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Clutch drag
snapper - 16/5/11 at 04:50 AM

Clutch drag
After bedding in the cam, it was time to take the car for a run and bed the rings in.
Had trouble engaging gear, thought it might be flexing pedal box (Lotus 7 replica, Kit Car), re built that, gained more clutch pedal movement (full).
Checked clutch release arm, good movement.
Started in gear and gave it beans round the farms hard standing, still dragging, can't change gear, car will creep forward in gear clutch depressed.
RS2000 bellhousing and sump
V6 gearbox with 30mm Caterham spacer between box and bellhousing.
Cosworth 2wd clutch cable.
Could it be driven plate not sliding on the splines?
I think it might be engine out again.
Anything I can look for before I pull the engine?


ashg - 16/5/11 at 07:45 AM

put the handbrake on while your rolling, clutch down and rev it. sounds like the clutch plate has stuck to the flywheel, has it been sat up for a while?. if its still stuck after a bit of abuse then you need to take it apart and investigate


jollygreengiant - 16/5/11 at 10:37 AM

The correct oil in the gearbox. T9 gearboxes LIKE the synthetic stuff.

Clutch cover stiff.

These are two that come to mind and are easily over looked.

The cover is easily checked, can you push the pedal down using only the index and second finger. If not the cover is stiff and needs replacing with a quality unit by someone like LUK. Oh and I know what I'm talking about because I thought the gearbox was U/S and changed it for a recon ford unit many years (20) ago. Then I replaced the clutch with a cheapy after market one. THEN I learnt my lesson £800 later when I changed the clutch again For a genuine Ford unit (rebadged by Ford from LUK). DOHHHHHHH.


RACER101 - 16/5/11 at 11:02 AM

Is the clutch just dragging or isn't it disengaging at all?

If its the latter, I agree with ashg that the friction plate is probably just stuck to the flywheel and you might be able to unstick it by doing as he suggests.

On the other hand, if the clutch is disengaging to some extent but not enough to completely clear and is therefore still dragging, then a couple of other possibilities open up.

First is that the clutch has simply worn out (engine out and replace the clutch, sorry!).

Second, it could be that the pedal leverage ratio isn't giving enough pull on the cable. I had a similar problem with a Vauxhall engined/Ford gearboxed Westfield. The answer was to weld a slightly longer cable pull arm onto the pedal to give a bit more movement at the clutch release end (or, if you are lucky, drill another hole closer to the end of the lever arm). Either way the principle is the same.............the further away the clutch cable hole is from the pivot point the more pull is given to the cable as the pedal moves through its movement arc. This made the clutch a tiny bit heavier to operate but nothing to worry about.

Third option is that the release bearing itself might be worn or collapsing. Many of them are made of cheapo plastic which wears and deforms which means that even with the pedal fully depressed you are not getting full movement at the clutch end (engine out again I'm afraid!).

Not sure how much room there in your car but with the aid of a helper in the car pressing the pedal you might be able to see whether the clutch release arm could move a bit further which would be enough to stop the drag. Possibly rig up a G-cramp or a ratchet strap onto the clutch release arm just to see if it can move another few millimetres to test the idea.

Good luck anyway ; )


rusty nuts - 16/5/11 at 12:58 PM

Another possible cause of the problem is the spigot bearing in the crank, wouldn't be the first to partially sieze and cause the 1st motion shaft to turn at engine speed giving clutch drag symptoms . Guess how I know!


britishtrident - 16/5/11 at 01:20 PM

This is fairly normal on any engine after a lay-up, as ashg said in his sensible post the clutch driven plate is stuck (ie rusted) to the flywheel.

Two ways to cure either the brutal method start the car in gear and break the bond between the parts by brute force ie stamping on the brakes with some throttle applied or a clutch strip down.


atspeed racing - 16/5/11 at 02:02 PM

Was this a new or a used unit??
If it is new and you are sure have enough movement then the problem is that you could have bent the drive plate on assembly by letting the engine or gearbox hang on the spline or if it is a low quality or a second hand cover, the diaphram could be lifting uneven.


snapper - 16/5/11 at 05:40 PM

Clutch cover and plate are uprated, low milage, clutch cover balanced to crank and flywheel, no noticeable wear on the driven plate, engine and gearbox assembled together, engine on the crane, gearbox on a trolley, both on blocks to keep them level.
I think it was quite tight on the splines.
Looks like it comes apart this week.


snapper - 17/5/11 at 09:16 PM

Rusty Nuts gets the prize

Problem identified tonight.
Temporary solution effected
Road test tomorrow.

I mocked up on an old V6 gearbox using an RS2000 bellhousing and long bolts with nuts as spacers to replicate the Caterham spacer, measured a standard type 9 input shaft spigot etc and did the same on the mockup, whilst the measurments werent exactly acurate enough for a definitive answer it did make me think that the spigot might be jamming in the back of the crank.
Released the bellhousing to engine bolts one at a time and inserted a 2mm washer in each, bolted it all back up, sat in the car, gear engagement felt better, started the engine, carefully engaged gear, it went in no crunch.
Tomorrow off the stands and run up the road, I hope.
Now need to work on a permanent solution.

[Edited on 17/5/11 by snapper]


eddie99 - 17/5/11 at 09:20 PM

Glad the washers worked a treat


rusty nuts - 18/5/11 at 07:28 PM

2mm washer? about the thickness of the plate between the engine and gearbox? or is the spigot bearing proud of the crank?