radial tyres

[mellem]

With radial tyres fitted all round the steering is very heavy at low speed and almost impossible when parking. Has anyone else had this problem, and what is the cure [except that is going back to cross plys]

Bryan

[brian marshall]

join the gym :lol:

[Ken B]

If you have a original normal size steering wheel, then there is something wrong as it shouldnt make hardly any difference whether you have have radials or x plies, unless you are running wider wheels.
You haven’t given any details about your car which would help us diagnose.
If you have a small sports wheel there is no cure other than what Brian said. You could fit Vauxhall Corsa electric power steering, but thats a bit of a faff.

[Aubone]

Do you have a siezed steering idler.

This can make it feel as you need a block and tackle just to turn the wheel.

[JBV]

Hi
As Ken says, it shouldn’t make any difference.
I swapped the cross plies on my 997cc Anglia to 155 80 13″ Radials.
Except for driving a lot better it hasn’t made any difference to the steering.

[mellem]

I came across an article in Practical Classics about reducing front wheel camber to accomadate radial tyres. Well it may be that I have caused my own problem. Many….many years ago I tried to improve the stability of the car running on cross plys by relocating the track control arms 1” further out [2″ overall track], and indeed it made a real differance, now it still runs as straight as an arrow but it could make for the heavy steering at low speed. I will have to get out in the cold garage and restore the original location to see if that is the problem. One can be too clever sometimes!

[Ken B]

Then whoever wrote that article should be shot as you are altering the geometry of the suspension. The pivot point of the TCA and the pivot point of the steering arms should be in the same plane as each other. To alter camber you should lengthen the TCA, or pull the top of the strut in by using offset top monuts.

[JAN]

@Ken B wrote:

Then whoever wrote that article should be shot as you are altering the geometry of the suspension. The pivot point of the TCA and the pivot point of the steering arms should be in the same plane as each other. To alter camber you should lengthen the TCA, or pull the top of the strut in by using offset top monuts.

Well, it was Practical Classics…

[mellem]

Well I admit to acting in total ignorance but Ford set up was far from satisfactory with its bad understeer which changes to oversteer. My 1948 MG Y type could out corner the Anglia and keep on the straight, but then it had Issigonis design the unequal wishbone front end and Panhard rod rear end [1938 design]. My claim is that on cross ply tyres I didnt make matters worse! I think it was Porsche who in the end sorted it out.

[mellem]

In thinking this through I would assume the change in toe in as the suspension was compressed would vary only slightly by locating the track control arms 1″ further out. In fact having recently spent time trying to get 1/8″ toe in I wonder if it makes much differance anyway. If in considering the unequal wishbone suspension the toe in must change even if the track remains the same. What is I think important is that the tyres are taking the load along the verticle axis while cornering and not trying to roll of the wheels, and this I did in achieve in some small measure. What I am interested in is if the radial tyres require a change in pressure from that of the cross plys, and has anyone found any improvement.

[Ken B]

I’m having trouble following what exactly you are trying to acheive here.
I’ve run Anglia on standard suspension on radials for years on a daily basis. Generally at 26 to 28psi. I dont drive lightly either as anyone on here will tell you. I have never experienced any understeer, tyre rolling, weird wear patterns or anything else that wouldn’t be unexpected for a car of this vintage. The toe in settings for radial; i’ve always run at parrallel tho some prefer 1/2 degree of toe in to compensate for the action of car going forward probably pushes wheels back to parrallel anyway.
If you are really bothered about the positive camber, then fit MK2 cast TCA’s, which bring the wheel upright without drilling anything of altering any thing else. They just happen to be the right length.
X plies require far less tire pressure due to the stiff nature of the sidewalls, and if you are running radials at 22 psi probably explains why your steering is stiff/heavy.

[mellem]

Sorry this is getting a bit cloudy but as I see it, looking at the unequal wishbone front suspension the camber becomes more and more positive as the car leans into a corner, so that in effect the tyre is pushed firmer onto the rim and less rolled sideways. This I tried to achieve with my Anglia on cross plys. Radials do seem to answer the maidens prayer for the McPhurson strut. Thanks everyone Bryan

[Jason105e]

I have never experienced any understeer, tyre rolling, weird wear patterns or anything else just a table cloth on the roof!!!

[JAN]

Changes in tracking angles should not occur with suspension movement. As Ken said, the inner pivot points of the track control arms and track rod ends are equal distances apart. These two components therefore swing through the same angles as the suspension rises and falls, so everything is in equilibrium and changes of angle don’t occur. If you alter the centre to centre of the tca’s though, you cannot easily alter those of the track rods. You then get unequal lengths so unequal angular movement, with constant changes to the toe-in / toe out. This is the problem when people simple fit an Escort rack, which has a much wider centre-to-centre dimension.

As far as camber angles are concerned, the issues are far from simple as they alter with body roll. This doesn’t happen with a beam axle, such as at the rear of the Anglia, where the wheels remain vertical. With ifs, the camber angle follows the angle of the body, so as the body rolls towards the outside of the bend, excess positive camber can result on that side. The shorter upper wishbone, mounted outboard of the lower wishbone mounting, reduces but doesn’t eliminate excess positive camber.

With a Macpherson strut system, other measures are taken to reduce the tendency towards positive camber on body roll. Firstly, the strut is mounted so that its top mount is inboard of the lower ball joint rather than vertically above – swivel pin inclination. The track control arm angles downwards from its inner pivot to the outer ball joint, so it too describes an arc with suspension movement. The effect is to move the lower ball joint outwards as the body on that side rolls downwards, so reducing the increase in positive camber. It should be pointed out that lowering the suspension in turn reduces the tca’s downward angle and so reduces the effect on positive camber, so from that viewpoint does not contribute to good road holding.

Comparing a cooking saloon such as an Anglia with an MG sports car, even of much older design, is hardly fair as the sports car is designed specifically with good handling / road holding in mind. It has a much lower centre of gravity and probably stiffer springing, both of which reduce the tendency to body roll, and in turn reduce the effect of excess positive camber. It has to be said that many cars of that era did have much more body roll than is currently acceptable, exacerbating the problem. Older Fords certainly roll badly on corners, and the camber follows.

To get back to the original question though, none of this should give rise to particularly heavy steering. I personall have run on radials since 1970 (100E / 107E) without problem. Most likely problem area is one or other of the idler studs and bushes, although there are other areas: top mounts, steering box, etc. Disconnect the steering joints one by one to ensure they’re all free.

[ady]

just pump the tyres up to 30psi & be done with it :roll:

[Author]

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