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MG MGB GT V8 Factory Originals Technical - Body style for V8: GT or roadster?

I'm starting on a V8 conversion, and I'd like to hear anyone's dispassionate views on using a roadster vs. GT body. I know a few BMW enthusiasts, for example, who tell me that the handling is much, much better on the M Coupe than on an M Roadster due to body flex. Now, those cars are putting down around 300hp which is more than my Rover V8 is going to get, and they have absolutely massive brakes to boot, but it seems to me the comparison between B roadsters and GTs must be similar, due to simple physics.

I don't really mind getting a BGT with a Webasto roof rather than a B roadster if the body stiffness is that much better. Any comments?
Bob D.

The roadster body is plenty stiff. If you plan to race competitively the extra bracing provided by the GT roof may give some slight advantage, but if you're that close to the edge driver skill is going to be a bigger variable. Might as well get the one you like better. Doing that may make a bigger difference.
Jim Blackwood

Bob,
How dare you mention BMW on this board, especially after what the done to M.G./Rover!!
The original factory car used a GT shell. It is thought that the factory thought that the roadster was not up to taking the power of the V8. However this rumour has never been proved to be true. A chap called Costello undertook some of the first conversation to V8 power. He used both Roadster and GT shell. Conversions over the years have used both bodies with no adverse affects. The factory eventually produced a Roadster V8 in the form of the RV8 during the 1990’s. I believe this car did not have any significant changes to the body structure.
The GT is a heaver body and can perform (top speed and 0-60 times etc) as fast as the Roadster because it has a superior drag coefficient. It is really what you want from the car that will decide which body style you want.
HTH
Cecil Kimber


Most any class of road racing would require a roll cage, and a good roll cage would substantially
improve your car's torsional rigidity. But I'm guessing if you were going racing you would have said so...
Even for non-racers, the GT body provides superior torsional rigidity and will therefore turn better.
The GT will also be more responsive to suspension tuning. If you're the kind of chap who likes
tinkering with dampers, springs, anti-sway bars, etc., than you'll care that subtle changes are easier
to detect on a stiffer car.

Since these are all old cars, most of them are a lot looser than when they were newly built. (The MGB
was a very stoutly built car for its day, but at its best it's nowhere near as stiff as a modern sportscar,
such as a Miata. ) Some of the roadsters - particularly rust-buckets - have really noticeable body
flex problems.

For what it's worth, I started with a GT and added a full cage and a number of other reinforcements,
including a "Monte Carlo bar". (It's a piece of box tubing that spans from one fender to the other.)
I feel like they were worthwhile additions. Perhaps they also made the car safer.

But of course roadsters always FEEL faster than GT's. Wind in the hair and everything...




Curtis

Besides rigidty there is also the noise to consider. Hoods tend to make more noise than a GT fixed roof. Here in Europe it's easy to have the occasional 100mph+ burst or even prolonged 90+mph cruising. Then I wouldn't want any more noise than necessary.

Frank
Frank de Groot

The availability of a Webasto roof might be the biggest problem (Please correct me!). I'm doing a gt because it just seems right, I have little hair, and I have an Atlas 750 for the breeze.
angus

Not that you can't get away with a roadster shell in good shape, but the GT *is* stiffer. That's just basic physics. Because the MG suspension's so much less precise than on a modern BMW, though, you probably won't notice much difference.
Ted

"But of course roadsters always FEEL faster than GT's."

nuff said
Jim Blackwood

This thread was discussed between 22/06/2002 and 29/06/2002

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