Drivetrain Clunk.... I'm at my wit's end

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LeftFoot

Active Member
Posts
249
2004 Defender 110 (ROW Spec.)
300tdi, R380

Greetings,

I have been experiencing a significant clunk while taking up drive and when changing gears for quite a while. There appears to be slack in the drivetrain and takes effort on my part to keep the drive smooth and lurch free.

My investigations a year ago lead me to discover that my front differential had significant wear so I replaced it with one in excellent condition from a diso.

Rear diff appears fine at present with not much play at flange so I have ruled out the diffs as being the cause of my issue. Universal joints in rear prop were replaced recently (OE parts)and the front UJs have no indication of wear.

A-Frame ball joint replaced recently and all suspension bushes replaced including trailing arms, Upper link arms, Radius arms, Panhard, shock bushes etc.

All four drive flanges replaced recently (OE brand).

Yesterday I removed the PTO cover on the transfer box and given my box has a 1.667 Ratio I was able to remove the Input gear completely. The gear was in superb condition with absolutely no wear either to the teeth in the gear or on the Gearbox Output shaft. I was pleased to see it was the cross-drilled type and the bearings were in good condition.

So what else can I check at this point before I push this landy over a cliff???

Can the center diff in the transfer box contribute to this issue? Or, (this is a long shot) can a failing slave cylinder cause this?
 
I got that tee shirt on a 87 RRC
Doffs, props, shafts all good, new Poly bushes and a frame with self lever all tip top.
It may be a lay shaft in the box and like mine it may still be running good after 12 years?
 
LeftFoot said:
2004 Defender 110 (ROW Spec.)
300tdi, R380

Greetings,

I have been experiencing a significant clunk while taking up drive and when changing gears for quite a while. There appears to be slack in the drivetrain and takes effort on my part to keep the drive smooth and lurch free.

My investigations a year ago lead me to discover that my front differential had significant wear so I replaced it with one in excellent condition from a diso.

Rear diff appears fine at present with not much play at flange so I have ruled out the diffs as being the cause of my issue. Universal joints in rear prop were replaced recently (OE parts)and the front UJs have no indication of wear.

A-Frame ball joint replaced recently and all suspension bushes replaced including trailing arms, Upper link arms, Radius arms, Panhard, shock bushes etc.

All four drive flanges replaced recently (OE brand).

Yesterday I removed the PTO cover on the transfer box and given my box has a 1.667 Ratio I was able to remove the Input gear completely. The gear was in superb condition with absolutely no wear either to the teeth in the gear or on the Gearbox Output shaft. I was pleased to see it was the cross-drilled type and the bearings were in good condition.

So what else can I check at this point before I push this landy over a cliff???

Can the center diff in the transfer box contribute to this issue? Or, (this is a long shot) can a failing slave cylinder cause this?
Click to expand...
Have you done the obvious.. pop it in gear.... chock the wheels welland then get a volunteer rock it forwards and back. Whilst you lay underneath (length ways), you should be able to see drivetrain/a-frame movement quite easily.
 
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Could be your bushes. I had a worn bush on the hockey stick things that locate the front axle - it was hard to see when the car was still but driving it it clonked something terrible
 
If there is no clonk when you take up drive with diff lock in but there is when its open this could point to a problem with the center diff but only if all other external items have been eliminated.
 
You've covered almost everything already, but might be worth trying to pin down the play a bit. take the rear prop off, drive it in diff lock. If clunking goes away = rear drivetrain, most likely diff/driveshafts. If it's still there, front prop off and repeat. If it's gearbox related, might be worth a good look at the output flanges.
 
tottot said:
If there is no clonk when you take up drive with diff lock in but there is when its open this could point to a problem with the center diff but only if all other external items have been eliminated.
Click to expand...

I see where you are going with this. I will give this a try and report back. Thanks.
 
zeaphod said:
You've covered almost everything already, but might be worth trying to pin down the play a bit. take the rear prop off, drive it in diff lock. If clunking goes away = rear drivetrain, most likely diff/driveshafts. If it's still there, front prop off and repeat. If it's gearbox related, might be worth a good look at the output flanges.
Click to expand...

This is also worth trying. I will attempt this later and let you know. Thanks.
 
As an update:
Input gear back in place and gearbox refilled. When difflock is engaged there is no clunk when taking up drive. Switching back to high or low range brings the clunk back. It is almost impossible to drive smoothly now. So... i guess the center diff has to come out now .
 
A few years ago a mate had a similar problem as you with his V8 109. In the end we found the cross pin in the center diff had broken at one end and the hole for the other end had worn oval so a replacement was fitted.
 
Ok... so following on from the above actions to find the cause of the unbearable banging when taking up drive or changing gears I took the transfer box off the 110 earlier this week and got a chance to disassemble it earlier this evening. Took center diff out, removed front tapered roller bearing and separated center diff carrier. Can anyone spot what is missing in the attached photo? :eek:!!
IMG-20170331-WA0002.jpg
 
tottot said:
If there is no clonk when you take up drive with diff lock in but there is when its open this could point to a problem with the center diff but only if all other external items have been eliminated.
Click to expand...

Go to the top of the class sir!
 
There we are then,new pins and good to go? Or is there other damage ? Suppose it depends on how long it had been clonking. At least now you can sort it. Cheers mate.
 
Those gear teeth look to be in rather poor condition. Good job you took it apart to have a look. If you really want to bend the plastic, you might like to try an Ashcroft's limited slip centre diff. I fitted one of these just over a year ago and it's made my transmission smoother. However, replacing with a good bog-standard one should make a big difference. Isn't it great to get the smell of EP 90 on your hands? Makes it feel like you're doing some real mechanics and not just faffing about.
 
The thrust washers are actually completely gone. Disintegrated into a bronze paste. Pins appear ok.

I had ordered a new gear set from Ashcroft transmissions plus a HD crosspin and new thrust washers in anticipation of issues with the center diff. Later this afternoon I will install these parts and begin re-assembly.
What i did notice was that the gears from Ashcroft are the same size as the original gears but the smaller set of 4 for the pins actually have one addition ridge or "tooth" but I don't anticipate that should make a difference as I am completely replacing the entire gear set and using the new ones.
 
LeftFoot said:
It does smell a bit bad doesn't it...
Click to expand...

Well, 'distinctive' I'd say. But I quite like it as it makes me feel like I'm really delving into the bowels of the car, not just messing about changing windscreen wipers and light bulbs.

Some of the teeth look like they're 'notched'. Or is that just the way the light is catching them?
Ashcroft's to the rescue again! Mr Ashcroft you are a prince amongst men.
 
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