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by Joske Vermeule, September 1
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Jun 14th, 2026
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Joined: Sep 2011
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Since the rate of the of the two springs combine when they are pressing against each other and then suddenly falls when one of the springs (the rebound spring in our case) is fully unloaded the only way to avoid a falling rate system is to ensure that the rebound spring is free at static ride height.
If you want a stiffer suspension the answer is to increase the rate of the main spring. Those with the Suplex or SSL systems have the option of requesting SSL for a suitable spring from the race kit.
Peter ![[Linked Image]](http://bradley.it/public_images/drive.jpg)
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Joined: Apr 2017
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Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Apr 2017
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Since the rate of the of the two springs combine when they are pressing against each other and then suddenly falls when one of the springs (the rebound spring in our case) is fully unloaded the only way to avoid a falling rate system is to ensure that the rebound spring is free at static ride height.
If you want a stiffer suspension the answer is to increase the rate of the main spring. Those with the Suplex or SSL systems have the option of requesting SSL for a suitable spring from the race kit. Also with the SSL you can adjust the height to get the correct level as the springs settle and the new kingpins loosen up slightly. After a year and 3000 miles my new set up has settled by about 5mm so I will correct that with the adjusters..
Bob
2009 Black Roadster
1999 4/4 2 litre Zetec
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Joined: May 2010
Posts: 9,545 Likes: 132
Needs to Get Out More!
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Needs to Get Out More!
Joined: May 2010
Posts: 9,545 Likes: 132 |
My rebounds are just in contact with the hub and can be rotated when the car is at rest on a level surface. This, to me, is the neutral position when the only loading is from the weight of the car. I also think the upper spring should be neutral (or very close) with perhaps just a hint of compression. In this setup when driving, the springs react from neutral to cope with absorbing travel or releasing as the need arises. By having this neutral, just in contact setting there will be no free play that needs to be overcome before the correct effect is met. Balancing spring rates is important, coupled to suitable pitch of the coils. Very simplified I know but it seems a decent base to work from.
I am tempted by the SSL system for the front but would like to try a car with it first.
Plus Four MY23 Furka Rouge
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Joined: Apr 2017
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Talk Morgan Enthusiast
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Talk Morgan Enthusiast
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The upper main spring has to be in compression to take the static weight of the car.
If the car weighs 800kg i.e about 1800lbs then assuming 50/50 weight distribution there is 900lbs at the front or 450lbs per corner.
If the spring rate was 150lbs/inch for example, that would need 3 inch compression to just take the weight of the car.
Maybe a bit more with your surge inducing "heavy" V8 lump.
Bob
2009 Black Roadster
1999 4/4 2 litre Zetec
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Joined: Jun 2015
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Talk Morgan Expert
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Talk Morgan Expert
Joined: Jun 2015
Posts: 2,093 Likes: 74 |
My rebounds are just in contact with the hub and can be rotated when the car is at rest on a level surface. This, to me, is the neutral position when the only loading is from the weight of the car. I also think the upper spring should be neutral (or very close) with perhaps just a hint of compression. In this setup when driving, the springs react from neutral to cope with absorbing travel or releasing as the need arises. By having this neutral, just in contact setting there will be no free play that needs to be overcome before the correct effect is met. Balancing spring rates is important, coupled to suitable pitch of the coils. Very simplified I know but it seems a decent base to work from.
I am tempted by the SSL system for the front but would like to try a car with it first.
Fully concur with views on rebounds BUT as far as uppers are concerned, isn’t this trying to defy gravity? They have to carry the weight of the front of the car and no matter how strong the spring, or how long or short, it will always be loaded by that weight, so can never be “neutral” like the rebound springs can be. Apologies if I have misunderstood?
Doug
2011 Plus 4 in Rich Maroon
1972 750 “ComDom” sprinter
1958 Triton 650
1992 Triumph Trophy 900
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Maybe a naive observation on my part as I don't pretend to be wholly mechanically minded in this area, but all the comments regarding the optimal setting of the bottom rebound spring seem to be based on user experience rather than technically specified factory data.
Presumably the cars leave the factory with all components set to specified tolerances, clearances etc and further maintenance should aim to maintain these settings unless one chooses to deliberately change them for whatever reason?
Rob T
2017 Tungsten Plus 4
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Joined: Feb 2016
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Needs to Get Out More!
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Needs to Get Out More!
Joined: Feb 2016
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Have you read the article by Peter Ballard linked above Rob?
It may be backed by his user experience but makes sound technical sense.
Interesting also is that he explains how trad Morgan suspension may improve with age on comfort stakes at least, as the springs shorten with use, particularly the longer compression one, lowering ride height but importantly removing any rebound spring pre-load that may have been present, hence softer linear rate over bumps.
Richard
2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone
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Joined: Jul 2011
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Has a lot to Say!
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Has a lot to Say!
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Rob my car came out of the factory new. The set up was a right mess, so I for one would say do not trust the factory to have set the suspension correctly. They rely on the end user to sort it out using their knowledge & or their dealers.
4/4 Ivory 4.1:1 axle, Mercedes A200 AMG
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Talk Morgan Enthusiast
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Talk Morgan Enthusiast
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Posts: 1,799 Likes: 4 |
As I understand it, the factory viewpoint has changed over the years.
In the old days the front suspension was set with both springs in compression with the consequent falling rate effect. That's just the way it was then.
What I don't know is if the factory now sets the front up as we describe it or do they still use the old set up.
And if they did adopt the new set up, when?
Bob
2009 Black Roadster
1999 4/4 2 litre Zetec
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Joined: Dec 2008
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Roadster Guru Member of the Inner Circle
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Roadster Guru Member of the Inner Circle
Joined: Dec 2008
Posts: 22,366 Likes: 354 |
The front spring rates have changed a few times over the years. The 2016 set up was with SSL springs.
The 2005 set up was with Eibach.
Peter Mulberry has all the rates in his head.
The 2016 suspension is very well resolved. So much so that I've kept the standard Spax and not even thought about changing them yet.
The rears have changed from six leaves in 2005 to four leaves now. The change was around 2012, which was when the weak leaf spring period occurred.
I can only comment on the cars I've had!
On my Plus 4 there's about 5mm compression on the rebounds. It doesn't bother me as 5mm is a tiny amount. Had there been more thread on the base of the kingpin I'd have added spacers under the plate to eliminate it, but there isn't really enough thread.
DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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