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MG MGF Technical - Lightweight F/TF Best way?

Hi Guys

Hopefuly have a new (to me) TF soon, was thinking about some mods to do and thought about the Xpower exhaust/manifold/springs jobbie and pos the light weight wheels.

Then came along another thought, 'what if I could make the car lighter? mmm'

So here's my musings

1. Carbon Fibre Boot and Bonnet
2. Light Weight Seats
3. Light Weight Hood Frame, Pos Carbon again?

Any thoughts on the above or other ways of lightening the car?


Mark Catterall

Swap contract to one 4an Elise ;)
Dieter K.

Given my location, it is probably of no help to you, but late last year I made molds for the boot, bonnet and doors in fibreglass for my MGF. I made eight molds all up with both an outer and an inner for each panel. The weight reduction was very significant as the lay-ups were very thin. I bonded 6mm alloy plates into the final pieces for hinge attachment points. It all took time but the resulting weight loss was worth it.

David M
d mottram


Problem is I cant get in a Elise as ive got mobility probs and I like the MG community a lot.


Have you got any pic? Id Like to see the results as I'll be back home (I'm an ex Pat Aussie :) ) in jan feb.
Mark Catterall

Your secret is out, no wonder your F perfoms so well !.
Andrew Regens

Hi all,
Dave, have you made any weight comparisson between a "naked" steel door (without all electrics/loudspeaker etc.) and the doors you made ?Still use the original glass or deleted it on the glass-fibre one ?

Carl Blom

VERY interesting.... but not that much I could add, except the following: the TF ULW 16" alloy weights: 7.395kg. Adding a Goodyear Eagle F1 Unidirctional tire (215/40x16) under the correct pressure brings the weight to 15.574kg. HTH.

Very cunning David! :o)

Mark, wouldn't carbon fibre be extremely expensive? Would be sure to make a significant difference though, as David indicates.

other weight reducing strategies would be to see what interior trim components could be lost. How spartan are you prepared to go - and what are you going to be using the car for?
Rob Bell

Diet - Cheapest solution of all, it would sertainly help my "Gross Weight".
Steve Ratledge

As an example of the mass saving.......the bonnet in GRP is less than 3 kg. In steel it is 12kg. The doors with glass etc are 25+kg and in GRP a couple of kg. Overall you can strip out 60-70 kg which is not to be sneezed at. The doors do not have the intrusion bars fitted therein, but my car has a full rollover cage with intrusion protection built into the cage. The factory hardtop as fitted to the CUP cars (mine has the same top) is 17kg. Best to run without it whenever possible. I only run it at two circuits.....Phillip Island and Sandown Int Raceway. Both these circuits involve flat chat top speed potential whereas Calder, Winton and Mallala are not such high speed circuits. My car currently weighs 1035kg which is still too heavy...but I have not fitted the GRP panels yet. They are made and waiting to be fitted over the summer break in the racing. My racing mate Nick Gough has the bonnet fitted after his son Ben crashed the car at Sandown last year. As yet he cannot beat me so I do not have the motivation to up the performance of the car. Over the summer I hope to get the car down to around 950kg. The MGBs that I race against are around 820kg so I have a hard time catching them...........the current 185kg is a terrible burden on the track.


d mottram

Rob, not really a cunning idea. The late Colin Chapman was a great fan of adding lightness and I am a great fan of his cars.......currently owning five of the GRP things. I did have an Elise as well but for financial reasons needed to move it on after 85,000km.


PS Incidently, I have finally settled on my Brake conversion for the car. At the rear I will be using modern Cooper S discs with the original MGF calipers. This gives me 285mm rears of 22mm thichness. The caliper has to be spaced out a la MS front conversion. At the front I will be fitting Mazda RX7 series 5, 4 spot calipers with WRX discs (305mm machined to 24mm thichness)mounted on my self made alloy top hats. This will give me 16% R and 20% front increases and given that the rear brake limiting valve is not fitted , the set-up should be better and should not be out of balance. I have just one more race meeting for this season and I can then start fitting these bits and pieces during the summer break.
d mottram

David - I too am a big fan of Mr Chapman's famous mantra of only adding lightness :o) I'd have a Lotus were it not for a sequence of events that means that the MG will always be on my drive! LOL

How hard would it be to construct these replacement parts - bonnet, front wings, boot lid etc out of a composite - and keep the car practical as an every day driver?
Rob Bell

Rob - Didnt think of GF as oposed to CF dont mind as long as it looks ok. Car will be an everyday car so needs some creature comforts but I intend to track it as well, though I do like the idea of removable interior (like the GT40 which has velcro on the carpet for easy removal on a track day IIRC)

Mark Catterall

I think that GF would be the way to go, but wow, wouldn't CF look cool! :o)

Like the idea of velcro carpet too - as a matter of fact, I think that the F's carpet is held in place by velcro - although it isn't that easy to remove without taking out all the interior trim.

AFAIK, there is no such thing as a lightweight hood frame. The solution that a number of people use is to jettison the frame altogether, and replace it with a lightweight removable hard top - like the Cup car item David mentions. It can be made to fit on a car without a roll cage.

Quite a lot of how far you want to take "adding lightness" depends on how practical a car you want - and how much you are prepared to invest. You could, for example, junk the exhaust back box in favour of a carbon can motobike style silencer (EBC could make one of these for you). You'd shed a few kilos - but at what cost?

Might be worth having a chat with Roy at Techspeed - he was heavily involved with the Cup car project, and will know a few areas where weight can be saved.

BTW if you get GF or CF panels made for your car, bear me in mind, as I'd be in the market for them - but I'd want to retain standard hinges where possible :o)
Rob Bell

is that GirlFriend v Companion Friend, I don't know, we're getting to PC around here ;-)
Mike (Mersea Office)

Once the GRP is painted it looks exactly the same as painted metal. It is generally not left "bare" like carbon fibre. Of course one could always lay up the visible face in woven mat (like CF) with black tinter instead of chopped strand. That way it would have all the appearance of CF but be much cheaper.................better to paint it I reckon.

WRT daily driveability with the GRP panels, it would be no different to your metal car. You would however need to bond in a side intrusion bar into the door for safety reasons. Much of the weight savings actually come from ditching the glass and electric motors etc which would preclude daily use in the land of the wet.

Incidently, Roy at Techspeed actually built my car back in 1995 as part of the original Japanese MGF Race Series.
d mottram

David, sounds like you have one of the oldest ('95) and most used Fs around here. What is your history of HGFs, or have you not had any due to better servicing than that from the corner grease monkey?
Neil Courtney

Neil, the car has now done nearly 13 thousand race and rally miles and still has the MG Sport lead seals on the engine put in place in 1995 to ensure no fiddling with engine. The car raced in Japan from 95 until 2000 and was shipped to Australia for the 99 and 2000 Targa Tasmania Rally where it won its class each time. I purchased it and immediately went racing in our local All MG Race series here in Victoria. To date I have done 32 race meetings which constitutes over 100 individual races as well as another 8 sprint days when it is often used by 3 people on the day (me, my wife and my son). The poor little beggar sometimes doesn't even have a chance to cool down before it is out there again! The car i snot fast as it has a standard 1.8i engine (the only mod AFAIK is that it has solid lifters and presumably a different Camshaft to suit). I have reduced the weght somewhat and will reduce it even further in the coming off-season. I have also played with the hydrospheres and now control both the initial gas pressure as well as the fluid pressure. Naturally all four spheres are seperate. The engine is now getting tired and I have lost a few seconds per lap at our long circuits (about 4 seconds in 100 seconds) I have built a new engine for it but to date have not installed it as I am still competitive on the old engine and still having heaps of fun in the back half of the field. As to HGF........I have suffered from that to date. I always leave the car running after a race for about 5 minutes to allow the water temp to stabilise across the cooling system and hopefully remove some of the heat from the heat soak of the hot engine. I have raced many different cars over the last 25 years and this is by far the most fun I have had. The reliability has been 100% ( never has it DNF'd) and the prep between meetings is straight forward, cheap and simple. A really great little race car!

d mottram

the last message should read.....HGF...I have not suffered.........
d mottram

You almost want to make me emigrate to Oz just to go MG racing David! LOL

What have you done with the new engine? I'm not going to ask for race specific mods! ;o)

Did I send you Simon Erland's article regarding the K-series? There's a strong emphasis on engine balancing that appears critical for longevity on a track engine.
Rob Bell

Rob, Piper BP 300M cams. solid lifters, forged pistons, lightweight alloy flywheel,VVC head with std VVC Ivey valves and twin springs, self made DTH quad throttle bodies, will do an extractor system for it in due course. dry sumped (on this motor........baffled on the current one) probably does not need the dry sump but I had a Caterham alloy sump left over from a job so thought I would put it to good use....that's about it. Nothing really special or innovative.
Yes thanks, you did send me the Erland article which I found most informative.

d mottram


thank you for the report with your experiance. This makes me smile ... It's great to reading.

So we only _talk about it_ and you just did it. Find me envious !!

Dieter K.

Nice one David. Planning a similar engine - I can't decide whether to port my spare head, or whether to sell it and go for a VVC... decisions decisions...
Rob Bell

>go for a VVC...

Of course. Take it and through the VVC to garbage. The nearly unknown German tuner I visited recently does the same *standard*. Was co-driver myself in an Elise with 200bhp from a similar modified K-engine, reliable setup since 3 years now.
Carl, he is 30 minutes distance from Hannover airport using airport transfers tunbridge wells ;)
Dieter K.

The decision is made more difficult for me Dieter because:
1. I'd like to learn how to port an engine, so if I pop over to DVA I could probably do this on my spare 1.8i head that I have for reasonable money
2. A ported 1.8i head will flow better than a standard VVC head - but then again a ported VVC head will flow better still
3. To make the most of a ported VVC head, you need an extremely high rev limit - over 8500rpm. Engine reliability issues notwithstanding, low-end torque and therefore tractibility may be adversely effected... A flowed 1.8i head maybe better for low end torque!

Argh! So it boils down to a need to nail down what kind of engine I want to end up with, otherwise I could end up spending a lot of money and not achieving very much :o(
Rob Bell

Chaps, I fired off an email to Smith & Deakin - the people who manufacture the Trophy style front splitter.

They seem interested in producing replacement GRP panels - they just need the original metal items to use as a pattern - shouldn't be too hard to arrange. No idea as to costs just yet though - probably somewhere in the region of 80-120 quid depending on panel being replaced.

Out of curiousity, who'd be interested in a set of ligthweight GRP panels?
Rob Bell

I wasn't too impressed with S&D, my front wings came with cast in rust!

Be aware that S&D make panels for racing - where the finish is not expected to be good for close up viewing.

The panels I have are fibreglass rather than GRP.
Will Munns

LOL! I guess that means someone gave them a rusty panel to take a mold from Will!

Good point made regarding the quality of finish - I'll definitely ask about that.

Need to give this some thought, but will continue my enquires if others are interested in LW panels... and perhaps even in panels with rad vents let in, ala 200HPD...?
Rob Bell

Getting GRP panels made is a bit like decorating the better the preparation, the better the product, so use a well polished mould and good quality materials.

The cheapest panels are usually no more than two layers of 8oz chopped strand matt heavily filled with a resin based on polystyrene and an undefined gelcoat on the surface layer to provide a finish of sorts.

A much better option uses an epoxy resin for toughness, gradually decreasing the resin:fibre ratio from the gel-coat to the inner suface, minimum of 3 layers of cloth which increase in coarseness from the outer surface inwards.

The term "GRP" is easier to write and say, and is more descriptive than "glass fibre", but they both mena the same thing. The common understanding is that both are polyester/styrene reinforced with glass filaments. The glass can be either chopped or continuous forms and made into either woven or knitted cloths or a non-woven mat.

Since most of the cost in laying-up panels is labour you can easily move up the quality scale, first by using an epoxy resin instead of polyester. Most cowboys fall away at this stage because they are only familiar with styrene mixtures.

Moving up again you can specify carbon/kevlar cloth which is tougher and cheaper than carbon alone and almost as light. The problem is it needs special cutters.

Christopher Marshall

The quality of S&D's Trophy splitter is pretty good by all accounts, and they also do a boot spoiler and hardtops for the T/TF... so they are capable of a highly acceptable finish.

Chris, thanks for your explanation/ summary of composite materials - the latter sounds as though it would suit Mark's needs, but I don't know (yet) whether S&D offer this material option?
Rob Bell

This thread was discussed between 26/09/2004 and 08/10/2004

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