Stag Clutch

[mikew]

As I have nothing more to do on the estate at the moment I thought it was time to attend to some outstanding jobs on my Stag which I have neglected a little in the past 12 months. I have been driving it a lot in the past month, due to the good weather, and I realised how much work was now needed. Although I hate doing gearbox removal in a Stag due to the poor access to the top engine / gearbox nuts and bolts - and yes I do let the box drop down and use a very long extension socket to get to the top bolts.

There are 3 jobs, too much play in the steering rack, and an exhaust rattle and a very notchy clutch with long pedal travel. Both the rack and the gearbox removal need the exhaust removed, which I will refit afterwards, and using my now filled oxy-acetalyne bottles I can now heat and bend one of the rear exhaust pipes where it goes through the rear crossmember to remove the annoying rattle / vibration at certain speeds. I've always had this problem, its an issue with pattern parts.

Anyway this morning I removed the exhaust, and the rack which I will send off for reconditioning and refit later.

I dropped the gearbox out, and had assumed that the clutch issue would be a broken cross pin, in the cross shaft. It wasn't.

What I found was about 2mm play in the cross shaft bearings, and the cross shaft too is badly worn, which you can see in this photo, the wear is just above the pin.



and the bearing carrier has also worn, there are a series of indents where the fork has worn the carrier away one of which you can just see here, in the centre of the lower groove in the bearing carrier



I have not seen this before, but it means that it won't be going back together today, i was just going to bang a new cross shaft and fork in, but now I am going to fit the tilton hydraulic release that I have, so off to get some machining done on Tuesday. Still it should be finished next weekend.

mike

[Richard B]

Can we have some pictures of the new setup when it's finished Mike?  :-/

[Flying Farmer]

I have come across this sort of wear on the bearing carrier before. Since there was no significant play on the gearbox nose, I saved the carrier by fitting another little rollpin to the carrier at 90 degrees to the original, which put the thrust from the fork on to an unworn section of the carrier
Neil

[StagNL]

My clutch cross shaft was worn like yours.  Thankfully my work is applying wear resistant coatings so I could re-use my cross shaft after giving it a nice coating that shouldn't wear in 100 years.
Realease fork pin was knackered on mine too.

Julian

[mikew]

Richard_B wrote:

Can we have some pictures of the new setup when it's finished Mike?  :-/

Will do

mike

[mikew]

699 wrote:

My clutch cross shaft was worn like yours.  Thankfully my work is applying wear resistant coatings so I could re-use my cross shaft after giving it a nice coating that shouldn't wear in 100 years.
Realease fork pin was knackered on mine too.

Julian

Every big engined triumph I have had, has had cross shaft issues of one type of another sooner or later, so its going, Tilton release here I come, no more clutch woes.

mike

[mikew]

Ok, I have finished a "trial" placement of the Tilton parts using a cut down nose shaft.





The front of the white tape on the input shaft marks the location of the clutch pressure plate fingers. The internal finger gap is 45mm, so I have chosen a release bearing with a 52mm ID, that puts the pressure where I want it towards the end of the fingers for maximum leverage and least pedal pressure.

You can see from the pictures the tilton release mechanism needs to have a large gap between itself and the bell housing, so here's a sketch of a plate I am going to get machined (I may do this on cad at work tomorrow), this plate sits on the nose piece shaft, which then needs turning down to sit inside the tilton release (this ensures the bearing is concentric with the nose piece)






This picture of the nose piece and tilton release gives an idea of how it fits together, but obviously the tilton release should fit lower down.



When fitted there will be approx 15mm clearance between the tilton mechanism and the plate fitted on the nose shaft. This is important because I will need to make some spacers (of custom length) to ensure that with a new clutch plate fitted, and the tilton release fully retracted there is 4 to 5mm clearance between the release bearing and the pressure plate fingers. (as the clutch plate wears, the fingers move out reducing the clearance, if you don't allow for this the clutch will drag and then slip with wear) - too much gap and the release will pop out!

When I get the machining done I will post more pictures

mike

[Andyr]

Hi Mike,
that looks like a very interesting approach.... there are many moans of poor Stag release mechanisms.  I'm interested in how this turns out and look forward to the updates.

Are you using the 400 Series ?  i'm guessing PN. 61-401  for the 9" Stag clutch and 62-002 for the release bearing - is that right ?   Sourced in the USor in UK  big-bucks or not ?

Nice work......
cheers.....Andy

[mikew]

Andyr wrote:

Hi Mike,
Are you using the 400 Series ?  i'm guessing PN. 61-401  for the 9" Stag clutch and 62-002 for the release bearing - is that right ?   Sourced in the USor in UK  big-bucks or not ?

Nice work......
cheers.....Andy

Yes its the 400 series 61-400, 52mm contact on the release bearing (not sure of the part number), in the end I got it in the UK, with the dollar pound as it is, it owed me £230 inc delivery, and it comes with the hoses and unions too.
Competition Supplies (www.competitionsupplies.com) were the supplier.

To replace all these items with original Stag parts inc slave cylinder from a supplier in the UK costs out at £170, so its not too big a difference

There are no bulkhead fittings in the kit, which I have ordered separately, so that I can mount the bleed nipple on a plate on the bellhousing, rather than have a hose and union flapping around. The american pipe fittings are 3/8 UNF so fit the Stag with a 3/8 to 7/16 converter, so plumbing is simple.

The supplied flexible pipe needs cutting to fit the supplied unions, but is long enough to run to the master cylinder, which I may do, as its brake pipe grade, and certainly won't swell under pressure.

.

My friendly machine shop says all the parts will be ready tomorrow, so I will report further when I get them back.

All I need to do then apart from refitting the gearbox is to fabricate a pedal stop, to prevent over throwing the clutch.

mike

[Andyr]

Thanks Mike,
Yes, at today's exchange rates there don't tend to be the trans-atlantic bargains of a couple of years ago  - but when you compare to the costs of replacing all the clutch actuating components it doesn't seem too bad.

I hope this comes together nicely.... really interested in how it turns out, it has got me thinking !

cheers........Andy

[mikew]

I got the parts back from machining today



and assembled



and a trial fit in the gearbox.



I have made a small modification, with a horizontal grub screw, which will tighten the plate down on the nose piece and stop any tendancy to rotate, this is just visible above the red plug blanking the Tilton air bleed.

I have a new oil seal, and gasket, so at the weekend I will assemble it all, re-measure, make any adjustments and refit the box, and test.

I suspect there will be a great deal lower pedal pressure, I now wish that I had measured before and after to see the difference.

The machining cost �50

mike

[Andyr]

Looking Good mike - hope it all goes smoothly at the weekend - good luck !
(looks like the pound sign has messed up the numbers in you last post )

cheers........Andy

[mikew]

Andyr wrote:

Looking Good mike - hope it all goes smoothly at the weekend - good luck !
(looks like the pound sign has messed up the numbers in you last post )

cheers........Andy

Yes it was 50 pounds.

Anyway after working on my estate project first, I finished the gearbox and clutch assembly.

I renewed the nose shaft oil seal and gasket, and then fitted the clutch parts. The spacing I required after measurement was 34mm from the front of the bellhousing. As it happens using 2 of the spacers (that came with the kit)  on each leg of the Tilton assembly gave exactly the right spacing.

I tightened up the nuts and bolts on the legs (as there is clearance round these), and checked that the bearing was concentric what ever the position of the mounting. The mount was then tightened down using the grub screw with a hose connection uppermost

Pictures here







Hoses were made up as per the Tilton instructions, but I found it was easiest to connect it to the 7/16th existing Stag pipe, via an adapter, 7/16 to 3/8ths where the old clutch cylinder used to be

Does it work ?

Well I have the gearbox back in the Stag, although I am still fighting with 2 bell housing bolts (top passenger side) - always a swine to get to.

The clutch self bled via gravity when it was connected to the Stag hydraulics and the bleed nipple opened.

I did however carry out a normal bleed sequence.

The clutch does work, although I haven't run the engine yet, propshaft etc to go back on, the pedal is really light with a very nice smooth action, and the clutch does disengage. The disengagement point is with the pedal about 2 inches off the floor, so thats about right.

Weather and other jobs permitting it will be finished tomorrow.

mike

[mikew]

Its Alive !, it runs and drives.

The clutch is fantastic, light progressive, no notchiness, as good as any modern.

I am really pleased wish I had done it years ago, even Mrs W will drive it now - she used to hate the Stag clutch.

if anyone wants the drawings or any other details please send me a PM

mike

[Rubce]

Hi Mike

Can we have an update please on how your clutch mechanism is performing.

Thanks

Bruce

[Make mine a V8]

I think this was cross posted in the SOC forum. Interesting looking project that Stagdad is looking at doing The clutch was a pain for me but I think this has been solved now