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play in my IRS diff


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Hi there,

I will take my IRS diff out for new lip seals, an inspection and to fit a drain plug, also I hope the play of 7 deg. can be reduced.

Others here, and my mate who helps me too, told me the diff will always have „some“ play, my hope is we can reduce it.

My thought is: a propshaft or U joint with 7 deg. play I would indicate as worn, this can not be OK on the diff.

Am I wrong?

Does anybody know how much it was when new, or when new rebuild is possible, please?

Ciao, Marco

Edited by Z320
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Hi,

diff is out and without opening i found out:

- I have no preload on the bearings of the pinion wheel / ingoing shaft

- the backlash between crown wheel and pinion should be 0.10 - 0.20 mm on the crown wheel (workshop manual)

- but is about 0.50 mm on the ingoing flange

- but the total play is 8 mm on the ingoing flange, caused be the differential itself

This should be easy to repair and if checking the contact point of the teeth is OK I do a small repair.

Ciao, Marco

Edited by Z320
0.20 mm, not 0.02 mm
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Hi Marco,

I found my diff in similar condition when I removed it for the restauration.

I tightened the crown nut on the pinion shaft, but not to the torque described in the WSM. My thinking is is was quiet before and had done many miles in this condition, with no visible wear/markings on the teeth. So just removing the excessive play to eliminate the clonk was my aim. 

So far this works out ok, but I have only driven 2000-3000 km.

Waldi

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7 hours ago, Z320 said:

Hi,

diff is out and without opening i found out:

- I have no preload on the bearings of the pinion wheel / ingoing shaft

- the backlash between crown wheel and pinion should be 0.10 - 0.02 mm on the crown wheel (workshop manual)

- but is about 0.50 mm on the ingoing flange

- but the total play is 8 mm on the ingoing flange, caused be the differential itself

This should be easy to repair and if checking the contact point of the teeth is OK I do a small repair.

Ciao, Marco

Sounds like what we describe as a differential re-shim. 

Torque the pinion flange nut up to factory spec. Before you start to strip anything internally do a tooth contact engineer's blue check, this is so you have a guide of how it is now and what you expect when you have re shimmed the assembly.

Remove the crown-wheel carrier and differential gear set - Do not mix up the bearing caps position or orientation or the bearing outer races.  Carefully spread casing to lift out.

The sun and planet gears will need attention first.  Try fitting new thrust washers behind the sun gears first to try and reduce that back lash.  You may find the pivot shaft for the planet gears is worn, causing them to rock in their location - renew the shaft.   If that does not remove the back lash from the differential gears you will  need to replace the cup shaped thrust washers that support the planet gears.  These are different sizes - They usually have their size stamped on them.

Check the crown wheel attachment bolts are all torqued up correctly and loctite is used.

The Pinion bearings pre-load (rotating torque) is important.  Set with the seal removed. Torque to the factory spec. to do the check.  Simple to adjust with shims under the smaller front bearing to inner spacer.  Do not get all excited and try to remove the shims that maybe fitted under the pinion big bearing or its outer bearing race in the housing.  These are set at the factory to get the pinion head height correct.  If you choose to replace the big pinion bearing be sure to put back precisely the shim sizes you find fitted - Unless you have a pinion height setting gauge or some method of accurately measuring the pinion height before taking it to bits.

The crown wheel to pinion backlash is set by moving shims from one side differential carrier bearing to the other.  You will need a good bearing remover for this task as you could be doing it half a dozen times and you do not want to damage the bearings.   Again the preload of these bearings when fitted in the casing needs to be confirmed.   Do check, the axle may have been repaired before.

Once happy with that crown wheel to pinion back lash use engineers blue to mark the teeth of the pinion and see how the tooth contact pattern looks.

If good - Fit seal to pinion area, fit speedi-sleeve if required to drive flange seal area. Fit flange and torque to correct figure lock with wire or split pin.

 

Side output shafts you will need to deal with separately.

Peter W

 

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Hi Peter, 

thank you, this is the way we go.

Plus fit a drain plug.

Is it true the trust washers between the sun gears are made of „synthetic“ and not bronze?

The outgoing shafts are sealed but they get now lip seals, I already made a distancer for my 10 to press

Ciao, Marco

Edited by Z320
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Hi Marco,

Yes drill and tap the casing for a drain plug is a good idea

Yes the sun gear thrust washers might be bronze or fibre type material.    They are interchangeable as a set of two, of matched thickness and material.

Peter W

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Hi Peter,

the diff is open now and the pinion and crown wheel look VERY good.

Most of the play is indeed in the sun and planet gears, I get a feeler gauge 0.85 mm between the planet gears and the worn washers!

I'm really angry with myself not to check this already years ago. And with the story tellers telling me the pay I told them is "standard".

Ciao, Marco

Edited by Z320
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You can minimise the play but do not tighten it beyond factory spec.   The diff gets very hot when running and all those dimensions will change with the heat.  
Triumph fitted cooling ducts to the axle on some of the racing cars plus an alloy finned axle rear cover is now an useful racing accessory.

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1 hour ago, Ian Vincent said:

The Pete Cox section on rebuilding a diff on the technicalities CD suggests that the planetary gears need to be shimmed until they feel stiff. If I remember correctly, I think the word notchy is used.

Rgds Ian

Yes that is how I would do it too.

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1 hour ago, Z320 said:

We will fit new „bowled“ washers between crownwheel carrier and planet gears as shown by the workshop manual.

You will need new sun gear washers too while you are there.  

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We checked the contact pattern (?) toady, it was OK

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We gave some pre load on the pinion bearing (a 0.005“ mm shim out), less than due to the manual, because we did not fit new bearings.

And moved the diff body 0.005“ closer to the pinion, this reduced the backlash from 0.27 mm to 0.17 mm, changed nothing on the contact pattern.

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The sun gear trust washers are made of bronze and looked like new,

the planet gear’s "bowled washers" are stamped 0,056" (1.422 mm) but have been down to 0.8 mm  and 0.9 mm.

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We fitted a pair of new 0.064" washers, they slided in easy.

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The play of the ingoing flange I will check when it is completely assembled, but it is considerably reduced.

My special thanks go to my club mate Gerhard, he knows everything about diffs and owns ALL tools.

A drain plug I fitted some days ago in the aluminium cover

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In my thoughts this is the better position to catch a broken tooth out of reach of the crown wheel..?

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Finally I had to order the lip seals and some other bits and pieces,

but canceled my order at my UK suplier because of the serious customs fees and handeling fees and ordered at Bastuck / Germany.

Sorry me to tell you this, but I found it worth to mention.

Ciao, Marco

Edited by Z320
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What thickness were the sun thrust washers compared to new ones?  Were both the old ones the same thickness or had one worn more?   Looks like you are well on your way with the re shimmed differential assembly. Good approach and repair. 

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  • 2 weeks later...

Hi,

all assembled now,

with the new shims the play / way of empty movement of the propshaft flange

(with the outgoing flanges fixed) dropped from about 8.0 mm to 0.4 mm!

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WHAT A RESULT, I'm very excited about how this will change driving the car.

With my carb and ignition modifications the "jerking" is much reduced but still there.

Ciao, Marco

 

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Good idea,

but INDEED a friend of mine forgot to put oil in after he got it back from a workshop.

He thought they put the oil in, what a workshop never does.

What is your choise? I would buy any GL5 this evening...

Edited by Z320
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We had a gearbox returned under warranty many years ago.  When opened it was totally ruined, all the gears a nice blue colour and no sign of any oil.

We asked the customer if he had put any oil in and his quick accusing reply was, “Are you telling me you supplied this gearbox without oil?”

 

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26 minutes ago, Z320 said:

Good idea,

but INDEED a friend of mine forgot to put oil in after he got it back from a workshop.

He thought they put the oil in, what a workshop never does.

What is your choise? I would buy any GL5 this evening...

Hi Marco,

usually GL5 is not used as the high sulphur content attacks the 'yellow' metal (bushes/shims etc.

GL4 is the standard go to.    However if you diff does nt have these bushes then GL5 will work very well.

 

Roger

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1 hour ago, BlueTR3A-5EKT said:

We had a gearbox returned under warranty many years ago.  When opened it was totally ruined, all the gears a nice blue colour and no sign of any oil.

We asked the customer if he had put any oil in and his quick accusing reply was, “Are you telling me you supplied this gearbox without oil?”

 

Back in the eighties, a colleague had a new Rover SD1 2600 as his company car. After a longish motorway drive it stuck in fifth gear. A local Rover agent found there was no oil in the gearbox, and seemingly never had been. This was a week after he'd driven me from Derby to Gateshead - the oil pressure light was on, so I suggested he checked the oil level - he hadn't thought of that! The dipstick was dry, so we put a litre (well, maybe a quart) in, but it still didn't reach the dipstick. Eventually we'd added 6 litres, the stated oil capacity, so it had left the factory with no oil in the engine or gearbox!

Pete

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2 hours ago, stillp said:

Back in the eighties, a colleague had a new Rover SD1 2600 as his company car. After a longish motorway drive it stuck in fifth gear. A local Rover agent found there was no oil in the gearbox, and seemingly never had been. This was a week after he'd driven me from Derby to Gateshead - the oil pressure light was on, so I suggested he checked the oil level - he hadn't thought of that! The dipstick was dry, so we put a litre (well, maybe a quart) in, but it still didn't reach the dipstick. Eventually we'd added 6 litres, the stated oil capacity, so it had left the factory with no oil in the engine or gearbox!

Pete

Amazing that it even ran at all!

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