Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Bump steer on trad 4 wheelers

My 4/4 is of 2008 vintage but I am not sure the issue was resolved. The separate track rods leading from the steering rack onto the steering arm of the stub axles are canted upwards at an angle of just 1.25deg.
By some cosine trig I reckon that the levelling of the track rods (each horizontal on the rebound) leads to a tendency towards a greater toe out of just 0.2 mm.
On compression of the suspension however the angle of 1.25 increases and the tendency then is for toe in to be increased by about 1mm at the most (for the brief time the compression maintains).
I am unsure if this sheds much light on the issue of bump steer.

One or two of our local Devonshire dual carriageways have a trammelled depression into the road surface which does cause the 4/4 to wander alarmingly.

Are the "tram lines" linked to the bump steer? Surely this is the car just trying to fit in the groves left by the (heavier) wider tracked lorries (and cars)?

There are "tramlines" in a road I use and even my Focus is affected. I feel some "pull" when in them. The Morgan is no better/worse though. The "grooves" in the road have resulted from poor quality "resurfacing" using the quick-fix tar/chippings method that also leaves loose chippings to cause problems with loss of grip/raised banks of chippings etc.
The condition or roads is detriorating, I wonder if more money needs to be spent on them
Could the £billions be diverted from HS2?
OOPS!
taking us off thread - sorry

I believe the track lines are wider due to the wider track of HGVs and you could be right - the Mog likes to try to follow them - but my Volvo estate and daughters Toyota Yaris are not troubled the same way on this stretch of road.

Devonshire roads are deteriorating for sure. The bit I am referring to is the A38 Exeter/PLymouth section where it passes close to Chudleigh. There have been one or two accidents where vehicles have left the road here and some short sections of it have been re-surfaced but not all .. The Plymouth bound side is worst.

My 2009 Roadster with Suplex and brake reaction bars steers and corners almost like a normal car, but in some ways better in that lacking the dulling influence of power steering there is much feel and just enough feedback.

Our modern cars have excellent steering, but both lack much in the way of feedback and the feel is artificial. The BMW, without power, is impossible to steer at all.

Remember, on bump and rebound the axle end does not go up and down vertically, but slides on the king pin, which is inclined at 2 degrees. Therefore to minimise bump-steer, you would expect the track rod end to be tilted up at 2 deg, so that its arc of travel is tangential to the king pin at somewhere between static height and mid-travel. So I suspect that your 1.25 deg is not far off the optimal position.

P.S. Have driven the 4/4 in Spain, Portugal and France without coming across any of these trammeled motorways. However on return journey home last year heading up the A38 from Plymouth one of the first things I noticed was this awful section of carriage way as it heads up towards Exeter.

You think that's bad. You should try crossing from Switzerland into Italy. Then you really do notice a difference. The Autostrada is not too bad but the provincial roads are a disaster.

Talk with Darren at New Elms, I had a slight shimmy and buy adjusting the rack and setting it so track rods parallel no shimmy or bump steer.