Help, Still No Self Centering

[Guest paul thompson]

help guys,

I still do not have any self centreing on my 2b with double wishbones. I have turned thedummy struts around and it's still no better. I measured 3 degrees of caster both before and after i turned them, the KPI however changed quite a bit, went from 12 to 18 degrees. Still no self centreing, what can I try next? SVA is in two weeks. :boohoo:

[Guest petespine]

Hi Paul

 

I had the same problem when building my 2b, mine was sliding pillar though.

 

My steering rack when you looked at it from the front was not level from wheel to wheel, so I packed the rack up and got longer u bolts and this did the trick.

 

Yours Pete

[Guest Ianz]

Paul

 

I pumped up my front tyres to 40psi for SVA and got self centering

 

Cheers Ian

[Guest john]

I put mine through Sva with the donor wheels 165 x 13, and 30psi .

Self centreing was fine.

 

 

Good luck with the test.

[Guest Guy]

I had the same problem, I adjusted the tracking to give me some tow out and pumped up the tyres, I also gave it more caster as well. I had to adjust it all back after the test though.

[Guest paul thompson]

Guy,

How did you give it more castor? I have some measuring kit and rotating the dummy strut did nothing (as suspected) for the castor. It does however change the KPI and the castor trail. I have a really good diagram that explains all these terms, I'll try and get the scanner working so I can post it.

[Longboarder]

I think you are right that changes to the dummy strut can't change castor as the castor axis is a line drawn through the centres of the top and bottom wishbone ball joints. It should not change KPI either cos thats the same axis viewed from a different angle. All the 2B's I have seen have no adjustment for castor. My series three did but not enough and I decided to remake the top wishbone effectively with the front arm longer and the rear arm shorter to give 7 degrees of castor. Did some drawings and found local formula ford team who were advertising welding services. They were able to grind out the arms and reuse the ends and bushes. Result. Hairy chested self centering. Extreme but effective.

Main problem in finding a welder was getting them to understand what was needed.

 

Nigel

[Guest Guy]

Paul,

 

Mine's a sub-K so I don't have wishbones ( oh I feel so inadequate ) I adjusted the anti roll bar mounts forward.

[Guest paul thompson]

I have discovered that without the steering shaft connected (the big heavy thing between the column and the rack, I can push the wheels from lock to lock a lot easier than I can with. I looked at the UJ's at each end and found that one (the one at the column end was very stiff. The one at the rack end seemed to quite loose gy comparison. I have stuffed a load of grease up the rack bar and that improved the friction in the rack a bit. I am having a company I deal with look at the UJ's for me but one other thing I noticed is that with the shaft connected the column wants to move around a bit when forced by pushing the road wheels and that the shaft seems to be eccentric. When it goes round while attache to the car, the gap between the shaft and the manifold gets bigger and smaller as it goes round. That can't help I'm sure. I'm hoping that this firm will make me a new shaft, with a smaller dia shaft anyway. I know that they are about to start supplying westfield with an extended sierra shaft, and have already supplied Vintage motor co with some. These however have the sill rubber thingy in.

As I said in the last post turning the dummy strut does incease the trail, not sure yet what this does to the self centreing, I'm going to chat to a freind who works in vehicle dynamics at Jag (assuming he's not on holiday) to find out.

[Guest paul thompson]

Ok This is what I found out,

On Jag XK and XJ, typical Jaguar double wishbone set up, the run at 7 degrees of castor and 7 degrees of KPI. Xtype, a typical strut set up runs at 2.5 degrees of castor and 14 degrees of KPI. Apparently KPI affects returnablitity (to give it its correct name) as much as Castor. High KPI low castor, High Castor low KPI. Apparently increasing the KPI will improve matters and this can be done by screwing in the top ball joint. This will increase camber but I think I can help that by adjusting the height of the dummy strut. anyway, more camber won't adversley affect the returnability, may affect tyre wear but who cares for SVA right? So back out to the garage tonite to play with the KPI (so glad I have the measuring kit) Won't have the steering shaft back for a couple of days so I'll let you know how it goes then. Here's a thing, they said that would be interested in making steering shafts of far better quality with about half the weight, if there was enough interest. The proposal was to use a 15 dia bar, or a 22 dia tube and pressed yokes instead of the cast ones. No rubber disc. and no Welding, i.e. peened (standard production for most car makers) The 15 dia bar would give better clearance to the 4 branch manifold. That's what i'd go for, but they don't want to make one off. The exteneded sierra shaft was £40 each in batches of 10. Would anyone else be interested?

[Guest carl leonard]

Paul

 

Try removing the gaiters and greasing the steering rack throughly. I have known a number of people to do this and should ensure your car self centres.

 

You may find that the rack has never been greased since being manufactured!!

 

Carl.

[Guest ant.b]

hi paul

i found when i took the rack boots off before sva , there was no grease at all , so i filled loads of grease in them , plus both of the u/joints, mine passed with a degree of self centering wasnt perfect but enough to pass, said the tester, had 40psi in the fronts . i have noticed the same thing with the steering shaft as i have a slight clearance problem when turning the wheel, i tried another shaft but still the same, i think its because angle you have to put it at to avoid the 4 into 1 , i am going to try stiffer engine mounts as mine seem to have to much movement in the rubbers...good luck on the test ant

[Guest Ant]

i am going to try stiffer engine mounts as mine seem to have to much movement in the rubbers

Do such things exist? Any idea where and how much?

 

Ant

[Guest Battery Bill]

had 40psi in the fronts

I have heard a few comments suchlike, what are they like to drive with sky high pressures like this in the fronts then?

[Guest chris brown]

what are they like to drive with sky high pressures like this in the fronts then?

Just don't try cornering above about 20 mph!! it won't also potholes deeper than 2mm are interesting