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matts96zj
10-31-2004, 08:10 PM
I'm a noob here, but not to ZJ's. I do all my own work & do ALL my mods on a very small buget :roll: . My question is: how weak is the 29 spline version of the 9"? I already have a HPD44 w cast arm mounts, arms, & brakes that I'm buildingfor the front & I bought this 9" under the impression it was a 31 spline. I only paid $100 bucks for it, but if it's in any way comparable to the turd under my rig, I'll be looking for something else.

LouisianaZJ
10-31-2004, 08:20 PM
well ill put it this way
a D35 is like 27 spline
8.25" chrysler is 29 spline
a iron D44 is 30 spline

so i would not really run over 35's with that 9" rear. i imagine there are third member upgrades that would allow you to convert to the 31 spline shafts but i dont really know too much about that. mabey someone else will chime in

Alaska ZJ
11-01-2004, 12:05 PM
Matt, long time no see.

As for the streangth issue.

A friend of mine tested a 9" this weekend and compared it to a stock 14 bolt. Here are his conclusions.

http://media.diywelder.com/images2/102704-midshaft_IMGP0277.jpg

4600 ftlbs Ultimate Streangth on a 9"

Even at 1.5 diameter it is still not as strong as the 14 bolt 1.380 diameter. Here are the 14 bolt and the 9" side by side.

http://media.diywelder.com/images2/103004-real9comparedto14_IMGP0296.jpg

The 9" shaft is not NEARLY as hard either. Splines are cut at a 45 degree and that seems fine. 14 bolts are cut at 33 degree's.

Other things to consider.

that 9" you have is probably Toting the small bearing as well. Crappy.

Also probably has the small tubes and the thin housing....

Get a 9" out of a F150 or the like. Or check out Sierra Rock Controls housing......Not cheap, but cool.

The HP D44 is just fine for the front.

matts96zj
11-01-2004, 03:14 PM
Thanks for the info!!! I'm gonna truss the 9er so the housing doesn't bother me. The small bearing part & 28-spine shafts do though. I think I'll looke for a used 3rd w/the gears I want & change it over to 31-spline. The axle is out of an F-150... some of 'em actually came with the shitty 28-spline axles... figures I ended up with one. :roll: Anywho, since it's out of an F-150, I should be able to grab 31-spline shafts from any full-size & they'll be the right length.

Kraqa
11-01-2004, 04:16 PM
even tho you will be able to get the 31 splin shafts the bearing race is in the housing. you cannot just go to a big bearining with out changing the outer part of the housing.

matts96zj
11-02-2004, 01:03 PM
thanks alot!!! This is good to know, so I don't waste $$ on a third that won't work. I always assumed all the bearings in a 9" were either pressed on the shafts or in the 3rd. Guess I'll be lookin for another 9. :x

FinlayZJ
11-03-2004, 01:14 PM
Around my neck of the woods you can find 31 spline 9" for $100. It would be alot easier to ditch that one and find a 31 spline.

Check out www.musclemotorsports.com for 31 spline 3rds with detroits and choice of gears for $550 complete. I found them from Pirate, alot of people over there have used them. I got mine for a 79 Bronco and it was big bearing and 31 spline with a "good" housing.