FreeTaz · May 12, 2013

Hi All, Greetings from Australia.
After searching as many threads as I can find on IRDs, I think I need to start a new one.
I have a MY 2001 Freebie KV6 Auto with 145K on the meter.
Having replaced the VCU(RIP) & bearings, front propshaft and R/H driveshaft, I now face the need to repair/replace the IRD as the oil has a lovely metallic sheen and there is a rather expensive sounding noise at low speeds (similar to bearing noise). There is also some axial play in the R/H driveshaft coupling into the IRD.
At this stage I have not removed the propshaft pinion from the rear of the IRD to check the crown wheel and pinion, nor have I drained the IRD oil to check for gear dandruff on the drain plug.

My question is, knowing that the IRD for the KV6 is geared differently to the rest , does the rebuild kit with crown wheel and pinion that some people advertise on Freebay suit the KV6 IRD especially the crown wheel and pinion. I hope that the difference in ratio is in the countershaft to crown wheel shaft gearing. If not I will need to search further for the correct parts. Some of the Freebay sites have conflicting information in their compatibility charts.

As I am in Australia, a professionally rebuilt IRD is a rather expensive option due to shipping and deposit costs and I believe that bearings and shims will fix my Freebie.

Any info would be appreciated.

FreeTaz · May 16, 2013

Hmmm...just realized my error, the crown wheel is on the counter shaft, so I guess the ratio is varied elsewhere or is it the crown wheel and pinion that is different?

Nodge68 · May 16, 2013

There are some different gears and bearings used in the V6 IRD and the casing is different too. Sorry but I've no idea which parts could be used. Some more research is needed

FreeTaz · May 16, 2013

Nodge68 said:
There are some different gears and bearings used in the V6 IRD and the casing is different too. Sorry but I've no idea which parts could be used. Some more research is needed

Thanks Nodge, it's starting to look like I will need to open it up and find the numbers as I go. I can then compare them with the list and see if the kits are still value.
Just as well I have a spare vehicle for transport as there may be some time required.

FreeTaz · May 19, 2013

Update.
IRD open on the bench. Looking good at this stage, no gear damage, no bearing failure.
The only smoking gun is the diff shims, one large shim seems to have been forced off centre and the centre hole is fast approaching the perimeter. Not much swarf on the magnet, in line with the shim failuire. Counter shaft seems to have some pre-load still, so I might not disturb that. A little careful cleaning of input shaft and diff assembly and temporary reassembly should hopefully show if bearings are still OK.
New diff shims and a set of seals might be enough to keep it going till the next VCU change.

Nodge68 · May 19, 2013

:nopics::nopics:

FreeTaz said:
Update.
IRD open on the bench. Looking good at this stage, no gear damage, no bearing failure.
The only smoking gun is the diff shims, one large shim seems to have been forced off centre and the centre hole is fast approaching the perimeter. Not much swarf on the magnet, in line with the shim failuire. Counter shaft seems to have some pre-load still, so I might not disturb that. A little careful cleaning of input shaft and diff assembly and temporary reassembly should hopefully show if bearings are still OK.
New diff shims and a set of seals might be enough to keep it going till the next VCU change.

:nopics:

Can i just ask how the engine is doing? They get a lot of stick for being unreliable so just wondered how it's been in your warmer climate!
Personally I'd only have the V6! !
Good luck with it

FreeTaz · May 20, 2013

Nodge68 said:
:nopics::nopics:

:nopics:

Can i just ask how the engine is doing? They get a lot of stick for being unreliable so just wondered how it's been in your warmer climate!
Personally I'd only have the V6! !
Good luck with it

Hi Nodge,
Yes, I must get the camera out.
The engine is sweet, I'd have junked the car if I wasn't so taken with how well it goes. I bought it cheap with trans questions. Belt(?s) done at 100ks according to sticker on the engine. No other service history. The car spent the first 6 years in Queensland where it's warmer and the temp does not vary much. Tasmania is much cooler but not as bad as GB. As the 'stat brings the temp to the same number here as it does there, the icy conditions there cause a much wider temp variation and with alloy and steel bolted together, the engine problems must be horrific, even if the anti-freeze does it's job. If I lived there I would think some sort of electrical heating would be the only way to minimize the problems, but I guess that's not always practical.
Cheers

FreeTaz · May 20, 2013

As a further update, in partial answer to my own original question, the only parts so far that seem to be the same are the crown wheel and pinion, the pinion housing and some of the small parts. The input gearing is different, the countershaft gearing is different, the diff gear is different, the housing is different probably because of different shaft spacing and/or shaft/bearing sizes. As I don't have a 4cyl IRD to measure up, I will only learn more if I get bearing numbers, but as I don't like fixing things that are not broken, that may not happen unless a dry run bolt up shows any freeplay.

FreeTaz · May 20, 2013

Pics attached as requested (I hope I have it right) Let me know if you want more.

Nodge68 · May 20, 2013

So in answer to your original question, not many parts are interchangeable between the 4 cylinder and 6 cylinder engine's IRD.

FreeTaz · May 20, 2013

Nodge68 said:
So in answer to your original question, not many parts are interchangeable between the 4 cylinder and 6 cylinder enginengine's IRD.

That's how it looks, but my main concern was the crown wheel and pinion which seem to be interchangable. My next concern is bearings but if I'm not doing the whole set (a questionable decision, yes) I might as well just buy any I want locally by number, and be assured of high quality branding.

Nodge68 · May 20, 2013

FreeTaz said:
That's how it looks, but my main concern was the crown wheel and pinion which seem to be interchangable. My next concern is bearings but if I'm not doing the whole set (a questionable decision, yes) I might as well just buy any I want locally by number, and be assured of high quality branding.

Let us know what you find and how it turns out. With lots of pictures

FreeTaz · Jun 30, 2013

Update time...Still waiting for diff shims as maker was in the middle of re-tooling but they are now only days away.
I have replaced the three main bearings, 2 on the IRD diff and one on the input shaft, they each rely on the three for the preload, which was actually to the point of end float. Not sure if VCU failure puts enough pressure on the IRD to distort the alloy casing, but the new bearings did not change the free-float/preload situation. I have therefore started to replace the shim which governs this variable.
My problem is... how much preload is required? The only measure I have is to assemble the IRD standing on end (on blocks to clear input shaft). with a thicker shim than necessary, and no bolts in the casing halves, I can measure the gap between the mating faces, which I am calling the preload measurement. This measurement is currently 0.85mm or .034".
As the cases are alloy, they will expand more at running temp than the cast steel input shaft and IRD diff, so some preload is desirable, but my knowledge of expansion coefficients is tenuous at best, my calculation puts it at about 0.2 mm difference between 10degC and 85degC. This would reduce the preload at running temp to 0.65mm.
Anyone with the knowledge to confirm (or otherwise) these calcs is welcome to comment, and If there is a specified measurement, that would be most welcome.

FreeTaz · Jun 30, 2013

BTW, I have investigated the main differences between the V6 IRD and the rest.
As the cases are different, the shaft spacings and/or lengths must be different to cater for gear sizes. Cooler plate has different pipes as coolant lines come from different places.
V6 input gearing is 30:23 (0.7667) the rest are 29:24 (0.8276)
V6 c/s to output shaft/diff is 22:39 (1.7727) the rest are 21:37 (1.7619)
V6 crown wheel and pinion gearing is the same as the rest, 38:21 (0.5526)
Overall IRD ratio V6 1.359 the rest 1.467

FreeTaz · Jun 30, 2013

FWIW... I removed the cross-member to gain access to a few otherwise in-accessible items besides making removal/installation of the IRD a doddle. I did not remove the anti roll bar saddle from the cross-member,too hard to reach the bolts. I removed the links at each end as well as the selector cable end and took the bar with the cross-member.

FreeTaz · Jul 16, 2013

Job done!
With the lack of any definitive info, I rebuilt the IRD with new (large) shims in the diff and 3 new bearings on the input shaft and diff.
There did not seem to be any measurable difference between total assembly sizes with old or new bearings, but I was not happy with the floating effect of the diff which shows as slop in the output/driveshaft. My method of removing this slop was by making a thicker shim for under the cup of the output side bearing. Then with the IRD assembled in the main case standing vertical, I rested the end cover in place on the assembly without any bolts and measured the gap between the cases. I then removed the shim and reduced the thickness by the measured amount to create a zero force on the bearings.
In actual fact, there was some force applied to the bearings by the weight of the input shaft and diff and cover, but none by the end cover bolts.
My thinking is that even though the casing is alloy and would expand a little more than the cast steel internals, the bearings are the primary heat source and could run at a higher temp than the case which would make up for the difference in the expansion rates. Any preload could increase the amount of heat produced and therefore more preload = more heat etc, etc,
Only time and distance will now tell

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