Topic: front axle shaft

[pioneer4x4]

i have and 86 xj 2.5l dana 30 reverse cut axle up front and i was wondering if any of yall have locked the fork in the 4wd actuator housing using washers so it keeps the collar engaged on both ends of axle all the time? is there any drawbacks to doing this? its my dd so im currious. ive heard people say it will affect gas millage, but i dont see how since ur still pushing the front wheels anyway if there locked together or not. the only thing i can think would be different is turning, but how bad/different is it? also wondering if it affects the differential to work more or not, dont think so, but thought id ask. i plan on doing a home made posi lock set up, just want to go wheeling this weekend and if it doesnt have any bad dd effects ill just leave it and save the $$. thanks in advance.

[sharpxmen]

i have and 86 xj 2.5l dana 30 reverse cut axle up front and i was wondering if any of yall have locked the fork in the 4wd actuator housing using washers so it keeps the collar engaged on both ends of axle all the time? is there any drawbacks to doing this? its my dd so im currious. ive heard people say it will affect gas millage, but i dont see how since ur still pushing the front wheels anyway if there locked together or not. the only thing i can think would be different is turning, but how bad/different is it? also wondering if it affects the differential to work more or not, dont think so, but thought id ask. i plan on doing a home made posi lock set up, just want to go wheeling this weekend and if it doesnt have any bad dd effects ill just leave it and save the $$. thanks in advance.

the difference is that with the collar disengaged you only spin the spider gears, when engaged you spin the hole diff carrier and the front driveshaft - it won't affect your turning unless you have some autolocker or spool, that's what my understanding is. there is also a matter of spinning the driveshaft at high speeds as well, on YJs i read that they are not balanced in the front, so that can cause some vibrations if not other issues in time - but again that also depends if yours is balanced or not.

Apparently some TJs (i think, not sure) have a 1 piece passenger axle in the Dana 30 - that could be a better option if it would work in your axle rather than locking the collar), but the result would be the same other than i think a more solid setup with the 1 piece axle.

Some pple replace the vac actuator with a cable setup and weld the spider gears or use a full spool in front and engage the axle shaft collar when they want to lock the front, other than that would be basically 3wd when you have the t-case in 4wd - can't speak for how well it works or not since i never used it that way.

[Jeffy]

Apparently some TJs (i think, not sure) have a 1 piece passenger axle in the Dana 30 - that could be a better option if it would work in your axle rather than locking the collar), but the result would be the same other than i think a more solid setup with the 1 piece axle.

Actually, ALL TJ's and all '96 and up XJ's as well as the ZJ's, KJ's and everything else after 1996 have front axles that turn all the time.

So yes, you will probably lose some mileage since everything has to turn which causes parasitic drag.  If you have a spool or a LSD you will have understeer.  An auto-locker would at least unlock when turning so it wouldn't understeer.

Instead of screwing around with the vacuum disconnect and still having the two-piece housing as well as shaft, I would look to get a late model axle that is hi-pinion and without the disconnect.  D30's are pretty cheap.

Oh and those Jeeps with disconnects, the front driveshaft might not be balanced for high speeds which will cause vibrations as it's turning all the time.  Also, seals tend to seep a little as they aren't used to being used now.

[pioneer4x4]

this may seem dumb cause i still dont fully understand how the diff works, but i dont see how sliding the collar over would make the whole diff spin. my front drive shaft spins all the time anyway. i think it makes sense that when i shift tcase into 4wd it extends dshaft or something to make whole diff spin not just spiders, but not just sliding over the callar, but im probably wrong on how the diff engages. i thought that my 4wd actuator was screwed up cause my front dshaft would spin all the time and so i took fork out and ziptied the collar to the right(unenguaged) only to find that the dshaft still spins?

[Jeffy]

this may seem dumb cause i still dont fully understand how the diff works, but i dont see how sliding the collar over would make the whole diff spin. my front drive shaft spins all the time anyway. i think it makes sense that when i shift tcase into 4wd it extends dshaft or something to make whole diff spin not just spiders, but not just sliding over the callar, but im probably wrong on how the diff engages. i thought that my 4wd actuator was screwed up cause my front dshaft would spin all the time and so i took fork out and ziptied the collar to the right(unenguaged) only to find that the dshaft still spins?

The driveshaft should not spin if the vacuum disconnect is disconnected if you have an open differential.

When you're in 2WD the driverside shaft turns since it's always connected to the wheel.  The passenger side is disconnected so it has no resistance and so just the spider and side gears in the differential turn and not the whole carrier.  The stub shaft actually turn the opposite direction, this is why the driveshaft does not turn.  It's a bit complicated to explain so here's a video on how the differential works.  It does not explain how it reacts when not under power though but you can see what's happening a lot easier.

<a href="http://www.youtube.com/v/kJY9SxDOTog&amp;hl=en_US&amp;fs=1&amp;" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">http://www.youtube.com/v/kJY9SxDOTog&amp;hl=en_US&amp;fs=1&amp;</a>

[pioneer4x4]

thanks for the video man i appreciate it.

[DDUBYJ]

been through this a long time ago.   the best way if you are gonna keep the D-30

is to put a lock-rite  or a Aussie locker in it and get yourself a one piece shaft for a TJ

Take the vacum fork completly off and make a flat plate to cover the hole and seal it.

Works great and problem solved. very inexpensive.   

[VA_YJ]

The reason that TJs have a CV front driveshaft is to help eliminate vibes caused by the front driveshaft turning at all times (including highway speeds).  You can pick up a TJ or XJ front CV DS to help with this issue.  The 4 cylinder and 6 cylinder models are differnent sizes (tube diameters).

[sharpxmen]

The reason that TJs have a CV front driveshaft is to help eliminate vibes caused by the front driveshaft turning at all times (including highway speeds).  You can pick up a TJ or XJ front CV DS to help with this issue.  The 4 cylinder and 6 cylinder models are differnent sizes (tube diameters).

regardless if it's cv or not it still needs to be balanced, if the pass axle is 1 piece it will be balanced so if he finds something that matches the length that would work but he'll need to replace the t-case front output yoke in case he ends up with a cv d/s.

[jdarg]

The reason that TJs have a CV front driveshaft is to help eliminate vibes caused by the front driveshaft turning at all times (including highway speeds).  You can pick up a TJ or XJ front CV DS to help with this issue.  The 4 cylinder and 6 cylinder models are differnent sizes (tube diameters).

They have a CV because they are low pinion D30s and the angle is too steep to not use one. With a HP, non-disconnect D30 from an XJ you will be fine w/out one if you don't have one now.

[Bounty Hunter]

The reason that TJs have a CV front driveshaft is to help eliminate vibes caused by the front driveshaft turning at all times (including highway speeds).  You can pick up a TJ or XJ front CV DS to help with this issue.  The 4 cylinder and 6 cylinder models are differnent sizes (tube diameters).

Do not install a CV driveshaft on the front, you will not be able to rotate the pinion up enough in order to run it without vibrations.  IMO bad advice.

Instead of using washers, simply engage the shift collar in the axle and install the disconnect upside down to hold it in place.  A lot easier and cheaper than any other alternative.

[sharpxmen]

Instead of using washers, simply engage the shift collar in the axle and install the disconnect upside down to hold it in place.  A lot easier and cheaper than any other alternative.

hehe, never thought of that - good trick to know :)

[DDUBYJ]

Yopu could flip it but, that don't eliminate the WEAK center shaft. it will break easily.  IMO  one piece shaft is the only way.   

[Jlayne]

older XJ's with the selectrac system did not have the vac axle on them they are engaged full time. i had a 86 wagoneer that used this axle

[Jeffy]

older XJ's with the selectrac system did not have the vac axle on them they are engaged full time. i had a 86 wagoneer that used this axle

Better to use a TJ or +'96 XJ since they have the 279x U-joints instead of the 260x's.

Really though, if you're looking to keep a D30 in there the strongest is the late model XJ's since they are high-pinion as well as having one piece shafts AND axle tube.  Then add the 279x U-joints...