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[JasonH]

Are much research, consultation and experimentation I think I've identified the cause of my difficult gear change (2.5 V6 petrol manual).

Basically when the car is idling the gear change is fine. When the engine is cold it's not too bad either.
But once warmed up and with the revs about about a 1000 rpm it can be quite difficult to get in and out of gear. The best technique is to hold the clutch in till the revs drop then change gear - makes for some interesting progress  :-?

Changed the gearbox oil for Vauxhall's finest.
Reverse bled the clutch twice.

....Anyway I think my dual mass flywheel has gone wobbly or loose. The idle has also gone a bit vibey but the car runs perfectly (yes my ICV is clean, no oil in the plugs, no misfire, etc.).

Happened to anyone else? Anyone know of a 2.5 dual mass flywheel going spare?

[The Barge Captain]

Have you posted in parts wanted Jason?

[JasonH]

I have, I'm also working through all the Vx breakers in the UK (of which there are quite a few).

[Omegatoy]

when a DM flywheel goes you really notice it!!! believe me its a horrible vibration in the lower revs which smooths oout as you get higher in the rev range, myguess would be the clutch is worn badly hence the vibey fel
Omegatoy

[JasonH]

Interesting, it's definitely smoother at higher revs.

Perhaps mine is just starting to go. Gearbox has to come off anyway so a secondhand DMF for around £50 would be worth having to hand I think.

[Paul M]

My money's on the clutch dragging, assuming the fluid has been changed and bled. I'm no expert mind

[Admin]

Before doing things like this I would be checking the condition of the engine and gearbox mounts.

If these are worn you get flex which makes gearchanges awkward.

[JasonH]

Good point (and I appreciate all suggestions) but when tackling my gearstick shake some months ago I replaced both engine mounts and the gearbox mount. It reduced the shake a bit but wasn't the root cause.

[The Barge Captain]

I'm wondering if the best thing to do might be to make sure that the motor factors or wherever have a clutch kit in stock,take the gearbox off, and if it's just the clutch, nip into town, pick it up and fit it.  If it is the DM, then put the box back on until you can get hold of one.
Let me know when to bring the spanners over mate.

[JasonH]

I only want to take that box off once.

I will get a DMF, I will..........

[The Barge Captain]

Second time will be easy as we will know what we are doing then lol  

[Matchless]

Once you have the box off look for any free movement (rotation) in the flywheel, 15mm seems OK but any more than that suggests a broken spring etc in the flywheel. I suspect a NEW flywheel would have no free movement at all.
If you are changing the flywheel then change the rear crank seal at the same time, I didnt and had to go back about a year later.
You should get new flywheel bolts according to the manuals...they are angle tightened. Its not worth the risk of one failing.

I think it more likely to be contaminated clutch linings or dried grease on the gearbox splines, I had a DMFW fail and im sure it only caused harshness and vibration when accelerating.

[Matchless]

Second time will be easy as we will know what we are doing then lol  

I think the last time Mark and I changed a clutch it took less than 2 hours, he does the lifting and I provide the grunts.  

[JasonH]

Thanks Matchless, useful info.

When you say you and Mark I presume you mean Mark DTM which means it will take us about 3 times as long  

How hard was it to change the crank seal?

Courtenays told me they never changed those bolts and have done loads of flywheel changes. They just put loctite on and angle tighten as normal.

How heavy is the gearbox (roughly) ? Can one person lift one?

[Matchless]

Thanks Matchless, useful info.

When you say you and Mark I presume you mean Mark DTM which means it will take us about 3 times as long  

How hard was it to change the crank seal?

Courtenays told me they never changed those bolts and have done loads of flywheel changes. They just put loctite on and angle tighten as normal.

How heavy is the gearbox (roughly) ? Can one person lift one?

Yes, Mark DTM I think its the only Omega job where I have more experience (unfortunately)
Crank seal..dead easy but you must make a tool to protect the seal lips as you fit it. I had some brass shim stock that I wrapped around the crank and butt-joined the edges with sellotape^TM you could try coke or beer can for suitable material but make sure there are no burrs or overlaps to damage the seal lip. Slide the seal onto the tool then slide tool onto crank and either tap gently into place working around the seal (fit the old seal backwards onto the new one to act as a protector) or, if you are really lucky, you will have a piece of tube handy which is exactly the same o/d as the seal and can use it as a drift.
You have to re-cut the crankshaft threads to clean out the old loctite. I have reused old bolts with locktite but would rather use new if available.
Gearbox is too heavy for one person in safety, Ive done two on my own but its so much easier and safer with someone to help. The weight is about 2/3 from front 1/3 from back. I use a large trolley jack and found a ratchet strap to wrap around gearbox and jack head to stop it slipping.
Us locktite on the gearbox bracket to body bolts.