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MG MGB Technical - leaf spring 7 or 6 leaf ?

Replacing rear leafs on a 67' roadster, some recommend using the 7 leaf to replace the supposedly quickly sagging 6 leafs. Any experience or recommendations, good or bad idea ?
Thanks,
T. Murphy
T. Murphy

Forgot : The recommendation with the 7 leafs is to use 1 1/4" lower blocks
T. Murphy

Hello
ive been using 7 leaf gt spring on two cars for over 12yrs now with no sagging at all.
the car its level instead of ar*e sagging and is very slightly harder ride

ste


Ste Brown

Ste, did you also use the lowering blocks?
Thanks,
T. Murphy
T. Murphy

Depends on the weight of the occupants and your personal preferences as far as ride goes. The rubber bumper roadster initially had the GT springs, but reverted to one less leaf after about a year. They have a loading of about 60lb more, and do give a harsher ride. I don't subscribe to the 'harder the better' view, ironically one of the things the V8 was criticised for was having too hard a ride, it has springs 40lb 'heavier' than the 4-cylinder GT. I did raise the rear height of mine as I was fed up with bottoming and grounding when touring fully loaded, but did so with extended shackles to replace the harder springs as I really didn't like the ride.
Paul Hunt 2

Don't put too stiff of a rear spring on an MGB. You end up with a jumpy rear end. Even the Works competition cars used soft rear springs.
Steve Simmons

Thanks for your feedback --- 6 leaf original spring it is.
T. Murphy

Depends on what you use your car for. We use our 63 roadster for touring, often long runs with lots of luggage. It has been on GT springs for 5 years now, and sits nice and level. The rear end felt a bit restless, but after I replaced the shock absorbers with new standard lever arm units that has disappeared completely. I dont mind a little harder ride, but then I also have a 61 midget... Will never revert to standard roadster springs again.

If you want to maximize roadholding, soft rear/stiff front is probably the way to go. But be prepared to change the rear springs again in two or three years time.

Tore


Tore

I think if I was ever replacing my springs, I'd be going down the route of fitting parabolic springs instead. I hear theyre the bogs dollocks, and make the ride much more forgiving without sacrificing handling.
Ross Kelly

6 versus 7 leaves has nothing to do with ride height. It's only stiffness. Modern replacement springs are typically not made correctly so you sometimes get a higher ride height than planned.
Steve Simmons

7 leaves compared to 6 *does* result in a higher ride height precisely because they are stiffer - the car doesn't settle as much under its own weight, even if that is not the intended result. Stiffer 6-leaf springs i.e. rubber bumper roadster springs on a chrome bumper roadster will have a similar effect. That is why I rejected the stiffer spring approach to getting a slightly higher ride height at the rear and went for extended shackles instead.
Paul Hunt 2

Stiffness and rid height don't always go hand in hand. It depends on the arc of the leaves. A stiffer spring with slightly less arc will put the car at the same height as a softer spring with a greater arc.

Of course we're at the mercy of the cheap springs on the market these days, unless you can find a local spring shop to make up a set for you to the proper specification. These shops are unfortunately becoming harder to find.
Steve Simmons

I'm talking about the standard springs available from the usual suspects - move a given spring between cars of different weights and the stiffer spring intended for the heavier car will give a higher ride height *and* a harder ride on the lighter car. When talking about different springs for a given car yes you can make them do anything you want.
Paul Hunt 2

Picking up on the responses from Paul and Steve, can I ask a subsidiary question? I've just installed longer shackles at the back of my 73 BGT;exactly as described by Paul, to create 3.75" shackles, and gain 1" in ride height. Measurement from centre of rim to bottom of chrome strip is now 15" at the rear. Question is, if I now installed rubber bumper springs, would I gain another(say)half inch in ride height? Any advice gratefully received. Regards, John.
J.P. Hall

You will *gain* exactly the same amount as with changing springs using standard shackles, it's just that the final ride height will now be 'original' plus that from the extended shackles plus that from the harder springs.

Are you a fan of the 'submissive monkey' (i.e. a*se in the air) stance :o)

As to how much you will gain from the change of springs it all depends on the condition of the old and the spec of the new. If the old ones have sagged a lot you will gain more than if they haven't. But the biggest difference is going to be down to just what new springs you fit, there are some very hard ones out there, so much so that people can't get the rebound straps fitted using just the weight of the car.
Paul Hunt 2

Thanks Paul - no, I'm not into monkeys;I reckon the car is sitting almost perfectly now, at 15" rear and 14 1/2 at the front. I just wondered whether I should seek perfection, but I think not - I'm really happy where it is now. Also, you may recall from a previous thread, that my initial reason for raising the back, was that on the passenger side rear, the tyre was rubbing the rim at certain bends,bumps etc.? well, the longer shackles have taken the tyre nicely away from the rim, AND I've managed to pry the rear axle over to centre while (at the same time) doing up all the spring bolts etc., resulting in the rear axle now being only 1mm off centre. Terrific result! - so thanks again for your input re. the spring shackles - and thanks to T.Murphy for letting me pinch a bit of your thread! Kind regards, John.
J.P. Hall

This thread was discussed between 15/04/2008 and 25/04/2008

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