24 replies to this topic

[TopCatCustom]

Hopefully someone can tell me the weight difference between a normal steel rear valance and a fibreglass one? I like the look of Paul Wiginton's aluminium one but looks like a one off which only an experienced metal shaper could do!

[TopCatCustom]

Forgot I actually created this post- so disappointed nobody can tell me if I will save much weight yet!

[jcsmarttec]

NO ig won't!! Stop kidding your self and get a carbon fibre one and get on a diet! Ha ha

[ado15]

Steel one is 1.86Kgs. We don't sell GRP ones so can't help there!

Edited by ado15, 09 November 2010 - 01:55 PM.

[clambert81]

I'd be surprised if there is any difference at all, not enough to matter and why would you want to save just a few ounces?

[ado15]

I'd be surprised if there is any difference at all, not enough to matter and why would you want to save just a few ounces?

A few ounces here, and a few more there, can add up. The lighter the car, the quicker it will accelerate. Even if you have a minimum weight limit in a racing class, getting the weight below this means you can put ballast where you want it (regs allowing) to help with front/rear split.

[Bungle]

when i quizzed my MOT man about replacing a steel rear valance with fibreglass he said although it's not structural it is with in 30cm of the subframe mount and he would fail it

any MOT testers with their thoughts ?

[dhende84]

Steel has a density of 7.8 g/cubic cm. Glass fibre is around 2.5 g/cubic cm, but the finished component density will differ depending upon fibre to resin mix. A figure in the region of 1.9 isn't unreasonable though.
This doesn't mean that it is 1/4 the weight as steel pressings tend to be about 0.8-1.2mm (for modern cars). Fibre glass composites are unlikely to be much thinner than 3mm, and probably closer to 5 or 6mm. As a result the net weight will be similar.
Carbon will be around 1.6 g/cubic cm (depending upon composition) and can be made thinner than fibreglass as it is much stiffer and good weight gains can be made.

[benpopham]

I made one.. 300g's

Its much stiffer than the steel version.. and nicer looking, thats without any holes and including the closing panels on the inside edges.

Ben

[Wil_h]

If it's for a race car, why not just bin it ala Miglias.

I kept the steel one on mine as I liked the look, but my car has no boot floor and it was easier to keep the steel one.

[tommy13]

when i quizzed my MOT man about replacing a steel rear valance with fibreglass he said although it's not structural it is with in 30cm of the subframe mount and he would fail it

any MOT testers with their thoughts ?

Your tester is spot on, and further to this, from appendix c of the manual,

It is unacceptable for plastics to replace or reinforce corroded or weak metal in prescribed areas and load bearing sections.
It does however sound as though the OP will be using the car offroad only ??.

[Wil_h]

Rear valance is non-structural so the above dosen't apply. Problem is that MOT testers are neither chassis or structural engineers.

Edited by Wil_h, 09 November 2010 - 07:19 PM.

[tommy13]

Rear valance is non-structural so the above dosen't apply. Problem is that MOT testers are neither chassis or structural engineers.

While I agree we aren't structural engineers, as i have pointed out in various past posts, with reference to assessing structural changes to Z cars and the like. If you read Bungles post you will see that the tester states that the rear valance is not structural. However, both outer ends of the valance and the closing plates fall into what are called "prescribed areas"
ie they are within 30 cm of a load bearing point. Any excessive corrosion or panel replacement with a different material such as GRP in this area is a fail.

Edited by tommy13, 09 November 2010 - 07:48 PM.

[mini93]

If you were to have a beam and coilover suspension you no longer have the mounting apparently too close to the removed valance.

personly i think its daft if you have obviously removed it on purpose then so be it as long as it looks safe, which it appears to be then fine.
I intend on cutting off the valance and also the boot floor... i awate the IVA police

[geo]

It is unacceptable for plastics to replace or reinforce corroded or weak metal in prescribed areas and load bearing sections.

So what if you're replacing or reinforcing good metal? This seems to imply repairs rather than modifications.

I have a carbon boot floor and carbon rear valence. My brother, whom is an MOT tester, has told me that if he tests my mini he will fail it, however if I send it to him with the rear valence and boot floor removed he'll pass it.

Edited by geo, 09 November 2010 - 08:12 PM.