Rear Differential noises

[Julian B]

When I jack up my rolling chassis (no body attached) and rotate the front wheels they rotate smoothly and quietly, whether the front diff lock is engaged or de-selected. But when I rotate the rear wheels there is a slight "clonking" noise as the diff rotates - and I think it is coming from the centre of the axles (i.e. the diff). It is more slightly more pronounced when the rear diff lock is de-selected, and happens whether I rotate a wheel forwards or backwards.

Is this right, or a problem?

TIA

[heinkeljb]

Have you put oil back in there yet?

Could be that when you took the drive shafts out, you have put them back in slightly differently, you made mention of the little blocks with holes in them only fitting one way round, could they need to be fitted a further 180 degrees from the the way you have them at present?

Clutching at straws really, as the only other reason I can think of for a "clonking" noise coming from a diff is broken teeth!

John

[Julian B]

John, the blocks can only go one of two ways, and I doubt that turning them 180 digs would make much / any difference. They were complete pigs to line up, and I'd really prefer not to have to take them apart again. The oil levels are right too. Hmmm, I hope that no teeth are damaged, but I'll have another play over the weekend to see if I can more accurately determine what is wrong. Thanks anyway!

PS Would one normally expect the rear diff to sound the same as the front diff when the wheels are jacked up and turned by hand? Or would the rear diff normally be noisier?

[pathfinder700ap]

Hi Julian,

if both wheels are turning in the same direction, i.e. if the difflock is engaged, it means that you are turning the whole differential cage as well as the pinion gear via the crown wheel.

On the front axle, the pinion gear will rotate, but not more (as long as the front wheel drive is not selected). On the rear axle, the pinion gear sits on the output shaft of the gearbox. The gearwheels located on this shaft are loose, but might still be dragged along a little bit due to the viscosity of the oil and hence cause some sound.

If the differential lock is disengaged and the wheels are turning in different directions due to the friction resistance in the crown/pinion pair, both axles should be quite similar. However the front axle includes the CV joints, so the hub gears are sort of seperated from the differential in terms of housing and non-rigid connection, maybe that makes a difference as well.


Kind regards,
Constantin

[Julian B]

Constantin - if I understand you correctly you are saying that, with the diffs dissengaged, the front and rear diffs should make a similar amount of noise, but the rear might be slightly noisier due to the lack of CV joints in the rear diff. If that is so, then mine are certainly like that - all I need to determine is whether the level of excess "noise" from the rear is appropriate for a Haf.

I will see if I can record the noise over the weekend.

Many thanks!

[heinkeljb]

Julian,

Do you get the same noise all the time or does it change? (one rotation this noise, next a slightly different one?)
If you turn one of the wheels slowly do you "feel" when it makes a noise?
Is it always with the wheel in the same place?
Does it happen if you prevent the other side wheel from turning?
Is it more pronounced depending on which side wheel is turned?
Does it happen if you engage a gear?
Does engaging the diff lock change the noise? In gear, out of gear?

Have you put the engine back on? If not then does it change if you hold the input shaft to the gearbox?

Hopefully, you can narrow it down to some specific bit of Diff / Gearbox which will then limit the possible reason as to what / how the noise is produced.

I suppose this is a good example of "If it ain't broke, don't fix" - You always find some thing more that needs fixing, not just the thing you set out to fix!

John

[Julian B]

I have now identified what I am 99% sure the problem is - just need to make an adjustment. When the rear diff lock is engaged the noise stops. When disengaged the noise happens, but I noticed that the rear diff lock control arm was vibrating in time to the noise. So I need to adjust the selector rod that goes into the diff housing. Hopefully a fairly simple task!

That is the good news. The less good news is that the diff side covers are weeping some oil, so will need to remove them again to reseal them. Not good, as we found it very difficult to line up the "knuckles" correctly. Hey Ho!

[HaffyHunter]

Hi Julian,
The easiest way to align the "knuckles is to first install the blocks and inner shaft then slide the side cover and outer half-axle sleeve over the shaft. The other method that works well is to degrease the blocks and stub ends then apply a drop of CA cement (Crazy Glue) to the stubs to hold the blocks in place while inserting the whole half-axle assembly. The CA cement will provide enough hold if you work gently. Once the axle is installed the CA will easily break free and get dissolved by the heat and oil in the diff housing. The first method is the procedure described in the repair manual.
Cheers,
Steve

[heinkeljb]

Surely some thing like grease would be better? That at least is something which will provide lubrication.

My issue with using glue is that it might turn into some thing hard as a reaction to the oil / heat / pressure.

Still, what do I know? I haven't had to take Diff's apart on mine yet!

John

[AustHaflinger]

Surely some thing like grease would be better?

After getting very frustrated trying to get the front ones back in I used thick grease and it seemed to work reasonably well.

Garry

[Julian B]

Hi Julian,
The easiest way to align the "knuckles is to first install the blocks and inner shaft then slide the side cover and outer half-axle sleeve over the shaft. The other method that works well is to degrease the blocks and stub ends then apply a drop of CA cement (Crazy Glue) to the stubs to hold the blocks in place while inserting the whole half-axle assembly. The CA cement will provide enough hold if you work gently. Once the axle is installed the CA will easily break free and get dissolved by the heat and oil in the diff housing. The first method is the procedure described in the repair manual.
Cheers,
Steve

Hi Steve,

Sorry to be a bit thick with this, but I have to say that I sometimes struggle to understand what the Repair Manual is actually saying. First off, am I right to assume that the relevant section for reinstalling the (rear) half axles is 4-7, c) paras 1&2 ?

If so, why, in 4-7, c) 1), do they talk about "installing r.h.s diff side cover complete with … and diff lock selector fork" when the way I see things the selector fork is on the l.h.s?

And do I read 4-7, c) 2) correctly when they say I need to disassemble the hub gear assembly in order to get the knuckles to line up properly? If so, I can't understand why one needs to do this on the l.h.s but not the r.h.s. (And am I right to assume that the purpose of dissembling the hub gear assembly is so that the half shaft can be "pushed up within the half axle housing", enabling a better view / better access of where the knuckles meet up with / slide in to the diff itself?

I hope to do this on Monday morning, but am trying to understand what I need to do before then.

Many thanks!

[EDITED TO ADD] Also, section 4-6 IV. a) 1) says, when removing the half axle, to "Take off & mark the differential adjusting shim". I am ashamed to say that I did not do this last time, and I'm not at all sure what they are referring to. Any ideas? [/EDIT]

[HaffyHunter]

Hi Julian,
I agree that many sections of the Repair Manual can be a tad difficult to follow. I think some things may have been lost in translation and sometimes pieces were omitted altogether during republications.

If so, why, in 4-7, c) 1), do they talk about "installing r.h.s diff side cover complete with … and diff lock selector fork" when the way I see things the selector fork is on the l.h.s?

I think the manual is referring to the front diff at this point.

And do I read 4-7, c) 2) correctly when they say I need to disassemble the hub gear assembly in order to get the knuckles to line up properly? If so, I can't understand why one needs to do this on the l.h.s but not the r.h.s. (And am I right to assume that the purpose of dissembling the hub gear assembly is so that the half shaft can be "pushed up within the half axle housing", enabling a better view / better access of where the knuckles meet up with / slide in to the diff itself?

Yes you need to disassemble the hub gear. You only need to do this on the LHS as the RHS can be fully assembled complete with diff gear outside the vehicle then inserted as a unit to the housing. The RHS knuckle is easily aligned when you have the diff gear out of the housing. The diff gear and bearing are supported by the RHS diff cover during assembly and the knuckle joint will stay in place. Assembling the RHS first (LHS first for the front axle) allows you access to the diff lock fork for alignment when placing the diff gear in the housing. For the opposite side (LHS on rear axle), the hub gear must be disassembled (remove the small spur gear) to allow the axle tube to slide over the inner axle shaft after the shaft and blocks have been inserted in the diff gear socket. It is very easy to align the blocks when the diff cover isn't in the way. Note that the outer axle tube must be affixed to the diff cover before sliding it over the inner shaft as there is not sufficient clearance to install the fulcrum pins once the cover is in place due to the clutch housing.

However, if you are averse to disassembling the hub gear then try my CA cement or the suggested heavy grease method which works fine with a bit of patience and warm fingers.

Also, section 4-6 IV. a) 1) says, when removing the half axle, to "Take off & mark the differential adjusting shim". I am ashamed to say that I did not do this last time, and I'm not at all sure what they are referring to. Any ideas?

I think the manual is trying to help you to not accidentally interchange shims between front and rear diffs in the event that you have both ends of the beast torn down.

Cheers,
Steve

[AustHaflinger]

I am sorry to say that I find the 3rd generation photocopy of the manual extremely difficult to use - they layout, syntax and information is a disaster. I am glad that there are plenty of knowledgeable people on here.

I would have thought some enterprising person or organisation would have written a new version - I would buy it.

Garry

[Julian B]

Thanks Steve.

Section 4-7, c) 1) is definitely talking about the front diff (in my copy of the book at least), so can only imagine that the "r.h.s" is a typo.

Yes you need to disassemble the hub gear. You only need to do this on the LHS as the RHS can be fully assembled complete with diff gear outside the vehicle then inserted as a unit to the housing. The RHS knuckle is easily aligned when you have the diff gear out of the housing. The diff gear and bearing are supported by the RHS diff cover during assembly and the knuckle joint will stay in place. Assembling the RHS first (LHS first for the front axle) allows you access to the diff lock fork for alignment when placing the diff gear in the housing. For the opposite side (LHS on rear axle), the hub gear must be disassembled (remove the small spur gear) to allow the axle tube to slide over the inner axle shaft after the shaft and blocks have been inserted in the diff gear socket. It is very easy to align the blocks when the diff cover isn't in the way. Note that the outer axle tube must be affixed to the diff cover before sliding it over the inner shaft as there is not sufficient clearance to install the fulcrum pins once the cover is in place due to the clutch housing.

So I actually remove the diff gear structure from the diff housing (pull out towards the r.h.s), push the half axle c/w knuckles into the diff structure and then put the combined unit back in through the r.h.s? Eek, that sounds scary, but maybe it will all become clearer / easier when actually done. But (assuming that I have understood you correctly) that does all sound sensible and feasible. It would also explain why I only need to disassemble the l.h.s hub gear.

However, if you are averse to disassembling the hub gear then try my CA cement or the suggested heavy grease method which works fine with a bit of patience and warm fingers.

I think what I will do is slide the diff out and do the r.h.s. half axle easily first, then try the CA cement / grease method on the l.h.s. half axle, and if that doesn't work strip the l.h.s. hub gear and do it that way.

Your explanation has been really helpful - thanks so much!

[Julian B]

I am sorry to say that I find the 3rd generation photocopy of the manual extremely difficult to use - they layout, syntax and information is a disaster. I am glad that there are plenty of knowledgeable people on here.
I would have thought some enterprising person or organisation would have written a new version - I would buy it.

Where did you get your Repair Instructions book from? Mine is an english language reprint done by Verlag Verwuster, A-8055 Graz, Am Leopoldsgrund 106, Austria ( [email protected] ), but I can't find a date / version number. The text & b&w photos / diagrams are legible, but like you find the translation far from perfect. (For that I dont hold Verlag responsible).

See http://www.motorbooks.at/catalog/produc ... ir-manual/

[AustHaflinger]

Mine is a photocopy that came with my vehicle. Really only covers some mechanical aspects and is not very good. I thought there were no manuals that cover the later models and we had to put up with the older version.

Garry

[HaffyHunter]

Your explanation has been really helpful - thanks so much!

_________________
Julian B
W Sussex, UK

You're very welcome Julian. I know too well how challenging those blocks can be to align and tried several methods before really thinking through what the Repair Manual was trying to tell me. One other assembly tip is that the RHS of the diff housing has a spacer ring that needs to be placed on the diff cover before seating the gear assembly in the cover. It is necessary to this as the diff's ring gear is slightly too large to fit through the spacer's opening.

As for a new version of the Repair Manual, Jim Molloy had once alluded that he was working on development of a new version and possibly a video series of Haflinger "How To's". I'm not sure if he is still pursuing this venture but if so I'm sure will be a top notch effort and much appreciated by our community.

Cheers,
Steve

[Julian B]

Garry, I can scan the Contents page and a sample "main page" if you like, so that you can see whether it has the same info, and what the reproduction is like. If it is better than what you already have then it might be worth your while buying a Verlag re-print ...

[AustHaflinger]

Thanks Julian but I will be fine - I am finding I can generally find what I need from other sources.

[walderse]

Steve,
The project of a new manual is still in the works. Rather than reproducing another service manual only, the goal is to field the Steyr-Puch Haflinger tribute to John Muir's classic "How To Keep Your Volkswagen Alive..." reference. The delay is not for lack of interest but rather juggling a full time profession, organizing/hosting our annual Northwest MogFest event and prepariing for a special Haflinger journey in July of 2014. Work will once again resume in January 2014 with the goal to have this project complete by mid-August.

Take care.
Jim Molloy
Waldersee Farm
http://www.northwestmogfest.com