Clonking noise when changing gear

my 109 has always made a bit of a clonking noise when I change gear, well, sometimes it does and sometimes it don't but lately, it has got worse. It is particularly noticeable if I pull away from stand still uphill. I think it may be a UJ. Is it easy to judge their wear by simply crawling underneath and pushing up on the prop by hand or is there a better, more reliable method. Given the price of a new prop including both UJ's is it worth swapping the whole thing rather than farting about trying to fit new UJ's to the old prop.

Col

Colthebrummie said:

my 109 has always made a bit of a clonking noise when I change gear, well, sometimes it does and sometimes it don't but lately, it has got worse. It is particularly noticeable if I pull away from stand still uphill. I think it may be a UJ. Is it easy to judge their wear by simply crawling underneath and pushing up on the prop by hand or is there a better, more reliable method. Given the price of a new prop including both UJ's is it worth swapping the whole thing rather than farting about trying to fit new UJ's to the old prop.

Col

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I've always just jiggled the prop by hand and watched the joints to check them. If there's a bearing going tight, you have to drop the prop off to allow the joint to move freely to feel the tightness - but tight joints give rumbling noises when running rather than clunks.

If the sliding joint in the prop is OK, and the tube itself isn't corroded, then, I would replace the universal joints themselves. I did dabble with one cheap joint which came with my 109 when I bounght it - this only lasted 12,000 miles. I have found the GKN joints in a silver coloured box are better (you can also sometimes find them under the GKN number of 18196). With a good hammer and decent vice, they aren't difficult to do.

I had that 'clunk' and a bit of vibration from 35-50ish. Went underneath and could feel, and see that the rearward UJ of front prop was worn. Got replacement GKN joint and took off the prop. I then noticed that, even though there was no play in the other joint, it was a little stiff at certain angles so dismantled and cleaned it, greased the cups and refitted it. Fitted the new UJ without any hitches. My prop had also been fitted the wrong way around so I replaced with the slider closest to the transfer box. The 'clunk' is gone, the vibration is gone. Gear changes feel smoother and overall running noise is appreciably quieter. I didn't use a hammer, just a big vice and pushed the 'cups' with a 19mm socket into a 28mm socket (2001 TD5, Front Prop).....

Difficult to diagnose without hearing the noise; is it a metallic noise for instance? If so your theory could be correct. Another possibility occurs to me: that you have a broken gearbox or engine mounting? Another possibility: Exhaust touching on the chassis somewhere?
New prop-shaft versus new UJs? I'd fit new joints, it's such an easy job... A tiny bit of extra grease when you assemble it all but not too much or they tend to hydraulically lock up when you are squeezing them together.

I would also replace the UJ's rather than the prop if this turns out to be the problem. Last time I fitted a new prop the UJ's it came with lasted about 3 months. I can get about 18 out of the GKN ones.
Also if you are looking at the props underneath as well as feeling for loose joints and wear also have a look for any dry rust dust around the uj. Even if there is no play this is a tell tale that the joint needs replacing and there will very shortly be play in it.

Thanks to all for your replies. It's hard to describe the clonk, it sounds like two heavy hollow tubes bashing together, mostly happens when the drive is taken up, e.g. Moving off but also sometimes occurs when changing gear. Worn or damaged gearbox/engine mounts is a contender I guess. I don't think it is the exhaust but worth a look when I get under it. I've never changed a UJ but I remember watching a friend struggle with one once to such an extent he threw the prop and his big hammer down his garden in temper and went off and got another prop from a scrapyard. Looks like I need to brace myself for scrapped knuckles and raised blood pressure.

Col

Colthebrummie said:

Thanks to all for your replies. It's hard to describe the clonk, it sounds like two heavy hollow tubes bashing together, mostly happens when the drive is taken up, e.g. Moving off but also sometimes occurs when changing gear. Worn or damaged gearbox/engine mounts is a contender I guess. I don't think it is the exhaust but worth a look when I get under it. I've never changed a UJ but I remember watching a friend struggle with one once to such an extent he threw the prop and his big hammer down his garden in temper and went off and got another prop from a scrapyard. Looks like I need to brace myself for scrapped knuckles and raised blood pressure.

Col

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Like I said, easy job. All you need is a bench vice big enough and some sockets. Years of experience do help, I suppose...

Extreedoc said:

Like I said, easy job. All you need is a bench vice big enough and some sockets. Years of experience do help, I suppose...

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It is an easy job if it has been done recently and they press out ok. I can change one on the defender in half an hour including removal and refitting of the prop, but they get done about every 12-18months. Recently needed to do one on the series and I resorted to cutting the uj out so I was just left with the cups to press out, and even with my big vice I struggled. Eventually ended up using a combination of the vice and beating it out with a big hammer, took about 3 hours to swap a single UJ and I then had to do the other one as well.

dag019 said:

It is an easy job if it has been done recently and they press out ok. I can change one on the defender in half an hour including removal and refitting of the prop, but they get done about every 12-18months. Recently needed to do one on the series and I resorted to cutting the uj out so I was just left with the cups to press out, and even with my big vice I struggled. Eventually ended up using a combination of the vice and beating it out with a big hammer, took about 3 hours to swap a single UJ and I then had to do the other one as well.

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That's some bad luck you had there, I've never come across one that bad.