ah damnit....carrier swap in 8.25

so...my tranny has been refusing to upshift at all the last day....engages R D N P all fine....just wont upshift....so i did a tranny flush....and what do you know....nothing...then i realized...hey my back end isnt super tight like it used to be....

i have a 8.25 rear i bought with the 27 splines welded....and extra carrier and 29spline shafts/gears....

i pulled apart teh rear end and sure enought the welds are all but destroyed...
so im thinkin this might be stressing tranny makin it not want to shift (correct in thinking here?)

so i decide to swap out for the 29 spline...lil to my knowledge this means you ahve to change the carrier too?!...

so now here i am....wth my jeep on jacks and an empty rear end....i can get carrier in but its too stiff to turn...(yes jeep is in neutral)
and i dont knwo what the hell im doing....
is this something i get some hired help on...or something i can figure out on my own?...


thanks...

im not really seeing what your doing here with the carrier

if your tranny isn't shifting i dont see what that has to do with your rear end

but if you want to swap to a 29 spline rear you can just install 29 spline spiders into your old carrier i believe. the carrier should be pretty tight in there, but you should be able to turn it by hand

I don't believe you can just swap the carrier and shafts from a 29 spline into a 27 spline housing, a buddy tried to swap his and found out mid swap it wouldn't work, ended up haveing to put everything back together and swap the entire axle.

And you need to have the tools and knowledge to set up the gears too.

wishihad1 said:

but if you want to swap to a 29 spline rear you can just install 29 spline spiders into your old carrier i believe.

Click to expand...

Won't work! The 29 spline carrier is different from the 27, the bore that the side gears go into is larger on the 29 and will only fit the 29 spline side gears.

If the rear is locked up and the welds have let go from the LL then I would bet you have some major damage to the pinion bearings and the carrier bearings. Gear lube will pick up metal and carry it due to its thickness and if something lets go its a sure bet it will not just fall to the bottom of the diff. I would find another rear end at the JY or hire someone to fix it for you. You will need several "special tools" and some knowledge of gear set-up.

wishihad1 said:

im not really seeing what your doing here with the carrier

if your tranny isn't shifting i dont see what that has to do with your rear end

but if you want to swap to a 29 spline rear you can just install 29 spline spiders into your old carrier i believe. the carrier should be pretty tight in there, but you should be able to turn it by hand

Click to expand...

Sounds like the rear gears/pinion/carrier are toast. There should be someone Colorado Springs that can do a gear setup for you. At this point you're probably in over your head unless you have the special tools to adjust carrier preload/backlash.

wishihad1 said:

im not really seeing what your doing here with the carrier

if your tranny isn't shifting i dont see what that has to do with your rear end

but if you want to swap to a 29 spline rear you can just install 29 spline spiders into your old carrier i believe. the carrier should be pretty tight in there, but you should be able to turn it by hand

Click to expand...

well i was thinkin if there was an extreme load on the tranny it would not shift....(like going up really effin big hill or somehting)
and with the welds being toast i was thinkinit was binding up the spider gears in a not so fun way causing there to be heavy load on tranny...(see where im going with this?)
so i tried puttin in the 29 splines but like every1 said they are too large diameter to fit in 27 spline carrier...so i have the 3.55 gear 29 spline carrier....just not the tools or knowledge of how it goes in...
gonna drop axle and take it into my work see if our mechanic can do anthing aboutinstallin it...
if not..FRANK Z i amy have to buy some of your time and knowledge....

in4aride said:

and with the welds being toast i was thinkinit was binding up the spider gears in a not so fun way causing there to be heavy load on tranny...(see where im going with this?)

Click to expand...

Nope, I don't see where you're going with that.

The welds Dutch did in that axle were to intentionally bind up the spiders, thus causing both tires to positively engage. That's the purpose of the welds.......:twak: Just think that through a minute...... if the spiders bind up, you essentially have a solid locker.

Anyway, the others are right, the rear axle isn't causing the trans to not shift. If it were possible for the rear diff to jamb up enough to cause a load and overwork the transmission, you'd be having to press the gas pedal down a lot more to get the trans to work harder....... make sense?

Frank suggested you clean up the contacts in the Neutral Safety Switch - not a bad idea, but I'd think moving the shifter handle in and out of gear, park and through the gears would cause the contacts to work occasionally...... but stranger things have happened.

The TCU - Transmission Control Unit is easy enough to swap out and should be cheap at the yards.

You say you have a newer year engine, but are you still using the Renix computer and fuel system? If so, then all you have is a slightly better Renix and that shouldn't cause issues with the transmission.

Probably be cheaper off to get an entire 29 spline axle out of the JY instead having someone set up gears in your axle.

Maybe, but right now is the best time to go to 4.56's or 4.88's.

well yes lookin into another axle...i bit cheaper...keep the old one for when i do re gear i can do it whenever the hell i feel like


yella wit the neutral safety switchconnection being bad/dirty...would this be a symptom?:
i cand get to about 25 or so in first(ya i bit up there in the rpm) when i let off throttle rpm dies to idle and the jeep basically coasts...no engine brakeing nothing..jsut coasts...if i aplly the throttle again it free revs until the rpm is enough to move the jeep fster....



and ya i see where i was SUPER dumb with the binding idea...just trying to find the symple solution cuz i hate electrical and dont know squat about anything else (but im learning)

no wories frank i am going to try and take a look at my NSS...lol...i AM listenin...just no time yet/...doing axle swap and then tryin to look at tranny tonight..(work again tomorrow..so much for day off...)


but i jsut found something...


there was a hose/line hangin from my jeep....fell around the cross member...it was really dry and cracked and thats about right when the jeep started this stupid nop shift crap...is there any relavant vacuum lines/hoses on outside of tranny that could cause some issues too?

any pics of tanyy and or vaccum lines would be great if ya have any..im searchin too.....thanks

well i pulled out NSS to clean and check out...to say it was gunked up is an understatement

but sadly....(and i know its a suprise that I broke/stripped a bolt) i need to replace the bolt...


any advice where to get?

nevermind.....love the junkyard...lol

The hose is probably the breather hose from the tranny or t-case. I've never stripped the tranny selector shaft, thats gotta suck! All of the NSS's that I have done for myself and other people have just fallen right off.

ya well everyone that was on the NSS bandwagon im hopin have some other solutions....i fixed that broken piece.....and the NSS is SPOTLESS!!!!!!!!!!!!!
and still nothing...acts EXACTLY the same way....no better no worse....well actually now its a lil harder to find drive....its a lil below the indicator mark....who knows....ive got full covergae...i think imma go blow this jeep up in the @!#$!#%^! mountains and start over.......

xjtrailrider said:

The hose is probably the breather hose from the tranny or t-case. I've never stripped the tranny selector shaft, thats gotta suck! All of the NSS's that I have done for myself and other people have just fallen right off.

Click to expand...

well the coming off part was easy....gettin it to go back on was a lil more tight...and thats how it broke....lol

If any of you have an extra C8.25 29 spline, open carrier.......I would be interested in it if you do not need it.

Uncool Hijack.

Go look in the Classifieds, or look in your local forum.