28 spline 9" or 31 slpine9"

[ronjon21177]

hey guys
I have a 78 f-150 with a 28 spline 9" in it. I have 38.5 " ground hogs I do have ladder bars on it . But they keep breaking off the axle. Ok i bought this truck like this. It does have a detroit locker in the rear end. Do i just need to find a 31 spline? or 35 if they were manufactured.

 

[wonshot]

yukon 4340 alloy 31 spline. I broke 2 OE31spliners at the carrier, at different times, the side gear splines got F-d too. the new detroit and alloy axles have lasted over 3 years of abuse with 36/12.50 swampers

 

[ronjon21177]

ok i guess i need some real tech info. The truck currently has 28 splines i dont really put the truck in a real serious issue except flexing. the diff has 380 gears front 350? i haven't tore into it yet. also if any one could help on the ladder bars are for axle wrapping . i fell like i really havent put the truck in a serious manor to even acomidate for this option. ladder bars are they neeeeeeded?

 

[hillbilly]

ok i guess i need some real tech info. The truck currently has 28 splines i dont really put the truck in a real serious issue except flexing. the diff has 380 gears front 350? i haven't tore into it yet. also if any one could help on the ladder bars are for axle wrapping . i fell like i really havent put the truck in a serious manor to even acomidate for this option. ladder bars are they neeeeeeded?

first off front and rear gears need to be the same! front go's the same distance as the rear right? ladder bars might be braking because instant center not the same. new term I know. draw an line (in your head or on paper what ever) picture axle center and rear leaf spring bushing , draw that line. now same thing axle center to ladder bar front mount.were these lines cross is your instant center.point must be ahead of front rear spring bushing. does that make sense? if this is not the way it works out,your rear suspn. will bind. as it travels. under stand? if you want to lose ladder bars, just make spring clamps for all of the leafs in front of rear axle(2IN.X1/4IN. steel to clamp leaf spings together,use 1/2in. grade 5 bolts,thats ones with 3 lines on the head) that should control axle wrap up and wheel hop. hope this is clear enuff to understand. from the mountain .hillbilly

 

[s_reynolds_04]

I had 28 spline axles in my 83's F-150 9inch rear. i had trouble breaking them to. im running 39.5 swampers. i got a set of moser 35 spline axles from jeffs bronco graveyard. i also got a detroit locker for the 35 spline axles and haven't had any more trouble. The axles will set you back 435 dollors and the locker will cost you about 500. it will be well worth it.