Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Suplex suspension upgrade .

Peter, Thanks...

I had the thoughts in my head but struggled with the execution of them, sorry about that.

What you said about minimum rebound actually causing more road contact is just the opposite of what I was thinking.

I will look up the book at Amazon and maybe it's available at my local Barnes & Noble Book Sellers.

I'm going to stop asking questions now so maybe the rest of the guys can talk about what this thread was intended to be about. Didn't mean to hijack it this way.

Thanks again for the great lesson on suspensions.

If I understood that correctly; when the front gets light having unlimited rebound allows the suspension springs to help push the body of the car away from the ground. An effect partially limited by the dampers. In that case the body of the car would jump up in a sort of pogo stick effect and the higher it goes the more heavily it is going to crash down. If the car is going over a crest at speed it could travel quite some distance before it drops down again and all the while the ground is getting further away.

What an interesting thread. Thanks to those who have improved my education.

That’s what I was thinking as well. If you go over a bump fast enough to catch air, or drop into a deep pot hole, the front wheel(2) with the rebound limited coil overs will only be pushed down to fill the void until the bump stop is hit. With a limited rebound length of maybe an inch, I would think loss of contact with the surface would be inevitable. But Peter has compelling information to the contrary.

In my mind I’m still seeing the ride height set as to allow a certain amount of down travel of my suspension to try and keep the wheel(s) in contact with the road, but I could very well be wrong about this.

We have experts on this site and Peter is one of them. So I have what he’s told me and I understand the theory, but it’s still contradicting my very basic concepts of suspension motion.

I think I’ll do more reading on the subject to see what I can learn.

You can make suspension work to give good ride on sealed surfaces, you can make the suspension give good handling, you can make the suspension work well off road and you can make suspension stable under braking - BUT - unfortunately not all at the same time!

The SUPLEX suspensions for the Classic 4 wheelers and the M3W are set up to give good ride, high roll stiffness and predictable handling on sealed tarmac road surfaces. More development work costs more money that has to go on the price, but feedback shows that customers seem happy with the products, but each to his/her own preferences.

One can of course choose the spring & damper characteristics to meet a different set of needs/wants and compromises of course.

Dan ~ Ref allowing more rebound travel. Just do the maths to calculate roll stiffness with no rebound spring, with a rebound spring say 3 times main spring and finally with a rebound spring say 10x the main spring. Then you will see why there is great benefit in a stiff rebound spring for high roll stiffness. Also remember with linear main spring it is not so important to control rebound but as soon as one goes to a significant rising rate in bump then rebound stiffness is critical.

If bored have a read through http://www.ebay.co.uk/ctg/Shock-Absorber-Handbook-John-C-Dixon-Hardback-2007-/87248984

Have fun - Peter

PS I am building a 5 link rear suspension for my 4/4, back to the garage to dribble some more weld over my brackets.

Peter, I see your point.

It's like in the sales game, you can have quality parts, low price and great service, pick any two.....

What I'm looking at for straight line driving is contrary to your roll rate and with a longer rebound side of the coil over, the tight roll rate goes away. So as you've pointed out, customers like the tight roll rate and find the ride okay.

You have been a great resource of infomration and I greatly appreciate it, really!!!

I'll take your advise and do some reading. Thanks again!

Hi Peter, fascinating as ever, I do like reading your technical posts especially as its your profession and I'm just an enthusiastic ametur and enjoy learning as much as possible.

Could you tell me, the Spax adjustables I have say " filled with Krypton gas" on them. Are these mono tube or twin tube?

I expect they are better than the oil filled standard fair.

According to the Spax web site they are their premier damper, excepting for their premium custom alloy jobs of course.

Peter - thanks for all your posts on this topic. We are indeed v lucky to have you onboard as our resident Guru:))

Spax adjustables are cost effective twin tube dampers with I believe a bleed hole and tapered needle to bypass the valve to give adjustability.
The Krypton gas, or Nitrogen in some dampers is only the gas that keeps the hydraulic oil pressurised to prevent cavitation and foaming that would reduce damping with hard use. These gases do not corrode steel/aluminium and the molecules are large to minimise gas loss through the seals.
The damping is always with oil, the highly pressurised gas keeps it as a liquid. Non-pressurised dampers will foam the oil with hard use and indeed some are designed to do so and work thus!

The Bilsteins in the SUPLEX RS kit are also highly gas pressurised but have a separator piston so the oil is never in contact with gas - neat, but need a longer unit for that feature.

The more one learns the more one realises how much more there is to learn - in any subject. I am glad that I can pass on some tech nuggets, but a few years ago I nearly went out and bought a Lotus and not a Morgan, so things might have been quite different.

Cheers - keep the interest coming - PJB.

In a former carrer I used to work for Borg Warner automotive who manufacturer viscous fan drives for truck engines.

There are so many variables with different quantities and viscosity's of fluid and valving that it can boggle ones mind with regard to fan speed vs temperature maps.

I found it fascinating then and still do today.

There's more to dampers than meets the eye.