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9 inch + 35s

4K views 31 replies 15 participants last post by  helirich 
#1 ·
wasnt sure where to put this. ive acquired a 9 inch to replace my 8.8. id like to lock it and have been considering a spool or even lincoln locking it. its a 28 spline rear end and im currently running 35x12.50s (plan to for awhile too), how should it hold up? im not super hard on my truck but it definitely gets used
 
#2 ·
Might hold up if you can keep your foot out of it. but you wont have a vss to control your speedo or abs. Also affects shift points in an automatic. There is a company that sells a vss relocation kit to move it to the rear output on the tcase but i belive its $300. So you have to ask if its worth it at that point.
 
#8 ·
Id find a locker and some 31 splines. That would be much better then lincoln locking and 28's. if it was me id pull a pumpkin and axles from a yard with 31 splines. Did you use a relocation kit or use a transfer case with vss? Im curious because i swapped in an older tcase that has the vss in it and wondered what needed to be done if i went this route.
 
#21 ·
Here are my recommendations, having broken 9" axles, as well as 8.8's :)

use the 9!! but get some 31 spline shafts from the JY for it. you will regret 28 spline, especially if you start spending money on it (lockers and stuff) it's a very cheap upgrade and well worth it.

you can get used detroit lockers online for around $300.. that is a smoking hot deal, i've bought a couple of them and they work fine. they are 31 spline!

DO NOT spool/weld your rear, it will be HORRIBLE on the street, i repeat HORRIBLE. not only will it be extremely dangerous on slippery roads (as in you turn the wheel but keep going straight, and crash into a tree, ask me how i know) but it will also cause a ton of forward/backward torque on the axle shafts causing them to stress fracture and break in short order. also your tires will wear out very quickly.

i have converted two vehicles to "locked" rear ends, regretted it both times, and converted both of them back. took me twice to learn. don't do it!

also FYI a 9" from an 80-86 f-150 or bronco is a BOLT IN swap for your 8.8
if the axle you have requires retrofitting, it might be worth just getting a whole new 9 from the JY instead of trying to upgrade/fit the 28 spline one you have.
all 80+ ford truck/bronco 9's are 31 spline.
 
#29 ·
A 9inch with 31 splines and a Detroit locker should be a good combo for you with a stockish motor and under 38" tires. Your 28 spline axles will be a weak point that you will regret. A Detroit does have some quirks when street driven but is very livable.

I have twisted off three 31 spline axles and destroyed a couple of third members before going to a spool and 35 splines but I am running a bit more than stock HP ..... It's all in what your doing with it and torque/HP that you expect to run plus tire size.
 
#30 ·
I twisted the splines off a new 1541H 31 spine axle using a Yukon Grizzly last August on the Rubicon with my '79 Bronco on 35" MT's. I had thought the Locker gave out because I was still driving on it afterwards. Once back in Phoenix, I took it apart and was amazed at the break and surprised the ol' Bronc was still driving.

The big Bronco is too big for the Rubicon, at least until I get enough seat-time to drive smarter. For everything I've done in AZ, the 35's work well on my 9. I love the stance and ride on those big balloons.

Jim



 
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