Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Front Tire Mileage

This short video showing what happens to the wheel as it is moving up and down has more to do with going side to side than toe in or out.

Convinced me at any rate...

http://www.talkmorgan.com/ubbthreads.php/topics/143605/Front_Suspension_Geometry_Bump#Post143605

Hi Paul, at what ride height would you set the toe, as it dramatically alters with ride height. I would suggest putting may be 80-100 kgs of ballast in the car and then setting. I have driven round for weeks now with 3 25kg bags of cement in the passenger side and it transforms the handling. Doesn't do much for the performance though.

Yep, I've noticed a definite reduction in bump steer when I have a passenger on board, so the question is, does the improvement result from the increased weight or the reduction in ride height?

If the latter, then it shouldn't be too difficult to lower the ride height, either by modifying the spring platforms, or buying some shorter springs, or even lopping a coil off the existing springs.

I have done some fiddling with the wheel alignment. Adding a person to the car causes the alignment to move towrds toe in.
My handbook states should be at 4 mm toe out. When set at this at static unladen the addition of 1 person moves it to close to 2mm toe out. Two peoples would accentuate this.
When driving and hitting a bump the wheel lifts and again moves towards toe in
Hence when driving it is possible to transition from toe out to toe in which i am sure would be unsettling.
The morgan man here reckons toe out should NEVER be used on road and very rarely on track.
We have settled on 4 mm toe in static unladen as most desirable setting for my car ( neither or the wife are "heavy" ) so not so much effect wrt unladen vs laden alignment
I find that this works well. Hopefull always have some degree of toe in. Tyre wear pattern looks Ok. Have done 6000km and plenty of tread left. Also running tyres at 22psi
Once had them close to 28 inadvertantly and it was like being on skids. Danced all over the road.
Do all handbooks state the 4mm toe out setting? rumour has it that later models dont ??

I think that 4mm is still the recomended setting, I remember reading somewhere on here why the factory chose that, but can't find it now - does anyone know, I could always give the factory a ring I suppose, just like the old days!

A simple fix would be to have shorter but progressive springs combined with less toe out or perhaps even toe in which is the norm for road going rear wheel drive vehicles. A lower ride height would give less bump steer. Progressive springs would give less weight-dependence.

Harald

As I understand it, the usual for most vehicles is toe in. Just a small amount, and the effect of speed is generally to reduce this nearer to parallel by utilising the slack or free play in wheel bearings and steering joints.

Specified toe out does exist, but it is very rare and I don't know the rationale behind it.

Excessive toe, either way, will lead to tyre scrub and thus greatly increased tyre wear.

Certainly as tried in my playing around, toe out on a 4/4 gives very iffy handling, with the car darting left or right at the slightest provocation. Logic would suggest this is a pretty general effect as whichever front wheel has the best grip at the time determines the direction of travel.

As many have observed, the last thing you want is for the toe to be deflection influenced as if it is, both bumps, passengers and loads will have an effect. If the toe doesn't change under these circumstances, a static adjustment should yield both predictable and unchanging results, whether you are on a hoon round a track, or taking granny home from shopping down a bumpy lane.

I started out thinking as you did Harald, until it was pointed out that the angle of the upright, or King Pin, nowhere comes close to bisecting the front tyre and the steering rack knuckles are to far outboard, away from the wishbone pivot points, all basic stuff to any student of steering geometry.

So, lowering the ride height may help with getting the track rods parallel to the bottom wishbone, but it really needs a shorter rack with correspondingly longer track rods, and a shorter top wishbone, with the angle of the stub axle corrected for the different kpi.

This is not an easy diy job!

My front tyres were shot at 2.800 miles - in defence I corner hard and my tracking was out from new but that is a little steep considering its not front wheel drive! Have been recommended Blockleys!!

At 7,500 miles both front and rears are shot. I admit that I have driven this hard and enjoyed every minute! So in late winter, I will be trailering the beast to my dealer for new tires as well as the steering fix.