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Please help me figure out if transfer case Chain is stretched.

nnnswordfish

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Hi all, Can anyone help me figure out if my chain is stretched - here is the transfer case video where I am shifting from R to D and vice versa:
https://youtu.be/xwyoQc4uwEo?t=6

I am feeling some Clunking / Banging inside while shifting in this video.
Also, I am feeling Knock when up-shifting that rattles the dash or when fast releasing and pushing back the gas pedal.

Here is another video where we rotated it by hand: https://www.youtube.com/shorts/AhJeGs0BjYM

Are these signs of a stretched chain? How to make sure that my chain is stretched? any advice on how to detect this?
Also when driving in low gear and when Automatic gearbox shifts from first gear to second I feel a very strong Clunking / Banging.

Sorry for my English.
 

Shayne

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With a manual truck you can let the clutch out slowly while moving up to second gear so the chain comes tight silently . Not sure how you might replicate that with an auto but it might be possible i suppose if you can time it right to let your foot off the gas mid change ?
 

BobMurphy

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That doesn't look too bad to me, there is some play there but there is more than just the chain in the Transfer Box.

The chain is driven by the centre differential which has three pairs of gears running on the central shaft and the outer drum, this assembly (the 'Planet Carrier') wears with high mileage and hard use and develops slop. The Planet Carrier itself can break if it's overloaded whilst off-roading in low ratio with lots of power.

If you drain the oil from the transfer box it's possible to inspect the chain's fit on the sprockets through the level and drain holes. I don't know what is 'normal' or 'worn' in these circumstances I'm afraid.

What is the mileage on the car and what is it used for (heavy towing, off-roading, just going shopping) ??

There is always some slack in a system that has lots of moving parts, the slop on mine is quite noticeable, but I wouldn't consider it bad.

Bob.
 

nnnswordfish

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@BobMurphy I use it for both everyday driving and a lot of offroading as well, always driving in low gear while offroading. Miles are 170 000.
"If you drain the oil from the transfer box it's possible to inspect the chain's fit on the sprockets through the level and drain holes" I will do this.

Front right AXLE has some play - please check the video
I am changing gears from R to Drive and you can see it plays a little. The left side does not have so much play
. Can this also cause the problem I have?

What about this: the similar video but now I have recorded it in Low gear
- Play is normal here as well?

@Shayne Unfortunately I don't know how to do this on AUTOMATIC.

By the way, one guy from Australia FB group of Prado told me that it is ok to change chain without removing all transfer case, just removing the rear cover as shown in the attached image. Is this the right way to change it?

Thank you.
 

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Shayne

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Bob's the man with all the answers when it comes to transfer boxes .

If you can find it i posted a vid on here long ago of a Russian fella just removing a few links of the chain .
 

BobMurphy

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When you're in low ratio the centre differential is locked - meaning that the input shaft, output shaft and outer drum (annulus) are locked together.

Slack in the front output shaft is therefore caused by a worn chain or wear in the centre diff planet carrier. If you have done a lot of off-roading in low ratio you have been putting a lot of strain on that planet carrier that isn't particularly strong. I have had boxes sent to me with broken planet carriers that were caused by running on dry roads with the centre diff locked.

It is possible to change the hi-vo chain whilst the box is installed but you will find it easier with the box on the bench - there are a couple of tricky issues around the speedometer drive (very small ball bearing in a slot) and the selector shaft detents and interlock plunger.

If you've had a box apart (and together) before it should be possible, but personally I'd take it out.

The chain may not be the culprit, while the box is out I'd go deeper and remove the centre diff and check it over. It's not complicated and its worth checking for wear and breakage, such as this:-

DSCN7515.JPG



Has this 'clunking' started suddenly or has it built-up over time ??

Keep us posted :thumbup: .

Bob.
 
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nnnswordfish

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Thanks for the answer I will read it again when I get back home and provide feedback.

"Has this 'clunking' started suddenly or has it built-up over time ??" It has built up over time.

One more thing if this will be useful for you - If the tire pressure is low like 1.9 I can feel it more when driving in D in normal mode (no diff lock and low range), If I rise it to 2.1 or to 2.2 atmospheres it feeld much less...

One more - When Only Center diff is locked (and no low range selected) driving in D - it feels significantly less than in normal mode.
 

Shayne

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Low tyre pressure gives more rolling resistance . Centre diff locked all 4 wheels run at a more uniform speed keeping the chain taught i would imagine .
 

BobMurphy

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One more - When Only Center diff is locked (and no low range selected) driving in D - it feels significantly less than in normal mode.

If you are driving on normal roads in high ratio with the centre diff locked you are going to gradually get "Transmission Wind-Up" as small differences in tyre diameter and the different path taken by the front and rear axles cause all the slack in the system to be taken up. This is why the centre diff lock should only be used on snow, ice, mud, wet grass, sand or any surface that will allow the tyres to slip and release the built-up tension.

If driving normally on a dry road with the centre diff locked, one of a range of things can happen:

The car will start to feel sluggish, requiring more throttle. If nothing breaks it could eventually stall.
One or more tyres will start 'skipping' on the road (I've had this in a RAV4 with a faulty centre diff lock).
A half shaft will break (a certainty in old Land Rovers, DAMHIK).
Something in the Transfer box will break - usually the planet carrier.

So, no 'clonking' as everything is tight :icon-wink: .

I think the conclusion we're coming to is that over time your chain may have stretched as you suspected, but don't rule out other wear/damage in the Transfer Box.

We'll be interested to see what you find :thumbup:.

Bob.
 

nnnswordfish

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"If you are driving on normal roads in high ratio with the center diff locked you are going to gradually" I am not driving like this :) I just test it for a few seconds to compare slack with Normal mode. I am understanding how the system works.

I will update you when I have news, thank you for your help Guys!

Kind Regards,
Nick
 
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