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MG Midget and Sprite Technical - Chassis dimensions

Hi all
I'm sure someone on here will be able to help me, I'm looking for some vertical chassis dimensions for the midget. Seaching the net reveals plenty of horizontal and transverse data, dimensions between chassis rails, sills etc but nothing about groung to sill heights, ground to floor pan, ground to chassis rail etc etc. Is it really not that important or is it that the floor is parallel to the ground front and rear and everything else works from that?
Thanks
david jenkins

Height off ground will be determined by suspension set up, spring length/strength, use of lowering blocks, tyre profile etc etc The dimensions you should concentrate on are the ones you have data on.
Neil (K series)

Yes I agree, but can I ask you for any links or info regarding the dimensions you have managed to find, it would be a great help, Thanks, Dennis
d drury

Hi David

Are thes dimensions needed for working on the bodywork of the car or for setting it up on the suspension? The cars are best with the front end slightly lower than the rear.

Carl
C Bintcliffe

Sorry Dennis but I am certain when I say, like others I am sure, that the height of Midgets and Sprites will vary fron car to car depending on the matters I refer to above. Or am I missing something?
Neil (K series)

Thanks for the comments so far. I am aware that the ride heights will vary from car to car dependant on tyres, susp. settings, spring sag etc. What I am after is for bodywork rather than suspension. There is a load of info in the manual for the MGB but only minimal horizontal data in the Midget book sadly. Any links or info will be really helpful, and much better than what I have at the moment!!
david jenkins

Hi David,

I agree vertical data is scarce

I have looked past and present for some datums to try and plan suspension geometry around, it is sill height measurements, this all I found, hopefully it helps:

RT Jakeman (LR)149mm (RR)140mm
185/50 R14



Dean Smith (LF)152 (RF)156 (LR)159 (RR)152
73 RWA
Std Springs
lowering blocks
FL -1" Fr Spr

I am working on a sill height of 150mm as a start point at the base of the sill (ignoring the vertical welded return) this is at the same height as the floor

Cheers

Spencer
S Deakin

Thanks Spencer, Thats a good starting point, Ideally something like the image below would be great

Do I assume that the sill height should ideally be parallel to the floor or is there a difference front to rear?


david jenkins

Hi David,

The 'O' dimension would be 150mm in my world. With the 'E' dimension of 12.7mm being the sill return.

As far as whether the sill should be parallel?

It can be either an aeshetic consideration or:

The 'rake' angle of a car which with the rear higher / front lower - tends to help turn in (lots of reasons - roll centre / front and rear mass heights etc...)

My intention is to use 150mm as an average height and then trim from there if the front or rear responds better being higher or lower

But I have found little data other than the Dean Smith data which does indeed have the rear slightly higher than the front :)

cheers

Spencer

S Deakin

Hello, David. I post the page below some time ago, and while it's quite informative, it's for the Midget 1500. I'm not sure what differences exist between the two at this level of design, but if you can use the data, great...

http://www.ketcherside.net/chassis.htm

Cheers,

-:G:-
Gryf Ketcherside

Similar to the way I see it then Spencer, ride height for me will be lower, so long as I can get things level to begin with then everything should work itself out from there, flat and level garage floor permitting.
Thanks, Dave
david jenkins

Gryf you're wonderful and I love you, in a very manly way of course. That is exactly what I was looking for.

Many thanks, Dave
david jenkins

the one dimension missing from the factory data (Gryf's link) is how high should G be from the O surface of the frame.

The front frame rails sweep up something 3/8", 3/4"?

Darn, I don't have time to search the archive and look it up right now, but I do remember the frame sweep dimension was discussed here before.

I only bring this up because almost the whole rest of the underbody structure is a single, flat plane, with only this one curved part (not counting points E and F).

Norm
Norm Kerr

The upsweep angle matches the castor angle of the front suspension - that's why it is upswept. Angle is around 3 degrees. The bend is immediately behind the rear of the front suspension inner wishbone brackets.

Guy Oneandahalf Sprites

>>> Gryf you're wonderful and I love you, in a very manly way of course. That is exactly what I was looking for. <<<

I'll stop fluttering my eyelids long enough to remind you that those dimensions are from the factory manual for the 1500. ;-) So there may be differences compared to earlier models.

As for height from the ground, that's a variable at best...

-:G:-
Gryf Ketcherside

This thread was discussed between 17/12/2010 and 21/12/2010

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.