regretted it, and had to take apart everything and redo it all again a second time.
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r

EXACTLY! Things like gears and camshafts always sound big at first but later turn out to be adequate.

I have a good friend that used to have a truck with 6.17's and 35's. Initially it sounds like bull because NOBODY goes that big on gears and then to only have 35's makes it seem impossible to drive, like a tractor on the interstate. In real life the truck was actually very nice to drive; always in its power band, plenty of power from a dead stop and it cruised very well at 55 mph.
 
A good many of the 70's P-30 step vans came with 6:17's and an 11,000 lb rear axle capacity--many had 292 straight sixes ,some were V8's--most had SM465's too---they were able to cruise at 55 mph (the national speed limit back then),without much trouble,and even pass at higher speeds..

Of course,engine life was probably reduced somewhat due to the higher revs,but I still see quite a few on the roads still around here...
 
The problem with those deep gearsets is the pinion gets reallllllly small .

Up here we see lots of broken pinons with 5.38's and lower.
 
Ill be running 5.38s. 60 14 as well with an sm465 and 40s. The 14 bolt has the pinion support which means there no trying to climb the ring gear. The front im a little worries about but im real easy on stuff....so I think.

If it gives me trouble ill do the jantz setup. He has a kit to put a dana 70 ring gear in a 60...theres also a load bolt which is probably a major benefit even if you didnt do the bigger 70 ring gear.

http://www.jantz4x4.com//jantz.php?p=detail&pro=load_bolts
 
wetoolowdingbangow said:
Ill be running 5.38s. 60 14 as well with an sm465 and 40s. The 14 bolt has the pinion support which means there no trying to climb the ring gear. The front im a little worries about but im real easy on stuff....so I think.

If it gives me trouble ill do the jantz setup. He has a kit to put a dana 70 ring gear in a 60...theres also a load bolt which is probably a major benefit even if you didnt do the bigger 70 ring gear.

http://www.jantz4x4.com//jantz.php?p=detail&pro=load_bolts
Click to expand...

They still break , 14-bolts , 60's and 70's doesnt matter what you do the small pinion is inherently weaker

You may not have any issues , but I can tell you this we have seen enough failures that most of us have gone away from super low axle gears and gone with extra reduction from the t-cases and/or rockwells
 
yellowK20 said:
They still break , 14-bolts , 60's and 70's doesnt matter what you do the small pinion is inherently weaker

You may not have any issues , but I can tell you this we have seen enough failures that most of us have gone away from super low axle gears and gone with extra reduction from the t-cases and/or rockwells
Click to expand...

Its still an upgrade. Nothing is unbreakable.

The guy who took 3rd in the top truck challenge runs the jantz stuff and puts down about 600hp on 43s. I dont know what his gear ratio is but ill never make that much power lol. Most of our trails are a blazing speed of 3mph at most.
 
wetoolowdingbangow said:
Its still an upgrade. Nothing is unbreakable.

The guy who took 3rd in the top truck challenge runs the jantz stuff and puts down about 600hp on 43s. I dont know what his gear ratio is but ill never make that much power lol. Most of our trails are a blazing speed of 3mph at most.
Click to expand...


Well I'm gonna go with my personel experinces on this one isntead of what I see and read on the interwebs

No one really runs big power up here, it would use way to much fuel , and our trails are definetly low speed . We do have big tires and heavy rigs though. The breakage we see is when things are bound up and it literally snaps the pinion in two. No amount of special load bolts are Jantz setups will prevent that ,
 
yellowK20 said:
Well I'm gonna go with my personel experinces on this one isntead of what I see and read on the interwebs

No one really runs big power up here, it would use way to much fuel , and our trails are definetly low speed . We do have big tires and heavy rigs though. The breakage we see is when things are bound up and it literally snaps the pinion in two. No amount of special load bolts are Jantz setups will prevent that ,
Click to expand...

Good for you. Very smart indeed.
 
I ran 5.13s with a 454-400-205 on 40s for years in my Suburban and it was OK. Not spectacular but it wasnt horrible. I have since went to 5.38s and a 203-205. That being said the 5.38s now come in thick gears which is nice, and the difference between the .13s and .38s as far as pinion size is nil. Go 5.38s.
 
I have a Jantz "Jana 76" conversion in my 60, it's cool but it's a big mod. You have to modify the inner pinion bearing race pocket and grind a ton to clear the ring gear. I had my ring turned down 1/4" and still had a ton of grinding.
 
I run 5.86 with 44" ( Worn down to 40" ) Boggers in the rocks. I've broken one gear set...My fault for not changing worn bearings....For what little driving I've done on the road, I like what it drives like.
The last place I worked,I used to drive a 1990 2wd Super Duty, non turbo 7.3 with 5.86 gears in it. It rolled down the road just fine with the stock tires on it. Put it in 1st gear and you could pull a house down.
 
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