Making 2 Pack silicone Rubber Air Hoses
Discussion
Hi all,
I have previously prototyped a layered rubber air inlet hose for a kit car
Actually, a Pembleton with a 2CV engine. The reason for doing this is that the bonnet is very low over the carb and the Goose Neck inlet boot needs to be approx half the height. Still having the carb dimension to fit and the tube dimension at the top.
The boot shown has 4 layers. 2 rubber layers, a fiber glass layer and a final rubber layer.
|https://thumbsnap.com/228Z8Fmf[/url]
The shape was formed over a male plug taken from an original inlet boot, but lowered and blended together to give a smooth air flow.
The part as shown has worked well for 6 months, but I want to make a better quality 2 pack silicone rubber one.
Making inner and outer moulds is no issue. What I cannot find is information on the best silicone 2 Pack material to use for hardness and strength etc. and where from. Plenty of info about making silicone moulds, but not parts.
Has anybody done this before?
Thanks
I have previously prototyped a layered rubber air inlet hose for a kit car
Actually, a Pembleton with a 2CV engine. The reason for doing this is that the bonnet is very low over the carb and the Goose Neck inlet boot needs to be approx half the height. Still having the carb dimension to fit and the tube dimension at the top.
The boot shown has 4 layers. 2 rubber layers, a fiber glass layer and a final rubber layer.
|https://thumbsnap.com/228Z8Fmf[/url]The shape was formed over a male plug taken from an original inlet boot, but lowered and blended together to give a smooth air flow.
The part as shown has worked well for 6 months, but I want to make a better quality 2 pack silicone rubber one.
Making inner and outer moulds is no issue. What I cannot find is information on the best silicone 2 Pack material to use for hardness and strength etc. and where from. Plenty of info about making silicone moulds, but not parts.
Has anybody done this before?
Thanks
I watched somebody doing this a few years ago but I've never done it myself.
The approach I saw is to wrap un-cured silicone adhesive tape over your form sticky side out, and then over-wrap that with adhesive polyester reinforced silicone tape sticky side in - essentially the same stuff but with fabric embedded in it. It needs heat curing but all perfectly doable in a domestic oven. IIRC the form separator was chalk dust. If you can design the form so that it can be removed from the inside of the hose without excessive stretching I think this is a perfectly feasible DIY job.
ETA around the same time I was watching somebody make a rigid part off a similar mould using an impregnated tape that sticks to itself and sets hard - I think it was designed for medical casts. It's porus but might be useful for your former.
The approach I saw is to wrap un-cured silicone adhesive tape over your form sticky side out, and then over-wrap that with adhesive polyester reinforced silicone tape sticky side in - essentially the same stuff but with fabric embedded in it. It needs heat curing but all perfectly doable in a domestic oven. IIRC the form separator was chalk dust. If you can design the form so that it can be removed from the inside of the hose without excessive stretching I think this is a perfectly feasible DIY job.
ETA around the same time I was watching somebody make a rigid part off a similar mould using an impregnated tape that sticks to itself and sets hard - I think it was designed for medical casts. It's porus but might be useful for your former.
Many thanks, I will try to Google something on that basis.
I have spoken to somebody who has made face masks from 2 pack silicone. Probable way to go is inner former.
Use petroleum jelly as the release agent. Either do another outer mould or possibly paint onto the inner. When set wrap with polyester ribbon and re coat with an outer layer again. Inside a bigger outer shell mould.
Told it releases well from epoxy or polyester resin.
Can put dye in to have a black inner layer and for me red outer layer. Can go a bit longer then knife off to exact dimensions. Unless somebody tells me, seems 30 Shore A May be the way to go.
I like the idea of using proper heat cure silicone though.
Just a question of sourcing it.
Yes on the medical casting tape.
Not used it but watched YouTube videos.
I did try to make a rigid Goose Neck in fiber glass. Had rubber inserts where it would seal. Was too rigid to get over the carb properly or over the round tube.
Also with the part rigid felt it would not take the engine to chassis vibration. I do understand you are just proposing it to make a male former.
Thanks again
Thanks
I have spoken to somebody who has made face masks from 2 pack silicone. Probable way to go is inner former.
Use petroleum jelly as the release agent. Either do another outer mould or possibly paint onto the inner. When set wrap with polyester ribbon and re coat with an outer layer again. Inside a bigger outer shell mould.
Told it releases well from epoxy or polyester resin.
Can put dye in to have a black inner layer and for me red outer layer. Can go a bit longer then knife off to exact dimensions. Unless somebody tells me, seems 30 Shore A May be the way to go.
I like the idea of using proper heat cure silicone though.
Just a question of sourcing it.
Yes on the medical casting tape.
Not used it but watched YouTube videos.
I did try to make a rigid Goose Neck in fiber glass. Had rubber inserts where it would seal. Was too rigid to get over the carb properly or over the round tube.
Also with the part rigid felt it would not take the engine to chassis vibration. I do understand you are just proposing it to make a male former.
Thanks again
Thanks
Edited by Dutch Trader on Monday 10th October 14:30
Many thanks,
it helps to know.
Just to describe the Citroen 2CV engine.
2 cylinder air cooled, 602cc with a mighty 29 bhp. (Yes twenty nine)
Mine is from a 1984 car.
Std carb is a twin venturi Solex.
The carb inlet is VERY oval. 50mm x 80mm
A Pembleton SuperSport has 3 wheels (Morgan style) and weights about 380Kg.
So 29 bhp goes quite a long way to pushing her down the road.
As far as I know, unless designed for a Solex carb, a standard round carb connector could not be easily made to fit.
Possibly with a transition from oval to round. The very limited height does not give much room to work in.
The round hose connector on the top part is 53mm dia.
I do tend to keep all the suggested threads/ideas on a word sheet, as you never know when one may be useful.
Thanks again.
it helps to know.
Just to describe the Citroen 2CV engine.
2 cylinder air cooled, 602cc with a mighty 29 bhp. (Yes twenty nine)
Mine is from a 1984 car.
Std carb is a twin venturi Solex.
The carb inlet is VERY oval. 50mm x 80mm
A Pembleton SuperSport has 3 wheels (Morgan style) and weights about 380Kg.
So 29 bhp goes quite a long way to pushing her down the road.
As far as I know, unless designed for a Solex carb, a standard round carb connector could not be easily made to fit.
Possibly with a transition from oval to round. The very limited height does not give much room to work in.
The round hose connector on the top part is 53mm dia.
I do tend to keep all the suggested threads/ideas on a word sheet, as you never know when one may be useful.
Thanks again.
DT,
I'm all in favour of DiY, I make many parts and brackets for my classic. But cobbling together a hose connector for a critical application?
Try asking Samco, if they will make you one, if they do not have one in their enormous range: https://samcosport.com
John (no connection with Samco, save as a customer)
I'm all in favour of DiY, I make many parts and brackets for my classic. But cobbling together a hose connector for a critical application?
Try asking Samco, if they will make you one, if they do not have one in their enormous range: https://samcosport.com
John (no connection with Samco, save as a customer)
Just looks like carb to air filter ? some of the ones I linked would likely do.
Or yes, a few of the silicone hose places do custom work too, but unless you're providing them a proper pattern to work from, it could get very expensive.
Or it could easily be made from a composite type material, carbon, kevlar and some fibreglass types could work too.
Or fabricated from metal
Or yes, a few of the silicone hose places do custom work too, but unless you're providing them a proper pattern to work from, it could get very expensive.
Or it could easily be made from a composite type material, carbon, kevlar and some fibreglass types could work too.
Or fabricated from metal
Thanks for all the comments.
It is just a rubber angle boot to connect the top of the carb to a pipe from the air filter box.
Given the poor state of a pancake filter originally on it leaking air in via a number of places,
I am not sure I would class the application as critical. A none turbo and none vacuum assist brakes, low power engine.
I had already contacted a silicone producer, who was not interested.
Inquiries to a french produced standard silicone boot have not been answered either.
The Mehari Club boot below is even taller than the standard 2CV one.
I did have an indication from somebody of tooling being circa £250, plus the part.
Yes there are a number of materials that could be used. Plastic, resin, carbon, rubber.
It all works and is good, I just want a better solution.
I will contact Samco and see what they say.
As mentioned though, unless something is existing I feel it is likely to be expensive.
It is just a rubber angle boot to connect the top of the carb to a pipe from the air filter box.
Given the poor state of a pancake filter originally on it leaking air in via a number of places,
I am not sure I would class the application as critical. A none turbo and none vacuum assist brakes, low power engine.
I had already contacted a silicone producer, who was not interested.
Inquiries to a french produced standard silicone boot have not been answered either.
The Mehari Club boot below is even taller than the standard 2CV one.
I did have an indication from somebody of tooling being circa £250, plus the part.
Yes there are a number of materials that could be used. Plastic, resin, carbon, rubber.
It all works and is good, I just want a better solution.
I will contact Samco and see what they say.
As mentioned though, unless something is existing I feel it is likely to be expensive.
looking at the picture it would seem that a solution could be made by starting with an off-the-shelf silicone elbow.
find one on eBay in your preferred colour with the internal diameter required but, critically, get a '90 elbow reducer'. the elbow reducer type have a very tight angle (in fact the inside of the turn is usually a sharp 90 rather than a curve).
difficult to tell from the picture but suppose your horizontal diameter required is 70mm and the other end of your current solution goes over a 50mm pipe (ample sizes for 29bhp!) then get a 70mm 50mm reducer elbow etc.
whatever the pipe diameter is you could get a piece of aluminium tube reducer made to suit whatever 90 reducer elbow you get .
more detail of sizes would make guessing easier!
there's also silicone self amalgamating tape (eBay again) which you could wrap over the mould then cover with a layer of nylon netting (or the polyester netting in pound shops) followed by another layer or two of self amalgamating tape
find one on eBay in your preferred colour with the internal diameter required but, critically, get a '90 elbow reducer'. the elbow reducer type have a very tight angle (in fact the inside of the turn is usually a sharp 90 rather than a curve).
difficult to tell from the picture but suppose your horizontal diameter required is 70mm and the other end of your current solution goes over a 50mm pipe (ample sizes for 29bhp!) then get a 70mm 50mm reducer elbow etc.
whatever the pipe diameter is you could get a piece of aluminium tube reducer made to suit whatever 90 reducer elbow you get .
more detail of sizes would make guessing easier!
there's also silicone self amalgamating tape (eBay again) which you could wrap over the mould then cover with a layer of nylon netting (or the polyester netting in pound shops) followed by another layer or two of self amalgamating tape
Have you tried "rounding out" the oval to get a circle and get the closest one of these to fit?
https://www.ebay.co.uk/itm/384941626183?hash=item5...
https://www.ebay.co.uk/itm/384941626183?hash=item5...
NMNeil said:
Many thanks. I googled them and they have a UK distributor. Contacted their technical department and they have been very helpful both on material selection and how to make a good part.Thanks,
Yes I know Ambleton.
Previously he went by the name of Slowmax.
He also is building a Pembleton SuperSport, but Moto Guzzi powered.
I did get in touch with both the suggested Silicone hose companies via their web enquiry service.
Not had a reply from either yet.
Thanks for the suggestion.
I know he has 3D printed several parts.
Not sure about a pliable material.
I will ask him though.
Yes I know Ambleton.
Previously he went by the name of Slowmax.
He also is building a Pembleton SuperSport, but Moto Guzzi powered.
I did get in touch with both the suggested Silicone hose companies via their web enquiry service.
Not had a reply from either yet.
Thanks for the suggestion.
I know he has 3D printed several parts.
Not sure about a pliable material.
I will ask him though.
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