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MG Midget and Sprite Technical - Quarter elliptic springs

Hi all,
I would be very grateful for any advice regarding the refurbishment of a pair of old, original (I think), 15 leaf quarter elliptic leaf springs.
I obtained these some time ago when pulling together bits for my 1960 frogeye rebuild.

Considering their age the springs look in pretty good condition, and I am hopeful they will not sag when I fit them in due course.

Although the rear bushes in the springs look ok, I will replace them as a matter of course.
I did wonder if there was any particular benefit in using polybushes rather than the standard rubber bush?

Also is there any trick to getting them out, or is it just a matter undoing the rear clamp and putting some pressure on them using a vice. It does look as though the bushes are held pretty tightly by the last curled over leaf.

Finally, is it worth separating the 15 leaves and coating them with copper grease before rebuilding them, or will this stop the springs working effectively?

Any help or advice greatly appreciated.
Many thanks
Phil
P J Dent

Phil

You cannot really refurbish springs. They are either "tired" or not. I guess you could try and compare them with new springs and see if there is any undue deflection present, but even then, the condition of the springs may not manifest themselves until out on the road. Personally, if they appear to be in good nick, I would fit them, but do check beforehand for any obvious cracks etc.

Polybushing - yes a sound idea. Polybushing removes much of the lateral movement in the bush, lasts longer and stiffens things up a bit, all leading to improved cornering ability. Most folk seem to recommend it, and I certainly do.

Removal of original bushes is pretty easy with a socket set and a vice. Find a socket that fits inside the spring eye and place next to bush. On the other side of the eye, find a socket that fits onto outside of eye, but has an inner diameter that will accommodate the bush. Put spring and sockets in a vice and turn. Should pop out reasonably easily. Bit of penetrating fluid/soapy water sometimes helps.

Personally I would not disassemble the spring - it will be swine to get back if nothing else. Cannot think a coating of copper grease would do it any harm, but I would use Dinitrol or similar just because it adheres so much better and is more searching - ie better finds its way into any possible water traps.
Oggers

Phil
To release the springs you have to undo the u-clamp nuts and then undo the two bolts about six inches forward under the car in the strengthening plate. The spring has to be tilted and lifted as the bolt head of the bolt securing the leaves also acts as a locating pin in that strengthening plate. A top plate will come out with the spring. You'll understand the construction when it comes out.

Polybush v rubber. I have pollybush on one car and rubber on the other. Modern rubber is not what it used to be so I chose poly for longevity.

To grease or not to grease has been an arguement for many years. I use molygrease between the leaves. In times of old some used old engine oil.

It can assist assembly if you can put a lead on the two long bolts that go through the spring on reassembly and clean the receiving threads with a tap.

Once reasembled I sometimes run a 3/8 drill down the assembled bolt holes to clear a path for the bolts.

If you decide that your springs are not suitable any more and buy new ones then those available from Moss will require wedges from the likes of Peter May Eng. otherwise your Frog will look like a Hot Rod with its backside in the air.

Alan
Alan Anstead

if they are tired and saggy you can have then professionally rebuilt - if you can find a spring manufacturer to take it on. They would be disassembled and re-tempered to restore the correct curve and 'springiness'.
David Smith

Thanks for the comments everyone...very useful and just what I need to give me confidence.

I've compared the curvature of these old 15 leaf springs with a pair of heavy duty, quarter elliptics with 11 leaves (including the curled over ones at the end). The curvature seems about the same, so I hope that having more but thinner leaves, will allow the spring to settle to a reasonable ride height. I would rather not use Peter May wedges unless I really have to.

It is interesting that the leaves in the 15 leaf springs do not all seem to have the same thickness. I wonder if that is by accident or design!!

None of the leaves seem to be broken, but I can see a little corrosion between some of them. This really needs cleaning out so I will try and carefully take them apart, clean them up, grease and reassemble.

I asked about greasing the leaves as I wondered if the friction between the leaves on bending might have an impact on the deflection??

Anyway, we will see once the car gets on the road....it could be some time yet!!

Many thanks
Phil

ps Alan....do you have any of your impressive clutch release bearings left??
P J Dent

Phil
Shh.........
E-mail me.
Alan
Alan Anstead

Old pre-war cars often had heavily greased springs that were then wrapped to keep the grease in and the dirt out. Posh cars used leather spring gaitors, cheaper cars used something akin to Denso tape. The thought was that grease lubricated the spring, but also trapped grit which caused rapid wear where the leaves moved against each other. So you may want to think twice about greasing them, although there is no reason they shouldn't be wrapped if you do use grease.
Guyw

New steel is affected by grease and oil - the old prewar steel wasnt. Tape on the springs stiffens them.

I put new AH Spares springs on the OH's frog and it looks grim - too high, so I need to sort that :(
mog

Mog,

Why do you say that new steel is effected by grease and oil whereas pre-war steel wasn't? I can't think of any way in which a hydrocarbon would effect the steel of a spring at the temperatures they run at and the technology for controlling the steel composition has increased dramatically from pre-war days. I have been involved in writing software for the analysis of iron/steel melts and other alloys and the speed and accuracy at which it can be done these days far surpasses that of pre-war technology.
David Billington

Mog,
it isn't the grease on the steel that is the problem - its the grit that it holds and acts like a grinding paste, especially at the ends of the shorter leaves where they contact the adjacent longer one. After a while they wear a step in the spring which can then give rise to a fracture point.

Wrapping can be done to stiffen the springs by binding tightly. If wrapping just to keep dirt out it needs to be done more loosely. It sounds like you overdid the tension a bit!
Guyw

https://www.eatondetroitspring.com/greasebetweenleaves/

I am no metalurgist, but this topic and url was mentioned on a pre war car forum a while back.
mog

Phil - I just looked it up, and the original springs had ten leaves at 1/8" and 5 leaves at 5/32".
Nick and Cherry Scoop

Well that was fun!!!

Never done this before, but with trepidation just stripped down the first of the 15 leaf springs.

It became absolutely clear as I was peeling the leaves off that the lower leaves are the thickest exactly as Nick says.

The leaves had some scaly rust on the inside surfaces, but it wasn't extensive and didn't look too bad so I'm hoping that this won't affect their springyness! The leaves look pretty good now they've been wire brushed, not quite as they would have been new, but not bad considering their age.
I appreciate that the springs might have lost some of their temper but we'll see, and I am optimistic!
I shall definitely coat the springs to prevent further rusting before reassembling.

The most difficult bit was removing the bush.
Firstly I was worried that my bench vice jaws would not open wide enough to fit the spring and sockets I was going to use to press it out.
After getting a couple of sockets lightly jammed, I found that an eleven sixteenth AF socket was good for the driving end.
At the other end, a piece of open ended steel pipe turned out to be the best solution for me.
I found a length of old mild steel water pipe which seemed to have the perfect dimensions, and I cut a length off, just longer than the bush length.

For those looking to do this in the future, the cut pipe was about 34mm outside dia. and 27mm internal dia., lemgth 50 mm.
It worked for me!!

Anyway, just waiting for the new bearings to turn up, and then I'll start the reassembly.
Hopefully it won't be too challenging and I hope it's all worth it in the end!!
Phil
P J Dent

I have replaced rear springs 3 times over the years. Each time the car sat much higher at the back but settled fairly quickly. I never needed to wedge the springs. I always thought that lubricating them would reduce their damping effect and upset the handling, so I never have.
L B Rose

This thread was discussed between 29/06/2016 and 30/06/2016

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