Removing Bell housing/dry sump tank from 6 speed gearbox K series advice sought

[Sandpiper]

Dry sump 6 speed K series VHPD.

I have my engine out to replace my Clutch bearing and investigate an annoying weep at the bottom of the Bell housing to engine junction.  My first thought was crank rear main seal but after removing the flywheel this afternoon it revealed a bone dry front face and a very happy looking crank seal.

The back of the bell housing is a different story with plenty of oil thrown around by the recess for the clutch arm.  I am unsure whether the oil is from the gearbox as it looks more like engine oil i.e. dark and it doesnt appear thick enough. 

So I need to remove the bell housing from the gearbox to ascertain the source of my leak.. The question is can this be done with the gearbox in situ? the bell housing appears to be held onto the gearbox by 4 large headed bolts that are recessed into the forward face of the bell housing.  If anyone has a picture or a drawing I'd be interested to see it.  Engine and gearbox appear to treated like a single unit by all the assembly guides I have seen.

Edited January 31 by Sandpiper

[Englishmaninwales]

Yes. Remove the release bearing assembly and clutch arm. Put a jack under the gearbox for support (which should already be there at engine removal stage). Undo the 4 bolts and the belltank can be removed from the gearbox, usually needs a bit of help with a rubber mallet. 
Your oil leak will be from the gearbox selector rail oil seal. On reassembly, use silicone sealant  around this area. No gasket with 6 speed, but there is with 5 speed.

Malcolm

[Sandpiper]

Brilliant - thanks Malcolm.     I have a small ratchet strap which loops round the lower frame tubes and supports the front of the bell housing very useful for aligning the Gbox and engine. 👍

Just saw this in the assembly guide too

"6-Speed. Apply a thin layer of silicon sealant
to the front face of the gearbox and to the 'O'
ring around the selector rod. Ensure sealant
is applied to all of the 'O' ring. Using the four
M12 fine thread bolts, (polythene bag
'miscellaneous') and spring washers (ZGB14
item (3)) bolt the bell-housing to the gearbox.
Tighten the bolts to 45 lbft (61 Nm)"
 

Edited January 31 by Sandpiper

[SLR No.77]

You probably have it sorted, but be aware you’ll need to support the front of the gearbox itself as you remove the belltank … unless I’ve misunderstood your comment about the ratchet strap!

Stu.

[Sandpiper]

Thanks Stu, I shall be using another support for the gearbox when I part the bell housing from it.

Does anyone have a part number for the Selector rod O ring?   it's not to be confused with this is it? 

FRONT SEAL - GEARBOX - 5 & 6 SPEED £18.29 VAT incl.£15.24 VAT excl.Reference: 1602036

[rj]

2 hours ago, Sandpiper said:

Thanks Stu, I shall be using another support for the gearbox when I part the bell housing from it.

Does anyone have a part number for the Selector rod O ring?   it's not to be confused with this is it? 

FRONT SEAL - GEARBOX - 5 & 6 SPEED £18.29 VAT incl.£15.24 VAT excl.Reference: 1602036

It seems it has no number in the parts catalogue :-/

[Englishmaninwales]

Just as a further remark, in addition to the selector seal, I have also had an oil leak from the first motion shaft / housing oil seal in the front housing on my 5 speed, I think the 6 speed arrangement is identical  

The seal and housing to gearbox cork gasket (5 and 4 in diagram in RJ’s post above) are available from BGH Geartech or Road and Race. 

When re-fitting the housing with the new seal , lubricate the seal lip with oil and gently rotate the housing/seal 1/4 turn into position, so the seal lip locates correctly on the shaft and not turned over. 

The cork housing seal should not have sealant as this will cause the gasket to extrude on tightening the locating set screws.

Malcolm

Edited February 1 by Englishmaninwales

[rj]

8 hours ago, Englishmaninwales said:

 

My bad, please ignore!

 

Edited February 1 by rj

[Sandpiper]

Malcolm - you hit the nail on the head the 4 bolts on my release bearing guide tube were just over finger tight and the leak was past the inadequately clamped guide tube cork gasket- of interest there are different tq figures for these bolts 10Nm or 25Nm I think the higher figure is appropriate for the Caterham box. There was no leak past the selector shaft o ring.

 

So the oil passes through the input bearing race and fills the void between the gearbox and the guide sleeve then enters the bell housing through the gap between the outside of the sleeve and the hole it passes through into the bell housing which then gets whirled by the clutch/flywheel and dirtied by clutch dust see pictures 

[rj]

There should be no sealant on the mating surface of a 6-speed. That was actually what I was about to tell Malcolm until l re-read his post.

[Sandpiper]

Hi RJ this is the assembly guide that I presume my SLR was built IAW, the blue sealant residue looks like Hylomar 

[John Vine]

On 02/02/2024 at 08:55, Sandpiper said:

Hi RJ this is the assembly guide that I presume my SLR was built IAW, the blue sealant residue looks like Hylomar 

That's what I did on my R400D during build, and when I later re-furbed the 6-speed box:

JV

[rj]

On 02/02/2024 at 08:55, Sandpiper said:

Hi RJ this is the assembly guide that I presume my SLR was built IAW, the blue sealant residue looks like Hylomar 

I was told to do nothing - and it has never been leaking (there)

[rj]

But true. It says so in the build manual.

The blue stuff - has it dried up? It can be silicon sealant in spite of looking like Hylomar. I have blue silicon sealant... (But never used it there!)