What is a spline?

[modelbuilder]

I am trying to figure out if my Grand has a certain type of spline...Chrysler 8.25 29 spline.

Not sure if its in the 05 WK. I looked in the 7,000 page factory manual I have and nothing came up.

[Root Moose]

Splines are the long grooves in the end of the axle shaft that engage the spider gears inside the differential. There is nothing external to the axle that will allow you to determine what the spline count is. That said, I'm 99.99% certain all ChryCo 8.25" rear axles switched to 29 spline (from 27) sometime in the mid-late 1990s.

Are you sure what axle you have in your Jeep? Likely it is a ChryCo 8.25" but I'm not up on WKs; did they offer other axles?

[FlexdXJ]

I am trying to figure out if my Grand has a certain type of spline...Chrysler 8.25 29 spline.

Not sure if its in the 05 WK. I looked in the 7,000 page factory manual I have and nothing came up.

That is the number of splines used on the axle shafts.I am guessing it would be a 29 spline as they were used in the Cherokee's after '96 replacing the 27 spline. not sure what rear axle a WK would have though.

[tdesanto]

I am trying to figure out if my Grand has a certain type of spline...Chrysler 8.25 29 spline.

Not sure if its in the 05 WK. I looked in the 7,000 page factory manual I have and nothing came up.

These are the ridges on the end of an axle shaft. As far as I know, a 29 spline is the number of discrete ridges that it has.

For example, the rear diff in my Montero has 33 splines, the front, 28.

More info here (http://en.wikipedia.org/wiki/Rotating_spline), and here (http://www.pirate4x4.com/tech/billavista/PR-BV60/index1b.html).

[Exrunner]

*thinking, thinking* Should I tell him what splines are too??? *thinking*

ha ha...jk.:elkgrin:

[modelbuilder]

Found out my rear axle is 8.3" and is something called the Corporate...I guess there is no chance it will fit an 8.25" locker right.

[Exrunner]

Corporate? Hmmm. I thought that was a GM axle...Corporate 12 bolt, 14 bolt, etc??? In any case, no that Chrystler 8.25 locker will not work. Where did you find the information?

[modelbuilder]

On this website....

http://www.wkjeeps.com/wk_specs.htm#REARAXLE

[Exrunner]

ok, and whats your engine? Do you have the elec. limited slip? Do you know your gear ratio? I see nothing on there that says Corporate, but I do see Conventional. Im not sure what that is...maybe thats the Chrysler axle? Another thing you need to do is get on the ground under the Jeep (best place in the world by the way) and look at the markings on the axle...they can tell you a lot. If you need some help, take pics of the symbols and post them here and we can help identify.

[ntsqd]

8.25" rounds to 8.3"; Chrysler is 'corporate' to a Jeep. I dunno, I wouldn't give up yet.

[Exrunner]

I see where youre going with that, but Ive always seen the 8.25 referred to as an 8.25, never as an 8.3.

http://jeepspace.jeepforum.com/tednelson83
"told it is an 8.27 inch ring gear, slightly better than 8.25"

http://www.offroadadventures.com/articles/view/id/256
"the modern version of the Mopar 8.3"

http://www.jeepcommander.com/forums/showthread.php?t=4830&highlight=corporate+axle&page=2
Look at post #13 here.

According to a googled "mm to inches" website, 213 mm (whats on the page provided by the OP) is almost 8.4 inches. so thats strange.

[Root Moose]

"Corporate" is not a company per se, it is a reference to the manufacturer in question building their own axle.

GM Corp axles are GM axles. ChryCo Corp axles are ChryCo Axles. You could argue that a Ford 9" is a Corporate axle (as in Ford Corp) but no one calls them that.

The ChryCo 8.25" doesn't have a ring gear that measures 8.25". It may have been once upon a time but it doesn't in production the last 20+ years AFAIK. Kinda like the current Dana 44 in a JK isn't really a Dana 44 per se.

ntsqd is on the correct track I believe. 8.3 is probably someone's sloppy cut-n-paste from a spreadsheet with the field width set incorrectly.

[Exrunner]

The ChryCo 8.25" doesn't have a ring gear that measures 8.25". It may have been once upon a time but it doesn't in production the last 20+ years AFAIK. Kinda like the current Dana 44 in a JK isn't really a Dana 44 per se.

Just out of curiosity, and not trying to hijack, but why isnt the JK 44 really a 44?

Otherwise, you guys are probably right...why would they change the axles around so much for only fractions of an inch difference....8.3 is prob 8.25.

[Root Moose]

I forget the details but IIRC it has different bearings, the ring and pinion may be different in some way as well... either configuration or involute shape or something. I think I read somewhere they wanted to call it a Dana 48 or something but marketing said "noooooo!".

If you price some parts I think you'll see that there is a break point for the Dana 44 in 2006/2007. Different prices and part numbers on either side of that date for Wranglers. The change is a bit more than just the "thick" gears that TJs used (which is different from traditional Dana 44s yet again).

[ntsqd]

Late Jeeps use a D44 variation that has a shorter pinion gear shaft than the 'traditional' D44.

I'm not saying that the axle in question is the "Mopar 8.25", just that the evidence wasn't conclusive. Were it me I'd call one of the reputable axle shops (Tri-County Gear comes to mind) or one of the Differential mfg's and ask them about the axle.

[herdnerd]

You used to be able to contact Chrysler here (http://www-5.jeep.com/wccsapp/universal/J/index.jsp?appStr=wccs&titleStr=Contact+Jeep&familyStr=brand&franchise=J&actionURL=%2Fwccs%2Fbrand_forms%2Fus%2Fwebform.jsp&promotion=null&category=U) to request the build sheet for your Jeep. It should tell you exactly what axle you have.

[Waytec]

Here is a chart that my help. There are other charts available as well you will gust have to look on the net.
http://coloradok5.com/axleguide.shtml

[modelbuilder]

The 4x4 Commander has a C213R (Corporate 8 1/4). The ring gear diameter is 213mm or about 8 3/8".

What is the difference between the size of the Axle and the size of the ring gear diameter?

And how does this relate to the Spline? How can it be a corporate 8.25" axle and have a 8.3" ring gear diameter.

I contacted Jeep as well.

[StumpXJ]

Post a picture of your axle....


~James

[DaJudge]

The only axle I can find listed for the WK is the Chryco 8.25. (I have seen SRT8s with Dana 44s though). They switched to 29 splines I think in '96 so it should be a 29 spline. (although I would do more research to make sure of the spline count.)

If the cover is round and there is a flat line on the bottom of the axle housing looking at from the rear then it is a 8.25.

Here is a complete parts diagram so you can get an idea of how they look.

http://www.moparpartsamerica.com/partlocator/index.cfm?action=getJointLocator&siteid=214583&chapter=&Sectionids=23,0&groupid=10047&subgroupid=60093&componentid=0&make=17&model=Grand%20Cherokee&year=2005&graphicID=T048100&callout=23&catalogid=1&displayCatalogid=0

[modelbuilder]

Here is my WK Axle...

Thanks for helping me ID it!!

http://picasaweb.google.com/caprica75/Axle#





.

[Exrunner]

looks like the 8.25 to me, although your pinion yoke bolts are much larger than whats on my XJ. It does have the 10 dif cover bolts though, and everything else looks similar to me.

[modelbuilder]

So you think it will fit the 29 spline 8.25" aussie locker?

[StumpXJ]

Looks like my 8.25 as well, but like exrunner said, your pinion area looks different. Could just be the difference of models.

You could always buy it and try... if it doesnt fit, I will buy it from you. :)

~James

[StumpXJ]

Also, if it is indeed a 8.25, you should definitely have the 29 spline. My 96 is a 29 spline, that was the transition year from 27 to 29 spline.

~James

[modelbuilder]

Really? Sweet.

I think I'll go down to my local shop and have them open it up.

Get back to you soon.

[Exrunner]

another thing you could do is take off the dif cover and look in the carrier and try to count the splines and measure the ring gear. If its 29, youre probably good to go, and if the ring gear is 8 and 3/8ths or so, I think thats about right too (just from what Ive read on the web). Let us know what you hear from Jeep.

[modelbuilder]

Sounds good. I'm taking it to an off road shop on Saturday. I'll let everyone know.

[modelbuilder]

My rear Axle is a Variable Lock Differential.

Aussie said that even though my rear axle is a 29 Spline, 8.25" Corporate, the locker will not fit into the carrier. Hopefully I will get better news tomorrow.

Bummer!!!!

[FlexdXJ]

My rear Axle is a Variable Lock Differential.

Aussie said that even though my rear axle is a 29 Spline, 8.25" Corporate, the locker will not fit into the carrier. Hopefully I will get better news tomorrow.

Bummer!!!!

You will have to buy an open carrier for it so you will have to replace the LS carrier with the open carrier. I have the same problem!

[modelbuilder]

You will have to buy an open carrier for it so you will have to replace the LS carrier with the open carrier. I have the same problem!

How much money are we talking here?

[FlexdXJ]

How much money are we talking here?

It shouldn't be too bad for the part just as long as you don't go to the dealer for one. I have no idea of what you will have to do to the axle. They may have to set the gears up again to make sure you backlash and everything is good but i would say it is worth if for more traction. I plan on getting a front selectable locker before a rear locker, so i'm not too worried about it for the time being. It will eventually be swapped out with an explorer 8.8 for a little bit of overkill and disc brakes.

[Root Moose]

In order to replace the carrier you will need to have the gears set up again. That can run anywhere from $200 to $600 in labour depending on where you are located.

Personally, at that point I'd replace it with a full case locker since the whole thing needs to be disassembled anyway.

I'm not familiar with the "variable lock differential". Is this a clutch pack based diff? What drive system do you have in your Jeep? Select-Trac? Quadra-Trac? Just wondering if you are replacing a part that the electronics are relying on for feedback.

[modelbuilder]

I have Quadra Trac II.

[Root Moose]

Doesn't that system have some kind of a feed back from the differential when it senses slippage? IIRC it uses the ABS sensors to feed the system data.

There is this video of the system in action but I did't pick out anything about feed back.

http://www.youtube.com/watch?v=o1TqECPDCTM

I'd be REALLY leary of changing the rear diff without more research. I'm guessing that a true locker will not be compatible with QT-II.

[modelbuilder]

That Wk has the Quadra Drive system. It has an electronic rear locking diff.

The Quadra Trac II system has only a center locking diff. The rear axle is not locked when it is put into 4low.

I think a full carrier replacement locker would probably work. But I don't think I can afford that!