Hi all. My old 4 speed was dead so I put another one in today I bought off a member. I also put in a new spigot bush. I just took the car for a drive and it now has a bad vibration that increases with revs. I have never had this happen swapping a box. I also put in a new gearbox mount. The cat was originally an auto and has a modified mount for the manual. Could having the new mount in the wrong way round case the mount to be over tight and transfer the vibration to the car? It feels a bit like the shudder you get when you drop a cylinder but much worse. Car is running on all four though? Any help would be greatly appreciated. Cheers

Hi Camo, Does the vibration increase with revs or speed? Is there a vibration when free reving the engine while the car is stationary?(Clutch/presure plate balance prob).
Or does it get worse with increasing road speed.(tailshaft balance or gearbox to diff flange alignment prob).

It is very unlikely the gearbox itself would cause a vibration.

It's vibrating relative to engine speed, stationary and moving. Tail shaft is fine. Clutch is a new exedy HD unit. The vibration is happening clutch in and out. Got me stumped ??

To me it sounds like two things;

Your clutch cable adjustment may be out (a bit too lose, so the clutch is not fully engaging) and it sounds like the flywheel face (that the clutch contacts to) may need a fresh surface (machining).

If you adjust it so that the clutch is fully engaging and disengaging you may find that the shuddering will stop once the clutch is fully engaged (however you will get the shudder and feel it through the pedal when the pedal is on the way down and on the way back up).

The shuddering can sometimes exist when the clutch is only partially in contact with the flywheel face (in need of a re-surface). It happens on my A15 but only slightly, quite a subtle shudder and only when the clutch is about to be clamped on with full force by the pressure plate (so pedal halfway down).

I hope that helps.

The other issue it could be is the pressure plate spring pressure not being able to fully apply the clutch, some HD clutch's need a stronger pressure plate, perhaps a vanette one will suffice?

The only other thing I could think of is the input shaft but I do not think your symptoms apply to that.

Where abouts are you?

When you fitted the throwout bearing, did you retain it using the spring or is it just sitting against the fork loose? Does the vibration come through the clutch pedal? Or even at idle, put your hand on the fork and see if it vibrates like a bastard.

The clutch was replaced @ 100k's ago. The fly wheel was machined at the same time. The vibration is quite full on. It happens with the clutch engaged and disengaged. I am wondering if the spigot bush is not in properly or out of round it all look fine. I'm also worried the knocking the bush out has put some pressure on the bearings. I tapped it out quite lightly with a punch. ?? It feels like the car has a grumpy V8 with metal engine mounts. Never had this one before. ??

Its definitely a balancing issue of some sort as the vibrations are in sync with revs...

I had a similar problem and it ended up being flywheel bolts had come loose,ie no loctite on bolts,similar situation (new exedy clutch kit,machined flywheel,same amount of km's after reinstalling as well).Just thought i'd mention it,may be some help.

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Okay sorry I got confused it sounded like it (the shudder) comes on when the pedal is pressed in and released out but it sounds like it just happens the moment you start the engine., if this is the case then have you checked the flywheel is tightened up?

If it is balance related then I guess that answers it, pull it apart.

Although if the car is sounding like a grumpy V8 with steel engine mounts then I'd be inclined to give the engine a quick look over.

Engine is running fine. It is a daily driver did a 600k round trip 2 days ago. Have talked to a few people. My thought so far are the gearbox mount being in the wrong way, broken engine mount(s). I didn't check the flywheel bolts this time and I didn't lock tight them last time. I did torque them up to spec tho. Also wondering if the spigot bush is out of wack. It cant be to far out as it is brand new and the box spline went in easy. Thanks for all the help. Will keep you posted. going to check all the mounts now. Cheers