XJ front shaft too far stretched?
 

Im at about 6" of lift and this is the stock shaft with the AX15 manual tranny.
Do you think this is a bit too far for comfort?I'd like to see what a longer front shaft from an auto might net but I fear it could be too long, putting me on the other end of the problem with not enough compression.https://cimg0.ibsrv.net/gimg/www.che...8750afbda.jpeg

It's obviously out there pretty far... A few questions for an educated answer would be... How much spline is left in the yolk at rest ? Then how much at full drop ?? Get too far extended and the weird vibes start appearing on the road at speed...

I have a 6" lift on mine and only have about 1 1/4" of exposed shaft at ride height, so yours appears to be stretched out pretty far. Other than the fact that I haven't had any problems and have wheeled it fairly hard for the last 3 years, can't say for sure if mine is perfect, but hope it gives you a gauge.

Front Drive Shaft Lengths

Model/Year/Engine/Trans/Collapsed Length/Part #

XJ 87/88 2.5 Automatic 27.950 53003912
XJ 89/93 2.5 Automatic 27.970 53005540
XJ 89/01 2.5 Manual 25.310 53005541
XJ 89/01 4.0 Automatic 30.660 53005542
XJ 89/01 4.0 Manual 29.250 53005543
XJ 89/00 4.0 Manual 27.080 Export 53005544
XJ 89/00 4.0 Automatic 28.620 Export 53005545
XJ 87/88 4.0 Automatic Export 53005260 *
XJ 95/01 Diesel 27.640 Export 52098208

ZJ 1993 4.0 Automatic 30.530 52098341
ZJ 93/95 5.2 Automatic 32.870 w/o CV 53008427
ZJ 94/95 5.2 A500 30.625 w/o CV 52087805
ZJ 94/95 4.0 A500 w/o CV 52098790
ZJ 93/96 4.0 Manual 52098344
ZJ 93/96 4.0, 5.2 31.875 w/ 231, 242 52087805
ZJ 93/95 4.0 Manual 30.000 w/231 52088090
ZJ 93/96 5.2 33.000 w/ 231 53008427
ZJ 96/98 5.2, 5.9 31.250 w/ 249 & Model 30 52098379
ZJ 1996 5.2 Automatic 32.875 w/ 249 & Model 30 52098501
ZJ 96/98 4.0 33.000 w/ 242 52098707
ZJ 96/97 4.0 Automatic 31.250 52098850
ZJ 1996 5.2 Automatic 30.750 w/ 249 & Model 30 52099246
ZJ 96/98 4.0 33.500 w/ 249 52099260

Im sure this isn't the first time you've heard this BUT 6" of lift and still on short arms? You'd really benefit from going to a long arm suspension especially if its your DD - future investment*. Doing this will reduce the amount of travel your front driveshaft ultimately needs as well. The amount of travel in your front axle now is greater than what it would be than with a long arm kit. Shorter arms will travel in a more dramatic radius while the long arms have a far less drastic radius.

So where i've gone with this situation to find a suitable D-shaft length involves some wrenching and also use of an engine hoist/cherry picker. Lift the front of the jeep with the engine hoist and remove just the coil springs. You can then cycle your suspension to fully compressed basically set the jeep on your bump stops. If you dont have any then this is the same process for figuring out how long your bump stops should be, even figure out optimal shock length too. Most stick to the 1" rule and set their bump stops to first contact or resting weight contact at 1" separation from anything that could contact. This is to allow a little more squish and a safety barrier from ultimately maxing out. SOO track bar and steering linkage clearance from your oil pan for example. IF at full compression your driveshaft isn't maxed out for compression then your safe (you could measure the exposed shaft to then reference your max length at compression). Similar concept for setting your jeep up with limit straps or longer shocks at extended suspension. Lift the front of your jeep up until you notice binding in your tie rods in your track bar or steering links, or binding in your driveshaft u-joints. Not all of them - you'd have your max drop at the point when the first thing binds. Then lower the jeep again with the 1" rule from maxed extension to have your reference point. Measure your driveshaft length and you'll have your max extended driveshaft length.