Knock from front prop shaft/yoke?

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Dec 29, 2021
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Agnes waters, Australia
Long time crawler, first time posting.

I have a heavy knock sound I suspect is coming from my front prop shaft. Only happens when front end is articulating over structure. Particularly when FLS is raised and FRS is down.

I have check all rubbers and bushings, everything looks solid, nothing suspect here.

There is a bit of play in the front prop shaft, particularly around the yoke. Would i be right in thinking this is where the knock is coming from? It certainly sounds like metal on metal when it happens. I have greased all U joints and shafts recently.

Any response is appreciated.
Cheers
 
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Dec 29, 2021
Messages
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Agnes waters, Australia
Lock the center diff, pull the driveshaft and see if the knock disappears.
Apologies for my ignorance but I don't fully comprehend.
There is no CDL switch, and rear is LSD. So I'm assuming I would need to shift to 4 low range for centre to lock?
So remove front drive shaft, go 4 low, flex front and see if noise has disappeared?

Additional info, 1991 1hz.
 

ppc

M Go Blue
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No need to apologize. I see you are in Oz so not sure if you have AWD or 4WD. For AWD without a CDL dash switch you can shift into Low which should lock the CDL. At that point you can pull the fuse that powers the CDL, which keeps the center locked, shift back into High and perform your testing without the front driveshaft. The LSD has no bearing on this test. Not sure with 4WD what would be required as we didn't get that option in North America.
 
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No need to apologize. I see you are in Oz so not sure if you have AWD or 4WD. For AWD without a CDL dash switch you can shift into Low which should lock the CDL. At that point you can pull the fuse that powers the CDL, which keeps the center locked, shift back into High and perform your testing without the front driveshaft. The LSD has no bearing on this test. Not sure with 4WD what would be required as we didn't get that option in North America.
Yep, G'day from Aus. Its 4WD, transfer case runs 2H, N, 4H, 4L. I think I'll follow your train of thought and just remove the front shaft and go for a drive. If the noise persists I will have at least eliminated one suspect. And if not, I'll have the shaft out ready for a rebuild. Thanks for the help!

If anyone else has some useful info I am all ears
Cheers
 
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Looks like you've got a part time model, with the manually locking hubs on the front wheels, correct? In that case, with the front hubs unlocked and the transfer in H2, the front prop shaft/diff/axles will all sit idle and all the power will go to the rear. Does the noise still occur in that mode? If so, pull the propshaft like you planned and just leave it in H2. There's no centre diff to "lock" in the part time models.
 

mudgudgeon

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Recheck the front suspension.

I had an 80 that would make a loud clunk like you're describing.

Mine turned out to be loose radius arm bolts at the diff, and the bolt holes had become slotted sightly.

Could also be sway bay bushings.

Could also be cracking in the chassis rail around the steering box bokts, or around the panhard rod bracket on the other chassis rail
 
Joined
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Messages
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Agnes waters, Australia
Looks like you've got a part time model, with the manually locking hubs on the front wheels, correct? In that case, with the front hubs unlocked and the transfer in H2, the front prop shaft/diff/axles will all sit idle and all the power will go to the rear. Does the noise still occur in that mode? If so, pull the propshaft like you planned and just leave it in H2. There's no centre diff to "lock" in the part time models.
That is correct, manual locking hubs. Yeah noise has occurred once driving over a gutter. I'll get it out and go from there, cheers nemesis
Recheck the front suspension.

I had an 80 that would make a loud clunk like you're describing.

Mine turned out to be loose radius arm bolts at the diff, and the bolt holes had become slotted sightly.

Could also be sway bay bushings.

Could also be cracking in the chassis rail around the steering box bokts, or around the panhard rod bracket on the other chassis rail
Ahh lists. I love lists. Steering box has already been welded and new bushings in sway bar. I'll have a look at the radius arm bolts and see if there's any sign of play. Thanks mudgudgeon
 
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Also check the frame side panhard bracket for cracks at the frame. Mine made a similar sound when flexing when the panhard bracket was cracked.
Panhard bracket cracks by Adam Tolman, on Flickr
Damn, you nailed it mate. Went in with some degreaser and a brush to triple check. Found a fracture identical to the one you have posted. Ill take a pic an upload soon.

For the remedy, just take it to a welder and patch it back together? No need to disassemble anything from what I can tell?
 
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20211231_114209.jpg
looks like I've found the culprit. And there's additional fractures to the chassis rail. Bought this rig 3 weeks ago, the things you find once you start looking 🙄

Anyone recommend a decent welder in QLD Australia?
 
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Damn, you nailed it mate. Went in with some degreaser and a brush to triple check. Found a fracture identical to the one you have posted. Ill take a pic an upload soon.

For the remedy, just take it to a welder and patch it back together? No need to disassemble anything from what I can tell?
Grind out the crack to a V and weld it back up. Good time to weld around the end of the tube brace as well.
Besides the cracks in the chassis rail do a thorough check of the chassis rail around the steering box mounts. Those are prone to crack also. Best fix for that is to remove the steering box, plate the chassis and remount the box.
 
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Grind out the crack to a V and weld it back up. Good time to weld around the end of the tube brace as well.
Besides the cracks in the chassis rail do a thorough check of the chassis rail around the steering box mounts. Those are prone to crack also. Best fix for that is to remove the steering box, plate the chassis and remount the box.
I have found some great reviews of a bloke in the next state, he makes plates specifically for this. I'll add a link below. Reading through previous forums it sounds like an 8 - 10hr job to get a shop to do it. Disassemble and reassemble taking the majority of time... at a guess, id say this will cost close to $1000 aus.

 
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Big question, how dangerous is it to continue driving with occasional off road work (mostly sand driving) in this condition? I live permanently on the road, so will need to use this as my daily until i can get it into a shop. Likely in a months time.
 

mudgudgeon

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Big question, how dangerous is it to continue driving with occasional off road work (mostly sand driving) in this condition? I live permanently on the road, so will need to use this as my daily until i can get it into a shop. Likely in a months time.

That's a bit of a how long is a piece of string question.
Its hard to see full extent of cracking from a single picture.

There'd be many cruisers driving around unaware of this kind of cracking for long periods of time before it's bad enough that it can't be ignored.
I had this happen on my 105 series. I want aware until I felt an issue through the steering on hard right turns.

It's something you should fix ASAP now you are aware of it, but a few more road miles is unlikely to be catastrophic.

If you can do some prep yourself by grinding out along the cracks so its an open V groove, you could just find a muffler workshop, or mechanic to reweld along the crack.
Look at plating it later if time is an issue
 
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Big question, how dangerous is it to continue driving with occasional off road work (mostly sand driving) in this condition? I live permanently on the road, so will need to use this as my daily until i can get it into a shop. Likely in a months time.
I wouldn’t wait to have it fixed. I’d try to get the panhard bracket welded up ASAP. If it takes a month to get to the chassis plates for the steering box that will probably be ok. Just drive carefully.

The Rampt Customs plates are a very good solution for repairing the cracks around the steering box.
 
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That's a bit of a how long is a piece of string question.
Its hard to see full extent of cracking from a single picture.

There'd be many cruisers driving around unaware of this kind of cracking for long periods of time before it's bad enough that it can't be ignored.
I had this happen on my 105 series. I want aware until I felt an issue through the steering on hard right turns.

It's something you should fix ASAP now you are aware of it, but a few more road miles is unlikely to be catastrophic.

If you can do some prep yourself by grinding out along the cracks so its an open V groove, you could just find a muffler workshop, or mechanic to reweld along the crack.
Look at plating it later if time is an issue
Appreciate all the advice, it's been very helpful 🙏
 

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