Gearbox cover and insulation GT6

[Roger K]

Not sure where this topic should be, but gearbox is as good as anywhere...

The cardboard cover in my GT6 has disintegrated somewhat, with the whole of the bulkhead flange loose and broken.  What is the top suggestion for replacing this?  Not bothered too much about cost, good quality is the main concern.  I'm guessing the plastic ones are better than the fibreglass, but why would Canley (who I prefer to use) charge a lot more than Rimmers?  Or is that a silly question?  They're randomly described as 'plastic' or 'ABS', but there's no way of knowing how accurate those descriptions are.

What about insulation etc., on the inside?  My old plastic padding was draped over the gearbox and covered in oil.  Sound deadening here would be quite important, I'd have thought - what's best?

Thanks, Roger

[PeteH]

4 minutes ago, Roger K said:

what about insulation etc., on the inside?  My old plastic padding was draped over the gearbox and covered in oil.  Sound deadening here would be quite important, I'd have thought - what's best?

I`v been looking at using some of the "Noico" I got for the panels. There was a deal going on Amazon at the time.

[Clive]

Rimmers may have a better source (unusually) than canleys. As long as it is ABS.

Although I still prefer the original type, and they can be repaired with fibreglass and resin (the card is a better sound and heat insulator than the thin ABS)

And yes, plenty of insulation is a good idea. And good sealing. I believe the ABS type have a return lip, and teh best option is some thicker closed cell seal, not the one sometimes supplied or offered.

 

 

 

[Roger K]

10 minutes ago, clive said:

Rimmers may have a better source (unusually) than canleys. As long as it is ABS.

Although I still prefer the original type, and they can be repaired with fibreglass and resin (the card is a better sound and heat insulator than the thin ABS)

And yes, plenty of insulation is a good idea. And good sealing. I believe the ABS type have a return lip, and teh best option is some thicker closed cell seal, not the one sometimes supplied or offered.

 

 

 

Yes, there's good closed cell neoprene from Woolie's which I use for a lot of similar jobs.  What is best for insulation?  I've seen adverts for the metallised adhesive heat shield, but I think sound deadening will be more important.

I think my original cover is way past redemption, the whole front end is hanging off and all the holes have pulled through big time.

[Pete Lewis]

price can be down to  which supplier  .....who buys what from who 

dont forget to check (log in) club shop pricing 

some have used silent coat  as insulation   you can stick it everywhere .

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311&_nkw=silent+coat+sound+deadening&_sacat=0

Pete

[Roger K]

Thanks - the Noico, and the Silent Coat, are only 2mm thick - is that really enough?  Never used it, so probably a clever new material...  are these self-adhesive, and would they stick OK in that hot and oily environment?

[Pete Lewis]

do a search im sure there are a variety of thickness available 

as its anti resonance you dont need much for a big improvement 

Pete

[Clive]

I am no expert on insulation. But heat is often reflected by a metallic surface. Something thicker than 2mm would be wise  reckon, have a look at the silentcoat website for some ideas.

Maybe insulate mostly on the underside, and a bit inside the car.

[Paul H]

Another vote for Silentcoat , I used 2mm it’s surprising heavy , if the surface has been degreased silentcoat will stick . I used a heat gun to warm up the coat which helps with moulding round contours etc . A wall paper roller  (2ins) is good for getting the silent coat to adhere to tight corners . I used silentcoat for the boot floor , cabin, bulkhead , doors , gearbox cover in my Vitesse 
 

Paul

[Dick Twitchen]

And again for 2mm Silentcoat; made a marked difference in my GT6.

Dick

[Colin Lindsay]

The modern versions are sometimes a bit flimsy; I know the material is stronger than the original board but can be thin so allows heat and noise through much more easily. What I did a while ago was to take one of the original tunnel covers and reinforce it with fibreglass, which was surprisingly easy and worked very well, then coat the inside with sheets of Dodomat, £29 from eBay. The GT6 tunnel has very little heat transfer since, the carpets over the tunnel have gone from hot to barely warm, so I've done the same for the Herald tunnel.

 

[PeteH]

I`m considering putting the Cover back temporarily (in the bare shell) and "glassing" it whilst it is in place, in an effort to ensure the alignment is as good and accurate as can be. I recon; I`l use some Self Tappers Initially and put it on (say) cling film to prevent "sticktion"?. Then repeat the process on the inside, before Covering both side with the "noico".

Pete

[Clive]

Rather than clingfilm, newspaper or probably better greaseproof paper? clingfilm is too unpredictable, and I have no idea how it may work with resin.

remember resin goes off in minutes, so very possible to get the shape correct and do the mending, then take out to get proper access. 

[JohnD]

Agrre with clive!    Clingfilm will probably be dissolved by resin, like using white plastiv drinking cvups to mix it! (Use clear ones)

And the resin wil penetrate newspaper, sticking it all togther.   Greaseproof?? No idea.

But what will work is brown parcel tape.     It will stick to a clean surface, resist resin and release from the composite when that has 'gone off'.

When I was making moulds from the roof and doors, to build Silverback, it was useful and effective in preventing resin from sticking where that was not wanted.    This pic shows the C-post of the rooof with 'fences' attatched (to  make a multipart mould)   The fences, strips of alloy, were covered with brown tape, while the roof was polished with non-silicone polish as a release agent.

 

[Roger K]

I had to learn how to lay fibreglass when rebuilding the footboxes of my Cobra (yes, AC made the bodies of traditional aluminium, but the footwell boxes and front of the transmission tunnel were always fibreglass).  John Dickens' book 'Automotive Fibreglass Fabrication and Repair' is a brilliant little book which covers just about everything you need to know.  Polyester film is best for flat surfaces with gelcoat, as it doesn't deform or stick.  Gelcoat won't go off properly if the air can get to it, so the polyester allows it to go off and gives a lovely smooth finish.   PVA is the release agent to use in the mould.  Strongly recommend these guys, very good for materials and tints:

https://www.ecfibreglasssupplies.co.uk

All this takes me right back to being a dental student in the seventies, when for four years we had to do all our own laboratory work.  Casting gold crowns and firing porcelain ones was fun, casting cobalt-chromium denture bases was toxic, but we had to do the pattern making, mould making and pressure curing of every acrylic denture we made.  Cold-mould seal, lost wax technique, endless burns from hot plaster of paris as it sets... oh, how I miss the solvents...

[dougbgt6]

I got a plastic cover from the club shop, £20 cheaper than Moss, but when it arrived it had a Moss sticker on it. How does that work? 😊

Don’t buy the fitting kit, it’s expensive and you’ll have all the bits from the old cover.

The cover had an additional lip on the bottom and front which makes the gasket too shallow. Some have ground the lip off, others double up on the gasket (draught excluder).

I used silent coat on the inside of the cover, very effective and surprisingly heavy.

And cut a hole to allow access to gearbox top up.

Doug

[Roger K]

Silentcoat seem to recommend their 3mm offering for classic cars.  Most on here seem to have used the 2mm - is the 3mm too stiff to mould into the cover shape?

Edit - all 3mm is 'product unavailable' on their website, so I've ordered some 2mm aluminium coated.

[dougbgt6]

3mm seems readily available on EBay. I used 2mm, but you could double up, I can vouch that it will stick to it’s self. 😆

Doug

[Badwolf]

I used 2mm SilentCoat. Very handy stuff

As for a non stick paper for using under fibreglass, try onion board sheets or silicone release paper, the stuff you throw away from the back of self adhesive plastic sheets and other stuff. Put it glossy side up on your bench to stop the tunnel from gluing itself down.

I'm sure that we covered all this a couple of weeks ago on another thread!

 

[JohnD]

RogerK,

When reading up GRP work for my roof and doors project, I learnt that PVA was the stuff as a release agent, but I couldn't get it to stick to the surfaces.  Painting it on, it just formed droplets and ran off!    So I used non-silicone polish instead, which worked well.    Any idea why PVA didn't work for me?

Badwolf, how do you get the onion/silicone paper to stick to the work?    And the point about non-silicone polish is that silicone contaminates the final surface, so that paint will never stick to it.     Will the paper act similarly?

John

[PeteH]

There we go👍. Every days a school day on here👍. The back from self adhesive graphics?. I`m sure somewhere we have the remains of a roll of the stuff you could put on kitchen shelves?.

Pete

[Roger K]

1 minute ago, JohnD said:

RogerK,

When reading up GRP work for my roof and doors project, I learnt that PVA was the stuff as a release agent, but I couldn't get it to stick to the surfaces.  Painting it on, it just formed droplets and ran off!    So I used non-silicone polish instead, which worked well.    Any idea why PVA didn't work for me?

John

Hi John,

That's odd...  however it's so long since I rebuilt the footwell boxes that I honestly can't remember.  I was laying-up from scratch, so making the large white flat panels first, placing a sheet of polyester on a flat surface and starting with the gelcoat, then building up the back with resin and mat etc. so didn't need the PVA at that stage.  All the curved corners etc. and the exhaust manifold clearance sections were done in hand-formed sheet aluminium moulds, for which I used the PVA as release agent, but I don't remember any problems.

[PeteH]

Silicone, is an extremely useful product. Until it gets anywhere near Paint!. I suppose the same could be said about the PVA not working, Airborne silicones are anathema in paint shops?.

[Badwolf]

The point of the onion board paper/silicone backing paper is that it should not stick to the work and should act as a release/barrier to stop the fibreglass from sticking to anything like a workbench and can then be peeled of the fibreglass when set, unlike something like news/brown paper which will bond well. Sorry if my post was not clear on that point. As for paint contamination by the paper, I'm sure it should be no worse than using an onion board for mixing filler, I'm sure that the two types of paper are very similar, but a little anti fish eye additive to your paint and a good clean down with quality panel wipe beforehand should sort any problems.