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GT6 Gearbox cover


Alex Lowe
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I have a fibreglass cover which I didn't line but just filled the undeside of the parts tray with spray foam as it's a Vitesse and this area is exposed. Then glued an under felt over the rest of the cabin side of the cover before putting the carpet in place. It's been very effective although I did pay a lot of attention to also ensuring a good seal all the way round the edge...

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I used Dynamat on the underside a bitumen aluminum faced sound and vibration mat, which you mold into place, with a heavy duty felt cover with an upper black seal, glued to the upper or outside of the cover.

Also pay particular attention to the front vertical bulkhead seal as it only has two bolts clamping it at the front right at the top, only one each side, as well as the horiz floor sealing screws, a lot of heat can leak from the engine bay here. make sure you have a good seal and the bulkhead mounting flange isn't distorted.

I have a UK  supplied fiberglass gearbox cover and bluntly the vertical front face was very uneven and the bottom flanges not flat, I had to do a lot of fettling cutting and remolding to get it to fit and seal. in retrospect I think the poly covers are a lot better buy and fit!

I remember a fellow club members wife getting out of their Vitesse after a multi day run on a hot day really distressed and flushed, when I checked I could put my fingers in the vertical gap to the bulkhead, Jeff's  response was my sides OK, it was a quiet lunch! as a temp fix it we were able to jam some round poly seal into the gap, he'd removed the gearbox cover but hadn't replaced the top bulkhead bolts. His fiberglass gearbox cover was the same as mine as we'd brought them together from a UK supplier.  

Peter T

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Following on from Peter's post, I have used the same but went for Silent Coat which is equally as good but cheaper - with Dynamat you are paying for the name.

I have an OE tunnel on my Vitesse which required some repairs having seen better days, these were addressed using fibreglass matting and bonded accordingly. I also fitted a rubber bung to access the g/box filler point. With that done the SC was fitted and being very pliable it is an easy job and worth the extra work. You can buy the matting in 2mm and 4mm, but as you are requiring heat deflection the 2mm is ideal; if you use 4mm you end up with an extremely heavy tunnel.

My Vitesse is a CV and as such not an issue with internal heat, with the SC in place there is an improvement on reducing noise intrusion.

To finish off I purchased some closed cell foam to create the seal between tunnel and car.

Regards.

Richard. 

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1 hour ago, classiclife said:

Following on from Peter's post, I have used the same but went for Silent Coat which is equally as good but cheaper - with Dynamat you are paying for the name.

I have an OE tunnel on my Vitesse which required some repairs having seen better days, these were addressed using fibreglass matting and bonded accordingly. I also fitted a rubber bung to access the g/box filler point. With that done the SC was fitted and being very pliable it is an easy job and worth the extra work. You can buy the matting in 2mm and 4mm, but as you are requiring heat deflection the 2mm is ideal; if you use 4mm you end up with an extremely heavy tunnel.

My Vitesse is a CV and as such not an issue with internal heat, with the SC in place there is an improvement on reducing noise intrusion.

To finish off I purchased some closed cell foam to create the seal between tunnel and car.

Regards.

Richard. 

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I’ve taken the Silentcoat route and can recommend the product   At the time Amazon was cheaper than EBay 

Paul 

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Richard,

That looks just like mine! I also used SilentCoat, very heavy, but it does reduce heat and noise. To keep the heat down it's also important to seal the tunnel AND the holes in the bulkhead including the steering column. I've SilentCoat on the bulkhead, footwell and under the seats. All now very cool and quiet , but not so fast, for some reason. Oh, and I discover the heater's not working.

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Doug

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I used a cheap self adhesive engine bay insulation sheet from eBay, with foil on the surface and fire-retardant foam.

Seems to work well enough reducing noise and heat in the cabin, though no doubt the more expensive products like Dynamat may be even more effective.

Nigel

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I am repeatedly amazed, at the cost and trouble people go to to prevent heat "radiating from the gearbox"  or the exhaust pipe, and roasting them in their GT6.   Heat does seem to be a common problem - there used to be a macho 'club' of GT6 drivers who did so in shorts!

But it's not radiated heat that troubles you, as Doug has found.    It's heat from the radiator, and it gets to you via the many holes in the bulkhead, or else by a poorly sealed gearbox cover.   All that hot air has to go somewhere.    A new cover will cure any leak, whether or not you line it with heat reflective foil, as anyone is going to strive to seal it.       The bulkhead has many services going through it, originally sealed by rubber  grommets, which will have perished or been lost since then.    A torch-equipped assistant in the engine bay, while you get down under the dash, will reveal where the holes are today.

Why am I so confident in saying this?   Because I built the Silverback, the only Triumph ever to have had the radiator in the back.     That rad puts out, as heat, at least 60% of the energy burnt as fuel.      But Silverback was a cold car, so cold that I needed gloves in anything except really warm weather.    All the heat from the engine went to the rear radiator,   and there was no heat from the gearbox or exhaust pipe!

Save your money on heat reflective foil, invest in sealing strips and grommets!

John

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2 hours ago, JohnD said:

invest in sealing strips and grommets!

That should be a given, really.

I can certainly vouch for the heat & noise reduction by fitting new grommets etc can make.

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1 hour ago, dougbgt6 said:

John,

I new if I mentioned sealing the bulkhead you would mention Silverback! :)

Do you have any pictures?

How did you duct the water back and forth?

And, why did you do it?

Doug

It seemed like a good idea at the time!

And this canard of "the hot gearbox causes me to sweat" keeps on comong up, so I keep on telling people it'sd not true!   And mentioning Silverback, as proof!

Pictures?  I have few, but then again, too few - to put them all up here!

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This view of the engine bay shows the coolant ducting. The supply to the radiator went through a Laminova oil-to-water cooler, while the return you can't see because it went through the front suspension turret.   They went through the bulkhead, and then along the floor to the rear where they joined the radiator.

Why?  It was an experiment in aerodynamics.   Reduce the air that went under the car as much as possible - there was a front spoiler/airdam that wasn't fitted i these pics.  The radiator grille was blocked off, air intake for th engine from the heater intake in front of the winscreen - a filter was enclosed in the fabricated air box seen above.     The objective was to reduce airflow and thereby speed it, minimising lift, and even gaining some downforce.

If you're not very careful I could go on for hours!

John

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20 hours ago, JohnD said:

If you're not very careful I could go on for hours!

So what was the effect on engine temperature, are the fans at the back on all the time? They're sucking (?!!) so the air being pulled through the radiator comes from the interior which means there's air coming into the cabin all the time, which means it's COLD in there?

Doug

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Not very obvious in pic is an air intake, between the Moss sticker and the rear wheel.  Both sides.   The intakes were from Toyota MR2s.    The air was ducted to the front of the rad and exited out of the back.    The cooling was fine on the road, but tended to overheat on the track.   I always have my fans on when racing, but on the road, only as indicated.

SB was a cold car, as I said, but that was because it left all that hot air from the rad behind it!

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John, the SB looks an amazing car, I always like seeing pictures of it. Any chance of a fitting an article for the magazine? Be good to have a technical article like we use to have in the past.

Shame it got written off but the important thing you walked away, down to your engineering skills.

Graham

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