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MG MGB Technical - MGB rear leaf springs question

Hello all.
I know there's a lot of complaints about cheaply made springs which jack the back of the car too high. I was told when I bought mine 7 years ago to give them time to settle. Well, they still haven't settled. The sticker on them says "Made in England by British Springs Unlimited" I thought it was only the far east ones that were too arched. Anyway, my question is this: With no load on the suspension, and my car turned upside down on a rotisserie (which it is at the moment), shouldn't there be some slack on the rebound straps? I recently rebuilt the rear end and found it tough to reassemble due to the stiffness of the springs. Should I live with this, or take my chances on another pair? Have them "re-arched"???

Help

Scott
Scott

Scott. It would be useful to know the year and type of your car. The roadster and the GT used different springs and the cb and rb cars used different rebound straps. Thus, hard to say what is happening because we do not know if the correct parts have been assembled.

Generally speaking, when the correct rebound springs are used with the correct vehicle, you will see an S or a J curve to the rebound straps--they will not be tight. But, this applies when the full weight of the body is sitting on the springs with either the wheels on the ground or jack stands under the rear end. The rear end weighs a lot less than the rear half of the body and it is possible that, turned upside down, the force of the spring might be sufficient to cause the rebound strap to be at its full extension.

Les
Les Bengtson

Well Les,Who would you advise purchasing a set of rear springs from?
rich osterhout

Sorry about that. Car is a 1970 roadster. Springs were ordered from Victria British and the part numbers were correct for application as I recall. I would love to have the car sit about an inch lower, but don't want to resort to spacer blocks. I,ve tried 6 months with 200 plus pounds of bricks in the trunk, to no avail.
Scott Wooley

Scott.

What is the dimension from the centre of the wheel to the bottom of the side trim.

Paul's excellent site

http://www.mgb-stuff.org.uk/ride.htm#rideheight

should give you an idea how your car compares with others.

Dave

D M Tetlow

"British Springs Unlimited" isn't the name of the company that used to make them to OE spec in the UK, unless you have read 'Limited' as 'Unlimited'.

The springs are designed to be about half compressed with the weight of a fully finished car on them. If you have the car upside down I wouldn't expect the springs to be compressed at all, hence the rebound strap will be under tension. The axle (which is the only weight on the springs) weighs a helluva lot less than the car!

With a fully fitted-out car on its wheels you should see a distinct curve to the rebound straps, the springs should be nearly flat, and the lower pivot of the shackles should be behind the upper pivot. I've heard it said that the shackle can lock under the chassis rail in the fully forward position and give a very high stance. I'd say that was impossible on a chrome bumper given the position of the upper pivot, and even on a rubber bumper with its lower pivot I had no problems getting the shackle to pivot backwards as I jacked up the spring to attach the U-bolts and rebound strap, and once you have got that far it can't lock.

There have been many complaints of the rears being over-arched or too hard over the years, originally from America, more recently from the UK as well, when America seemed to be getting better stock. I've bought three sets of OE-spec springs over the years from various suppliers and had no problems with them being too high, in fact on the roadster as we do quite a bit of touring fully loaded I had to extend the shackles by about an inch to stop grounding and bottoming.

British Springs has ceased trading and there is currently no other manufacturer of *guaranteed* OE spec springs in the UK, at least. Unless you can find a supplier with old stock from British Springs the chances of getting good ones is pretty minimal, until the suppliers can work with a manufacturer to build, test and finesse the full range again, which is going to take quite some time, money and effort.
Paul Hunt

It's not unknown for an operative" to pack the wrong items. Early roadsters had 5 leaf springs, later had 6 and I think GT's had an extra leaf, making 6 and 7. There must be a someone over there who can re-set them for you.
Allan

Thanks for your comments.
The sticker does in fact say British Springs Limited, my apologies. After thinking about it for awhile, I guess it makes sense that they would be on the rebound strap with so little weight on them. When the car was loaded and on the ground, the measurement from the center of the hubcap to the bottom of the chrome strip was 15 1/2". They look like well made springs, but they are just a bit stiff. I'll count the leafs when I get home and make sure they are correct. Does anybody know what's involved with having a spring re-arched? Does this have to be done on the car, or are can the desired distance I would like to have the car lowered be calculated on a set of springs brought to a spring "specialist"? The loaded springs on my car are most definitely not flat unless I add significant weight to the trunk.

Scott
Scott Wooley

I believe John Twist has springs for the MGB. Would be worth contacting him.

Larry
Lawrence Hallanger

Re-arching is definitely done off-car (unless you load up the boot with paving slabs and go and find some sleeping policemen) and almost certainly involves dismantling and dealing with each leaf individually, which is how the factory arched them in the first place, with a combination of bending and heat. As well as the different numbers of leaves for roadster and GT the leaves themselves changed over the years. Some people reverse one of the leaves which makes for a flatter spring, including reversing the main leaf which puts the eyes on the other side, but that is more for lowering a rubber bumper car to chrome levels, I think. 15 1/2" is definitely rubber bumper territory, chrome bumper should be around 14" to 14.5". Rubber bumper springs were a bit harder but by far the majority of the extra ride height came from lowered mounting positions on the chassis rails, so your springs are definitely incorrect. Note that they could be too hard, or too arched, or both.
Paul Hunt

You could fit reverse eye springs.

I did this and brought my ride height down by 2 1/2".

I have a rubber bumper 75 with chrome bumpers fitted.

After she had settled I bought some of the nylon type rebound straps made to the dimension I needed.

Dave
D M Tetlow

After seeing this post, I went home and measured the distance from the center of the wheel to the bottom of the stainless trim on my '72 roadster, and found 14.25" on the right rear, and 13.75 on the left rear. I seem to remember something reading something a few years ago about a 3/4" difference like this, has anyone else seen that on their cars? Is it worth considering changing out the springs? (original, with new bushings), or might the cause of the difference be a twist in the body that shows up this way?
Joe

Generally you change springs when they sag too much or the top leaf cracks at the hole.
A good remedy for an over-arched new spring is to combine old and new leafs (leaves ?)It is not difficult to undo the clips. I did this on my "A" - new VB springs. used only the new top leafs.
Art Pearse

The 3/4" difference that is commonly quoted is in tyre clearance to arch i.e. position of axle in the body, not ride height. The drivers side commonly sags, simply because most cars usually do most miles with only the driver in them. Also Abingdon only allowed 150lb per person, how many of us weigh that or less today?
Paul Hunt

Scott
If you want your car to sit lower take your springs out and take them to the spring people and tell them how much you want them flattened by and they will do it. Ask a few of the truckies around your area where the best place to go is- They will know who to stay away from etc. Cheers Willy
WilliamRevit

Hi Guys

A quick neat trick is to take the bottom leaf or two and place on top thus having the effect of spacer blocks at no cost. Also makes the springing a tad softer.
I did this on my racing A without any problems and to my knowledge has done many thousands of miles with this set up.
I assume the B spring has a similar format of the leafs within the spring.

Worth a try.

Mark
Mark Dollimore

Mark

I did that a couple of years ago with my new springs and now I need to remove them and put the leaves in the right place because the rear is too soft and bottoms out too easily.
Ian Buckley

This thread was discussed between 24/02/2009 and 14/03/2009

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