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#520917 - 06/07/18 12:22 PM Re: series 1 Roadster sump damage [Re: DaveW]
SimonH Online   content
Talk Morgan Regular

Registered: 23/02/10
Posts: 574
Originally Posted By DaveW
The oil pick up isn't modified although I would be very tempted by an even shallower sump with a shortened pick up.

The Mulberry bearings will lift the front slightly if you retain the original springs. More lift if you dont have the factory bearings.

And spacing the engine mountings gains a few mm.


The Mulberry Bearings wont lift the front up if you retain the the factory springs....

The rebound springs are stiffer than the main springs by about 3-1, so all you will do is compress the main spring further, adding to the preload and the ride will get worse....
You'd need to cut down the rebound springs to raise the ride height, and remember they really shouldn't be touching the stub axle housing at ride height

Simon @ SiFab.co.uk

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#520937 - 06/07/18 02:24 PM Re: series 1 Roadster sump damage [Re: Ray from Brighto]
DaveW Offline
Roadster Guru
Member of the Inner Circle

Registered: 11/12/08
Posts: 15578
Loc: South Yorkshire
That's interesting Simon, because for my Roadster, Peter recommended a shorter reduced rate spring to retain the ride height, which replaced the original Plus 8 spec springs and damper blades..

When I did Bumble I just swapped the factory bearings for the Mulfab bearings. I didn't measure the difference........!
_________________________
DaveW
2005 Corsa Red Roadster S1
2016 Saffron Yellow (Narrow) Plus 4

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#520946 - 06/07/18 03:46 PM Re: series 1 Roadster sump damage [Re: DaveW]
SimonH Online   content
Talk Morgan Regular

Registered: 23/02/10
Posts: 574
Originally Posted By DaveW
That's interesting Simon, because for my Roadster, Peter recommended a shorter reduced rate spring to retain the ride height, which replaced the original Plus 8 spec springs and damper blades..

When I did Bumble I just swapped the factory bearings for the Mulfab bearings. I didn't measure the difference........!


It's only a shorter spring, the rate is the same @ 140lb/in

Simon @ SiFab.co.uk

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#520948 - 06/07/18 03:46 PM Re: series 1 Roadster sump damage [Re: Ray from Brighto]
DaveW Offline
Roadster Guru
Member of the Inner Circle

Registered: 11/12/08
Posts: 15578
Loc: South Yorkshire
Ah OK.
_________________________
DaveW
2005 Corsa Red Roadster S1
2016 Saffron Yellow (Narrow) Plus 4

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#521158 - 08/07/18 10:02 AM Re: series 1 Roadster sump damage [Re: Ray from Brighto]
CBY Offline
L - Learner Plates On

Registered: 20/12/11
Posts: 242
Loc: South West France
One comment:

when you cut down a spring you increase its stiffness and when the rebound spring gets compressed the total stiffness (main spring + rebound spring) will be higher and the rebound travel shorter.

If you have a clearance at static ride height for the rebound spring the stiffness is only due to the main spring and is lower.

If there is no clearance, both springs being compressed, the preload doesn't change the stiffness but only the ride height and the point where the rebound spring becomes free.

SSL front suspension kit solves the problem by adjusting the preload of the main spring independently of the rebound spring
which is free at static ride height.
_________________________
Regards
2005 PLUS 4

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#521179 - 08/07/18 11:35 AM Re: series 1 Roadster sump damage [Re: Ray from Brighto]
sospan Offline
Charter Member

Registered: 31/05/10
Posts: 5188
Loc: Llanelli
The accepted advice is that the rebound spring, when car at rest, should JUST be rotatable by hand, I.e. neutral/no compression or gap. When you next look underneath try the hand test and watch how the spring compresses as you jack the car up. The weight of the wheel/hub plus some push from the main spring combine.
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Red Plus8

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#521793 - 11/07/18 06:08 PM Re: series 1 Roadster sump damage [Re: SimonH]
CBY Offline
L - Learner Plates On

Registered: 20/12/11
Posts: 242
Loc: South West France
Originally Posted By SimonH

You'd need to cut down the rebound springs to raise the ride height, and remember they really shouldn't be touching the stub axle housing at ride height

Simon @ SiFab.co.uk


The problem is to know how many coils to cut, depending on the suspended wheight on the wheel and the stiffness of the main spring.
When you cut a spring the initial closed end becomes an open end which is not optimal in term of surface contact.
_________________________
Regards
2005 PLUS 4

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#521802 - 11/07/18 06:37 PM Re: series 1 Roadster sump damage [Re: CBY]
SimonH Online   content
Talk Morgan Regular

Registered: 23/02/10
Posts: 574
Originally Posted By CBY
Originally Posted By SimonH

You'd need to cut down the rebound springs to raise the ride height, and remember they really shouldn't be touching the stub axle housing at ride height

Simon @ SiFab.co.uk


The problem is to know how many coils to cut, depending on the suspended wheight on the wheel and the stiffness of the main spring.
When you cut a spring the initial closed end becomes an open end which is not optimal in term of surface contact.


Yup, entirely correct
I didn't say it was a good idea......
Not least because the spring rate changes if you remove coils

One day I'll finish getting the double wishbone Trad Mog kit production ready and at a reasonable price

Simon @ SiFab.co.uk

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#521843 - 11/07/18 10:27 PM Re: series 1 Roadster sump damage [Re: CBY]
IvorMog Offline

Learner Plates Off!

Registered: 17/04/17
Posts: 270
Loc: Staffordshire
Originally Posted By CBY
One comment:

when you cut down a spring you increase its stiffness and when the rebound spring gets compressed the total stiffness (main spring + rebound spring) will be higher and the rebound travel shorter.

If you have a clearance at static ride height for the rebound spring the stiffness is only due to the main spring and is lower.

If there is no clearance, both springs being compressed, the preload doesn't change the stiffness but only the ride height and the point where the rebound spring becomes free.

SSL front suspension kit solves the problem by adjusting the preload of the main spring independently of the rebound spring
which is free at static ride height.


Unless I am corrected by Dan White or Peter Ballard I'm going to suggest that the above is not quite right.

The threaded adjustment on the SSL is not there to adjust the pre-load it is there to adjust the ride height so that the rebound spring can be set accurately to just kiss the hub at the static ride height.

Admittedly, if the rebound spring is already in compression, it will adjust the pre-load but in this condition the main and rebound springs will be adding to each others rate and the ride will be very harsh.

The idea with the SSL is that you determine the ride height you want with the spacers in the kit then adjust the threaded seats to just get the rebound spring to turn at the static ride height.

To get the extra ride height relating to sump clearance the spacers go in with the rate riser spring above the stub axle and to get a lower ride height the spacer goes between the rebound spring and the stub axle.

The total difference in ride height in the standard kit between the 2 spacer settings is 20mm.

The big benefit with the SSL is that you can get the relationship between the main and rebound springs set perfectly ( albeit with a bit of experimentation and readjustment ) without having to chop the rebound spring.

Chopping the rebound spring is not a good idea as mentioned above so the only other way to get it spot on is to have a variety of rebound spring lengths and keep changing them until the clearance is perfect. Of course as the suspension settles or the main spring sets a little with time you would have to change the rebound spring whereas with the SSL you can simply adjust the threaded spring seat to suit.

I guess you could just start with a shorter rebound spring and shim it to get the correct clearance but that would be a real pain and you are starting off with a short spring in the first place which is a bad idea.

Added to that the rate riser spring helps to prevent bottoming during hard sudden bumps.

As you can tell, I'm a big fan of the SSL although you do need to understand it and play with it a bit to get it perfect.

If Dan or Peter are watching, I stand to be corrected.
_________________________
Bob

1999 4/4 1.8 Zetec Silvertop

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#521955 - 12/07/18 03:54 PM Re: series 1 Roadster sump damage [Re: IvorMog]
CBY Offline
L - Learner Plates On

Registered: 20/12/11
Posts: 242
Loc: South West France
Originally Posted By IvorMog
:

The threaded adjustment on the SSL is not there to adjust the pre-load it is there to adjust the ride height so that the rebound spring can be set accurately to just kiss the hub at the static ride height.



I have installed myself the SSL kit on my 2005 PLUS 4.

The threaded adjustement allows to adjust the rebound spring free. When the rebound spring is free, the suspended wheight is balanced only by the main spring... which is pre-loaded by the adjustment rings. There is only one balance position for a just free rebound spring. I you screw or unscrew the adjustement rings the gap of the rebound spring decreases until contact or increases because you compress or de-compress the main spring (pre-load).
With my first initial adjustment after assembly, the rebound spring was compressed and I have to unscrew the adjustement rings until getting a free rebound spring after 3 trials. Only the spacers allows to adjust the ride height. With the spacer on the top, the ride height is determined by the free length of the rebound spring (65 mm).
_________________________
Regards
2005 PLUS 4

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