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Series 3 109 2.6 Transmission problems...help!


jordan_meakin

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Hi all; new to the forum but am in need of some help!

I have just got my 1976 Series 3 109 (2.6 petrol) on the road after a long restoration. The vehicle was off the road since 1991 and I bought it 5 years ago as a new galvanised rolling chassis with engine/transmission fitted. Because I bought it at this stage I chose not to dismantle to double check everything worked (I was too excited to get it on the road!) and so the engine and transmission have been relatively untested until this point.

I have finally finished it and it has passed it's MOT, however, the transmission is making some very bad noises! As it moves off, there is quite a judder which I assumed was a dirty clutch due to standing but now I have changed my mind. Having driven it a mile or two, I noticed that the transmission makes some very worrying noises (I have had series before and know these noises aren't normal). There is an grind/groan that kicks in as if something is trying to engage as the load increases which it seems to do in all gears. The 4 wheel drive seems to be working properly and I have double checked the selector shafts to check they haven't seized in half positions or anything. There is quite a loud rattle along with the groan other than the typical series noises. There is always a loud "ticking" noise as the load is reduced and vehicle slows down. It does drive relatively smoothly and once it is moving the initial judder stops. There doesn't seem to be any pulling from the front wheels typical of 4 wheel drive being engaged and I have checked oil levels. It isn't engine issues as the engine runs exceptionally well now. I have't used it since the MOT as I don't want to damage it anymore than it already might be. Can anyone help? I know the description is very vague but it's very hard to describe.

Thanks in advance

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Juddering on take off is oil contamination on the clutch surface as a result of the rear oil seal from the motor (?) or a totally worn out clutch. My old 88" had this exact problem, I diagnosed by taking the inspection plate off the bell housing and spraying brake cleaner onto the clutch assembly.

It completely fixed the judder for about 5 miles haha so I then knew it was time for a new one!

The ticking and groaning sounds like it could be UJs.. Remove 1 prop at a time, drive and see if it stops. It could also be layshaft bearings in the gearbox.

A grown up will be along soon, I don't know much about the gearbox side of things :)

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Have you checked the hand brake is disengaging fully? That causes horrible noises and can cause judder at low speed if partially engaged. The lever pulls up on a vertical rod, which has two nuts (one to lock the other) above the lever's rotating eye. The lever should have two clicks of free movement before taking up the slack on that rod, ensuring the brake is off when the lever is down. There is also an adjuster on the inboard side of the back of the drum plate which should be set so that the shoes are close to the drum but don't drag with the brake released.

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Thanks for the replies. I'll check the UJ's later and see if it solves it. I think the clutch may be on the way out, but will the intermittent groaning apparently coming from the gearbox be caused by either the clutch or the UJ's? Are layshaft bearing replacements a big job? The hand brake is definitely off but thanks for the suggestion.

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Bearings are a very big job - the whole transmission has to be removed (a day's work in itself, if the bolts are all free, more if they're seized), and the units have to be stripped down. The transfer box needs partial stripping just to separate the gear box form it, and that has to be done for access to the lay shaft's outer race.

The ticking is typical of a prop shaft UJ, though could also be a bad bearing. I would first try a run with the rear prop removed and 4wd high selected. Be gentle with the clutch to protect the swivel UJs, but once in gear, accelerate as before to try to replicate the judder and ticking. If the issues go, you know it was the prop shaft or possibly the rear diff.

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Had a look this afternoon... I have solved the ticking; that was just a bit of metal catching the rear prop. The groaning is still coming from the box but easier to hear now. I did jack the rear end up and moved through the gears with the wheels in the air and the noise didn't come from the box so it's obviously something that occurs under load. Thanks for all the help anyway; i'll keep working on it! Hopefully i'll work it out...

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