Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 3 Wheel Drive

Thats v interesting - thanks for the info!

Very pleased to hear there will be a Suplex Kit soon. I have just taken delivery of my M3W and I am not happy with the bump steer / steering kick back it has that was not present with the early production demo I tried before ordering. It is not impossible to drive but it isn't good on the poor roads surfaces we have now. It seems amazing that the specification of the car is changed to make it worse, most companies improve the product over time. It would be nice to think that Morgan will sort the problem and do the work under warranty.......or maybe I will just order the Suplex kit and enjoy driving the car like it should be.

The main reason I believe that Morgan changed from SUPLEX to SPAX for production is that the production volumes were suddenly increased (high demand - so its all your fault then ;-) and SUPLEX could not then ramp up production quick enough and SPAX could but by buying in from foreign climes I believe.
It was a shame as the ride and handling work had been done by SUPLEX at their cost and the demo cars were so fitted but production was given to SPAX. This is not an unusual situation in automotive component supply, but always stuck me as somewhat unfair. Regards PJB.

I think Suplex should have written a minimum quantity into their contract with MMC to cover the R + D costs, unfair is an under statement.

I understand that the latest Spax units fitted to production cars have been modified to replicate the special characteristics of the original Suplex units. Having just come back from a short drive in my new car, collected yesterday, I am sorry to say they do nothing to minimise the steering kickback! Very disappointing. I may yet be beating a path to Suplex's door.

Williams Morgan near Bristol, are also working on a mod. to lift the height of the track rod end, which will minimise the amount of deflection of the front wheels, either side of the horizontal. I don't know if they have had a chance to test this yet however.

I am not a great specialist but as far as I know the bump stear is mainly a geometry affair. The height of the steering rack and the geometry of the axle (especially track rod ends)during wheel movements are the principle things that cause bump stear.
Different shock absorbers or springs will tend to minimise a little the effect (mainly if they are stiffer and consequently minimise in some cases the vertical travel of the wheels) but do not correct the source of the problem.

Quite, The main problem is to do with the fact that the steering rack cannot sit lower because of the bellhousing. The only ways to offset this is either to raise the height of the steering arms on the upright, or lower the suspension, or of course, go for a fancy set of springs and shock absorbers, which is what Suplex appear to have done.

Williams will effectively be raising the height of the track rods, but I can't help wondering what dropping the ride height by an inch or two would do? There is plenty of ground clearance.

Peter?

Hi Lotusien, as I understand it the Suplex ones lower the ride height there by lifting the track rod ends in relation to the rack which in effect reduces the bump steer.

Try a small experiment, stand on one of the front chassis outriggers (what the number plate fastens to), and bounce up and down a bit whilst looking directly at the top of the front mud guard. The amount of steering angle on the front wheel will alarm you. That is bump steer and should not be present.

If you are familiar with the Elise, when you lower the ride height for competition porpoises (40mm over all) Lotus sells a steering rack spacer to move it 40mm further up the bulk head to get rid of the bump steer. At the rear this can be dialled out using shims and adjusting the rear control arms. Lotus specifies no more than 0.040" of deflection in total.

On the M3W I measured 0.647"

It's like having rubber track rods!

Come on Suplex were all chomping at the bit here.

As I understand it the ride height was increased when SPAX replaced SUPLEX hence the increased bump steer, this was done mainly because the SPAX spring rate was linear and they needed to extra bump travel.
It is a geometrical problem, of course the ACE cycle car has the rack at the front with good geometry and UJ articulation angles. Regards PJB.

Blimey Dab of oppo .I've just tried your experiment, it really is amazing how much the wheel moves, thanks for that !
If the Suplex shocks will lower the front end presumably the rears will need changing too? The car sits parallel to the ground at the moment .