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Front drive shaft after TNT LA Install

F

fdsa487

NAXJA Forum User
Location
El Cajon, a.k.a. The Box
I have a question about my front drive shaft length. For anyone that has installed a TNT LA. I moved the axel back into the stock wheel base position after the install (I forget the measurement now) but my drive shaft appears to be to short.

I went to a shop where there put my Jeep on a rack to rotate the tires and I noticed (sway bars disconnected) that the passanger side drooped allot more than the drivers so I went to look at it. The DS looked like it was maxxed out and would not allow any more droop.

I have ~6" of lift 4.5" ZJ springs and a 3/4 inch puck on a 2000 XJ W/ AW4 and a NP231 TC. Has anyone had to lengthen their DS due to extending wheel base? Here is a picture below as the XJ sits on level ground.

It looks like the shaft is supposed to rest in the slip yolk where the paint ends. Is that correct or would that not allow for compression because its so close to the base?

aaaaaa.jpg


aaaaa.jpg
 
The slip/spline shouldn't travel much at all with La's because they are very close to the same length. It does look like you need a longer shaft though.
 
I have the exact same set up as you, except its a 89. Mine is extended but nowhere near how far yours is out.
Are you sure your wb is stock, or did you lengthen it a bit?
Try talking to a driveshaft company locally and see how much it would be to lengthen your ds. That might be a lot cheaper then getting a new shaft.
 
Starboard M said:
I have the exact same set up as you, except its a 89. Mine is extended but nowhere near how far yours is out.
Are you sure your wb is stock, or did you lengthen it a bit?
Try talking to a driveshaft company locally and see how much it would be to lengthen your ds. That might be a lot cheaper then getting a new shaft.
Click to expand...

Im going to have a rear shock mount that busted re welded today at a shop that also does DS work so I'll ask them about it.

The wheel base is pretty close to stock. I don't remember the exact measurement but its like 1/2 an inch less than stock if I remember correctly or mayby 1/2 an inch more. lol I forget.
 
The shaft looks like it is a inch or so extended more than it should be, it shouldnt be at the black line, but about half way
 
My jeep is sitting at about 7 inches of lift with the TNT la kit and I didnt need to change anything with the front drive line. Make sure your caster is set correctly. and the drivers side should come down more but the driveline kind of holds it back. You need to find a happy medium for the caster and the drive line angle for the best movement of the front suspension.
 
There is no way you put your xj back to stock measurements and the driveshaft is to short. When you removed your old arms did you measure from center of bolt to center of bolt on each end of the arm? Caster will not make much of a deference in your drive shaft length. Actually if it was rolled to far forward then it would have helped your drive shaft. But not your steering sense it would steer into the ground. How much adjustment do you have in your long arms? I would adjust these before getting a new DS. I have fullwidth axles, and I used the Rusty's Kit. I was able to push my front axle 4" forward. No reason why you should be short.
 
Okay I found a picture!!!

This is the wheel base measurement AFTER the LA install. What do you think?

aaa.jpg



caglezxj said:
There is no way you put your xj back to stock measurements and the driveshaft is to short. When you removed your old arms did you measure from center of bolt to center of bolt on each end of the arm? Caster will not make much of a deference in your drive shaft length. Actually if it was rolled to far forward then it would have helped your drive shaft. But not your steering sense it would steer into the ground. How much adjustment do you have in your long arms? I would adjust these before getting a new DS. I have fullwidth axles, and I used the Rusty's Kit. I was able to push my front axle 4" forward. No reason why you should be short.
Click to expand...
 
kubtastic said:
low pinion dana 30?
Click to expand...
I think you may be on to something here.
 
I have a 2000 with 5" lift, Stock D30 and TNT LA's, same as you. I had to get a new front driveshaft as my old one was seized up and couldnt' extend further. I previously had longer LCA's and fixed UCAs, which pulled my axle back a bit. When I went to LA's, it did move my axle forward, so my DS was too short.

Chris
 
ckh550 said:
I have a 2000 with 5" lift, Stock D30 and TNT LA's, same as you. I had to get a new front driveshaft as my old one was seized up and couldnt' extend further. I previously had longer LCA's and fixed UCAs, which pulled my axle back a bit. When I went to LA's, it did move my axle forward, so my DS was too short.

Chris
Click to expand...

Cool so your in the same boat. I need to get the DS extended a little bit. Prior to my LA's I had 5.5" lift with RE fixed arms.
You live in SD. I need to see your jeep! =)
 
Guys I don;t think you need a new shaft. The wheel base on my 01 was 101 from the factory. On a drive shaft you should have at least 1 inch of collapse and 3 inches of extension. Ever pulled a DS apart? The splines are quite long inside the shaft.
The concern you should have is: will I flex it to where the shaft pulls apart? and more important, will I collapse the suspension where the shaft bottoms out and damages the T-case. With the travel you have sitting level, I think that's great. If you're not sure, pull the drive shaft, seperate it, and see how much spline is still inside the tube before it falls apart while wheeling. Sitting where you are, collapsing it is not a concern.
Then make your decision on whether to extend it or replace it.

D.
 
DaffyXJ said:
Guys I don;t think you need a new shaft. The wheel base on my 01 was 101 from the factory. On a drive shaft you should have at least 1 inch of collapse and 3 inches of extension. Ever pulled a DS apart? The splines are quite long inside the shaft.
The concern you should have is: will I flex it to where the shaft pulls apart? and more important, will I collapse the suspension where the shaft bottoms out and damages the T-case. With the travel you have sitting level, I think that's great. If you're not sure, pull the drive shaft, seperate it, and see how much spline is still inside the tube before it falls apart while wheeling. Sitting where you are, collapsing it is not a concern.
Then make your decision on whether to extend it or replace it.

D.
Click to expand...

Good call. I might do that this weekend and no I have never pulled one apart.
I have flexed it all the way and looked at it and the DS does not come out enough to see any splines either.
 
when I was at 6" of lift, I had a 30" ds, now that I am at 8, I have a 33 or 34", but it doesn't travel much with LA. It is nice though cause if needed, I have a spare shaft that is 35" which works for either the front or the rear.
 
i would recomend calling tom woods and asking for his input. Unless its long splined you typically only have about 3 inches of spline, so i think that your shaft is probably to short. As for why it is too short, im not sure, but i would guess that it being the LP dana 30 is the contributing factor. I dont know the difference in shaft lengths between the LP and the HP, but you should have at least 1" of spline in the shaft, otherwise your no good.
 
I set my wheelbase based on where the tire is when stuffed.I have both my 95(HP D30) and my 2000(LP D30)set at 100-1/2".My front driveshafts sit at mid-travel and only move about +/- 1/4" during cycling.Since the TNT kit is almost a carbon copy of my builds(Geometry/arm lengths/mounting points) I would look at taking a better wheelbase measurement and adjusting from there.The driveshafts are also interchangeable front to back on both XJ's also.
 
My driveshaft is extended farther than that, and it has never come apart. The front driveshaft is longer than you think. If your axle droops more to one side than the other, it is probably your track bar.
 
Measure your DS from the center of the rear u-joint(just on the shaft not on the CV) to the end of the fat part of the DS. I found some of them are shorter. One I had was 19" and another in a friends jeep was 21" using the measurement I described. With my drop brackets my WB appears to be a little longer than stock and the shorter DS does not work. I put it in a friends jeep that has short arms and no brackets and it works just fine so I stole his longer DS.

Just some info I found out shuffling 3 front shafts around.(using measurement method above)

My 97 AW4 21"
My Parts Jeep 91 AX-15 231 19"
Friends 89 XJ Aw4 242 19"
Friends 94 AW4 231 21"
 
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