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Help! Horrible rear axle noises

Jon_Tallis

Member
Joined
Jul 29, 2012
Messages
142
Country Flag
wales
I've got a rear axle problem on the 80. Happened 3 times now. Pull away from parked, get maybe 50yds and I get a REALLY heavy knock from the rear axle - heavy enough to feel right through the vehicle. First time I was towing, thought I had a trailer brake problem, reversed about 20yds and hey presto, noise gone.
About 3 weeks and a good few hundred miles later, she does it again, this time with no trailer. Again, reversed 10 yds, no noise. Drove about 20miles, parked up, pulled away, same knock except REALLY heavy, feel like the left rear is driving over a few bits of timber! Reversed, no better, drove a bit at walking pace, no better, but noise got a little better as I turned left then disappeared when I turned sharp right. Drove home 10 miles, no noise.
Truck is a '97 80 series petrol auto. 240k miles. I've owned it 9 months and it has been really well looked after. Wheel bearings are all good, prop UJ' s are all tight and well greased. Diff is a bit noisy when towing but just rumbles, no knocks etc.
Had the rear disks off tonight and no smoking gun there.
Ran the truck on stands and there's a tiny knock from the rear diff, but hardly audible.
The noise, when it appears is so horrific in really worried there's something come adrift in the diff, but these things dont just fix themselves!

So, questions...

Has anyone experienced (and fixed) anything similar?
I'd there anything else I should check before I bite the bullet and rip the diff out?

Also, if I take the diff out, should I take it out in locked position or unlocked? Looks like I have to take the kick actuator off anyway so maybe that answers the question....
 
Id drop your rear diff oil and have a rumage around for bits, contamination etc Iv never had Diff issues apart from the odd whining one... So cant really advise. If what you say is right regarding U/Js bearings etc and they are all OK ...Id start thinking along the lines of Teeth Missing/ Shot bearings in the Diff... Someone with more Knowledge than me will Be along soon... Good luck with it Jon...
 
Id drop your rear diff oil and have a rumage around for bits, contamination etc Iv never had Diff issues apart from the odd whining one... So cant really advise. If what you say is right regarding U/Js bearings etc and they are all OK ...Id start thinking along the lines of Teeth Missing/ Shot bearings in the Diff... Someone with more Knowledge than me will Be along soon... Good luck with it Jon...

Thanks Higgy,
I changed the oil a few months back, dropped it again last night and no smoking gun there either, a few particles on the mag plug but certainly no big bits. In thinking the same (broken tooth, collapsed bearing) but those things don't fix themselves, so why is the noise intermittent. Halfshafts are now out so think I'll have a look in the holes with the endoscope and see what I can see........
 
I would have thought any diff problem would leave very convincing evidence in the diff oil. Are the gearbox mountings and engine mountings broken?
 
Are you sure its not the rear brake shoes? Sometimes the material rusts/falls of the shoes and either locks the wheel, or rattles about catching every so often.
 
I would have thought any diff problem would leave very convincing evidence in the diff oil. Are the gearbox mountings and engine mountings broken?
Me too but no evidence.......
Lets see what the Endoscope shows tonight, maybe if nothing I'll box it back up and cross my fingers.....
Mounts are all good
 
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Are you sure its not the rear brake shoes? Sometimes the material rusts/falls of the shoes and either locks the wheel, or rattles about catching every so often.
That was what I thought but brake shoes are immaculate - almost unworn. Definitely no loose bits in the drums. One disk / drum is slightly warped due to an earlier sticking caliper (now sorted) so new disks will definitely go on when it's rebuilt.
 
Is the Shaft going into the Diff OK.. (Now you got the prop shaft off).. No excessive play etc etc.. Have you tried it in low box, Through all the gears... Rule out Transfer Box, Sound and vibrations Travel, Dont know what else to Suggest if your convinced its the Diff, Good luck mate, Keep us all informed.. It helps the next poor Sod along the line..:lol:
 
Is the Shaft going into the Diff OK.. (Now you got the prop shaft off).. No excessive play etc etc.. Have you tried it in low box, Through all the gears... Rule out Transfer Box, Sound and vibrations Travel, Dont know what else to Suggest if your convinced its the Diff, Good luck mate, Keep us all informed.. It helps the next poor Sod along the line..:lol:
Not yet taken the prop off - bolts are siezed and will need to be cut off so that is the start of the point of no return!
Input pinion however doesn't have any excessive play and prop UJ's are free-moving with no excessive play.
Ran the truck last night with the rear on stands (front wheels well chocked!!), there was a tiny click / rumble from the diff but almost inaudible.
Hence why with no "smoking gun" I'm a bit reluctant to just rip it all apart.....
That said I don't want my diff to explode on the motorway either!!
Lets see what the Endoscope can see......
 
I've had some rough trucks and never had seized bolts. they are usually very tight so you should be able to get them off with a spanner one side and a big bar the other. or a rattle gun
 
I've had some rough trucks and never had seized bolts. they are usually very tight so you should be able to get them off with a spanner one side and a big bar the other. or a rattle gun

Yep, like Karl I've taken a few prop bolts of some rusty old shafts and never had to even use heat. The bolts are very strong and will undo but you will need to use a lot of force/ leverage.
 
You seem to have covered many of the eventualities.

Other than it sounding like it comes from the rear axle, how do you know? Structural borne noise has a funny habit of not necessarily coming from where it originated.
 
Some people on here have been convinced they had a rear axle problem but found out it was the transfer box. How you check it for intermittent problem without taking it apart I don't know. Best to undo the grease nipples to stop the prop locking up when trying to compress it. Otherwise fighting the prop flange over the bolt ends damages the threads which I did with great effect. They are very fine threads.
 
If the propshaft hasnt been off for a long time, then how do you know the uj’s are good? You cant tell by just giving them a yank whilst mounted.
 
I've come across ujs almost completely free of needle bearings, but wedged tight when you shake on the prop in situ.
As Andy states, the laws of leverage will sort the prop bolts.

Did you check for play/rumbling in the wheel bearings whilst on stands?

Discount the ujs then move on to the diff.
You say it rumbles at the best of times.

that almost inaudible sound will magnify when under load.
 
Dave2000 on here had a similar problem only to find it was the transfer box. Perhaps drain the transfer oil to check. Even after big miles it should be clean and defo no lumps of metal. Be very interested to know the outcome.
 
Thanks guys for all the Intel..... And sorry for the silence. I think I've sorted it...
Inspected the diff with the Endoscope, all looked good, certainly no loose bits, missing teeth etc.
Rear wheel bearings perfect, no play or tight spots.
However Rear offside caliper was siezed - only spotted it when I was compressing it to get it over the new pads. Disk was also cracked so I recon the noise / bump was the pads in the siezed caliper picking up on the crack in the disk. Anyway, caliper overhauled, new disks and pads and no more noise (so far).
If it re-appears I'll check the prop fully (drop one end off) and the transfer box (drop the oil, check for bits and Endoscope check)
Rear diff is still a bit whiney so will need a rebuild in due course (I. E. When I've got some money!)

Thanks for all the advice - great forum as ever
 
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