MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Midget Chassis Rails

Hi All

I'm new here so please be gentle ;)

I have just started dismantling the midget I have owned for circa 10 years, after it failed its Mot about 5 years ago... Sadly other things have got in the way. Anyhow, I knew the sills/floors/wings were shot, but that seems to be a case of adding some props to keep the doorways in shape. The problem I hadn't expected is that the chassis rails are twisted - certainly ahead fo the engine/suspension cradle and quite possibly behind as well. There's a lot of rust to the underside of them too. Before I get too involved in this, has anybody got any advise for trying to line up new chassis rails? It look as though they simply project forward independantly with no sort of bracing up/down or left/right.

Here's a picture from above the rails...

Thanks

Ed


Ed_BMC

The legs ahead of the x-member project forward independently, as you suggest (and have a slight upward curve towards the front too).

I suggest you check the chassis for alignment... then decide the best place to cut off old to insert new... maybe even have a whole new H-frame.

It's always possible to make panels fit a chassis out of true, but... do the job once, properly IMO, and there'll be less chance of finding a weakness later, or some strange handing behaviour.

A
Anthony Cutler

Hi Anthony

I guess by H frame you mean the part I've seen listed as with the cross member already attached to the chassis rails? That's a 450GBP part, so I'm hoping to rescue the cross member and attach it to the new rails. The rails seem to be circa 45GBP each, so that's a bit easier to swallow;) I think you're also suggesting that I could chop the existing rails off at some point between the crossmember and the body tub?
BTW, this is with the hope of going either K series, or turbo with the car. Turbo parts sitting in the shed, but K sounds a more reliable route...
Thanks
Ed
Ed_BMC

Ed, from your photo the horns - ie the bits ahead of the front crossmember are certainly shot. replacements for just these sections are quite easy to fit and although alignment needs to be reasonably well done, it isn't absolutely critical. They appear upswept, but actually simply continue the upward trend of the main chassis rails from further back.

Replacing the main chassis rails is much harder as they carry the suspension pick up points and accuracy here is essential. There is obviously much more welding to be done. I did one side of mine and made up a jig with a threaded bar and brackets to align the suspension inner fulcrum brackets. Take a good look at the area. It may be possible to simply replace the base section of the chassis rails, leaving the existing top hat box in place. So it depends how extensive the rusting is in the area.

Whilst inspecting, check things like upper spring turrets to look for rusting and deformation. The engine bay side of things usually gets well protected with oil but under the wheel arches and up around where the rebound rubbers and springs fit are vulnerable.

Another rust point is at the rear of the main chassis rails where they meet up with the footwell sides. The triangular cross member formed by the footwell bulkheads and toe boards is rust trap where it meets the chassis rail and this area can disintegrate from the inside outwards. It needs testing by much poking with a large screwdriver. Only when you have inspected it all can you really decide if the full H section might be the best option.

Guy
Guy

Hi Guy

Thanks for your input, the rails really are pretty poor underneath, perhaps as a result of the twist. The lower panel on the near side has corroded through underneath the cradle, so immediately next to the lower suspension pick ups. I haven't had a chance to look at the upper area of the suspension yet, this lower bit concerned me straight away!

I'll be forever asking questions about this, so can anyone recommend a restoration book? I've seen one from Haynes by Lindsay Porter (Haynes Resto Series) another by Graham Bristow and another from Terry Horler. Any favorites in there?

Cheers

Ed
Ed_BMC

The Lindsay Porter is good

Wish I'd had it before I finished mine :)

I used "Practical Classics On Midget/Sprite Restoration"

sort of Lindsay Porter Lite in a way

worked out OK for me

ISBN 0 948 207 48 5 (very old ISBN, they may have renumbered it by now)
Bill 1

Hi Bill

A late reply but the book is on its way and the engine and gearbox should be removed this evening.

Thanks

Ed
Ed_BMC

This thread was discussed between 12/09/2011 and 26/09/2011

MG Midget and Sprite Technical index

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