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Differential bearing replacements

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08 Aug 2017 20:22 #183254 by Bosanek
My Jimmy has recently developed a repetitive (cyclic) squealing sound coming from the rear differential casing whenever the vehicle is slowly moving and the gearbox is connected to the engine (in gear, clutch pedal depressed).

I suspect that the diff bearing towards the rear propeler shaft is worn. But who knows until the entire diff assembly gets removed for inspection .....


You can imagine my thrill and joy now, especially being in a 3rd world country where no Jimnys can be found in vehicle junk yards.


Has anyone else had a similar issue? What else inside the differential casing could produce the same symptoms?

Does it pay off to replace this bearing? What else to replace once the differential and the rear halfshafts are out?

And most importantly, what are the specifications of all the rear differential bearings?
I need to buy replacement ones possibly from SKF, Timken or Koyo. I suppose that Suzuki OEM ones cost more than my entire 10 year old car.

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08 Aug 2017 20:38 #183255 by mlines

Martin

2003 M13 early KAP build.
3" Trailmaster lift with 1.5 Spacers on front
Customised winch bumper and roll cage
235/85R16 Maxxis Bighorns on 16" Rims, 4:1 Rocklobster, Rear ARB locker and on-board air
Corrected arms all-round, rear disks, Recaro seats and harnesses

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09 Aug 2017 13:52 #183272 by Bosanek
Thank you Martin for the links. I don't recall seing those bearings in your shop before, so I suppose that they are a recent addition.

Can these two bearings be replaced without removing the differential assembly from the housing? Or at least the outer bearing? If not, I suppose that I will have to remove both rear halfaxles and the entire differential assembly first?

Is there anything else that would make sense to replace once the differential assembly is already "on the table"?

I've read somewhere that a badly worn diff pinion bearing usually causes excessive wear of some other (much nastier) component in the differential assembly. Any experiences on that?

I have also read somewhere that it is rather tricky to assemble a differential back together, as some special adjustments are necessary to avoid poor seatment of the components and subsequent excessive wear. Any advices on that? I would not personally perform the job, but I want to be acquainted with the pelicularities in order to properly supervise the work ...

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09 Aug 2017 16:54 #183278 by Riccy
Having recently had my diffs apart for air lockers i can say that its tricky, but not impossible. I dont know if you have to remove the crown gear and planetary assembly to get to the bearing on the input shaft?

I remember seeing it in the workshop manual and looked do-able. If you have to remove the crown and planetary, then you will need to mess around setting the 'backlash' again to get it balanced properly. Its not hard but you need a special dial indicator to measure it. Most of the special tools in the manual are not needed.

J999 MNY, ULYSSES M18 VVT with ITB's Dyno tested at 130hp

Pickup/tipper, R7me gearbox & 6.4 Rocklobster, 31" Toyo MT, 2x ARB air locker 3.9 diffs in braced axles, 6" total lift, Floating rear conversion, Raptor painted, CB, Recaro's, Caged, etc, etc...

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11 Aug 2017 13:02 #183352 by Bosanek
Thank you for the information.

Can you describe that dial indicator a bit more - what's that?

Two reputable mechanics with experience in servicing all terrain vehicles told me that it's a rather risky endeavor to repair a worn differential assembly.
They say that even if just the bearing(s) are worn, some other gear(s) in the differential assembly usually get "scarred" by worn bearings over time. The scars don't matter until you put in new bearings, which then can't be properly matched with the scarred gears. The result is that the differential will be noisy after the repair even with new bearings. This then leads to premature wear of the assembly afterwards.

Even if the gears are not scarred, they say it's a demanding job to properly assemble the differential (to set everything just right), driving the repair cost high.

Due to all this, they recommend a full replacement of the differential assembly from a vehicle junk yard. Replacement of the entire differential assembly can be done without dismantling either the old or the new assembly (just take the halfshafts out, take the old diff assembly out, put a new diff assembly in, put the halfshafts in).


However, the transmission ratio of the new differential has to be the same as the old one.

Now, as I am a lucky owner of a diesel (DDiS) Jimny, I suspect that the transmission ratio of my differential is not the same as in petrol Jimnys.

I need help in determining the ratio of my differential and to find compatible ones from petrol Jimnys!

I know that DDiS Jimnys have never been sold in UK, but if someone has proper access to Suzuki's technical database, they might be able to help me out. I would highly appreciate the help indeed!

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11 Aug 2017 17:43 #183353 by Riccy
Yes, Your welcome and more than helpful yourself!

The dial indicator is a simple but precise device for measuring pressure on a pin-point. Below is a link to the one i bought for the job:

www.machinemart.co.uk/p/cm220-dial-test-indicator/

Also yes, your mechanic is correct about it being much easier to just swap the entire unit, and the worn gear scenario. To fit my ARB lockers into the diff meant removing the crown gear and swapping onto the new ARB planetary unit. I retained all the bearings and other bits, just changed the planetary really, took about a day for the first one then half a day on the second! The job you need to do is that plus more to get to the bearing. The K9K diesel engine (from renault) is fairly common in europe. It does have different ratios to UK jimnys in the diff. See the 'final drive' column in this wiki link:

www.bigjimny.com/mediawiki/index.php?tit...erential_Information

Do you know what gearbox code is fitted to your diesel jimny? R72 with a elec t-box would have had 4.3 diffs in the UK with a 1.3 petrol.

Also do you have the workshop manual on PDF? its pretty good about describing the 'setting the backlash' business, similar for all diffs.

J999 MNY, ULYSSES M18 VVT with ITB's Dyno tested at 130hp

Pickup/tipper, R7me gearbox & 6.4 Rocklobster, 31" Toyo MT, 2x ARB air locker 3.9 diffs in braced axles, 6" total lift, Floating rear conversion, Raptor painted, CB, Recaro's, Caged, etc, etc...

www.youtube.com/user/riclemus

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18 Aug 2017 21:30 - 18 Aug 2017 21:36 #183491 by Bosanek
Thank you very much for your help. After reading the original service manual (section about repairing a differential), I have a much better understanding of the topic. It certainly demands a mechanic with a good experience, and who will do every step carefully and correctly.

My biggest constraint in this situation is having a diesel edition. I have determined that differentials from diesel Jimnys have specific transfer ratios to them (3.416 apparently). So no petrol differential is compatible (both differentials have to have the same transfer ratio).

The only consolation is that all diesels have the same differentials, so at least there are no revisions there. I just need to find a DDiS differential.
However, finding a DDiS differential is four times as hard and at least four times as expensive than finding a petrol one. I see petrol differentials going for 70-100 pounds in UK, while in Germany a DDiS differential (if you even find it) is several hundred euros or close to a thousand, depending on the alignment of stars and the period of the moon.


I could replace both of my differentials with a pair of differentials from a petrol Jimny. The casings and spline counts on the connections with the halfshafts are the same as in petrol Jimnys.
However, as far as I know, there are two editions of differentials for petrol Jimnys (with higher and lower transfer ratios - 4.3 and 4.09). Correct? Does anyone know how to differentiate these two types?


In the case of 4.09 diff, my total transfer gear ratio would be reduced by 19,7%.
In the case of 4.3 diff, my total transfer gear ratio would be reduced by 25,8%.

Both reductions are too extreme, unless very large tyres are used to compensate (but then the mechanical stress on the driveline is increased).

For example, in the first case, my RPM at cca 100 km/h in 5th gear would increase from cca 3000 RPM (now) to cca 3600 RPM. The second case is even worse.


Regarding the gearbox, I don't know which model it is (I am eager to find that out, but don't know how). I just know it probably is not R72 because the casing looks very different (I think it is DDiS specific). But I think that the electric transfer box is the same as in petrol Jimnys.

I just pray that my DDiS gearbox does not malfunction one day, because that will be the day when a car funeral will be a cheaper ceremony than a car repair .,.



P.S.
What does this dial indicator measure? What units does it display on its gauge? Is this a dynamometer?

Why didn't you preventively replace the bearings while you had the differential dismantled to install the locker? Or you judged them to be in such a good condition as new?


My mechanic will open the differential on Monday. Then we will know the situation inside. If I am lucky, just the bearings will be worn. But should I preventively replace or somehow refurbrish anything else? Should I replace all bearings regardless if some of them are still good?

What bearing brand to recommend or to avoid (Timken, Koyo, SKF, NGK, etc.)? Most shops over here sell SKF. But some people tell me SKF is not reliable (non-consistent quality)?
Last edit: 18 Aug 2017 21:36 by Bosanek.

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19 Aug 2017 05:50 #183493 by Lambert

Riccy wrote: Yes, Your welcome and more than helpful yourself!

The dial indicator is a simple but precise device for measuring pressure on a pin-point. Below is a link to the one i bought for the job:

www.machinemart.co.uk/p/cm220-dial-test-indicator/


Dail indicators measure distance not pressure usually in 10ths of millimetres but also in 100ths thought the finer the resolution the more expensive the tool. Test indicators are essentially the same but much more accurate and usually don't have as much range of measurement. Typically a dial will have a range of 0to25mm and a test might be 0to10mm. As i understand it from my work in machining.

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19 Aug 2017 06:45 #183494 by Riccy
The diffs are not that difficult to take to bits, but it does need you to be organised with the parts and manuals. When i did the lockers i didnt need to take the input shaft out, hence i took the 'aint broke, dont fiddle' approach to the bearings. I think it might be possible to take that shaft out from the input flange end without taking the whole planetary gear/ring gear apart.

There is a third option for petrol diffs - 3.909, which is what i have. These were fitted to manual petrol M13 jimnys 2000-2005. That would be the closest match to your original diffs. These cost me £160 for a pair in the UK.

To work out the ratio in a diff - divide the number of teeth on the crown gear by the number of teeth on the input shaft that connects to it.

You could also look at swapping the transfer box if ratios need to match better, but you would probably need a custom made prop to link to the gearbox. The 3.909 diffs would have been mated to a stick shift style transfer box with a 1.3 output. the push-button t-box's have a 1.0 output.

11/60 has a much better description of the dial indicator in his post above than mine. Its used to set the 'backlash' on the crown wheel. This is effectively a sort of balancing of the bearings and diff in the housing. If its too loose then you will get noise from the diff, too tight and it will wear prematurely and use more fuel (drag effect). The amount of backlash should be measured before taking it apart, and put back to the same amount when re-installing. This could be the issue you have if the bearings are ok?

J999 MNY, ULYSSES M18 VVT with ITB's Dyno tested at 130hp

Pickup/tipper, R7me gearbox & 6.4 Rocklobster, 31" Toyo MT, 2x ARB air locker 3.9 diffs in braced axles, 6" total lift, Floating rear conversion, Raptor painted, CB, Recaro's, Caged, etc, etc...

www.youtube.com/user/riclemus

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29 Dec 2017 18:05 #187878 by Ronstan
Replied by Ronstan on topic Differential bearing replacements
I will not bring anything useful into this conversation but I would like to drag out some 100% confirmed information.
You mentioned about swapping over the diffs between petrol and diesel versions.
So, are the diffs fully interchangeable? If there are petrol version axles, is it possible to fit into them diesel version diffs and vice versa ? Is it just plug and play?

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30 Dec 2017 07:29 #187886 by Riccy
I cant say for certain, but would expect them to be interchangeable.

The axle housing will likely be the same in all years/models. the difference will be the tooth count on the crown wheel and corresponding input shaft. For suzuki to make completely different axle casings when they could just swap the two gears would be odd.

J999 MNY, ULYSSES M18 VVT with ITB's Dyno tested at 130hp

Pickup/tipper, R7me gearbox & 6.4 Rocklobster, 31" Toyo MT, 2x ARB air locker 3.9 diffs in braced axles, 6" total lift, Floating rear conversion, Raptor painted, CB, Recaro's, Caged, etc, etc...

www.youtube.com/user/riclemus

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30 Dec 2017 07:46 #187887 by Lambert
The axle case is definitely different between automatic transmission and later manual as my diff didn't fit when I had to replace my original axle case.

Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
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