Another reason to remove the transmission tunnel - and how to avoid it

[Waynebaby]

Hi All,

I really thought I'd done everything possible in order to reduce the frequency with which I was having to remove the transmission tunnel from my Mk3 GT6. I'd had my gearbox and O/D rebuilt by Mr Papworth, fitted a new three part clutch kit, got a fettled release lever from Uncle Pete, put on a new slave cylinder filled with silicone hydraulic fluid (and added a remote bleed nipple for good measure), moved the O/D switch to the steering column to avoid wire chafing and even cut a hatch to access the gearbox filler plug. What had I missed?

My O/D stopped engaging this weekend and I eventually traced the problem to the micro-switch which is actuated by the 3rd/4th gear interlock. The nut which holds the switch onto its bracket had vibrated loose until the switch was no longer making contact with the interlock. Five hours of wrestling with the tunnel plus electrical continuity testing, all in order to carry out a two minute fix with a spanner and a couple of drops of Loctite!

If your car is fitted with this micro-switch, I recommend that next time you have the tunnel out (and you know there's going to be a next time!) you Loctite the b*gger in place.

Wayne

 

[Colin Lindsay]

I recently changed the oil on a Spitfire 1500 gearbox through a side panel in the tunnel and it was a total nightmare trying to get down amongst the pedals and see what I was doing, whereas I never had many problems working from underneath... unless the exhaust was hot.

Another Herald driver arrived recently with no tunnel cover at all, which gave unparalleled access to almost everything , including the road below... 

I think we need to work on some kind of detachable section - and a MAJOR section - to allow easy access as frequently as required without hours of prior dismantling.

[Badwolf]

Why not just cut the cover in half down the middle, front to back. Pop rivet 3 or 4 of those metal clip things you get on music/equipment cases on each half so they join together fit it, carpet it. Then it carpet out, pop the clips, take off half the tunnel cover, do the job, refit... or some similar variation?

[Ian Foster]

Wayne

Totally agree, it is one of the worst jobs on a GT6. I have followed a similar path with hoped for bullet proof components, but have still had to take it out on numerous occasions to fix bl**dy stupid things like cr*p gear lever spherical bearing etc. (one on the eve of the RBRR having put in a new one only 150 miles before).

It not just the tunnel cover, its the dash centre, the radio, the dash support and getting the tip of the tunnel past the lower vent hoses is always a real battle. These were a Mk2 retro fix, so no wonder it's all so tight down there. The guys on the Triumph assembly line must have been contortionist midgets !

I have seriously considered a removable section at the base of the gear lever (albeit I think I now have a reliable gear lever bearing) but so far haven't actioned anything as the last time I had it out, I just needed to get it back in quick.

I share your pain.

Ian

[Pete Lewis]

A 3D printed inflatable one sounds a plan

Pete

[Waynebaby]

A 3D printed inflatable one sounds a plan.

Pete. Are you on the wrong forum again!

Wayne

[Pete Lewis]

How would I know 

Youre lucky on  the big saloon  you have to drop the box down underside, theres no sleep on the seat while you sweat

Its get out and get under  , Heave  Ho

pete

[Gully]

I'm putting off changing my clutch slave cylinder as I can't face the tunnel out hassle in this warm weather. Must be the final component that hasn't been changed over the past 5 years! What's really irritating is that 14 months ago I put it back together so well I needed to use the heater through the winter!

Gully

[Jim-GT6]

Hi folks,

Old thread I know, but searching for examples of access panels people have cut in their tunnel covers. Anyone got photos?

How to make it actually work? How did you choose to fix / seal it? Do you now just peal back the carpet on the side of the tunnel to reveal the cut access panel?

My tunnel is original type, and very weak /broken. Held together with gaffer tape at the top front upstand. No good seal. Just old bits of one. Had it out last summer for a clutch slave replacement. I read a good thread (somewhere) on how to strengthen and straighten the old type with glass fibre mesh and resin repair. The author was of the opinion that restoring the original type with this method gave a better outcome than a new plastic or GF replacement.

Early summer I plan to remove, repair, modify for access, get a good seal, and hopefully sound / heat insulate. I've seen some of the products - Dodo, Silentcoat etc. What did folk pick? Hoe tick to go? I see the 4mm (thick option) is suggested for tunnel covers.

Do folk put heat proof matting on the underside and more sound deadening on the outside? Or just one? I want to dampen the transmission noise primarily, and seal in the cabin a bit. A little heat insulation wouldn't hurt. The many missing grommets and poor tunnel seal don't make for good cabin air.

I'd be keen to see photo's of people's mods!

The split tunnel idea in the thread above is quite interesting. Would in to need to be cut into 3 parts though to avoid having the take out the H support etc.? If you were to make two cuts from front to back, either side of the mid line, you might be able to create a centre section that stays in place, and good sized side 'wings' that remove?

[Pete Lewis]

all i can add is i got a slab of  18mm foam form dunelm cut strips and glued to tunnel 

its soft and big enough to fill nasty gaps and compresses well when screwed down 

doesnt have to be closed cell foam it a draught excluder not for soaking up flooding petrol

think we used 6mm acme threaded selt tappers with a hex head so easy to remove with a drill and socket

non of the tunnels fibre  plasticor abs  are very strong , a long cut section could be hard to keep its shape without a lot of 

added locational /overlap joints 

pete

 

[Josef]

The fibreglass repair thread will likely have been Colin L (and I think is in this months Courier too). Andy Cook (I think) had a relatively recent article (past year or so) on making a hatch for one of the ABS tunnels too which you should be able to dig up. 
 

https://www.tssc.org.uk/tssc/uploaded_files/500 February Courier 22.pdf Page 32 for Colin’s article, will see if I can find the other.

 

Edit: can’t find the hatch making article in my paper copies, I don’t keep hold of them long anymore though. My internet is being extra slow so I don’t fancy going through all the online back issues! 

[dougbgt6]

Jim,

Here is my tunnel. I have recessed lighting in one of my bedroom and bought an auger (?) to drill the holes in the ceiling, it also did the hole in the tunnel. I bought a giant bung on Ebay and sealed it with bathroom sealant. The tunnel is lined internally with SilientCoat. You'll notice there's a lip on the bottom and the front. which I think is there to increase rigidity, but because of it I had to double up on the rubber gasket with draught excluder. My brother repaired his cardboard tunnel with fibreglass, more fibreglass than cardboard now, not pretty, but functional. 

There are 3/4 threads on here with other people's solutions.

 

Doug

[Jim-GT6]

25 minutes ago, dougbgt6 said:

Jim,

Here is my tunnel. I have recessed lighting in one of my bedroom and bought an auger (?) to drill the holes in the ceiling, it also did the hole in the tunnel. I bought a giant bung on Ebay and sealed it with bathroom sealant. The tunnel is lined internally with SilientCoat. You'll notice there's a lip on the bottom and the front. which I think is there to increase rigidity, but because of it I had to double up on the rubber gasket with draught excluder. My brother repaired his cardboard tunnel with fibreglass, more fibreglass than cardboard now, not pretty, but functional. 

There are 3/4 threads on here with other people's solutions.

 

Doug

That does look good Doug. Surprised the hole can be that small. Was expecting to need an access hole something more postcard sized. Did the tunnel, seal and lining make a big difference to the heat / noise / fumes?

Jim

[Dick Twitchen]

This is how i did mine 

[JohnD]

And here's mine:

 

The rectangular forward patch, that incorporates the flange, is because the OE cover didn't clear my pre-engaged starter.  That is permanently secured with pop-rivets.

The oval one for the gearbox filler is secured by S/T screws, into Spire clips on the GRP edges of the hole.     The hole is not circular because my first drilling wasn't centred!      I suggest a small one first, 1"?   Enough to peer through while the filler is illuminated by a torch from below, check orientation and expand hole to suit.    The cover is rimmed by a strip of closed cell foam, to prevent air leaks, which can bring a lot of heat into the cabin.

.

 

How are yours secured, Dick?   How do you access the filler?   Are they screwed in?

John

[dougbgt6]

2 hours ago, Jim-GT6 said:

Surprised the hole can be that small.

You have to Measure VERY carefully, twice. The access bolt is right in the centre, I'm very pleased with it, except having done it I thought I'd better top up. I got half an egg cup full in! 

It appears I have the only non-leaking gearbox Triumph ever made. 

You will notice Dick and John's don't have foot rests, difficult to do with such large access holes. You godda have a foot rest for sophisticated motoring!

Yes, noise, heat and fumes reduced, from that area. For FULL reduction you have to seal the bulk head, lots of holes into the cabin to cover and, more SilientCoat required.

Doug

[Peter Truman]

A large hole isn't reqd, I use the female end of a 1/2in socket extension bar ie the internal 1/2in square loosly fits over the sq of the gearbox top up plug and I've drilled  a in hole in the bottom of the sq socket of the extension bar and fitted a small magnet into it to hold the plug so I can extract and replace the plug without loosing the plug or having to use your fingers down a small hole, there are cheap extension bars so its a special DIY tool, assuming the daughter hasn't pinched it when I want it!

[Stratton Jimmer]

15 hours ago, dougbgt6 said:

Here is my tunnel.

Looks like the same tunnel that I have albeit the PO had hacked it about mercilessly. I filled in "his holes" with a shaped piece of thick plastic from a five litre fence paint container (SPOT THE BODGE) and rivetted it into place as the hole was huge. I sealed that with Gorilla glue and then using contact adhesive, lined the inside of the tunnel with foil thermawrap insulation. I am now so adept at tunnel removal and refit that I can do either task in less than ten minutes. There had been a hole for gearbox filler access which was incredibly fiddly to use so I filled that too.

[Clive]

The TR cars use a large grommet, about 3" diameter. Be easy enough to fit one of those, with a suitable holesaw.

(EDIT, fits 2 1/2" hole, so approx 3" OD)

https://www.trgb.co.uk/products/grommet-gearbox-filler-grommet-all-trs

[Jim-GT6]

15 hours ago, JohnD said:

the gearbox filler is secured by S/T screws, into Spire clips on the GRP edges of the hole.     The hole is not circular because my first drilling wasn't centred!      I suggest a small one first, 1"?   Enough to peer through while the filler is illuminated by a torch from below, check orientation and expand hole to suit. 

Thanks John. That's how I was thinking to try and secure it too.

13 hours ago, dougbgt6 said:

notice Dick and John's don't have foot rests, difficult to do with such large access holes. You godda have a foot rest for sophisticated motoring!

😂 I was thinking to remove mine! I swear it's why my non-moulded carpets sit so horribly in the footwell. I've currently got a buried footrest under a big pleat of carpet that gets in the way of the clutch! Doesn't fell very sophisticated 😁

 

12 hours ago, Peter Truman said:

I use the female end of a 1/2in socket extension bar ie the internal 1/2in square loosly fits over the sq of the gearbox top up plug and I've drilled  a in hole in the bottom of the sq socket of the extension bar and fitted a small magnet into it to hold the plug so I can extract and replace the plug without loosing the plug or having to use your fingers down a small hole

Thanks Peter. That sounds ideal. Think I've already got everything needed to copy your tool knocking about. I hadn't thought about extracting the plug without dropping it. Save a lot of swearing!!

 

1 hour ago, Stratton Jimmer said:

I am now so adept at tunnel removal and refit that I can do either task in less than ten minutes.

Last time I did it (which was the first time I'd done it), I was about 2 hours each way! You could get a job in a pit crew Stratton!

 

Seeing all these pictures is super helpful. Now I've got a better idea of where to aim, I'm beginning to think I could try this in situ on my old cover without removing it, enlarge out from a small hole, top up my gearbox, do a fairly crude patch until summer, then rework with a new lined tunnel once the weather warms up. Doug - don't suppose you jotted down those careful measurements by any chance? 

Prepping one off the car, rather than fixing up the old one, will also make it less of a big single job.

[Clive]

16 hours ago, JohnD said:

And here's mine:

 

     The hole is not circular because my first drilling wasn't centred!      I suggest a small one first, 1"?   Enough to peer through while the filler is illuminated by a torch from below, check orientation and expand hole to suit.    The cover is rimmed by a strip of closed cell foam, to prevent air leaks, which can bring a lot of heat into the cabin.

 

John, have you tried making a small hole into a large one with holesaws? Unless you know the technique, it is hopeless as no centre/pilot hole.

The technique is known in the trade as the "F^<k-up saw" You pop the larger holesaw onto the arbor, then screw the one that was used to cut the existing hole. That keeps it centred. 

Used by electricians when replacing downlights and the new ones are larger. Doing the other way is more of a challenge (I got a job recently because I found a solution to that, other sparkys all suggested new holes and repairing the existing holes...)

[Jim-GT6]

8 minutes ago, clive said:

tried making a small hole into a large one with holesaws?

Hi Clive, that neat trick will only work if you're in the right place first go. You'd have to keep going bigger from wherever you started. Agree it would be very difficult / next to impossible to start a new location on ABS without a centre drill. It's too hard and skiddy. I don't think so bad on fibreboard though. With patience I imagine you could probably do it using the hole saw by hand, with no centre bit fitted. All the way through, or well enough started to finish with a drill. I'll report back if I try it

[Clive]

1 minute ago, Jim-GT6 said:

Hi Clive, that neat trick will only work if you're in the right place first go. You'd have to keep going bigger from wherever you started. Agree it would be very difficult / next to impossible to start a new location on ABS without a centre drill. It's too hard and skiddy. I don't think so bad on fibreboard though. With patience I imagine you could probably do it using the hole saw by hand, with no centre bit fitted. All the way through, or well enough started to finish with a drill. I'll report back if I try it

Honestly, hole saws have a mind of their own. If you need to recentre a bit of thin wood bridging behind the wrong hole, fitted with a woodscrews (and washer in the case of a tunnel) outside the new cutting area would be my suggestion. Gives a new pilot hole.

[JohnD]

A hole saw is good for a sighting shot, but resiting and enlarging is easier with a padsaw or fretsaw, hand or powered.

Nothing worse than a powered tool that isn't totally controlled!

[dougbgt6]

22 minutes ago, Jim-GT6 said:

 I was thinking to remove mine! I swear it's why my non-moulded carpets sit so horribly in the footwell. I've currently got a buried footrest under a big pleat of carpet that gets in the way of the clutch

I cut a footrest shaped hole in my carpet and got some free edging material from the carpet manufacturer which I stitched around the hole. I have a similar problem to you under the accelerator pedal where two sections of carpet overlap and SilientCoat beneath raises the floor level and the pedal stop needs adjustment.

Doug