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 Twin Top and Underslung?		  Forum Locked
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Reinout

USA
250 Posts
Posted - 02/04/2025 :  19:32:59  Show Profile
This is a 1933 ad for the L-Type, taken from the book Advertising MG by Daniel Young and published by P4 Spares in 1989 (ISBN 0 9511760 6 4).

It refers to the gear box as a "twin top type". I searched all forums, but can't find anything about what that might be.

It also mentions the "well tried M.G. underslung chassis". MMM chassis are usually called 'upswept'. Are upswept and underslung the same things?





Reinout Vogt
Emma
1931 M-Type 2M/2735
Edited by - Reinout on 02/04/2025 19:36:23

Onno

Netherlands
1092 Posts
Posted - 02/04/2025 :  20:38:59  Show Profile
The underslung refers to the rear of the chassis going under the rear axle (IMO the biggest handeling improvement from the C over the M)
And to me it is a very well known terminology that is referred to in plenty of periode documentation.

Onno "J,D,M" Könemann
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Simon Johnston

United Kingdom
6533 Posts
Posted - 03/04/2025 :  09:20:46  Show Profile
I posed the question about 'twin top' to ChatGPT and it suggested that, as there was no obvious technical definition, it was perhaps just a marketing term for the fact that with a four speed box, third was much more usable as an alternative to top gear than would be the case with a three speed box.

Any alternative suggestions?

Simon J
J3437
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sven

Sweden
454 Posts
Posted - 03/04/2025 :  09:44:00  Show Profile
Hi all
I thought that the "twin top" or "silent third" referred to the fact that third gear is engaged by internal splines instead of sliding the gear in engagement. The third gearset is thus in constant mesh. "Silent" compares with second and first.
Hope this makes some sense!

Regards

Sven
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DK6780

United Kingdom
417 Posts
Posted - 03/04/2025 :  11:34:08  Show Profile
I agree with Sven - twin top refers to the usability both from the point of view of silence of the gears and the engine with the (relatively) high 3rd gear with helical teeth.
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Reinout

USA
250 Posts
Posted - 06/04/2025 :  20:13:34  Show Profile
Thanks for the clarifications. The chassis being upswept in the front and underslung in the rear makes sense. And although I was not aware of the term, I am actually experiencing the twin-top's usability of 3rd and 4th gear. Since installing a 4-speed gearbox in my M, I find myself driving in 3rd quite a bit.

Reinout Vogt
Emma
1931 M-Type 2M/2735
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