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A different approach to 80 series front axle rebuilds. Really?
- Thread starter Chris
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Of course. Agreed. But looking at the diff I am pretty confident that it's not about to explode or something and I can always drop the prop to take any load off it for now if I start foaming at the mouth. I don't think that it's something that can be masked or improved really without pulling it and sending to the clinic. Are some diffs just destined to be noisy? When I source some new CVs I can pull this one and put the other spare in there. That was good too but this one as JW says has had new bearings and a solid spacer so it was the obvious choice to go in the build. This is the original from the white truck. This was tuned up and went into the silver truck which then got the 4.56's in there. The other one is the straight factory 4.1 that was in the silver truck that came with the busted auto box. So it's only done 70k too.
I thought that the noisy diff (when in the silver truck) was actually the transfer box. I did all sorts of tests and finally found the T box had a hole in it somewhere and was full of sand. Red sand? I swapped that out and all went quiet. BUT this rather coincided with the swap to 4.56. Not exactly empirical research if you follow me. Change one thing at once. Errr, oops. Funny thing is the diff has always been noisy. That is why JW rebuilt it for me. We need an axle casing chopped up so that you can put a diff in there, fill with oil and then spin it up with a motor and have a listen!
I thought that the noisy diff (when in the silver truck) was actually the transfer box. I did all sorts of tests and finally found the T box had a hole in it somewhere and was full of sand. Red sand? I swapped that out and all went quiet. BUT this rather coincided with the swap to 4.56. Not exactly empirical research if you follow me. Change one thing at once. Errr, oops. Funny thing is the diff has always been noisy. That is why JW rebuilt it for me. We need an axle casing chopped up so that you can put a diff in there, fill with oil and then spin it up with a motor and have a listen!
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Chris is there plenty of play between the half shafts and the dif ? They aren't too long and pinching the dif are they ? If you jack the front axle off the ground and disconnect the front prop you should be able to turn the diff flange and cause the road wheels to turn fairly easily. I say this as it is not in its' original axle tube with all matching shafts etc so worth checking.
Frank, all of that is fine as far as I saw. I have done a fair few of these and would / do spot anything that doesn't go quite right, you know? If something doesn't feel right, I don't get tempted to whack it with a BFH. The prop felt good. No headache in that. The diff was sweet and went in fine. The shafts all slid in perfectly with the correct end float seen at the stub axles where the snap ring goes so the end of the half shaft certainly shouldn't be hard up against the diff internals. It's always been noisy and this is the third truck it's been on!
At the diff companion flange there is the usual 5 mins of clock face backlash at most and yes it turns the road wheels by hand with little resistance. Now from memory again not science, I seem to recall that this diff has always been hard on oil. Back diff comes out like honey whereas the front comes out looking chewed up and broken down for the same miles. I got some different oil once (again memory issues here) and that faired much better. This stuff is straight off the shelf motor factors EP90. Not unicorn tears in 5ml sachets. I am sceptical about oil sometimes it's all made from the same dead dinosaurs. But now we are into semi synth I wonder if that is part of the problem. Are there good synthetic dinosaurs and bad ones? There is a standard and this oil meets it.
But it's so noisy there has to be more than the oil.
At the diff companion flange there is the usual 5 mins of clock face backlash at most and yes it turns the road wheels by hand with little resistance. Now from memory again not science, I seem to recall that this diff has always been hard on oil. Back diff comes out like honey whereas the front comes out looking chewed up and broken down for the same miles. I got some different oil once (again memory issues here) and that faired much better. This stuff is straight off the shelf motor factors EP90. Not unicorn tears in 5ml sachets. I am sceptical about oil sometimes it's all made from the same dead dinosaurs. But now we are into semi synth I wonder if that is part of the problem. Are there good synthetic dinosaurs and bad ones? There is a standard and this oil meets it.
But it's so noisy there has to be more than the oil.
not going to be the oil, assuming there is some 
just have to have another look at it when it comes back out Chris and go from there.
just have to have another look at it when it comes back out Chris and go from there.
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Went for a spin at lunchtime to go and get a salad. I know, salad; what's the world coming to. Listening to the diff noise I do wonder how much of that is actually vibration being transmitted up through into the cabin as opposed to acoustic noise being generated by the diff sitting there submerged in oil. When I say vibration I don't mean out of kilter, off balance 'bad' vibration, but just the normal mechanical movement of bit parts turning. When you open the window, there is no noticeable noise out there except the wind. I wondered if hardening old bushes in the arms and body mounts contributed to the transmission of rotational noise.
Oh I put some oil in the diff as well and it's much better now.
Oh I put some oil in the diff as well and it's much better now.
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Some tyre tread patterns make whining noises directly related to road speed as the dif is. Jack all four wheels off the ground and go for a drive with your left foot on the brake ?
I change my dif oil often and it always comes out milky. There is always some grease that gets in on 24,000 miles. That's why they tell you to change it at this mileage.
I change my dif oil often and it always comes out milky. There is always some grease that gets in on 24,000 miles. That's why they tell you to change it at this mileage.
Sorry Frank, it didn't make this noise with these tyres on and the old diff in there. I didn't change the diff and the tyres. I can play a tune on the diff on and off the power, Whirr, hmmm, whirr, hmmm. It's not the tyres. I have been here three times before. I am just kicking myself that I forgot the damn diff made so much noise when I picked it from the pair I had. Half minded to pull the bastard this weekend and put the other one in. Other than I'll probably find that one's even noisier.
I have had these tyres on two cars and they waft along beautifully. No noise at all. Jon has driven it and so has the North's leading potato merchant and I don't think they noticed anything.
I have had three 80's Frank and not covered anything like 24 000 miles across the three for them and yet I have done in excess of a dozen front diff oil changes. Shattered CVs, ratio changes, mar tacking shafts, diff bearings it's an endless list. Each time the oil has come out looking nasty and that's with virtually new seals in too. Many of those changes were with this particular diff. Which is sort of my point I think.
It's the devil's diff. Other than an exorcism, JW's the only answer I think. Nurse prepare the anaesthetic. I'm going in.
I have had these tyres on two cars and they waft along beautifully. No noise at all. Jon has driven it and so has the North's leading potato merchant and I don't think they noticed anything.
I have had three 80's Frank and not covered anything like 24 000 miles across the three for them and yet I have done in excess of a dozen front diff oil changes. Shattered CVs, ratio changes, mar tacking shafts, diff bearings it's an endless list. Each time the oil has come out looking nasty and that's with virtually new seals in too. Many of those changes were with this particular diff. Which is sort of my point I think.
It's the devil's diff. Other than an exorcism, JW's the only answer I think. Nurse prepare the anaesthetic. I'm going in.
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You describe polluted oil, I think? If due to a defective dif the oil would have fine metal particles in it rather than just looking "chewed up and broken down". With the front dif on the 80 the oil is always milky due to migration of some grease. The oil seal works mainly one way to hold oil in the dif rather than the other way round. The hubs are not vented so pressure caused by brake heat works against the seal like a ratchet effect. If your noisy dif is polluting your oil you would have very obvious witness marks somewhere and if due to dif noise these would be on the mating surfaces on the crown wheel/pinion.
Not quite sure we're on the same page with this one Frank. I don't think the oil is polluted and it certainly has never been milky. I am not convinced that with new seals and a full tidy up that within less than a 1000 miles, enough grease would have come from the hubs into the axle oil Frank. I have done changes at 200 miles before now. The hubs may nopt be vented, but they are not sealed that's for sure. They vent through the stub axle past the end of the CV shaft for one thing. That's a huge gap in terms of air and pressure.
I guess it's hard to relate all of my experiences here and detail gets lost in short exchanges. There is no metal dust on the magnetic plug and never has been. It's just like the oil has been in a blender. Whisked, chewed and chavelled into submission.
I guess it's hard to relate all of my experiences here and detail gets lost in short exchanges. There is no metal dust on the magnetic plug and never has been. It's just like the oil has been in a blender. Whisked, chewed and chavelled into submission.
I have tickets for Donington on the 16th and plan to be using them ...
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Yes difficult to summarise Chris, only that the hubs do build up heat pressure as there is nowhere for the air to get out other than past the one way seal and through the axle vent. Otherwise you would have water in your hubs.......oh you have 
Oh yes Frank. Regularly but I know where that is coming from. It's the price you have to pay for having fun I guess. But I know the water isn't going in through the breather, past the diff, over the retainer, through the inner seal and into the swivel. Whcih if the swivel was as sealed as you say, would be the only route?
Still not convinced that the inner axle seal is the ONLY way that air can vent from the swivel. There is the wiper seal to start with. No way is that a pressure seal. And I don't buy that the stub axle drive flange and cap are gas tight either. You would have to raise the pressure quite some way surely to push past the axle seal and as the grease is pretty immobile there is a finite amount that would ever get to the lip of the seal to be pushed past. Then it would have to get past the oil retainer inside the axle. I mean I am not saying that some couldn't, but I don't really believe that shovel fulls are going that way. The drive shaft does slide back and forth in there on the seal face so there had to be a certain wiping action which might take grease through or in fact wipe it off before it can.
To be honest, I have rarely seen water in the swivel. In the hubs and bearings yes. But little in the swivels. It drains out you see .. same as the air
Still not convinced that the inner axle seal is the ONLY way that air can vent from the swivel. There is the wiper seal to start with. No way is that a pressure seal. And I don't buy that the stub axle drive flange and cap are gas tight either. You would have to raise the pressure quite some way surely to push past the axle seal and as the grease is pretty immobile there is a finite amount that would ever get to the lip of the seal to be pushed past. Then it would have to get past the oil retainer inside the axle. I mean I am not saying that some couldn't, but I don't really believe that shovel fulls are going that way. The drive shaft does slide back and forth in there on the seal face so there had to be a certain wiping action which might take grease through or in fact wipe it off before it can.
To be honest, I have rarely seen water in the swivel. In the hubs and bearings yes. But little in the swivels. It drains out you see .. same as the air
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I wonder why my front dif oil is regularly polluted with grease then? I rebuilt the front axle at 90,000 miles more out of interest rather than curiosity. The previous 3 oil changes showed slight grease in the oil. After the rebuild I checked the oil after 1000 miles and it was ever so slightly greasy unlike the rear axle which always has golden oil. I've done 139,000 miles now of fairly rapid cornering acceleration, braking etc and I have never had any problem whatsoever with the front axle. I never got any pollution, grease or whatever in my 7 Land Rover and 3 Range Rover front axles just golden oil all the time. That is because they had EP 90 in the hubs. There was no recommended oil change interval whereas the oil change interval is 24,000 on the 80. BTW my 100 dif oil is golden. It only takes 1 teaspoon of CVJ grease to make 3 litres of oil go off colour.
Don't worry Frank. You can't expect to be brilliant at everything. Pop it round and I'll do it properly for you.
I think I have answered this really Frank. My oil is never in there long enough to be contaminated with grease. I'm buying oil in 20l barrels I get through so much of it.
It's more the consistency of the oil rather then the colour. Like I said, it's like it's been put through a food blender.
When I have done 90 series in the past on the front IFS axle I have wondered why I am bothering. Always looked like new in there.
I'm telling you Frank, it's the devil's diff this one.
I think I have answered this really Frank. My oil is never in there long enough to be contaminated with grease. I'm buying oil in 20l barrels I get through so much of it.
It's more the consistency of the oil rather then the colour. Like I said, it's like it's been put through a food blender.
When I have done 90 series in the past on the front IFS axle I have wondered why I am bothering. Always looked like new in there.
I'm telling you Frank, it's the devil's diff this one.
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Not disputing your terrible dif Chris just the my fault off topic swivel hub/wheel hub design. The LR's had an almost identical design and hot/thin EP90 stayed in OK so they were airtight. That is until the chrome pealed off and shredded the wiper seal and/or the hub bearing seal went. Have you got another same ratio dif you can try?
I have Frank. Mentioned that a couple of times actually. Got a very low mileage 4.1 that I can stick in. But weekend looks shocking and I don't fancy it. Plus I'd rather wait until I get some new CVs. It's all done up so nicely iin there that I can't face pulling it all out again to swap the damn diff.
Hey it might wear itself in with a good run to Donnington. I need a long run to see if warmer oil makes any difference either way. I did have a good look at the teeth before I selected this one to go in and as I have said repeatedly, it just looked and felt 100%
If it was just a knock about 80 I'd live with it, but the thoughts of a long trip down through Europe with it sounding like an army convoy just fills me with advance disappointment.
Hey it might wear itself in with a good run to Donnington. I need a long run to see if warmer oil makes any difference either way. I did have a good look at the teeth before I selected this one to go in and as I have said repeatedly, it just looked and felt 100%
If it was just a knock about 80 I'd live with it, but the thoughts of a long trip down through Europe with it sounding like an army convoy just fills me with advance disappointment.
