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MG Midget and Sprite Technical - Axle position

Can anybody tell me the dimension between the front and rear wheel centres. My rear axle is offset by about 20mm on one side. Making the tyre quiet close to the front edge (Sill) of the wheelarch.
Thanks Ian
I Pickering

Ian

All versions I can find data for give 6'8" for the wheelbase, which is the dimension you are asking for.

Some experts can convert that to EU standard measurements if they wish

:-)

Hope this helps

Ref: Lindsay Porter -

MG midget - Austin Healey Sprite Super Profile



Excludes Frogeye Sprite (but doesn't really, no difference in wheelbase)

ISBN 0 85429 344 2

Haynes Publishing Group
Bill

Thanks Bill
Do you think it would be acceptable to elongate the holes in the floor and front spring hanger plate to allow for some movement??
I Pickering

I wouldn't enlarge the mounting holes. Better to relieve the offending arch and/or control the static lateral alignment using a Panhard rod.

A
Anthony

Ian,
Are you saying that the rear axle is not at 90 degs. to the axis of the body? That sounds like a problem that would need to be corrected, and although elongating the support plate holes might be a way around it I wouldn't advise that. Not least because two of the holes have captive blocks for the bolts to screw into. Do you know what the cause of the mis-alignment is? Has the car had new cills or floor fitted out of position at some time?

Guy
Guy Weller

Guy is right at times like his it is absolutely imperative that you analise exactly what the fault is. Is this a heritage shell? is one of the springs fitted the wrong way around? Check as many dimensions as possible
Bob (robert) Midget Turbo

In these days of dodgy springs, compare the two rear springs. Put a bolt/rod through the front eye (springs removed from car) and compare length to the centre bolt. We had a pair that was 10mm different in this dimension. To do this in a simple preliminary way, measure alonmg the spring with a tape while it is still in the car. measure from a reference point on the front mounting bracket to the centre of the spring in situ.
Paul Walbran

Are your "U" bolts done up tight enough ? You can test this by putting your boot down hard and then lifting your foot off the accelerator. If you feel a pull to one side then "U" bolts will be your problem.
Geoff Mears (1970 Midget)

Ian

as the guys say don't bugger about with fixing holes

If the displacement is wrong fix the actual problem

If the axle should lie 17 inches (for example!) from the rear body cross member along the spring there is something causing a misalignment and that is where the trouble is seated and needs sorting

Geoff is telling you that he has a very well fitting tee shirt from a "U" bolts situation a couple of years ago :-)

We really ought to know what sort of axle/spring set up you have are you working on a Frogeye/mk1 Midget setup or a later semi elliptic spring with a shackle at the back and a fixed pivot at the front

'til we know we are all making unhelpful guesses so what is the score? semi or quarter elliptics?
Bill

Ok I have the later type semi elliptic springs the car has had major welding work done buy a previous owner/garage and i purchased it as a basket case the one thing I have noticed is the bolt heads that go through the floor into the front spring plate are approx 15mm further forward than the other side
I Pickering

So is that the cause of the mis-aligned axle? Or are those bolts further forward as someone's botched attempt to correct faulty bodywork repairs? It sounds like you need to start doing some very careful measurement from known fixed points.

A good way to do this is to park the car on a clean level area of concrete (garage floor?) Then use a plumb line to transfer various chassis points to the floor, marking accurately. Move the car and draw diagonal lines connecting pairs of points. eg rear of the cill on one side to the front of the opposite side cill. These will form a series of crosses, the lines of which should intersect on the centre line of the car. A small discrepancy will be magnified this way, such that the lines don't intersect exactly on the centre line and this will show up if your frame is distorted.

Guy Weller

I've got a diagram some where with chassis datum points marked on it, I will have a search for it tonight
Bill

YertteZZ!

probably a take off from a factory book judging by the look of it

It refers to specifically Mk1 midgey stuff but can be taken as a good quality guide to dimensions you need to follow and adhere to

If the floor holes are wrong, for pity's sake get them put right competently

Do not use the same bodge merchant or his mate down the pub

hope this helps you get the ol' bird back on the boulevards


Bill

Its in the workshop manual, but I think is basically for the Frogeye. It uses the front suspension inner fulcrum brackets at the front and the outer corners of the spring mounts (1/4 elliptic) at the rear. Unless of course Bill has found one for the later cars. But either way you can choose any matching pairs of datum points you like. The important thing is that the criss-cross lines must intersect on a common centre line for the car.
Guy Weller

For what it's worth, I posted a similar spec sheet for the 1500. (You didn't mention what model you had, or I missed it.)

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

Cheers,

-:G:-
Gryf Ketcherside

Time warp posting again!
That's the one Bill, slightly later than the one I have but still for quarter elliptics. But it shows the principle of the criss cross lines.
Guy Weller

"for what it's worth"

it is worth a lot to have it all

the info there between us can give him enough for all models
Bill

Thanks for the information guys I will have a detailed look and measure tomorrow many thanks I will report back
Thanks Ian
I Pickering

Quickest start point is to check what Bill said, second message. Park up straight and measure the distance between front and rear wheel centres. Should be 6' 8" both sides. That will confirm if the rear axle is correct, then you can go on to check other dims.
Guy Weller

Thanks for all the information and drawings, sometimes it is easy to miss the obvious and get too technical with these things!! After lots of careful measuring I have noticed that the sill on the offending side has a slightly different profile casusing the problem. The only solution would be to cut it back and fold the edge over again but as this will cause considerable damage to the paint, I think I will just have to live with it and be happy I am making progress.
Thanks To all
I Pickering

If it makes you feel better, While replacing rear bushings today I found out that I inadvertantly welded my front spring plates to the body when I welded my floor pans in. At least you can say "$%^&* previous owner!" I keep cursing the current one.
C. J. Charvet

This thread was discussed between 25/07/2008 and 05/08/2008

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