Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Suplex 5L

Button. If you read through all the posts on the subject by people who have tried both the Suplex and the Morgan ARP4 systems all are in agreement that the 5 link suspensions systems give both improved comfort and handling.

The major problem with leaf springs is the stiction between the leaves. It can be improved by lubrication (motorcycle chain lube) but will never be as good a coil springs which,obviously, do not have this problem. The rest is geometry,engineering, and tuning of the components, springs and dampers. You can do much more with coils, including rising rate, than you can ever do with leaf springs.

Well it was You that I was waiting a report. I have a bit of experience with coil over suspension. Just enough to be dangerous however. So far as I can tell/read there is not much information on actual experience with the "Coil Over". Particularly Suplex.

Button

For example:
I have tried the Suplex Kit on My '61 DHC, '63 +4. and +8 Bitsa. Not just short test, but well over 1,500 miles on all types of road. They are as different as night and day. I am convinced that engine weight is a big player. But it is subjective for sure.

Button
Seattle

The main advantage of a five link on a live axle is for handling increased engine power output.

Live axles that have only the leaf spring for location are ok on a relatively light car with low power outputs such as the early 4/4 Series cars and 1300cc Ford Escort Mark 1s and 2s. Increased power output, competition and race starts stress the springs incredibly; they contort themselves into an 'S' shape, cause axle tramp and generally wreck axles. That's why rally spec RWD Escorts run five link axles and why a race Morgan generally will have anti-tramp bars unless restricted by in-period spec regulations.

Coils are a big improvement and do away with a long, flexible, heavy and generally uneasily changeable spring-rated means of providing both suspension and axle location.

But they together with the obsolete and idiosyncratic front suspension they are part of the car's character and charm. For some inexplicable reason, they work after a fashion and make their archaic contribution together with the coach-built bodywork to the essence of a Morgan!

Here's my report when I had the William's car for 200 miles

5 link report

Thanks Adrian,
I also ran into Andy G report of the difficulty of getting the rebound spring set properly. I too have had difficulty with this. On My +8 I am going back to the Mulberry setup. The Suplex Kit was best on the ZETEC powered '61 DHC. so it will be reinstalled.

On the +8 (Now Mulberry setup) I leave the rebound spring out. Drop the car on the front tires rather sharply. Now the gap is close. Add the two gaps and divide by 2 and cut the rebound springs a half an inch longer. I am with Tim Harris on wanting a snug fit of the rebound spring.

BTW: Do not own more than one Morgan at one time. What a PITA. But it is interesting to compare. Logic does not work.

Button

I wonder what the advantages of the Suplex 5L vs Bill Fink's trailing arm coil over design. If any. One item is that the coil over assy seems to be straight up on Fink's. Also maybe easier (cheaper) to fabricate.

Button
Seattle

I would add that if I had the money then for my 3.7 Roadster I would consider the 5 link, primarily to get more control over the axle. However before that strep I would try getting the rebound and bump better controlled and another anti tramp bar. I do have some reasonably cheap ideas to tune the rear shocks, and get progressive rebound.

I have spent countless hours (money) trying to get the front suspension under control. Only to find out it is the Rear Suspension that seems to be in control. Starting from a modified rear spring (too soft) and now to a 5 leaf spring (better), purchased a 6 leaf spring (from Bill Fink) to try this. Now that I have replaced the Suplex Kit with a Mulberry 140-2 and His thrust bearing(with installed 5 leaf rear) I will take a long run (weather permitting) to try this. I have a spare Salisbury 7HA w. Quaife LS that I will weld the brackets for a Coil Over rear suspension.

From the 3.0 Roadsters I have driven (3) they seem to be OK right out of the box. But as I built the +8 Bitsa from an assortment of parts ('98 Chassis/Crosshead, ''8? body tub, Chevy S10 rear axle, T-5 transmission and a Rover/Buick 215 3.5. Nothing is working as planned. Slowly I am getting it sorted, but it has taken 7 years so far and not up to my specs.

Button