New AX15, very chirpy but not the TOB

[brucecooner]

Back in April (4-5 months ago now) I got a brand new AX-15 into the Jeep.

I acquired it from Novak, but no way I could do it myself, so I went with a shop that does pretty good work (but a couple of things were like, hmmm).

 

The throwout bearing started chirping right away, but the guy from Novak said basically "some Jeeps do". Ok.

I've tugged on all the u-joints and they're all nice and tight, nothing is slipping there (though that would be a clunk more than a chirp I guess).

 

The bearing has gotten quieter, but a different chirp has started that definitely isn't the TOB.

 

You hear this once you get it up to or above 10-15 mph, and this chirp is tied to the wheel speed and not engine speed.

Once you're at speed, you can clutch in and coast, and the chirp continues.

Disengage the clutch and shift through all the gears, still chirping.

No matter the state of the selected gear or the clutch, you hear this chirp.

As you coast to a stop, the chirp slows with it, disappearing below about 8mph, it seems driven by wheel speed alone.

 

It sounds like it's coming from just behind the shift lever, BUT I left the plastic cover and boot off for now because they don't fit over the new lever, so I'm hearing sounds from all over the underside.

 

Today I put it up on jack stands so I could at least remove the front drivetrain from the equation and, there's no chirp at all.

In 2H I can run it up to third gear, 25-30 mph, and I don't hear the sound, when I definitely was hearing it on the road.

I put it in 4h, to get the front drivetrain turning again, but there was still no sound.  Put the TC in neutral, still no sound.

 

I did lock the front axle CAD just before the transmission install, so who knows how long everything up front had been static before the install.

I was hoping maybe something in the front driveshaft or system was noisy, but I can't really say that's the case (the chirp was not heart in 4H).  And like I said, the front u-joints are nice and tight.

 

Anyway whatever the sound is, it ONLY seems to be happening when the system is under load.

That says u-joint or other power transmitting point to me, rather than a bearing, but I'm no expert.

 

I do have a slow seep from the transfer case drain plug, so I checked that after turning off the Jeep and it shows to be low, BUT I was just running it so I suspect the missing fluid is just up in the chain/gears.  Going to check it again later and besides, it wasn't chirping on the stands so I doubt the fluid is an issue. (EDIT: I waited a while, the fluid drained back down and it's barely below the drain plug now).  

 

EDIT: I went on an errand and came back and put it through the paces again.  The throwout bearing chirps like a coke addled canary sometimes, but the other sound is, again, nonexistent. I ran it with the TC in every stop too, 4H, N, 4L, no sound.

 

Anyone else ever have something chirp under load that seems totally unrelated to the clutch?

 

 

[M.T.Hands]

dry u-joints will chirp, I know you mentioned they feel tight, but the first sign of u-joint trouble for me outside of total failure was a squeak when vehicle is/was in motion, If the frequency stays the same or increases/decreases with speed tells me it is something consistent with a part that is turning (drivetrain) if you have serviceable u-joints I'd try loading them up and make sure that grease is going completely through the joint 

 

I have had zerk fittings on tractors and equipment that would not take grease, it's an easy check and not expensive

 

 

 

[brucecooner]

3 hours ago, M.T.Hands said:

dry u-joints will chirp, I know you mentioned they feel tight, but the first sign of u-joint trouble for me outside of total failure was a squeak when vehicle is/was in motion, If the frequency stays the same or increases/decreases with speed tells me it is something consistent with a part that is turning (drivetrain) if you have serviceable u-joints I'd try loading them up and make sure that grease is going completely through the joint 

 

I have had zerk fittings on tractors and equipment that would not take grease, it's an easy check and not expensive

 

 

 

Interesting.  Like I mentioned, I have the shift lever boot off right now, so I'm getting an earful of stuff I don't normally hear, and I might be hearing a u-joint very early in its death throes that I'd never know of with everything buttoned up.

 

These joints were on there when I got it almost three years ago, at 188K, so I can't say how old they are.  They definitely don't look very fresh, covered with a good layer of caked on dirt, which may be a sign they're running dry.

Definitely worth a look, I'd be happy if it is just u-joints chirping.

[brucecooner]

From what I can tell, I need series 1310's for both front (D30) and rear (D44) shafts, but there are 3 in the front (it's double jointed at the TC), for 5 in total.

 

I can't get a clear reading on the front though, are all 3 of the front shaft 1310's?

 

 

[ghetdjc320]

1 hour ago, brucecooner said:

From what I can tell, I need series 1310's for both front (D30) and rear (D44) shafts, but there are 3 in the front (it's double jointed at the TC), for 5 in total.

 

I can't get a clear reading on the front though, are all 3 of the front shaft 1310's?

 

 

That’s correct but there are two types of joints, one for driveshafts and one for steering axles. Both have the same cap diameters. The driveshaft ones are spicer/dana part number 5153X. They are all the same for all driveshaft joints

[gogmorgo]

If you’re changing the ujoints in the CV for the front driveshaft, get the centring ball for it too. The ball on its own is Dana part number 10018465 or for not a lot more money you can get the whole centring yoke with the ball in it, 211355X.

And yes for ujoints the Dana 5153X imo is the best option out there, as long as you grease them.  I’ve used others in the MJ and never had them fail, but we run 1310 shafts for the crank-driven PTO shaft for the hydraulics on our plow trucks. The Dana u-joints have a nice meaty cross where the grease nipple is and are easier to get a grease gun into than the others. In that application this was critical because not getting grease onto them meant they seized up within a few months and then they’d experience catastrophic failure. And I don’t think I need to tell you how much carnage can be done by an 18” piece of steel being whipped around by a 15L diesel engine. 

[brucecooner]

On 9/23/2024 at 10:24 AM, gogmorgo said:

If you’re changing the ujoints in the CV for the front driveshaft, get the centring ball for it too. The ball on its own is Dana part number 10018465 or for not a lot more money you can get the whole centring yoke with the ball in it, 211355X.

And yes for ujoints the Dana 5153X imo is the best option out there, as long as you grease them.  I’ve used others in the MJ and never had them fail, but we run 1310 shafts for the crank-driven PTO shaft for the hydraulics on our plow trucks. The Dana u-joints have a nice meaty cross where the grease nipple is and are easier to get a grease gun into than the others. In that application this was critical because not getting grease onto them meant they seized up within a few months and then they’d experience catastrophic failure. And I don’t think I need to tell you how much carnage can be done by an 18” piece of steel being whipped around by a 15L diesel engine. 

An engine that big could whip around a shoestring and do some damage.

 

I went ahead and got the complete centering yoke and a fistful of 5153X's.  I don't know how old anything is under there so might as well freshen it all (if the darn weather ever cools off here).

 

I do have another question. 

There's a telescoping connection in the rear driveshaft, closer to the front (TC end), with a grease fitting on it.

Obviously it expects to be greased, but is there anything in that connection that would ever need service or replacing?

[gogmorgo]

14 hours ago, brucecooner said:

 

I do have another question. 

There's a telescoping connection in the rear driveshaft, closer to the front (TC end), with a grease fitting on it.

Obviously it expects to be greased, but is there anything in that connection that would ever need service or replacing?

The factory rear driveshaft doesn’t have this. It has a slip yoke in the transfer case tailhousing. 
Its likely you’ve got a slip yoke eliminator setup. It’s less critical with the MJ’s longer driveshaft but on a shorter wheelbase Jeep with enough lift you might have enough travel in the slip section as the axle moves up and down to pull a slip yoke too far out of the transfer case. Similar to the front driveshaft. It’s also sometimes done to help with driveshaft angles. Usually you’d see it with a full CV like the front shaft, but not always.
There’s a few different outfits that produced them, there’s also a couple common DIY methods, and plenty of driveline shops custom building things. It’s tough to say what you’ve got without knowing. 
But in general there’s not much inside the sliding section. There’s usually a seal on the female end, but other than that you’re really just looking at greased splines sliding in greased splines. Not necessarily the worst idea to pull it apart and clean any debris out of there that might have worked its way in, but if it’s been kept well greased and the seal’s in okay shape it’s not usually a huge concern. 

If for whatever reason you do decide to pull it apart, mark the alignment so it goes back together the same way. You don’t want the driveshaft U-joints going out of phase or you’ll get some hellacious vibrations. Although if it does come apart on you and it’s not marked, it’s easy enough to line the ujoints back up. Just drop the shaft on a flat surface and make sure the u-joint caps are both sitting flat. 

[brucecooner]

8 hours ago, gogmorgo said:

The factory rear driveshaft doesn’t have this. It has a slip yoke in the transfer case tailhousing. 
Its likely you’ve got a slip yoke eliminator setup. It’s less critical with the MJ’s longer driveshaft but on a shorter wheelbase Jeep with enough lift you might have enough travel in the slip section as the axle moves up and down to pull a slip yoke too far out of the transfer case. Similar to the front driveshaft. It’s also sometimes done to help with driveshaft angles. Usually you’d see it with a full CV like the front shaft, but not always.
There’s a few different outfits that produced them, there’s also a couple common DIY methods, and plenty of driveline shops custom building things. It’s tough to say what you’ve got without knowing. 
But in general there’s not much inside the sliding section. There’s usually a seal on the female end, but other than that you’re really just looking at greased splines sliding in greased splines. Not necessarily the worst idea to pull it apart and clean any debris out of there that might have worked its way in, but if it’s been kept well greased and the seal’s in okay shape it’s not usually a huge concern. 

If for whatever reason you do decide to pull it apart, mark the alignment so it goes back together the same way. You don’t want the driveshaft U-joints going out of phase or you’ll get some hellacious vibrations. Although if it does come apart on you and it’s not marked, it’s easy enough to line the ujoints back up. Just drop the shaft on a flat surface and make sure the u-joint caps are both sitting flat. 

I swear, some days my brain ain't with me.  It's been a while since I was under there, but crawled under again this evening to take another look, and that telescoping connection is on the FRONT driveshaft, not the rear.  My memory was turned around 180 degrees.

I'm guessing this is a stock arrangement.

 

And I'd guess the same advice applies to the telescoper, check it and/or grease it.

 

I took another look at the centering yoke though. 

Dang thing is well buried above the trans mount.

Looking at it, I can't figure out if you're supposed to just remove those four bolts on the TC side, or if you disconnect the front (axle end) joint, then pull the shaft out of the TC, bringing the yoke with it.

 

 

I haven't seen a good guide for removal/replacement/resintall of this end either.

If anybody knows of a clear set of instructions out there, I appreciate any pointers.

 

And thanks gogmorgo for all the info.

 

 

 

 

 

[89 MJ]

The front driveshafts do not have a slip yoke, so you’ll have to pull the four bolts at the axle and the other four bolts at the transfer case. 

[gogmorgo]

Yeah the front shaft is not the nicest thing to remove. You unbolt the driveshaft from the flange on the transfer case, which wouldn’t be such a big deal except for there’s very tight clearance for getting onto the bolt heads, and they tend to have not moved for a long time which means they don’t want to.

I think it’s a 5/16” hex head, if memory serves. The box end of a wrench is the easiest thing to get on there but if you don’t have a very good fit on it they’ll want to turn into circles. I’m nervous even using a high-end 12-point wrench. 6-point wrenches are getting difficult to find, but it’s the one of the few places I’d want to use one. And it’s not a great spot to get heat onto to help loosen them. 

[Eagle_SX4]

I have had good luck using a 6 point 5/16" 1/4" drive socket with a wobble extension for the front pinion bolts. I think the transfer case side bolts have 1/2" heads and you can use a 1/4" drive socket on those as well. You will just need to rotate the driveshaft to get to all of them.

[pizzaman09]

When you reinstall the front driveshaft, make sure you remember to actually torque the bolts.  I'm very lucky I didn't make a huge mess out of the bottom of my truck when the front u joint straps came off and the drive shaft, pointing forward was lightly bouncing off the ground as I drove it around.  

 

A great tool for the little bolts is a ratcheting box end wrench.