5245 broken front diff

[rupert]

Hi,
Just bought a 5245 (early model) with a Burder (Australian) loader and a front diff that has failed.
Have had it since Thursday night (two days). It has 1700 hours but has had a hard life and the previous owner was not inclined to spend much on it. Still goes well but looks grim. The previous owner took the 4WD lever off so nobody could select 4WD accidently and sent it with the tractor but it never arrived. I will chase it up with the transport company next week.
Symptoms are when I jack up one front wheel and rotate it the propshaft doesnt turn. (4WD not engaged). Makes a sort of bump, bump, bump sound and the propshaft twitches and turns a little bit on some bumps.???
Has anyone any experience, first, second or thirdhand or ideas on where the drive might have failed?
Crownwheel , pinion or both? Axle spline or gears? I guess it would make more of a grating sound if it was the spline or gears but I dont know.
Im surprised that I cant find more stories on the web about broken Zetor front diffs. Is it very common?
Ive searched the Zetor forum for a thread on broken front diffs but havnt found one.
If there is one already can a moderator put this query in there please?
I have bought an operators manual on Ebay but havnt received it yet.
Havnt found a workshop manual yet but Ive been too busy playing with the new toy.
Theres plenty to do on it. The power steering doesnt work and I cant find a power steering resevior. The charging system doesnt work....
Ive been trolling through the threads and saving 5245/5211 & other posts of interest to a Word file. There is a wealth of information here for someone like me who knows nothing about Zetors yet.
Any and all thoughts and answers gratefully received.

 

[rupert]

Found the power steering resevior. It has oil in it.
After reading some posts i think the power steering probably is working but not well enough but I will change the fluid to Dexron ATF & pump up the front tyres a bit as per Renze's post.
I might even try to bump the pressure up a bit as per Renze's posts as well but the first priority is the diff.

 

[Renze]

The 5245 as well as the heavy UR1 axle differentials, use a lot of parts from the 3011 rear differential: at least the satelite wheels.
Are you sure its the diff, and not a propshaft somewhere ?

 

[rupert]

Hi Renze,
Thanks for replying.
That's a possibility I missed, thanks.
I'll check again but more thoroughly this time and reply.
Be nice if it was just a part of the propshaft.

 

[Renze]

Markku said the other day that when using a loader on a no-spin diff equipped axle, the propshafts tend to break under hard use. When they break inside the housing, it wont be tossed around so you can see its failure, but just not deliver any torque to the wheels.

As you say, propshaft doesnt turn when rotating the wheel, you already know it cant be the dog clutch in the dropbox.
Do the U joints at the wheel pivots turn when rotating a wheel ?

 

[rupert]

Unbolted & slid the propshaft back so I could view the front uni joint behind the front diff.
Jacked up left front wheel only and rotated it. Noticed the uni joint at the wheel hub was rotating with the wheel but the front propshaft uni joint was not moving.
The same applied when I jacked up the right hand side wheel.
The clunking /bumping sound is coming from the diff.
It bumps/clunks 34 times (approximately) for one wheel revolution. This may help work out where it's broken. Considering the possible ratios (not known) for the reduction hub and crownwheel & pinion may point to the damaged part/s.
It's looking more like I'll be pulling the diff out though.

 

[rupert]

Sorry, I need to correct my last post.
I should have written " Unbolted & slid the propshaft cover[/] back so I could view the front uni joint behind the front diff"

 

[rupert]

Attempted to pull the diff out of the front axle housing after I checked the oil level and found it empty.
I pulled the steering (kingpin) bearings (top & bottom) on the side opposite the steering ram and tried to pull the axle out but it's stuck and I don't want to use the very big hammer till I find out if there's anything else I should do to disconnect it.
I still don't have a workshop manual .
Does anybody know if there's something else holding it in or is it possibly seized/rusted in there from working with no oil?
I attempted to pull the steering bearings on the other side (steering ram side) and got the bottom one out but when I tried the top one I found that someone before me had tapped the jacking holes to 1/2 inch UNC and all but stripped them.
I tapped them out to 9/16 inch UNC and used 2 X 9/16inch UNC bolts to jack the bearing up. It needed a lot of force and then the top plate with the column on top came up but the bearing in its shell stayed in the uni joint housing.
I will clean it up with emery tape and put the top plate back on with the 4 bolts and some loctite. Let it set for a couple of days and try again. Hopefully the bearing will come out with it if the loctite holds.
Any information on getting the axles out would be greatly appreciated.

 

[Renze]

I am fixing the 5245 front axle too: Ours jammed the front wheel saturday. It turned out that the driveshaft needle bearings were gone, as well as the oil seals. There was shavings and sand inside, and no oil. Because of the misaligned gears in the hub, the toothed ring gear broke a tooth, the upper part was pushed between two teeth.

(Off course, this is caused by severe lack of maintenance: you guys dont have to rub it in, my father didnt want to spend any on maintenance because the farm lost a lot of money on the pigs)

Test that too: If you grab the U joint between wheel and axle, and you can wobble it in the housing, it is likely a hub problem. These needle bearings are even more sensitive to poor lubrication than the ball bearings of the diff and wheels.

Another tip: While i had the kingpin bearing off, i drilled a 5mm hole through the center of the bearing stub, and cross drilled it to the side of the plate its mounted on. On the side i tapped M8 thread to accept a grease zerk. It has been 7 years ago that i replaced this kingpin bearing, and both times the bearing failed because of rust.

I will weld a little extension on the lower bracket of the front mudguards, to protect the grease zerk on the steering arm from damage.

 

[rupert]

Hi Renze.
Regarding installing grease nipples on the steering bearings I'd say it's a must. The one top bearing I got out was just starting to go a little rust coloured while both bottom bearings were OK.
I dismantled one of the final drives on the front axle while I had the wheels off because I drained the oil from both of them and it was very dark and had quite a lot of metal shavings in it. They both had about .25 litre as per the owner's manual so no leaks I guess.
There was more wear on the teeth of the big ring gear than the teeth of the pinion . All the bearings are OK.
If the final drives on the front axle are prone to severe wear (and with a loader mine will probably wear faster) I intend to (1) use a magnetic drain plug and
(2)Use an expensive synthetic gear oil in them (only .25 litre in each so wont add much to the cost of the job) It will also be a good test of whether expensive gear oils are worth the extra money.
Here's a link to a comparative test of most gear oils available that's worth reading before you put the oil in your front hubs.
http://www.synthetic-oil-tech.com/Gear%20Lube%20White%20Paper.pdf

 

[Renze]

Dont know if they are prone to wear, but i do know that needle bearings are very sensitive to dirt and dry running.
The bearings and seals together cost less than 35 euro, but a busted up hub with wheel bearings and all, costs 15 times as much.

The pinion is hardened, the ring gear not. I need a new ring gear because some teeth broke, but the pinion is only scratched. On the right hand side i will use the same pinion, as long as it doesnt lock up as well before i have time to do the other hub.

The bearing housing in the stub axle is worn away into the axle stub: I will resurface this one and use it on the right hand side (the right hand side has a cast iron version, which isnt repairable with a welder anyways)

 

[bobnz]

I have had a 6245 wheel assembly off the main axle housing and to withdraw the live axle or half shaft the large circlip is not obvious.

With the outer yoke and wheel assembly pulled away the axle slides out of that freely. The axle is retained in the diff housing by a large cirlclip.

It is best to clean away all dirt and also any light rust which would be in the path of the bearing on the axle as it is pulled out. There is not a lot of room to get at the circlip with the axle in place as the U on the axle holding the universal cross piece makes it harder to get at the circlip.

My circlip pliers were not up to the job. A decent pair with a 45 degree angle bend in the jaws would be to be easiler to get in.

I got a pair of long nosed vice grips, cut the jaws half way along and welded the pieces back at a 45 degree angle to make a "bent" nosed vice grip. I then ground down the tips of the jaws to fit the circlip holes.

The beauty of the vice grips is that you can get very good leverage by adjusting the jaws so they lock when the circlip is compressed. The action is much better than circlip pliers as the tight spot for access becomes less of a problem when one hand can be used to hold and guide the vice gripes and compressed circlip out while the other hand is free to use a thin screwdriver to ease the cirlip free. The circlip on one side was well rusted.

The axle was nudged out with a lever on either side.

With the axle out it is possible to press the bearings and light gauge ( about 1.6mm) steel covers out with a small hydraulic jack or expanding wedge and packers. The round but dished covers can then be drilled and grease nipples installed.

Stripped 12mm x 1.25mm pitch holes for the two bolts used to press off the top and bottom sections of the swivel pin bearing pins are a pain but rust looks to be the likely cause of weakened threads. There are 16mm locating pins in line with these threaded holes.
I found that a large fine edged cold chisel driven into the joint in several places soon moved the top and bottom caps with the top one being more frozen. I then ground four small wedge points for a cold chisel to work more effectively next time.

The bearings can be extracted without removal of the live axle. With the top and bottom caps off complete with the bearing cones and rollers on the pins, then the sheet metal caps can be tapped down a little with a drift to allow grip of the bearing outer cone with a puller.

I made one up using four 12mm bolts with the heads cut to a thin edge to go under the bearing. With four of then in place ( two may do ) I made a packer to fit between them so jambing them hard against the bearing with the thin heads under the bottom of the outer cone. It was then just a matter of placing a flat steel plate with holes for the bolts over the four , using a packer and winding down the nuts. Bearing came out without fuss and undamaged.
The internal bearing cones came off the pins with levers and suitable packers. Once again nothing damaged
I can email a picture of the puller made up if that is useful.
Both top and bottom bearings were rusty and pitted. I dismantled the bearing and cleaned out all rust using electrolysis and a final light etch with phosphoric acid.

The bearings cleaned up but still with some pitting evident. They work fine as they are far stronger than what is needed. A good smothering of grease is essential before assembly. Mind the rubber seals when pumping grease into the complete assembly. Give time for any air pockets to work out and then try adding a little now and then after use. Some should work out past the seals eventually

 

[rupert]

Hi BobNZ'
Thanks for the info particularly about pulling the bearing cones.
I eventually got the axles out of my 5245 and the setup is a little different.
At the outer end of the axle there is a collar that fits snugly into the outer end of the housing. This collar goes around a ball bearing around the axle that guides the axle centrally in the housing. This collar has a v shaped groove cut into the outer circumference of the collar. The walls of the v are at 45 degrees to the surface of the collar making the V 90 degrees. At the rear of the housing there is a threaded hole through the housing located at the outer end where the groove is. A hardened metal thread with a screwdriver slot on the outer end and a point on the inner end screws into this hole and locates into the V groove in the inner collar thus retaining the axle.
Once this is screwed in tight there is a locknut on the outside around the thread that tightens down on the surface of the axle housing.
The collar seals against the inside of the housing with an O ring in a groove adjacent to the V groove.
On mine the thread had been screwed in so hard that the point had widened the v groove at that point and crowded the steel into the O ring groove narrowing it at that point and pinching the O ring.
All my steering bearings are OK but I will install grease nipples and reassemble them with plenty of grease. Your tip about greasing them gradually is a good one.
I pulled the diff out. It's a banjo style so comes straight out once the axles are clear.
The pinion was completely toothless and the crownwheel was worn very thin on the teeth.
There was about a half a cup of oil in the diff housing. (and about the same amount of metal shavings).
The crownwheel comes off easily once the 2 end caps holding the inner assembly are removed.
I'd imagine that the end caps should be marked in some way (centre punch?)so that they go back on the same side base.
With that assembly out of the way the pinion shaft drives inward after the nut and seal plate are removed.
I've bought a second hand crownwheel and pinion from a tractor wreckers for AU$550 but it will take a couple of days to get here. Provided it's OK I should be mobile again next week.

 

[rupert]

I now have the new second hand crownwheel & pinion set.
I have been researching the diff setup and its a fairly exacting job to do it right.
I still have no workshop manual and need 3 or 4 diff setup settings.
1: pinion bearing preload.
2: ring (crownwheel) & pinion backlash
3: how to set the diff side bearing preload (possibly listed as something like tighten till no play then extra so many degrees or notches)
4: and then possibly the pinion depth
Id be grateful if someone with a 5245 workshop manual could post these settings. Hopefully theyre in the manual.

 

[Renze]

There are only 8 5245's sold in Holland so i didnt even attempt to find used wheel hubs.

I decided to try to weld and resurface the stub axle housing i replaced, because this was the most expensive part. So i ordered parts for just one hub. One week later, and about 1 hour of operation, the right hand hub locked up, i could drive forward around the workshop and had to drag one wheel to get it in.
The kingpin bearing was also stuffed with hard grease with rust in it, so when its done it should steer like brand new...


I might be able to scan some pages in the shop manual later this week...

 

[bobnz]

I have now got access to a workshop manual covering the 5211 through to the 7245. It is printed 1984.

If you still need the settings then I will have to scan the pages and email them to you.
In the manual it shows the circlip arrangement holding the axle bearing close to the swivel pin universal end. This looks to be similar to the 7045 also. The collar ( part 32 on the diagram ) can stay in place in the axle and the bearing comes out on the axle complete with its sealing O outer ring.
The puller I made up for the swivel pin bearing cups is simple enough and I can email a photo of that is it is of any help . I think it should work for any of the heavier style front wheel drives of that period - UR1

You may have it all running by now.

 

[rupert]

Hi Bob,
I have the diff assembled and have been experimenting with different settings for side bearing preload, backlash and pinion depth then using bearing blue to take a contact pattern of the pinion and crownwheel gear faces. Pinion depth is apparently finely set by the pattern.
More importantly the side bearing preload is critical. Too much and the side bearings will wear and maybe even break the diff casting at the bearing mounts under load. Too little and the bearings will move and not seat correctly resulting in misalignment of the bearings with their faces and misalignment of the gearset.
Zetor Direct (Parts Australia) have told me that the front diff in a 5245 is a Cararra diff made in Italy and is a comparatively light duty diff. So I want to set it up by the book and would appreciate the settings. I will Email you and if you can send them that would be great.
All I am waiting on now is a dial gauge indicator to measure the backlash (once I know the settings) and I hope to get one within the next few days.
Cheers,
Ian

 

[Renze]

Front diff of the 5245 has part numbers beginning with 3011 which means the basic design is of the 3011 rear differential.
They began using Carraro diffs halfway the 3340: First ones still had the Zetor axles, later ones the Carraro axle. There has not been any crossover, Zetor axle with Carraro diff.

When i changed the oil of my 5245 there were no shavings at all, and oil up to max. level.

About extracting the wheel pivot bearings, the easiest method is to weld a good bead through the center of them, and then weld a piece of metal to it. The welding heat reverses the hardening process, which makes the metal mild and it shrinks back to its original size. After welding through it, you can just rip it out with a small crowbar or big screwdriver.

 

[bobnz]

Renze is a good tip about shrinking the cups with a weld. The contraction under cooling is certainly effective
The simple puller I made up moved two very tight bearing cups and salvaged them with little effort. Most claws on the common universal pullers don't get in under the cups.
Although I used four bolts in the puller , three if two would do I am sure.
The steel centre spacer could be a block of wood. I can send you a couple of photos by email if there is somewhere to post them .
Regards Bob

 

[bobnz]

Queensland Nut

Ian
I have sent four scanned pages.
Good Luck

 

[rupert]

Well, the front diff is repaired successfully and has passed a tough trial run.
Sorry this info took so long but Ive been busy repairing the brakes (new shoes, new wheel cylinders, new rear diff axle oil seals & gaskets, O-rings, shaped seals, axle guide bearings (6009 2z) new handbrake bands & brake lines)

I had not set up a diff before and all I had going for me was a lot of enthusiasm but with the help of some expert advice from BobNZ, I was able to set it up without recourse to the manual ( which was hard to follow anyway).

With Bobs permission, I include exerts below of the relevant bits of advice from Bob that I did not find anywhere on the net despite much information being available on general settings & contact patterns etc. in the hope that it might be useful to anyone wanting to attempt a diff repair. It is not hard, you just need patience.
Have to make 3 posts of this as there is a limit on post size.

I learned that an understanding of crownwheel & pinion gearface contact patterns, how a diff loads up and how the loading affects contact patterns & the dangers of edge loading is the key to setting up a diff successfully.

From Bob:

Setting up diffs is a bit of an art from my experience.
Zetor instructions from memory are pretty straight forward but go into measuring distances and calculating shims. There are other ways. I think zetor also uses some markings of numbers stamped on the casings but that will be clearer when I grab the workshop manual and scan off the pages
I have found that the manuals leave out or gloss over many operations assuming a mechanic would not need detail so sometimes a bit of head scratching is needed.
There is no reference to checking the face contact pattern with blue. The crownwheel and pinion come marked as a pair and set up is made on measurement. I guess it is a low speed tractor so robust contact without any edge loading is their main aim.
It may well be simpler than multiple assembly and testing with blue procedures often needed with unmatched pairs.
The carrier head at least can be set up without the hard work of bolting up and unbolting the diff housing.
I have not done a diff for some years. The blue pattern on the teeth is the final call as to whether it is set up OK.

Do you have a good section in any manual as to what the blue pattern should look like?
Generally it should be broad and mid tooth on the crown wheel.
High or low bearing I have found cracks the hardening on the teeth.
Similarly heavy bearing near the ends of the teeth creates cracking and fracture.

In my experience all end and edges should be clear of bearing.

I am interested as to what the tooth count is on the new crownwheel and pinion. I see Carraro diffs feature on some of the much later Zetors as well but they may be very different models. Perhaps a workshop manual covering one of these later models may have some good info applicable to the Carraro driving head setup.

If your setting up brings contact into an area outside of the old wear pattern then the chances are you will have point loading on the edge of the zone of wear and newly used surface. ( that may be on either the crown wheel or pinion.)

The contact pattern on the drive side which looks to be the more upright face on the Crown wheel, seems to look as though it is bearing toward the inner end of the teeth. If all options have been tried then increasing the backlash may help remedy the contact as the crownwheel moves a way from the pinion.

The used diff would have developed an increase in the back lash and that will be reflected in the wear pattern on that gear set.. A bit of backlash is pretty normal in used diffs and is usually best left alone.

 

[rupert]

Try using a tiny thin smear of blue on the pinion and see where it transfers to the crownwheel as that can help getting an idea about high spots in the meshing forces.

In setting up, the pinion has its preload, then the crown wheel is moved to give the backlash aimed for.. When that is Ok without any bearing play then the crown wheel preload is increased from either side of the crown wheel to maintain the same backlash. The pinion preload and the crown wheel loading can now be measured through the pinion giving the total combined preload as measured at the pinion drive.

Not all setups do it that way but a large number do and it is the better method.

Once the combined preload is set and the backlash is close then use the blue sparingly as the depth of blue needs to be minimal or a false impression can be given.

Cleaning the old blue off each time you change anything is also important.
After you have lightly smeared the pinion and tested forward and back, clean up and then lightly smear a few teeth of the crown wheel and see what shows on the pinion forward and back.
As the coating of blue thins the picture becomes more focussed on high points. This can be a bit frustrating but it does give a better idea of just what is making contact
.
A play with the crown wheel position at that point can give a idea of contact change for crown wheel direction. Backlash will alter of course but an indication is all you are after before figuring any pinion movement.

Wear during use should be absolutely minimal in any short term.

Under load the steel flexes. Teeth will flex as does the carrier and bearing towers. Some compression of the pinion bearings will also allow small movement so it is a live situation. The movements are slight but as you can imagine load changes and so will the movement and contact pattern between the faces It is a while since I spent days finding compromise on worn and unmatched pairs.

Cracking of hardening seems to happen when edges are taking load, particularly at the heel and toe. When cracking starts then the hardened surface looses some of its tensile strength and more force is transferred to the metal under that hardened surface. The less hard and more flexible substrate metal then moves a little more without the hardened shell being in tact and so flaking of the hardened outer can start.

Leverage on the edges also can apply greater force for a given area as well as the force causing greater flex with the less supported edge metal.

I have seen mismatched pairs with the crown wheel teeth like razor blades on the tooth tops as well as seen inner end of crown wheel teeth showing flaking of hardening and a array of fine cracks when cleaned off, dried and then heated lightly to show the oil in the cracks. This damage occurred with full oil levels.

A high powered magnifier and good light moved around at various angles gives info not seen with the naked eye.

My impression from what you have described is that you may find the best compromise some where near the old wear pattern. It is pretty hard to take into account what movement under load will do in changing the contact pattern.

There is bound to be some small variation between your carrier and the previous carrier that the gear set was working in so a absolute matching of the old pattern would not be exact anyway. As you have it no load is on when doing the blue test so you probably can guess/allow a little.
The crown wheel will flex away and the pinion will push into the bearing under drive load and pinion climb toward the crown wheel under reverse

 

[rupert]

Once it is as close to what you feel is possible to a good pattern and following close to but maybe a small improvement/ allowance on the old pattern if it doesn't want to match that closely, then that must be it.

A long running in time with light loading when in 4WD would make a lot of sense. Use on soft ground would also lessen point loading as it "wears" in.

Two manuals say 150Nm for castle pinion nuts.

As the diffs are Zetor and not Carraro then the data is not strictly for your diff. I imagine that seems a reasonable torque for a half nut castle type.

I found a reference crownwheel backlash of .008" to .011" mentioned in the notes on 6745 front diffs.

The pictures of blue patterns seem to have sorted out reasonably well and your backlash is a good common figure. The Zetor figure of 8 to 11 thou may help the bearing to come out a fraction on the tooth but no doubt you have tried that.


End of Bob's info.

For the record:
I set the backlash at .008, the carrier preload plus the pinion preload measured 22 inch pounds at the pinion nut (using new pinion bearings). The pinion preload on its own at the pinion nut measured 20 inch pounds. The pinion castle nut I torqued down to 170 foot pounds (where the slots lined up to put a split pin through), well in excess of the manuals 150 NM. According to the thread torque tables itll take it.

The thread is 20 X 1.5 (but only half the amount of thread)
The chart lists 687 NM for 10.9
482 NM for 8.8

Found a formula for side bearing preload measured at the pinion nut
Example:

Crownwheel teeth divided by pinion teeth

My CW = 33 teeth & My Pinion = 7 teeth ratio = 4.7 so 5 is the factor (is close enough)

Preload pinion = 20 (inch pounds) desired side bearing preload = 7 to 15 say 10

10 (desired side brg. preload)/5 (factor) = 2

total preload = 22 approx..



The above info in addition to the nuts & bolts info from web sources made the difference between success and failure for me.

Regards,

Ian

 

[blackswan]

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