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MG MGB Technical - Lowering Rear Springs

The rear of my 1974 CB roadster is quite high. 61cm ground to wheel arch lip.

While I know one can buy lowering block kits, I am thinking about lowering the the springs by turning over one or more of the leaves. I thought I would start with the second, counting from the top.

My assumption is that once the leaf that has been turned over has come to an equilibrium with its neighbours the spring rate will be similar to before as each individual leaf should have the same resistance to bending in either direction.

Does anyone have experiance of doing this? and what was the result?

Thanks

David
David Witham

Don't mean to take all your fun away from you but couldn't you just buy the lowered springs from Moss? They come in 1inch and 2inch (lowered) versions so i believe and seem a darn sight easier than mucking about reversing leaf directions...!

Just a thought ~PHIL
Phil

Phil,

Once you have the springs off the car all you have to do is slip off the clips and undo the bolt through the centre. Then you turn the leaf over and reverse the process. 15 minutes per spring I would say and free.

If you look at the specs of leaf springs you will see them quoted as minus one inch etc. but unlike front springs Moss will not commit themselves to what the resulting ride height is because they don't want to commit themselves on the standard springs.

David
David Witham

An old hot rodding trick in the US (not used so much on these little cars) is called reversing the spring eye. The upper leaf if the spring is removed, and the arc reversed (essentially de-arching until there is zero arc, then continuing into a negative arc until the arc radius matches the original arc but on the opposite side. (yes, I've donr a poor jiob of explaining this)

Why do this rather than flip the second leaf as you've suggested? IIRC the second leaf has an arc smiliar to the fist and third leaf, so it's impact is additive in a negative direction. It will always fight the third leaf and only support the first leaf where it's pulled up tight. You'll end up softening the spring.

By reversing the spring eye, you lower the car the diameter of the spring eye (about 5 cm by my non-metric eyeball). The spring rate stays the same.

Any good leaf spring shop (I use a blacksmith in, of all places, downtown Santa Ana California) should be ablt to accomodate this simple change
Greg Fast

The rear was done using a little of my own imagination as follows. I have before converted the rear to gas shocks.
Out of old spring cut one to the size of bottom spring (not small support plate).
Disassembled the spring assembly and inserted this made spring upsidedown on top of top spring. Added bottom support plated on top of that and re bolted the lot together.
Result is a little flatter spring assembly. Added new nylon top & bottom insulators and re fitted the whole lot back to the car.
Rear height from 360mm to 335mm and front down to 330mm (with cut coils) - nice!
. . . . . henry
H O

David,
I did this on race car and I am quite pleased with the results but I turned over number three as number two is as long as the top spring and would not fit. Your springs maybe different.
Leland Bradley

of course you could always wait a few more years and they will de-arch themselves. The springs on my 69 B are begining to arch in the opposite direction. Have helper springs on the rear of the springs which helps a little. Because of the helpers they look more like a sideways "S" that has been streched! You only have a few more years to go.
Robert

Where did you get the helper springs from? I changed mine because I thought they were knackered, but the new ones aren't much better. No problem with local driving but fully laden on touring holidays makes it very low and bottom out on bumps. I've seen helpers on another car at a garage but they didn't know where they came from.
Paul Hunt

I had trouble when I'd have to haul heads or cranks back from the machine shop with my B. The helpers just helped break the old springs faster. So for the B I'd take camping and parts hunting, I put a set of GT springs on...the spring shop made me GT spec. springs and I used the shorter mounting hardware. This seemed to work good for a heavily loaded B...but I wouldn't autocross the car that way.
James H.

Paul

I seem to recall something combining Doug at British Automotive and helper springs, although i think specifically the application was for the carbon springs and tube shocks....

Obviously this may not be right for your set up, but a speculative email maynot go amiss..?

http://mgbmga.com

And email him from there!

Regards


~PHIL
Phil

Thanks Phil.

I've tried rubber bumper roadster in the springs in an attempt to solve a different problem. The ride-height was only slightly higher unladen and it didn't sag when fully laden, but they gave a very harsh ride over some surfaces so I went back to the standard ones.
Paul Hunt

I have not a clue where my helpers came from. They have been on the car for at least 10 years. It is time to do alot of restoration on the car which will require the springs to be replaced- so the helpers will go into the attic. But at this point I am scared to take them off of the car, the springs would no doubt invert themselves.
Robert

Someone on this BBS has mentioned using tube air shocks intended for a '70s VW on his GT for the occasional parts hauling duty. They have a built in balloon-type device that you just pressurize to restore your ride-height when the car is laden. The '72 VW Type-1 has rear shocks of approximately the right range (10.5"-16.125"), and both Monroe (MA803 - Max-Air) and Gabriel (39507 - HiJackers) are still available. For a car which has been lowered in the rear, '83 Corvette shocks be a better fit (Monroe MA785) since they are shorter (9.5"-14") than the VW shocks.
~Jerry
Jerry Causey

This thread was discussed between 24/04/2003 and 28/04/2003

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