Discussion
Anyone else out there suffered from clutch judder? When I first took delivery of my 05 CV8 in March 2005, the very first time I pulled away I noticed clutch judder. Initially I thought it might be newness, but after a few weeks and 500 miles it remained. I took the car back to Drive who did accept after the car was left with them that "there is something there". They replaced the clutch and flywheel assembly which improved things though some judder still remained. This gradually improved over the first summer to a level where though not quite perfect was acceptable. During the first winter though it deteriorated again. At the first and second services I complained but Drive's technician would not accept there was any problem.
Followers of my posts will be aware that I bought my car due to the improved gear ratios it was promised to have. Unfortunately Vauxhall messed up and UK CV8s didn't get the improvement, and the UK brochure I based my decision on was incorrect. I took legal action against Drive knowing that we could revisit the clutch when the gearbox was changed. I lost the legal action but pursued getting the correct gearbox myself. I finally got the correct one in August 2007.
When changing the gearbox I removed the clutch and examined it. Both the pressure plate and flywheel showed areas of reduced wear over approx 90 deg, mirroring one another. Further examination of the pressure plate showed that it was not applying uniform pressure appearing to be slanting, applying the least pressure at the least worn areas.
I obtained a replacement standard GM assembly (From Monkfish). This was better again, though not perfect. It did improve and is nearly perfect now. If anything it now has the reverse characteristic of before. It now occasionally judders after a period of town driving.
I contacted LuK the manufacturer who provided some limited technical advice but would not accept the part back for any kind of technical examination. They dismissed my observations and blamed the clutch actuation. I'm not convinced by this because all 3 clutches have shown clear behavioural differences. I think it just crap quality. I've never noticed a problem with other cars eg hire cars etc, they have always been beautifully smooth.
I took the assembly back to Drive who also would not accept it back for any examination. Vauxhall customer care just suggested I put the car back together and take it to another dealer. Obviously I could not risk wasting all my effort putting it back together just to be arbitrarily refused warrantee cover again.
Looking at other car forums, clutch judder with newish cars was invariably fixed by exchange clutch assemblies. The problem was dealers did often argue that some judder was normal.
The design looks pretty standard though it is noticeable that both the flywheel and pressure plate are slightly concave, e.g. they grip around the edge first. Both are approx 0.2mm further from the friction disk at the inner most point of the contact area. The used friction disk has partly taken up this form, e.g. thinner at the edge which is just apparent in the radial slots. Presumably this is normal.
It was worst when cold in the morning and after a period of town driving improved but always came back when left over night. It was generally worse in cold and damp weather. My theory for this is the disk takes up the deformation in the flywheel and pressure plate when left engaged for long periods eg over night. So it then judders as the high and low points go in and out of phase. Town driving then gradually smoothes out the friction disk. Don't know about the weather effect. Maybe the friction disk is hydroscopic or something.
Followers of my posts will be aware that I bought my car due to the improved gear ratios it was promised to have. Unfortunately Vauxhall messed up and UK CV8s didn't get the improvement, and the UK brochure I based my decision on was incorrect. I took legal action against Drive knowing that we could revisit the clutch when the gearbox was changed. I lost the legal action but pursued getting the correct gearbox myself. I finally got the correct one in August 2007.
When changing the gearbox I removed the clutch and examined it. Both the pressure plate and flywheel showed areas of reduced wear over approx 90 deg, mirroring one another. Further examination of the pressure plate showed that it was not applying uniform pressure appearing to be slanting, applying the least pressure at the least worn areas.
I obtained a replacement standard GM assembly (From Monkfish). This was better again, though not perfect. It did improve and is nearly perfect now. If anything it now has the reverse characteristic of before. It now occasionally judders after a period of town driving.
I contacted LuK the manufacturer who provided some limited technical advice but would not accept the part back for any kind of technical examination. They dismissed my observations and blamed the clutch actuation. I'm not convinced by this because all 3 clutches have shown clear behavioural differences. I think it just crap quality. I've never noticed a problem with other cars eg hire cars etc, they have always been beautifully smooth.
I took the assembly back to Drive who also would not accept it back for any examination. Vauxhall customer care just suggested I put the car back together and take it to another dealer. Obviously I could not risk wasting all my effort putting it back together just to be arbitrarily refused warrantee cover again.
Looking at other car forums, clutch judder with newish cars was invariably fixed by exchange clutch assemblies. The problem was dealers did often argue that some judder was normal.
The design looks pretty standard though it is noticeable that both the flywheel and pressure plate are slightly concave, e.g. they grip around the edge first. Both are approx 0.2mm further from the friction disk at the inner most point of the contact area. The used friction disk has partly taken up this form, e.g. thinner at the edge which is just apparent in the radial slots. Presumably this is normal.
It was worst when cold in the morning and after a period of town driving improved but always came back when left over night. It was generally worse in cold and damp weather. My theory for this is the disk takes up the deformation in the flywheel and pressure plate when left engaged for long periods eg over night. So it then judders as the high and low points go in and out of phase. Town driving then gradually smoothes out the friction disk. Don't know about the weather effect. Maybe the friction disk is hydroscopic or something.
Im glad Im not your mechanic lol.
You seem to be having a lot of problems with your purchase...all appearing in various forms. There does seem to be one common denominator though, and I dont mean the car.....anyhow.
It would be interesting to see pictures of the clutch, but obviously wear is perfectly normal. Neither flywheel, friction plate or the cover will stay perfectly flat for its entire life.
I had one flywheel friction surface bevel by about 2mm once on a steel insert on an alloy flywheel. The car still drove perfectly though.
Wear is normal.
But certain things can cause judder. Like uneven surfaces on the flywheel or cover like hot spots caused by someone slipping the crap out of the clutch are some things that can lead to a juddery clutch..
You seem to be having a lot of problems with your purchase...all appearing in various forms. There does seem to be one common denominator though, and I dont mean the car.....anyhow.
It would be interesting to see pictures of the clutch, but obviously wear is perfectly normal. Neither flywheel, friction plate or the cover will stay perfectly flat for its entire life.
I had one flywheel friction surface bevel by about 2mm once on a steel insert on an alloy flywheel. The car still drove perfectly though.
Wear is normal.
But certain things can cause judder. Like uneven surfaces on the flywheel or cover like hot spots caused by someone slipping the crap out of the clutch are some things that can lead to a juddery clutch..
Well maybe its me then. Anyhow I'm really enjoying the car now. I guess I am lucky, having a nice garage to work on the car in, good friends prepared to get under it with me, another petrol V8 car to use in its place. If Drive were too stupid or mean to help me then that was always there prerogative.
No as I say they are both concave. The inner edges of the contact areas are approx 0.2mm further from the friction disk. So the assembly grips around the edge first. New one was the same. I asked Luk why but they didn't offer an explanation. Friction disk is warn more around the edge but not very warn in absolute terms - 24,000 easy motorway miles.
New clutch has dome 5000 miles now and as is virtually perfect. Did judder a bit when new. What is really noticeable is how smooth it now is first thing in the morning. The old one in the pictures didn't like cold damp starts.
I'm certainly glad I changed it even though it was at my own expense and Drive refused warrantee cover. It was obviously such an opportunity with the gearbox removed anyway.
New clutch has dome 5000 miles now and as is virtually perfect. Did judder a bit when new. What is really noticeable is how smooth it now is first thing in the morning. The old one in the pictures didn't like cold damp starts.
I'm certainly glad I changed it even though it was at my own expense and Drive refused warrantee cover. It was obviously such an opportunity with the gearbox removed anyway.
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