Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Suplex Again

Hi,
I have had my 99 Plus 8 recently serviced and after 32k miles the king pins are showing slight signs of wear and will need replacing.This was no real surprise considering the mileage. It was suggested the way to go is fit Suplex and will most likely have to fit a steering damper as well to prevent the shinny. The present set up is Mulberry steering bearings and AVOs on the min setting. I have no issues with ride and no wobble. I thought I have been following the threads on Suplex, I can't recall seeing anything about having having to fit a steering damper following installation. The present set up is Mulberry steering bearings and AVOs on the min setting. I have owned the car for over 10 years and no issues with the ride and no wobble. I thought I have been following the threads on Suplex, I can't recall seeing anything about having having to fit a steering damper. Is having to fit a damper the norm?

Haven't heard that you need to fit a steering damper with Suplex.

If all is good with the Mulfab setup why change? Just get talk to Mulfab and get new king pins and bushes from them.

Cain

As far as I can see all Morgans are not created equal in the area of front suspension. Some people who have fitted the steering bearings to replace the blades have had shimmy problems because of insufficient castor angle. This has not occurred on all cars but where it has occurred the fitting of a steering damper has resolved the problem. When Morgan started fitting the bearings in production they increased the castor angle and this has resolved the shimmy problem.

When a Suplex kit is fitted the lower spring is not loaded at static ride height so the steering bearing is not compressed between the two springs but carries only the weight of the car. In most this would reduce the load on the bearing so the steering does become lighter by comparison to the standard springs. I believe that the Mulberry set up also uses a very lightly loaded, but stiff, lower spring. I would think, therefore, that if you are not experiencing a shimmy with the Mulberry set up it is unlikely that you would experience a shimmy with the Suplex.

Peter Mulberrys kit uses the standard lower rebound spring so it's not a case of it being a stiff lower spring so much as it's the OE spring. The main spring is" different as it's shorter and of a different rate to the OE Main. Suplex suits some but not all owners, some love it, some are indifferent and some have had it removed as they did not like the handling afterwards. It certainly does change the comfort level and having followed 2 cars with the kit fitted (one was one of the ones I have fitted) you can certainly see the difference Suplex allows the road wheels to move at a different frequency than the bonnets, to explain if you look at an OE equipped car the bonnet line and road wheel tend to move at a similar rate, with the Suplex fitted the front wheels can be seen to be moving independent of the car and it's isolation from road undulations is far more apparent.

The question of Suplex front suspension mods will be dividing the Morgan community for years to come.

I am one of the converts, and for the type of motoring that I do now , manly long distance touring, it is certainly an improvement in ride comfort, and in my opinion it rolls less (but others disagree here)

The steering does feel lighter, and I can see that this won't suit everyone, but it does make it easier to drive at low speeds (e.g. London parking) . There is a slight lack of "feel" at the front in some conditions around the straight ahead position, but this disappears as the steering loads up for a corner. You might feel that you have to "trust" that it is all under control, as it most certainly is. I got used to it in one single drive, and have never regretted my choice.

The only real downside is the amount of time it takes to set it up correctly. With the MMC OE set up you bolt it all together and then leave it until the next rebuild. With Suplex, once bolted up , you need to find the optimum set points , and this does take time, so you do need to allocate some time to playing with it and experimenting. Once found, this point has not changed for me.

I have never thought the steering needed a damper , but mine is a rack and pinion car , not steering box.

I fitted the Mulberry bearings some years ago, and suffered from terrible wheel shimmy. I found out this was because my car was set up with 4 degrees of castor angle rather than the 6 degrees on later R&P cars.

I refitted the damper blades and the problem went away.

When I went to the Suplex system I kept the damper blades and all is fine, and like Andy I'm a convert. Getting the correct setup takes a bit of effort, it's true, but I think it's worth it. I also think that it seems to suit better if the car is run with a low ride height, i.e. with the spacer below the stub axle.

I would say if you are not getting shimmy problems with your current setup, you are unlikely to experience it if you fit the Suplex kit.

The purpose of a steering damper is to damp out steering oscillation. If you need a damper to do that then there's something wrong with the steering and suspension, or something is bent and not in alignment.

- or the design of the system has not been refined enough to provide natural damping, as in the early Morgan suspension, with its steering box and steep castor.

HFS's solution was to fit the damper blades, which has proved to be pretty good at providing the necessary damping.

Later on, the move to rack and pinion steering and a 6 degree angle provided sufficient natural damping for the damper blades to be unnecessary.

At least, that's the way Peter Mulberry explained it to me at the time, I have no reason to doubt his expertise.

Suplex or not - I'd say that it's a question of preferences. I personally like Suplex's slightly softer 'normal' ride and the progressive spring rate.
If you're not experiencing any wobble with the Mulfab setup I can't see any reason why it should be a problem with the Suplex.

It also provides a bronze bearing surface that separates the hardened steel of the spring from the hub.