Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Missing in action - bump steer!

PaulJ. I agree that toe-out gives straight line instability, but I am really not sure that toe-out causes quick turn-in.
As one turns the steering wheel the outer front wheel increases in vertical load and the inner wheel looses. Thus as the outer wheel gains vertical load it provides more lateral force.
Thus if the wheels were toeing out when you turn the steering wheel the outer wheel will actually be going from toe-out to straight to toe-in as you turn the steering wheel. Thus the outer wheel has to come through straight ahead before it provides lateral force, thus delaying build up of lateral force and turn-in. Whereas, if the wheels are toed-in then the outer wheel is already turned into the corner as you load it. So toe-in provides quick turn in, toe-out deadens turn-in. Regards PJB

Like HJP I had the lower wishbones replaced and haven't noticed less bump steer and the car wanders a bit.

Is it now definitely all 4 that are being replaced or just the lower 2 still? I'll ask the lovely people at BHM when I next go there as we all know this is an ongoing discussion albeit it will no doubt be sufficiently resolved fairly soon.

And does anyone have latest toe-in / out settings to quote?

Oh - and my car like some others is a lot better with more weight on board. Took my 15 stone pal (bit of a squeeze but he loved it!) in the 3W yesterday and noticed that the car felt a good deal more settled than when it's just me and 11 year old son (who's still quite skinny).

Weight will obviously reduce the ride height a bit.

Peter, thanks for your input, I have been trying to get my head around suspension and steering behaviour for years, and the more I find out, the more I realise, the less I know! This is probably why I have a bit of a bee in my bon..whoops, I mean, cowl, about the current 5 speeder, also the fact that it started good and has gone downhill.

I'm wondering if cars made in the early and mid part of last year are suffering more from this? Judging by the comments on here, there are some like Wiscos and myself who really notice it, and others who don't, and I have to say, that you couldn't not notice the antics of the steering wheel and car when the bump steer is present.

Maybe the benefit of extra ballast is lower ride height, or perhaps it is just the evening out of weight distribution? I'm not sure. Whatever the reason, it is very noticable how much better the steering is with weight on the passenger side.

PaulJ, yes suspension and steering is a 'fun' subject - luckily I got paid to work on such. One of my first jobs back in the 1980's was on modelling/predicting Leyland Trucks' ride and handling - you know open section flexible chassis, unknown bodies bolted on top and stiff cart springs - oh that sounds familiar!
The only new M3W I have driven had the SUPLEX units up front, I noticed no bump steer - but gosh did that motor vibrate!!!! PJB

It still does, but THAT really is part of the character of the car! It just wouldn't be the same without the big V twin aircooled motor.

Leyland Trucks? If it was in the '80's you probably didn't know Jez Coates who also worked there on something similar? He went on to Caterham as Engineering Director to help eliminate bump steer in the live axle cars, and other important stuff too, of course.

Yes, Jez was in the Leyland Trucks student engineer intake one year after me I think (1972 or 1973 to start degree). He worked in Test Operations playing with the real things and I was in R&D doing the maths to model and improve ride and handling. We had a good time together, Jez played with Elans if I remember right.
I met him again at Stoneleigh RaceTec show this year, he was not impressed that I was working with SUPLEX on Morgan suspensions - no idea why ;-) Its a small world thank goodness! Regards PJB.

I lived in Caterham as a kid and grew up with the sounds of Se7ens tooling past the driveway as they took other potential customers for a blast around Kenley Aerodrome, the old WWII fighter station. I was very very close to buying a 1700 SuperSprint in the early/mid 80’s and went to a few Caterham events at Goodwood. Jez was a very helpful chap and his main development driver (a Reg someone I think), was very quick.... Small world.

I bought a Europa Special in the end - BVTC with 5-sp box. Lovely it was. Hoping my 3-wheel'd Spitfire will be too.