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MG Midget and Sprite Technical - !*#'@'%$&^+? 1/4 elliptical springs

I've so far spent 2 evenings putting new 1/4 elliptical springs and freshly painted axle casing onto my Frog and still haven't finished.

The main problem I am sure are the springs supplied by the well known company whose name rhymes with Toss.

So far I have found that at the body end the peg that locates in a hole in the main chassis plate doesn't have a chamfer. This chamfer is important as it guides the peg into the hole so if there is surface corrosion reducing the diameter of the hole slightly the chamfer will allow it to drop in and tightening the bolts will clear the hole and allow the spring to bed down. With a parallel sided peg this sin't happening.

Also, at the axle end the clamp closing the eye that grips the rear bush has been fitted the wrong way up. The threads are pointing upward but should be pointing downward. If they point up they foul on the mounting bracket stopping the axle from rotating enough to get the bolts through the reaction rod bushes.

Having sorted both out (I hacksawed the threads off) I still cannot get the spring mounting bolts through the bracket and bush. I can push the bolt in from either side (with a bit of force from a handy hammer)but the bush is missaligned enough to prevent the bolt exiting. I have come to the conclusion that the spring metal is a bit thicker than it should be so when it forms the eye around the bush it is too fat to bed properly in the bracket.

Any advice?

Rob
Rob aka MG Moneypit

Well yeahhh, sure but.... did you remember to buy a 4 of pack of charmin tp today ???

Sorry....it can be really frustrating, hang in there
Prop and the Blackhole Midget

Rob
Your springs are thicker roughly equivalent to what BMC used as competition items. The reason usually given for using thicker steel leaves is poor steel quality. BMC used spring wedges. You'll have to get a pair from such as Peter May engineering at about £40 a pair otherwise you'll end up with the cars rear up in the clouds doing its best to emulate an American hot rod.
You may have to drop off the top leaf to allow the spring, with wedge, to enter the chassis box.
The spring clamp plate that sits atop the spring within the box may need its top side edges chamfered to allow it to sit nicely in the chassis.
I haven't experienced alignment problems at the axle ends. Is your axle casing bent? I have fitted a Polypro bush at that end.
Alan
Alan Anstead

I can't see any signs of past abuse on the axle.

I've got a laser pen so I'll try shining it through the 4 holes in the 2 brackets to see if there is any miss-alignment. I'll have to do that tomorrow now.

Why do they only supply the 9 leaf spring now? Is it really so hard to get decent steel?

I will have to get it to fit for now otherwise I will miss my target of being on the road by April. I still have the original 15 leaf springs so might see if anyone in the Manchester area can re-temper the leaves and swap them back. After all this practice I should be able to do the whole back end in two or so hours.

Anyone tried the trick of inverting one or two of the leaves to lower the ride height?

Rob
Rob aka MG Moneypit

Hi
Taking three leaves from the top and placing them at the bottom is supposed to soften the spring. I tried it for a short while but then reverted to norm'. I cannot recall the ride height effect it had as it was a long time ago.
Alan
Alan Anstead

When I wanted to soften the springs on my frogeye I removed the longer leaves, I tried 2 but found that a bit much so put one back, this was on a 15 leaf set. I removed the longer ones as I felt this would give a more even loading in the leaves, removing the short leaves would increase the bending stress in the leaves near the chassis mounting possibly leading to them yielding.
David Billington

Sorted at last.

One of the main engineering rules I forgot was don't tighten any bolt until you have fitted all the bolts.

But other annoying factors were as follows.

PO overtightening the bolts that go through the rubber bush at the axle end of the spring crushing the bracket slightly. I had to spread one by about 1mm by wedging a bolt inside the bracket with a nut on the inside then unscrewing the nut on the bolt.

PO of the axle I bought had painted with hammerite smooth everywhere including inside the brackets. Filed the paint from inside near the bolt holes and lightly covered in grease.

One of the Toss supplied springs were ever so slightly twisted (or it could have been the rubber bush). Can't be more than 0.5 mm but enough to stop alignment with bolt holes. Un-doing all the spring bolts helped here so I could twist the spring as well as undoing the last spring shackle (the one nearest the axle) which I turned the correct way up at the same time.

That got me the two radius arm bolts in and the RH spring bolt in. The last one was the most difficult as you could put the bolt in from either side but it wouldn't go all the way through due to bolt hole and bush not lining up sufficiently well.

I got the last bolt in using the "lost bolt" method.

So I'm a happy chappie at the moment.

Rob


Rob aka MG Moneypit

I bought springs from the MGOC a few years ago and they were fine, ride height not too high, no wedges needed.

I seem to recall I slightly enlarged the floor hole the pin on the spring goes through. This isn't precision engineering.

Other notes on this process.

Don't tighten anything up until every bolt is a least through where it needs to go and threaded. (Good practice for any job).

If you are fitting new spring clamp plates you'll need to run a tap through the threads, check your bolts turn easily in the threads.

The spring clamp plate bolts should have a taper on the end, if they don't put one on (leaving a nut on the thread to tidy it up afterwards. Again check they still screw in to the clamp plate.

If using new bolts at the spring eye end check they go through the bush, sometimes you have to take the black coating off with some emery paper.
Jeremy Cogman

This thread was discussed between 29/01/2014 and 03/02/2014

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