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27 spline vs 29 spline stregth (searched)

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MPETESS10

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Discussion starter · #1 ·
how weak is a 27 spline compared to a 29 spline
I have a 99 with a 29 spline but I wanna upgrade to 3.55's from my 3.07's
and the cheapest way to do that is to buy a complete diff from the local u-pull-it for 60 bux
96 and olders are ALOT more prominent in the yard which means I have alot more vehicles to choose from if I go with a 27 spline
plus it appears there is a few more choices for lockers for 27 splines

my jeep will be more a daily driver than anything but with a little weekend wheeling here and there
but even in stock form the 3.07's just seem weak to me
I plan on upgrading tires but probably only to 30x9.50's
maybe at the absolute max I might go with 31's but I do plan on locking it

is it really that much of a step backwards going from 29 to 27 spline
the way I see it is alot of you guys wheel the crap outta 27 spline XJ's with 31 and even bigger so why is it really a step back on a jeep thats mostly a DD
and I dont plan on getting rid of the 29 spline so if I ever decide to go bigger I will still have the 29 spline laying around for upgrade purposes
 
#2 ·
Its like putting a D35 back there. A 8.25 27 spline is if I remember correctly, just as weak as a D35. A 29 spline 8.25 is comparable to a D44.
 
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#4 ·
MPETESS10 said:
how weak is a 27 spline compared to a 29 spline
I have a 99 with a 29 spline but I wanna upgrade to 3.55's from my 3.07's
and the cheapest way to do that is to buy a complete diff from the local u-pull-it for 60 bux
96 and olders are ALOT more prominent in the yard which means I have alot more vehicles to choose from if I go with a 27 spline
plus it appears there is a few more choices for lockers for 27 splines

my jeep will be more a daily driver than anything but with a little weekend wheeling here and there
but even in stock form the 3.07's just seem weak to me
I plan on upgrading tires but probably only to 30x9.50's
maybe at the absolute max I might go with 31's but I do plan on locking it

is it really that much of a step backwards going from 29 to 27 spline
the way I see it is alot of you guys wheel the crap outta 27 spline XJ's with 31 and even bigger so why is it really a step back on a jeep thats mostly a DD
and I dont plan on getting rid of the 29 spline so if I ever decide to go bigger I will still have the 29 spline laying around for upgrade purposes
Click to expand...
4.10s and 30s FTW :drool:

Seriously if the Jeep is never gonna be more than 31s it won't matter at all....in fact the only 8.25 breakage I ever see are 27 spliners with 35s.
 
#5 ·
go with an older d35, non c-clip, i *think* that it would be an 88 or older xj. that way, if incase you do break an axle, the tire wont fall off, and since you said you wont ever go over a 31, a d35 would be fine.

:thumbsup:
 
Discussion starter · #6 ·
thanks for the tip
I will keep those in mind
although since I have a 5 spd I willprobably stay away from a D35 tho strictly because locked with 31's and the added stress and driveline shock from a quick lift off the clutch pedal could be equal in my mind to the stress of 35's

plus it seems like all the XJ's I have looked under at the yard that have d35's they seem to be leaking something FIERCE
theyu rae al always COVERED in sludge and grease and grime
leads me to beleive there was issues with pinion seals on thos diffs
is there any truth to that thought
 
#7 ·
BIGNUTT said:
People are tell you wrong if you think a 27 spline 8.25 is as weak as a d35.
Click to expand...
Exactly.

I'd say the 27 spline is a little better than the D35, yet the 29 spline is almost comparable to the D44.

So basically Dana 35 < 27 spline < 29 spline < Dana 44

I killed my Dana 35 within months of getting my Jeep and I'm only on 31's. Now I have a 27 spline back there (I think)... It came from a 96 XJ.. Dunno if it was late model or not. Been too lazy to pull & count, to see if I lucked out and got a 29. It was free, so I'm not complaining.
 
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#8 ·
tvisXJ said:
Exactly.

I'd say the 27 spline is a little better than the D35, yet the 29 spline is almost comparable to the D44.

So basically Dana 35 < 27 spline < 29 spline < Dana 44

I killed my Dana 35 within months of getting my Jeep and I'm only on 31's. Now I have a 27 spline back there (I think)... It came from a 96 XJ.. Dunno if it was late model or not. Been too lazy to pull & count, to see if I lucked out and got a 29. It was free, so I'm not complaining.
Click to expand...
how hard were you on your jeep when you broke ur d35? i have a 29 spline 8.25, and i am also on 31's and i have never been really hard on it, i have done 1 big burnout before i got my 31's put on. and it held up to that. also, i have heard that the 27 spline and the 35 are about the same strength wise. so, i donno if the little added strength makes up for the 27 spline being a c-clip.

EDIT: but, the 89 and newer d35's are also c-clip axles as well, so look for an older cherokee to pull that out of if your looking for that

-Jeff
 
#9 ·
I would say get the 29 spline just in case you ever went bigger tires. I have my 29 spline on 34" trXus locked and I wheel it pretty regularly and no issues.

Its all how you drive
 
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#10 ·
You Most Likely won't break the C8.25 29spline as long as you don't go up to 35s w/ lockers, and even then you can always rebuilt the axle to make it beefier.
And I wouldn't even think about swapping in a 27spline due to the fact that you already have a good axle and don't need to get rid of it.
Everyone had said this.. but you don't really have to regear 'til you go up to 33s
:) :thumbsup:

I must refer to Ericsxj's book again; there is a jeep with full armors, 31x10.5s, limited slips front and back with only 3" lift that conquers Rubicon with ease, lie xjrrrdx has already said, it's all how you drive :thumbsup:
 
#11 ·
the 27 spline 8.25's advantage over the dana35 is its 3" axle tubes. I'd have a little more piece of mind having it under my jeep than a turdy5. But, i have a 28 spline, so i don't have to worry about that :laugh:. As for the regearing to 3.55, I would just suck em up and keep the bonus strength and higher gears. If you could find a wrecked 97+ auto xj though, you could snatch the 3.55's out of that and shove them right in yours. And if it's in a wrecking yard or pick n pull, why not save a little cash and just gut the axle and take what you need instead of paying for the whole axle...
 
#12 ·
white98xj said:
how hard were you on your jeep when you broke ur d35? i have a 29 spline 8.25, and i am also on 31's and i have never been really hard on it, i have done 1 big burnout before i got my 31's put on. and it held up to that. also, i have heard that the 27 spline and the 35 are about the same strength wise. so, i donno if the little added strength makes up for the 27 spline being a c-clip.

EDIT: but, the 89 and newer d35's are also c-clip axles as well, so look for an older cherokee to pull that out of if your looking for that

-Jeff
Click to expand...
I wouldn't say I was all that hard on it, but I wouldn't say I babied it either. I changed the fluid just after I got the Jeep and the old fluid looked fine. I'll take a pic of the gears one of these days. I just shredded them :D
 
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#14 ·
another 35inch tire user using the 29 spline 8.25 rear end right here :)

i'll be locking it soon. Either way, if you're only gonna be running 30s, you won't really have to worry about breaking the 27 spline 8.25, so it's pretty much up to you and what's available in your area.

my personal judgement would say to search around for a 29 spline 8.25 just because it's a direct swap in just like the 27 spline, so you might as well go that route.
 
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