What about a 7.5" axle, 33" tires...and 5.13 gears ?


JoseBronco

15+ Year Member

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Mar 1, 2008
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1984
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Hi,
I had reading something about the 5.13 gears for 7.5 axles, something like that gears are not strong enough to take trail driving. I would like to know some experiences with that gears. My BroncoII has actually 4.56 gears. I will install a front D35, and I would like to mantain the rear 7.5" .

Thankyou for any info.
 
I doubt the 2.9 has enough torque that you would actually break something with the 5.13's. If you swap up to anything more, like a 5.0, you'd probably want to change it. 33's you shouldn't have any problem though.
 
From I had reading, the problem is not the factory engine torque (I have a 2.8L) , is the tooth of the gears are too small or so, and it breaks easily ¿?

Forgot to said it, I also have a Detroit Locker in it. Never had a problem, but I do not want to start with rearend problems by just swap in 5.13s.
 
I have the 7.5 with 4.56's in my Ranger and I was told that the 5.13's pinion gear is too small in diameter and will snap under a certain amount of load. Like if spinning wheels on dirt and then them grabbing when hitting pavement.




Allen
 
With the 2.8L engine, you may be OK. The pinion head does get pretty small with that ratio though. I wouldn't romp on it at all.
 
whats the worst that could happen you could distroy a 7.5 and blow the mony you used on gears.. i just had 373s with my 33"s and i didnt have much of a problem. but if you have the $$ give it a go!! Look at the bright side if it breaks then you have a reason to find a 8.8 31 spilne.

Ben
 
Great point liteflop!

One of the main reasons why I did'nt want to do that gear size in my 7.5 was becuase of the pinion size. I might reconsider now though because I would really love to run 33's eventually. I was thinking I had to swap in an 8.8 but I guess I was thinking "inside the box" huh?



Allen
 
Who cares how small the pinion is? As long as the gear (from the tooth valley) is the same diameter or greater than the pinion shaft, it should be plenty strong enough. And I'm pretty sure the gear is bigger than that on a 7.5 5.13 gearset.

It can't be much smaller, if smaller at all than the 5.13 pinion on my D35, and I can romp on that with no problems, and that's with a 4.0L. EDIT: Granted, that is on the front axle.
 
Last edited:
Yeah, there's a big difference in load the axle is subjected to when out back vs. up front.

I'm usually careful if I have to reverse up an extremely steep hill any distance (which transfers most of the load onto the front).
 
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