Transfer trouble

[Chris]

Not posted much recently, so I thought I'd share this in anticipation of any wisdom out there.
Noticed the other day that when on the over run with CD locked, I was getting a pretty loud, speed related Duuuuurrrrrrrrr. BAck on the gas, it went away, off again Duuuuuuurrrrrrr. Without locker in there didn't seem to be any difference. Now I have always suspected that the front bearing on my tranny box was a bit dodgy si I figured it was probably time to have a look. I did try to get the front housing off once before whilst it was on the stuck. You can't. There just isn't enough clearance.

I have a spare box sitting in a wheelbarrow in the front garden, so one option would be to swap it out. But as I have no provenance on it, I'd rather not just do a straight swap.

I dropped the front prop and went for a drive. Noise gone completely. Incidentally, I was really surprised at how much drive the viscous coupling gives without the centre box locked. It was only a decent hill that beat me in the end. I think I can rule out the front diff, it's a JW model with very few miles on. THe props are both fine with no play in the yokes althoug there is a little bit of a headache in both splined sections of the front and rear props.

Next, time to drop the T box. Well what a ****** *&£$@% ar** b*****d %$£t of a job that was. Half a doz more bolts and I could have had the whole of the transmission out. There's a couple of really stupid bolts to get to. Every trick in the book was needed. Including dropping the transmission on the centre cross member half an inch or so.

I took the front housing off and I have to say that there was some play in the bearing. It's hard to know exactly what it should be like, but whilst it ran smooth enough, I could 'weathervane' the shaft around like an old Maxi gearbox. The end of the shaft gets very well supported inside the splines of the T box so that rotary movement is not going to be very much. I pulled the front off the spare box in the wheelbarrow and have to say that it was better. I decided to swap just the fronts over. I still feel that there is some clunkage in the backlash between front and rear companion flanges. Not just the usual 'clack clack' that you'd associate with backlash - there's almost an intermediary feeling too. I shone a torch through the actuator motor port and spun the innards round a few times. Couldn't see anything. On its own, the rear flange feels perfect.

So, I don't know really. The oil was the same colour as old ATF again. I just don't know where the dirt is getting in, but between the joint of the T box and the autotrans was packed with mud! I shall be checking for pin holes in the casing. Having that sludge washing around in there cannot be good for bearings etc.

Won't get to rebuild it until next weekend so the truck is off the road for now. Any experience gratefully received. Given the lack of noise with no front prop, I'd have to say that it was something to do with this part of the system. The VC seems to be working well so I wouldn't suspect that either. It's only when the splined collar locks the main drive section to the front extension shaft that I can hear something. All those splines look fine. Most likely it is the bearing thrumming when loaded up on the over run.

Time will tell

Chris

 

[Jon Wildsmith]

If the TC front housing swap doesn't fix it, it's possible you have chipped a tooth, either in the centre diff, or the front diff. That front diff was super tight and had a lovely drive pattern but they are not indestructible, as Ian proved

 

[Chris]

Thanks Jon. I have to say that the noise is very constant and only when CD is locked. No noise at all under normal driving. I have spun the companion flange round and round on the front diff and there isn't so much as a hint of a thunk, clink or clack. The back lash though measured as rotational movement on a clockface is about 1 hour. Is that about right? I am pretty sure that all is well up front. When driven up a steep bank even with lockers in, there are no noises. My guess is that this is something to do with all the load being off and the companion shaft of the TC being able to 'vibrate' as it were.

I can't say that I have exactly punished the truck off road either. I never set out to break stuff. Couple of goes and if it's not looking likely, I'll go around. Drove it to Scotland as I said, and it really did waft along. There and back. It was only with the locker in that the noise appeared. Next weekend, I shall take the PTO cover off and have a look inside too. All looked well through the other holes that I could see. The oil really did look like mud though. I can't see where the crap is getting in. Must have changed the oil three times in less than 5k miles.


Chris

 

[Jon Wildsmith]

Doesn't sound like the front diff then About 1 hour is right. Very strange how mud is getting into the transfer case

 

[Chris]

It is Jon. I almost suspect a hole somewhere. Box is pretty clean now so I shall have a poke about at the weekend. Breathers are all clear - you know, the obvious stuff. But rammed in between the trans and the box was a pretty good handful of clay / mud. Go figure. It really cannot be doing the gears any good running in that. I shall pass the oil through a sieve and see if there is any solid matter in there.

Chris

 

[Chris]

Well. That hasn't gone quite to plan.
I rebuilt the front of the box and this morning managed to get it back on without much difficulty actually. Went together pretty sweet. Took me about 4 hours from start to finish. As I said previously, I found a lot of mud between the T box and Auto box which was really odd. Today I found two cut outs in the A box face which may have let this in. I also found a drain hole at the bottom presumably to let it out again. This was blocked so I cleaned it out. I cleaned the T box up too and looked for any holes that might have been letting the dirt in to spoil the oil. I didn't see anything.

So, test drive results. Noise gone completely. Great. It was the front extension housing bearing. But now I have a steady drip of oil from the JOIN between A box and T box. If you look at the picture of my spare box, there is a leak roughly where the circle is. The fill level is shown approx by the red line. There is a seal around the input shaft and before you say that oil may be leaking from there through into the join, it started leaking before I had even driven it. So this is a leak from the static head of oil in the T box. I can only think that there MUST be a pin hole that has been allowing dirt in but hasn't allowed fluid out to this extent in the past. Now that it's all cleaned up, the T box oil is getting out, welling up in the join and leaking out through the gap. I suppose after a bit, it will fall below the fill level and stop. But it rather looks like it's all going to have to come off again and be repaired.

Doesn't it.


Oh joy.

Chris

 

[Chris]

Well wouldn't you just know it. Been for another drive and the noise is back.

Maybe it's not the transfer box then. Huh? Don't get that. Oh well. I think I'll just buy a new one.

Chris

 

[silvercruiser]

Bad luck Chris i hope you find the cause soon.


Joe

 

[Jon Wildsmith]

Maybe it's the transfer box but just not the front output if it's been running on dirty oil. That oil leak is very strange as well, might be more to that than just the leak?

 

[Chris]

Jon, the leak seems to be in exactly the same place as the mud build up between the two boxes. Maybe there has been corrosion (like locker actuators) and that's where the crud has been getting in. I did change the oil not that long ago and when I drained it last weekend, you should have seen it. It looked like the banks of the Thames. The oil wasn't just coloured, it had solids in it.
I would think that this may well have done for the T box as you suggest. But it's fine in normal drive. I am now wondering if it's the VC that might be making the noise. When you lock the diff, the only two bits affected really are the Front shaft and the VC really. Maybe it's the VC that's rattling. This happening due to the fact that the front wheels on over run are effectively driving the box.

I think that next weekend, I shall have to drop the box again and I may as well put the spare on. I don't know its provenance, but at least it's not been running in grinding paste. It has to come off anyway, whatever.

Chris

 

[Andrew Prince]

You could try leaving the VC out when you whip the t/case off. Somehow I doubt this would be the source of the noise, particularly as the VC is just ballast most of the time when you have even traction front and rear. It seems to sound like the problem is related to gears somewhere - you've ruled out the front diff, so maybe centre or rear? If the VC is toast maybe its acting like a partial locked CD but I have never noticed my 80 making any different noises from the drivetrain when the CD is locked, so even if the VC has seized, I am struggling to see why this would cause the whirring... A puzzling one!

Maybe you have a new form of tinnitus that's triggered by your 80?

 

[Chris]

Thanks Andrew. I think that the easiest test (easy he says ) is to swap the whole T case. I shall put the front housing back onto the spare case as it's clearly smoother and tighter than the one I took off last week.

Now there is one more option, but I can't think that it's really this and that is that it's the prop itself. The yokes are fine, but there is a little play in the slip splines. Reason I don't think that it's this is that the VC gives so much drive to the front prop under normal conditions that with all 4 wheels connected to the tarmac, locking the centre doesn't really have much effect when on the over run in a straight line. So I'd hear the noise under normal driving if it were the splines.

I can't emphasise how bad the oil was - again - when I drained the diff. Inside the gears all looked good, clean, shiny and without chips. But if it has been running in that grinding paste all this time, I suspect that you may be right about it being the internals. Nothing broken, just worn to the point that it can vibrate under reverse load.

Of course it may juts be a loose nut on the steering arm......

Chris

 

[frank rabbets]

I assume your propshaft bearings are in phase. Not out. And that the flanges are in parallel planes.

Frank

 

[Chris]

I'd assume so too Frank unless someone has been along in the night and taken them off. This has happened completely out of the blue. Not gradually and not following any event. Not doing it one day, then doing it the next. Something has reached critical somewhere. It ONLY does it on over run with CD locked.

Outside of that it drives like a dream. Did 700 mile round trip in wafting (dented) luxury.

Chris

 

[Chris]

Well, on the drive all day. Now an authority on removing 80 transfer boxes. I had to swap the box completely because of the noise and because of the leak / contamination issue. I swapped this only a fortnight ago since which time it's done about 10 miles.

Here's the oil that came out.


It was like gravy. The joint between the T box and A box was leaking badly and as I split them, it poured out. I have been unable to find where it was leaking form. I have poked and prodded, scraped and cleaned and can't find a single sign of a hole or crack. But mud was getting in and oil was getting out.

I took the PTO cover off and had a look inside. It all looked really nice, no chips or anything with all the gears turning smoothly. But running in soup must've taken it's toll. I have to say that I was impressed with the size of the gears inside the case. They're pretty big and cut with quite a heavy bevel / fluting for improved contact area and smooth meshing.

So, all the ancillaries swapped over from the old one to the spare using the best bits.



Cleaned the opposite face up again which was covered in fluid. I had considered whether ATF was somehow getting out of the A box into the T box. But firstly I don't think it could, secondly I am not missing any ATF and thirdly, there was a pile of mud built up in here when I opened it last time - mostly red Lincomb sand.



OK the results. Very tired arms that's for sure, skinned knuckles too, but the noise does seem to have gone completely. The lockers all work fine and I have to say that the drive feels a little 'tighter'. I shall give it a good run round and check the oil after a few miles.

Hopefully, that's a job - jobbed. I have no desire to lift that damn thing again.

Chris

 

[Jon Wildsmith]

Fingers crossed for you Chris but there's got to be a good chance it was whatever damage that nasty oil has caused that was responsible for the noise. Time to have a proper look inside the old transfer box now?

 

[Chris]

Might take it to bits for fun Jon. Nice to know what's in the box.

C

 

[Chris]

Well that didn't fix it. The noise hadn't gone. So today, I gave everything a right good shoogle. Couldn't find anything loose or catching. Until, I had a crack at the OS front wheel. Deff movement in the bearing despite checking this the other week and adjusting the opposite one. So all torqued up and rebuilt. Went for a spin and as far as I can tell it has gone this time. Hmm.

Wasn't detecting any bearing noise at all otherwise. The T box needed replacing in any case so whilst a PITA it was a necessary job.

Kept me busy I suppose.

Chris

 

[Matt Wright]

Wow. Nice work Mr J.. So handy having spares! I have a spare truck, but no spares lol.
Seriously, I think we need to do a group buy on a set of NEW 80 series..........

 

[Chris]

Hah hah let's get a bid in on the Chequered Flag closing down sale

Chris