material for underbody aero work

duncan · Post by **duncan** » Thu Dec 27, 2007 9:36 am

I am looking to make up a bigger rear diffuser and smooth off as much of the underbody as possible to aid air flow under the car and to create downforce from doing this by using the low pressure created to suck the car down onto the track.

Obviously the ideal would be carbon fibre but this does have drawbacks (aside from the cost which can be silly money) in that it cannot be bent or moulded after manufacture.

I am thinking that ABS plastic would make an ideal material for rear diffuser and cooler areas under the car as I can manipulate this with a heat gun to create the contours to fit to existing body panels.

Ideally I would like to create a curved and multi-vaned rear diffuser which would be easy to do in ABS as well as cheap to experiment with.

I am also looking to fully undertray the front but I would have thought ABS would get too hot for it to be a good structural material for this task.

Anyone got any views, info, tech experience etc?

GT4Dave · Post by **GT4Dave** » Thu Dec 27, 2007 9:59 am

I have removed all my original black plastic front undertrays and iam going to make a front undertray out of 3mm aluminium.. it can withstand the heat and its easy to fold, cut, shape and drill to whatever size and shape it will take,, and its relatively cheap to buy... i will get round to doing the rear undertray the same way,,, but that can wait for the moment.

duncan · Post by **duncan** » Thu Dec 27, 2007 10:14 am

Dave - have you got a good supplier for the Ally ?

martin · Post by **martin** » Thu Dec 27, 2007 12:56 pm

Duncan why dont you go for fibreglass im a GRP laminator so can soon bang a mould up and make what you need and the colour you want or you can have it painted as it will be a smooth gel coat finish :-D

duncan · Post by **duncan** » Thu Dec 27, 2007 12:58 pm

martin wrote:Duncan why dont you go for fibreglass im a GRP laminator so can soon bang a mould up and make what you need and the colour you want or you can have it painted as it will be a smooth gel coat finish :-D

hmm - sounds like a possibility. I will chat to you on msn.

martin · Post by **martin** » Thu Dec 27, 2007 12:58 pm

dynamix wrote:
martin wrote:Duncan why dont you go for fibreglass im a GRP laminator so can soon bang a mould up and make what you need and the colour you want or you can have it painted as it will be a smooth gel coat finish :-D
hmm - sounds like a possibility. I will chat to you on msn.

Ok i will log in

323ian · Post by **323ian** » Thu Dec 27, 2007 6:39 pm

PM Woody as he may be able to help you.

duncan · Post by **duncan** » Fri Dec 28, 2007 7:17 am

323ian wrote:PM Woody as he may be able to help you.

Done.

But I think cost might be prohibitive

Fast Eddy · Post by **Fast Eddy** » Fri Dec 28, 2007 11:10 am

Duncan,
I have used black 3mm abs for front splitters before and have a part sheet at the moment. Better than grp as more forgiving if you scrape a speed bump or something. I agree with Dave re the heat resistance (or lack of it) so use abs for the front undertray and then use grp or ally for the back of the car.
Eddy

martin · Post by **martin** » Fri Dec 28, 2007 12:36 pm

Fast Eddy wrote:Duncan,
I have used black 3mm abs for front splitters before and have a part sheet at the moment. Better than grp as more forgiving if you scrape a speed bump or something. I agree with Dave re the heat resistance (or lack of it) so use abs for the front undertray and then use grp or ally for the back of the car.
Eddy

GRP will be perfectly fine eddy if where the important parts are like the sump a sheet of alloy is inlaid into the layup. GRP is more forgiving than what you think and can cope with heat no probs :-D

Basic chop strand

But if you choose to add some of this to it makes it a different ball game and very strong

Woven mat

And the cost to use GRP is relatively low compared to other materials and is easier to form to what you want