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G50 Clutch Change


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This thread is related to the engine drop: 3.2 Engine drop and G50 Clutch Change

Over the last year or so my clutch has been getting progressively heavier to use and last records show it was changed 50K miles ago. Also 3 independents who have driven it have all commented on how bad the clutch was. It would also make a horrendous racket when you put the pedal on the floor as if something was being driven into the mechanism with associated vibration in the pedal. We stopped that by adjusting the pedal stop as an interim fix. So after 3 more track days and due to the prices of Sachs clutch kits, I decided on a DIY approach. After dropping the engine (linked above) you need to separate the box. 'Simply remove the bolt from the cross shaft retaining bracket and pull the cross shaft out'!!! We tried fitting a 6mm bolt in the end of the shaft and using vice grips and various hammers tried to get it to budge - nothing. So i called the Jevvy hotline and tried his method of getting angry and hitting it back in to release it - nothing. So I went to the local body shop that worked on the car and borrowed his slide hammer:

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A serious bit of kit. using 6mm bar and some sockets and washers you get this:

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Even using this, it would not budge and at one point I though i must have missed another bolt and rechecked the Bentley. Remembering the Jevvy method I kept smacking the slider back and eventually 'POP':

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But not a pretty sight:

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last time I saw a rotating shaft this colour and state it had come from a failed C130 Hercules gearbox

the box came off easily after this was out to reveal the clutch fork and roller bearings:

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Is this the culprit? One side of the cross shaft is smooth and the other has these grooves where the bearings have almost cut splines in the shaft. The bearings also make a lovely crunching sound when you turn them.

looking at the clutch I think it must have been changed again since the record of 50K mile ago, the difference between the old and new thickness is 10.5 mm to 9.5mm on the old one:

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I thought i was going to find damage somewhere but the friction plate and spring plates look fine and no scratched on the flywheel.

IMG_0139Medium.jpg

 

So could the cross shaft have been causing the problem and the crunching noise when you push the pedal onto the floor was causing the shaft to vibrate in the non-rotating bearings?

Also how do i check if this box has had the cross-shaft mod?

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Gents,

 

Some more questions:

 

1. Want to get the GBox cleaned up - anything I need to be careful of if I get it steam cleaned or with chemicals regarding seals etc?

2. If my box needs modified I can get it done by Steve Bull or can i use the Weltmeister kit without modification? Along with uprated release fork and guide tube?

3. There looks like a leak at the bottom of the flywheel - To get the flywheel off, looks like 9 torx headed bolts - any idea what size?

IMG_0139Medium.jpg

4. Are these the crank sensors? Should I remove and clean or just leave alone?

IMG_0133Medium.jpg

Edited by Andy Young
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Good work Andy - goth there in the end.

 

I'd pull the flywheel and check the seal behind it - all that oil might have been from a previous leak that didnt get cleaned up? Just buy a set of torque drive thingys - they are handy to have about. Lob a clutch bolt back into the flywheel and use a double ring spanner between that and a gearbox stud to hold the crank still while you undo the flywheel bolts. You can then clean the sensors up a bit without disturbing them.

 

Pressure plate, clutch and flywheel seem to be in good condition in the pics - are you going to swap them?

 

I think the roller bearings are at the end of the shaft on a modded case not in the fork. You dont need the case modified if you are going to use the welmeister kit - it comes with bits to do both but id rather more meat on the case lugs(they are reamed to fit the bearings in)

 

You might want to yank the guide tube off and check the input shaft seal too - easy to change but dont knock it too far of you will be pulling the diff - ask me how I know!

 

I'll bet the clutch will be sooooo soft after you have sorted it you will think its broken!

 

Good luck mate.

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Good work Andy - goth there in the end.

 

I'd pull the flywheel and check the seal behind it - all that oil might have been from a previous leak that didnt get cleaned up? Just buy a set of torque drive thingys - they are handy to have about. Lob a clutch bolt back into the flywheel and use a double ring spanner between that and a gearbox stud to hold the crank still while you undo the flywheel bolts. You can then clean the sensors up a bit without disturbing them.

 

Pressure plate, clutch and flywheel seem to be in good condition in the pics - are you going to swap them?

 

I think the roller bearings are at the end of the shaft on a modded case not in the fork. You dont need the case modified if you are going to use the welmeister kit - it comes with bits to do both but id rather more meat on the case lugs(they are reamed to fit the bearings in)

 

You might want to yank the guide tube off and check the input shaft seal too - easy to change but dont knock it too far of you will be pulling the diff - ask me how I know!

 

I'll bet the clutch will be sooooo soft after you have sorted it you will think its broken!

 

Good luck mate.

Cheers Jevvy - I have just bought the Tx drive sockets and was about to ask how to lock the flywheel- you is psychic! Ditto on the guide tube, some good info in the 101 projects on what to look for.

 

Don't know about swapping the clutch bits - is it false economy not to? But with only 1mm of wear there is lots of life left. As for the spring plate, again should I change due to the rust on the springs? The kit I have is the one from Tripe that needs the surfaces cleaned as it was stored in damp conditions (before Tripe got it).... the wife wasn't particularly happy when I then kept it in the airing cupboard :blink: This one:

G50 Kit

 

With the Weltmeister kit - do I need to get a different release bearing to the one in the kit as well as a new fork and IIRC a larger guide tube?

 

What about having the GBox cleaned - you would probably DIY ;)

 

Andy

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Andy - I would change the clutch components.

 

The knocking you mentioned and we have spoken about is probably down to the spring plate.

 

As I told Tuts split my engine and box trying to track down the same noise in my car. The did the fork mod and found a release bearing red raw with rust but elected to re-use the clutch components which were showing no real wear.

 

I still have the knocking noise - though now 'eliminated' through pedal adjustment.

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4. Are these the crank sensors? Should I remove and clean or just leave alone?

IMG_0133Medium.jpg

Andy - yes, they're the speed and reference sensors. It's worth checking the insulation on the leads - if it's intact and you had no running problems before the engine drop I'd leave alone, your's look OK in the picture. Removing the sensors to clean them may just cause the brittle insulation to crack (as mine did !).

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Andy - I would change the clutch components.

 

The knocking you mentioned and we have spoken about is probably down to the spring plate.

 

As I told Tuts split my engine and box trying to track down the same noise in my car. The did the fork mod and found a release bearing red raw with rust but elected to re-use the clutch components which were showing no real wear.

 

I still have the knocking noise - though now 'eliminated' through pedal adjustment.

Chris,

 

Did they change to the bigger release fork and bearing as part of the mod? My theory was that when the pedal traveled far enough, the shaft would bind in the roller bearings and grab causing the juddering. Hence the groves cut in the shaft - i.e. it would only turn so much then start to vibrate. There are no signs of damage on the spring plate or anywhere else.

 

Andy

 

Andy - yes, they're the speed and reference sensors. It's worth checking the insulation on the leads - if it's intact and you had no running problems before the engine drop I'd leave alone, your's look OK in the picture. Removing the sensors to clean them may just cause the brittle insulation to crack (as mine did !).

Thanks - I will have a better look when the engine tin is off and leave alone if I can. All was well before, but what would the signs be of dodgy sensors regarding engine running?

 

Andy

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All was well before, but what would the signs be of dodgy sensors regarding engine running?

In my case it was high speed hesitations - I think others had engine's the wouldn't rev over a certain rpm.

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Update - pulled the guide tube and there was some signs of a weep but not sure if that was the Rost Off I had used to get the screws out. i think it has been changed before as there are witness marks on the housing. I will try and get a better shot in the daylight. As I am not sure i might change this on spec?

 

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The thing I was most surprised and worried about was this:

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See what i see?

 

Of the 3 nuts in the pic, one was lying in the bottom of the case with washer missing! The other 2 were loose. :o

 

Could the vibration of the clutch juddering have caused these to undo?

 

IMG_0165Medium.jpg

 

It does look like the main crank seal is leaking so will change that. I will post that question in the engine thread.

 

Never know what you might find and glad I spotted it now. :blink:

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Update - pulled the guide tube and there was some signs of a weep but not sure if that was the Rost Off I had used to get the screws out. i think it has been changed before as there are witness marks on the housing. I will try and get a better shot in the daylight. As I am not sure i might change this on spec?

 

I changed the input shaft seal and it was less fun than the rear main seal - mainly because I tapped it too far and had to pull the diff to retrieve it and the old seal was also a bugger to get out. Remember the fill level is below the line of the seal so the seal is only holding splashed oil mostly apart from when you are braking.

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See what i see?

 

Of the 3 nuts in the pic, one was lying in the bottom of the case with washer missing! The other 2 were loose. :o

 

Could the vibration of the clutch juddering have caused these to undo?

I'm surprised to see those nuts undone - has the engine ever been rebuilt ? I'd be tempted to check as many of the case perimeter nuts as you can access - IIRC there are ~26in all. You may have had some oil weeping from between the case halfs below the seal given both nuts were undone - if so tightening should stop or sigfnificantly reduce this.

Edited by MaxDiesel
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I'm surprised to see those nuts undone - has the engine ever been rebuilt ? I'd be tempted to check as many of the case perimeter nuts as you can access - IIRC there are ~26in all. You may have had some oil weeping from between the case halfs below the seal given both nuts were undone - if so tightening should stop or sigfnificantly reduce this.

 

Hmm, if it was me I'd pull the whole thing apart and re-seal the case, but I'm a bit of a nutter and enjoy engine rebuilds, in this case, I reckon Matt is right, re torque those nuts and hopefully it'll stay oil tight.

 

I seem to recall they should be 14mm nuts with coil washers not nylocs.

 

Add a blob of loctite too.

Edited by burgundyben
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Hmm, if it was me I'd pull the whole thing apart and re-seal the case, but I'm a bit of a nutter and enjoy engine rebuilds, in this case, I reckon Matt is right, re torque those nuts and hopefully it'll stay oil tight.

 

I seem to recall they should be 14mm nuts with coil washers not nylocs.

 

Add a blob of loctite too.

 

 

Are they Nyloc nuts? In which case, they probably need replacing, don't they?

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I'm surprised to see those nuts undone - has the engine ever been rebuilt ? I'd be tempted to check as many of the case perimeter nuts as you can access - IIRC there are ~26in all. You may have had some oil weeping from between the case halfs below the seal given both nuts were undone - if so tightening should stop or sigfnificantly reduce this.

 

The history with the car is quite extensive and no evidence of rebuild, if it had I'm sure there would have been other external bits changed. They are not nylocs and can only assume the clutch vibrations caused the issue?

 

My plan is to re-torque but to what setting as i don't have a re-build book - and use threadlock.

 

Hmm, if it was me I'd pull the whole thing apart and re-seal the case, but I'm a bit of a nutter and enjoy engine rebuilds, in this case, I reckon Matt is right, re torque those nuts and hopefully it'll stay oil tight.

 

I seem to recall they should be 14mm nuts with coil washers not nylocs.

 

Add a blob of loctite too.

Not in any hurry to do that, engine has been fine and pulled stock power on the dyno last year but i understand your point and all sorts of nightmare thoughts have been running through my head. :o

 

They are plain nuts with flat washers one of which is missing - hopefully I will find that on the floor under the dolly as it could have fallen out as i took the flywheel off.

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I changed the input shaft seal and it was less fun than the rear main seal - mainly because I tapped it too far and had to pull the diff to retrieve it and the old seal was also a bugger to get out. Remember the fill level is below the line of the seal so the seal is only holding splashed oil mostly apart from when you are braking.

 

Now I understand what happened - you had me paranoid about the critical place to put this - not too far in is the answer. ;)

 

What did you use to get the old ones out without damaging any of the surfaces? - Ignore that, just seen your reply on the engine thread.

Edited by Andy Young
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Andy

 

I think my noise is/was contact with the spring plate.

Chris,

 

Now that i can see how the various bits work, there must be a limit to how far the fork will travel - perhaps when it hits the housing? if the pressure is trying to drive it further it complains and judders? Or perhaps it's trying to over extend the release bearing and spring plate?

 

There is no sign of any damage on my spring plate or any of the other components so is that why there is an adjustable pedal stop? :twocents: Its a mystery unless anyone else knows the answer?

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  • 3 weeks later...

Advice please on getting the release bearing into the spring plate. Bentley says:

 

'Use press to lightly press down on pressure plate, using suitable spacers and steel bar'............ very helpful so how do you guys make something suitable?

 

Cheers

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I put the bearing on the floor, put the spring plate on then stood on the outside to compress the springs and get the clips on, make sure you get it all the right way round. I think I needed the combined weight of babs and me to get the clips on.

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I put the bearing on the floor, put the spring plate on then stood on the outside to compress the springs and get the clips on, make sure you get it all the right way round. I think I needed the combined weight of babs and me to get the clips on.

That paints such a wonderful picture :whistling:

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I put the bearing on the floor, put the spring plate on then stood on the outside to compress the springs and get the clips on, make sure you get it all the right way round. I think I needed the combined weight of babs and me to get the clips on.

Latest update - managed to get the new release bearing installed but as i don't have the combined weight of Jevvy and Babs available we did this:

 

post-438-1270337282_thumb.jpg Clamped a pry bar across the new bearing to provide leverage

post-438-1270337290_thumb.jpg Flipped it over and mate stood on the plate so i could access the back of the bearing with the clip. This got half of the clip in pace, we then had to rotate the lever 180 degrees and when we stood on the plate it snapped into place.

post-438-1270337302_thumb.jpg I did notice on the new bearing this jagged slot (apologies for the quality) - thought at first it was cracked but it looks machined so fitted the bearing. Is it supposed to be there?

 

I am using the Weltmeister quick fit clutch fork and cross shaft kit and will post pics of that later as it fits both modified and unmodified gearboxes.

 

Cheers

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