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Wales
by Joske Vermeule, September 1
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Forums39
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Jun 14th, 2026
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Joined: Sep 2009
Posts: 7,435 Likes: 122
Talk Morgan Guru
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Talk Morgan Guru
Joined: Sep 2009
Posts: 7,435 Likes: 122 |
It's not just about bump and rebound. It's also about cornering and roll stiffness.
As you turn a corner the outside wheel loads up against the main spring and the unloading of the inside wheel is controlled by the rebound spring.
If you remove the rebound spring, there is nothing to control that unloading and that side of the car would just continue to lift until it runs out of space as the stub axle impacts the bottom crosshead bracket. This will give you no roll stiffness control and a horribly wallowy feel as you turn in.
If it's just a case of too short a rebound spring you will initially have very poor control of the roll stiffness until the inside jacks up a bit and then the stub axle contacts the short rebound spring to give you back a degree of very belated roll stiffness. Not as bad as no rebound spring but still a very wallowy turn in..
The solution is to use perfectly matched bump and rebound springs with the rebound spring just kissing the stub axle at rest.
As said before, read the Peter Ballard article and take time to assimilate it because it's not immediately obvious. Or at least it wasn't to me. Very well put👍
'14 4/4 graphite grey
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Joined: Apr 2008
Posts: 12,268 Likes: 324
Scruffy Oik Member of the Inner Circle
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Scruffy Oik Member of the Inner Circle
Joined: Apr 2008
Posts: 12,268 Likes: 324 |
The solution is to use perfectly matched bump and rebound springs with the rebound spring just kissing the stub axle at rest.
And this is what the SSL kit gives you, with its adjustable spring seats.
Tim H.
1986 4/4 VVTi Sport, 2002 LR Defender, 2022 Mini Cooper SE
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Joined: Aug 2017
Posts: 504 Likes: 2
Talk Morgan Regular
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OP
Talk Morgan Regular
Joined: Aug 2017
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Thanks all for comments. I can assure you I have no intention to remove the rebounds, but I do feel satisfaction with understanding the system and why the different components are there for. Seems like cutting (the lower end, I have been told) of the rebound is a good and cheap idea, so now I have to investigate how to get them off in the easiest way. The SSL kit would be nice, but a little pricey. The video recommended was very illustrative, and also Mr. Ballards article. I have read it before, at an earlier stage of my morbus morganensis. Now it has gotten more serious, and I understand more...
Robbie the Norseman
2004 V6 Roadster
Sherwood green
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Joined: May 2012
Posts: 1,521 Likes: 61
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: May 2012
Posts: 1,521 Likes: 61 |
Robbie,
There is another issue to consider regarding pre-load.
Over time and many miles the main spring may lose some of it's initial spring and length, so nullifying any initial pre load.
If you were to shorten the lower spring, then later on in the life of the assembly you might find that it becomes sloppy with free play and require the lower spring to be replaced.
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Joined: Sep 2014
Posts: 2,272 Likes: 7
Talk Morgan Expert
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Talk Morgan Expert
Joined: Sep 2014
Posts: 2,272 Likes: 7 |
Robbie,
There is another issue to consider regarding pre-load.
Over time and many miles the main spring may lose some of it's initial spring and length, so nullifying any initial pre load.
Another reason to use the SSL kit with its adjustable spring seats , you can adjust the pre-load simply and quickly without dismantling the front suspension to renew springs.
Andy G
1999 +8 , Indigo Blue.
Ex-John McKecknie/Mike Duncan 1955 +4 racer.
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Joined: Oct 2011
Posts: 3,565 Likes: 14
Talk Morgan Addict
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Talk Morgan Addict
Joined: Oct 2011
Posts: 3,565 Likes: 14 |
Robbie,
There is another issue to consider regarding pre-load.
Over time and many miles the main spring may lose some of it's initial spring and length, so nullifying any initial pre load.
If you were to shorten the lower spring, then later on in the life of the assembly you might find that it becomes sloppy with free play and require the lower spring to be replaced. If this were to happen, would it not be possible just to insert a spacer of some sort below the rebound spring, until it just kisses the stub axle collar? Easier than buying a pair of new rebound springs with the hassle of installation etc surely?
Paul
[At last, I have a car I can polish]
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Joined: Dec 2011
Posts: 381
Learner Plates Off!
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Learner Plates Off!
Joined: Dec 2011
Posts: 381 |
Depending on your car, the rebound spring may be free or not at static state. On my PLUS 4 2005 the rebound spring was not free.
In this case the stiffness of the suspension was very hard on small bump and after becomes soft on big bump, the opposite of a conventional suspension.
When the rebound spring is not free at static state, the gobal stiffness of the suspension is the sum of the both spring stiffness and determines the static height of the car. If you cut the rebound spring and get it free, the stiffness will be lower because only the main spring acts and you may get a lower static height.
I have installed the SSL front kit, in this case you can preload the main spring like in the conventional cars and get a free rebound spring. The suspension on small bumps is soft and increasing stiffness on bigger bump. You get quite a conventional suspension.
During the assembly with the SSL kit the global preload of the springs is lower, preload being adjusted and increased after assembly. Assembly is easier, main spring being free at the beginning.
Last edited by CBY; 27/09/18 11:12 AM.
Regards
2005 PLUS 4
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Joined: Dec 2008
Posts: 22,371 Likes: 354
Roadster Guru Member of the Inner Circle
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Roadster Guru Member of the Inner Circle
Joined: Dec 2008
Posts: 22,371 Likes: 354 |
Robbie,
There is another issue to consider regarding pre-load.
Over time and many miles the main spring may lose some of it's initial spring and length, so nullifying any initial pre load.
If you were to shorten the lower spring, then later on in the life of the assembly you might find that it becomes sloppy with free play and require the lower spring to be replaced. If this were to happen, would it not be possible just to insert a spacer of some sort below the rebound spring, until it just kisses the stub axle collar? Easier than buying a pair of new rebound springs with the hassle of installation etc surely? This ^^^ is something I intend to look at when I fit Mulfab bearings to my Plus 4 over winter. I'll take some measurements when I dismantle of static loaded length and free spring length. There's an element of possible adjustment by using shims. One at the top of the kingpin so that the kingpin to bottom plate fixing is unaltered, and a U plate shim at the bottom to lower the rebound spring seating. In theory I reckon 5 or 6mm adjustment is possible, but I'll have to make the U spacers and look at the logistics.
DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Joined: Dec 2011
Posts: 1,943
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Dec 2011
Posts: 1,943 |
I was talking to a Morgan Racer the other day. "Bill, I do not expect Morgan handling to conform to Me. I make every effort to get the best performance as it is, not as I wish it was. I have raced against too many other Marques to not know that Morgan handling is very good and I am competitive against them."
Button
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Joined: Mar 2009
Posts: 3,830 Likes: 69
Talk Morgan Addict
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Talk Morgan Addict
Joined: Mar 2009
Posts: 3,830 Likes: 69 |
Depending on your car, the rebound spring may be free or not at static state. On my PLUS 4 2005 the rebound spring was not free.
In this case the stiffness of the suspension was very hard on small bump and after becomes soft on big bump, the opposite of a conventional suspension.
When the rebound spring is not free at static state, the gobal stiffness of the suspension is the sum of the both spring stiffness and determines the static height of the car. If you cut the rebound spring and get it free, the stiffness will be lower because only the main spring acts and you may get a lower static height.
I have installed the SSL front kit, in this case you can preload the main spring like in the conventional cars and get a free rebound spring. The suspension on small bumps is soft and increasing stiffness on bigger bump. You get quite a conventional suspension.
During the assembly with the SSL kit the global preload of the springs is lower, preload being adjusted and increased after assembly. Assembly is easier, main spring being free at the beginning. Surely if you cut the lower spring if it's not free you might find the static height higher? Nick
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