Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Suplex 5 link rear suspension

Hi all, thanks for your interest in the SUPLEX 5L rear suspension. I need to tread carefully as I am of course linked to SUPLEX UK Ltd who I consult for and am also viewed by Morgan directors as a supplier, but at heart I am a Morgan owner & driver.
As you know we fitted a 5L (Five Link) rear suspension to a 3.7 Roadster last week, it is a 'bolt on' system; so no welding but a few holes needed for the Panhard Rod cross member. This is PreProduction2. PreProd1 went onto a new 4/4 earlier this year, the prototype is on my 4/4 and has been for 18 months.
Some features of the 5L:
*Full use of all rear suspension travel.
*Progressive spring rate to give good initial ride and grip over poor surfaces that then stiffens in bump.
*Progressive roll stiffness that gives good compliance for small single wheel inputs for ride, but then stiffens up in roll, this is done by the link geometry and integral bush compliance as well as by the progressive spring rate.
*Adjustable monotube dampers with separator piston to give consistent performance when used hard, though nonadjustable monotubes will be available as the standard setup. Both have progressive bump stops.

This 5L kit must be fitted with the RS (or its development) up front, as the 5L is part of a complete Morgan suspension system. Thus spring rates, spring rate progression, damper settings must be compatible front to rear of course, like any other modern high performance sports car. Also like the Williams race car that is doing well, on which we have set up spring rate progression and damper rates front and rear to be compatible.

The RS (Refinement System) needs to fitted up front to give the front suspension spring rate progression to match the 5L rear; having the front suspension going regressive (softer) in bump as many Morgans are and then the rear suspension going progressive (stiffer) in bump makes no sense at all, and will not achieve best ride and handling. OK some owners have set up their own front suspensions that just might be compatible, but they can be assessed if the owners are interested in the 5L. We have also worked on the RS Bilsteins and have a slighter stiffer low velocity bump characteristic, that may be useful, but the proposed adjustable Quantums up front are going to be good; a single adjustable version of the double adjustable versions I set up on the Williams race car.

Four seater, this still needs to be done, but is on the list. Packaging and weights of course different.

Fitting agents; initially there will be a select few based on their known abilities and closeness to advice from SUPLEX people. In time other agents will be approved, that all sounds a bit formal, it is not a difficult kit to fit, but setting up needs to be right to ensure eg corner weights and rear axle alignment are correct.

Prices still to be announced, but that is a SUPLEX matter, I am only the techie.

Impressions from the 3.7 owner and the other renown Morgan ex-racer are more valid than what I would write of course.

I hope that this helps - PJB (Peter J Ballard)

First impressions of the 5link Suplex rear suspension

Last week I had the Suplex5L rear suspension kit fitted to my 3.7 Roadster, it took a day and a half to bolt on and set up, including removing the leaf springs. The system is very well made and fits so neatly under the parcel shelf. I have the RS kit fitted up front with slightly tweaked damper settings done by Peter Ballard. Peter estimated the required rear damper settings and adjusted them. Peter drove it around the block first, over speed bumps and potholes to check if there was sufficient damping dialled into the suspension units and there were no unwanted noises, all was fine - "as good as my car" he said.




I then drove it with a volunteer and then with Rob Wells. The car was driven hard by both of us over many miles of open roads I know, including hills & bumpy bends. It has really transformed the car's ride and handling, truly impressive. Rob was also very impressed and has ordered a system for his Plus8.




The rear suspension will now absorb speed bumps with no crashes or jolts, but more importantly is how well it copes with bumps at speed and its ability to put down the power on fast bumpy corners up hill and down. I am so pleased and I think we all look forward to the Morgan factory's response.
P.S. I will leave all the technical stuff to Peter Ballard and Suplex I will report on the development of the system as I make adjustments to ride height and damping.
I must make it clear that I am a customer of Suplex and have undertaken to give reports on what is a truly innovative rear suspension system. What a pleasure it was to be driven by Rob Wells!
I will keep TM updated.
Regards David

Peter,

would you be abe to make a comment on how well the Trad Suplex 5 link suspension compares with the ride of the admittedly IRS new Plus 8? For me that would help put it into perspective.

Peter

Well done Peter and Suplex.
Having fitted new rear springs and Panhard Rod to my 4 seater I would have definitely gone for the Suplex rear to match the front if it was available.
Looking forward to the 4 seater.
Is it possible to fit yourself or will it need to be a professional set up?

Peter J, I have only driven the new Plus8 once, and with a Morgan salesman on board, the brown demo car, yours I think? I found the new Plus8 a lot firmer at the rear than the 5L.
The new Plus8 has linear springs and no progressive roll stiffness so its spring rates have to be stiffer than the 5L to control roll. We have gone for a soft initial spring rate for good ride then with the progressive springs and a geometry that stiffens in roll, I think that the 5L gives better ride. I have not driven the new Plus8 very hard, so at this stage unable to comment on that aspect.
The 5L also has as an option of very sophisticated dampers, of a type used on race cars, ie the single adjustable Quantums (will be spec'd for the front too). The new Plus8 has twin tube Spax I believe. Even the base level 5L will have monotube dampers with a separator piston which are more sophisticated than twin tube dampers. OK the new Plus8 could have decent dampers fitted of course, upgrades are always available.
I hope this helps - PJB.

Titus, certainly initially we will only consider fitting by selected and thus approved dealers and specialists. One of the requirements is to be able to work beneath the car to access some of the fasteners. In special cases I think we will consider individuals fitting themselves, but that will be one a one by one basis. Setting up the corner weights and getting the rear axle in line is not difficult but is critical and the fitter has to understand. I hope this helps - PJB.

Well done both and many thanks for such a comprehensive report from both.

Am v sure that many drivers will be excited at this option.

What took so long to arrive at his point?!

Well done Peter, for getting it done, and David for testing.

I am sitting in the wings for a full set up!

Looks and sounds very promising.

I am certainly going to be near the front of the queue for the rears to match my Suplex RS front.
Do I understand that I may need to change the current Bilstein front dampers for some adjustable ones to be able to ensure that the front and rear damping is matched?

Andy my3.7 works fine with the non adjustable bilstiens on the front David