Hi All,

I downloaded a diagram of a top bone that had an offset of 22 mm instead of 8 mm.
I'm not sure who posted it now, (possibly Mark?) and I suppose I'm looking for
conformation that this mod will improve self centering on a book chassis.

I'v made a jig and got the first one tacked up, (see pic. the one on top is the old one),
and I wondered if anyone had actualy made and fitted them with success.


Any help will be much appreciated.

Cheers

Paul G

p.s. sorry the second pic is a bit out of focus.
Rescued attachment wish-bone-jig-s.jpg

I had to remake my top bones on friday. Dont know how well the pic will work.
Moving the center this far actually made my car fun instead of scary to drive.
Rescued attachment PICT0088.JPG

My top bones were modified for extra offset (can't remember how much - about 20mm I think). Self-centres a treat, and no issues at the SVA.

David

will shortly be amking rose jointed top bones for mine to achieve similar (by eye!!) to what you have 907

I made my top bones to have adjustable castor.
Not as much as 20mm though

Looking at the photo I think you may also find that if you fit the dampers the other way up it will also help the handling a lot.
Unless it is a gas filled monoshock it is unlikely to work correctly with the adjuster at the top.
Paul.

quote:

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Originally posted by emsfactory
I had to remake my top bones on friday. Dont know how well the pic will work.
Moving the center this far actually made my car fun instead of scary to drive.

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Well I've just splodged some weld round it and done a quick fit.

I must say it looks a lot, (see pic, taken from directly above)
but I suppose the proof of the pudding is in the driving.

What do you think of it so far?

Thanks for the replies.

Paul G
Rescued attachment bone-fitted-2s.jpg

I have a picture just like that
Rescued attachment FrontSusp.jpg

The self centring is upto production car standards, nice easy drive

Camera angles are misleading, but it looks like I may have a tad more than you Mark.
I'm itching for a test run.

Paul G

Looks right. Driving a car without self centering is a pain on long journeys when you have to actively steer the whole time.
Remember you will have to readjust camber and toe in. The steering arm on the hub carrier is also slightly moved higher and it may be necessary to shim up the rack to eliminate bump steer.

quote:

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Originally posted by 907
Camera angles are misleading, but it looks like I may have a tad more than you Mark.
I'm itching for a test run.

Paul G

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Rescued attachment Wisbone Modification.JPG

That's the one.

Now I know who's it was I can say thanks.


Cheers

Paul G

Do you like the cad system I used, very easy to master

quote:

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Originally posted by 907
Camera angles are misleading, but it looks like I may have a tad more than you Mark.
I'm itching for a test run.

Paul G

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Yup, love the cad system Mark.
I'v just got the hang of a pencil myself, even the "edit" bit on the blunt end.

Thanks for all the help everyone.

I'll make a matching one for the other side and take it for a spin over xmas.

While I was on the saw / pipe bender / lathe, I made enough bits to do six,
(slack spell at work) so I'v got three chances to get it right.


Thanks again

Paul G

Or you could rose joint it - I did it this way to make it easier:

Pat...
Rescued attachment 2.jpg

Trouble with rose joints is they do tend to make the ride a bit harsh....and of course the cost.

[Edited on 9/12/2005 by Viper]

Got a great deal on the joints from TadLTD and as I'm using 60 series 13's, it can't feel any worse than the Avon did!

At least I'll have some suspension travel this time

Pat...

quote:

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Originally posted by Avoneer
Got a great deal on the joints from TadLTD and as I'm using 60 series 13's, it can't feel any worse than the Avon did!

At least I'll have some suspension travel this time

Pat...

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quote:

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Originally posted by Avoneer
Or you could rose joint it - I did it this way to make it easier:

Pat...

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Bloody hell - it's not like anyone to listen to me - I'm normally the student!

I though it was a good idea though!

Viper - all the front shocks supplied with all the Avons I know were too short and with the bottom bones parallel, the shocks were fully compressed and resting on the small bump stops - that's why most Avon you see are jacked up at the front.

Pat...

I had a request for a pic of the jig.

It's now in my photo archive, although Mark should get the credit for the mod to the book dims.


Chris, you have an email.

Paul G

quote:

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Originally posted by Avoneer


Viper - all the front shocks supplied with all the Avons I know were too short and with the bottom bones parallel, the shocks were fully compressed and resting on the small bump stops - that's why most Avon you see are jacked up at the front.

Pat...

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Hi All,


After Christmas lunch we, that is the chap next door, my son Gaz, and myself,
thought it would be a perfect time to test the new bones.
Better than sitting about getting indigestion, (or washing up).

So complete with paper hats it was off for a quick blast. I hope no one saw us.

The 22 mm offset's were a huge improvement, but still not as much self centering
as a production car.
I've had a measure and I make them 7.1 deg, (see diagram), although it's not easy
to measure from the ball joint centres.

Does anyone think I could go more? If so, how much?

Many thanks

Paul G

p.s. we all lost our hats, need a windscreen.

[Edited on 26/12/05 by 907]
Rescued attachment castor-angle-diagram-s.jpg

Paul , I think it only needs to be seen to self center when tested . Got 4.5degrees on mine which seems to be OK . It doesn't self center as well as a production car I find it fine. PS a screen don't really help !

Paul,

Don't worry about it - all will be fine.

My SVA tester simply put the wheel to full lock, then started the car forwards - as long as the wheel started to turn forwards he was happy. This he did both ways.

In reality the self-centering with a 22mm offset is noticeable in normal driving - if I release the wheel at speed it does tend towards a straight (-ish) line.

David

I think I've put the bush brackets on the chassis to the book dims, within a mil or so.

The top bone has an offset of 22 mm.

This means the centres of the balls of the b/j's are now 26 mm out of line, giving a
caster angle of 7.1 deg. (if my trig is right)


Although you can just about let go of the wheel at say 40 mph, if you pull out of a
tee junction without hands on the wheel it won't straighten out, but would do a
full 180 deg turn.

Is this what other peoples cars do ?

I have enough spares to make another set of top bones and if I can improve the
steering it's no hassle to do so. A couple of hours at the most.

Thanks for your input so far. It's much appreciated.

Paul G

(I've added to the diagram if this helps to explain)
Rescued attachment castor-angle-diagram2-s.jpg

Paul
Have you checked for any tight spots in the steering mechanism, a tight bush in the column or the rack, ball joints etc any friction here has to be overcome by the self centreing action, 7 degrees should be enough

Wimmera

New ball joints tend to be a little tight and will ease with abit of use. Also tracking may be having an effect, excessive toe in/out ? when you get the bodywork on the extra weight may have an effect. If you have any signs of self centering it's probably enough.

So the general consensus is that I have enough to pass SVA, so for now I'll leave it at that.
As some of you said, the b/j's may free up.

I'll put the spares in a safe place to gather a protective layer of dust, and use them if I have
to do some fine tuning at a later date. (If I can find them. )

Thanks everyone for your help on this.


Cheers

Paul G

Are all the measurements on this applicable to a Sierra upright as well as a Cortina one?

I hope to get my wishbone mounting brackets fitted this weekend and may as well get them close to the right place for the castor adjustment, and hopefully can stick with the bones I have (off an MK Indy).

Castor angle is all about the line through the balljoint centres. This is unaffected by the geometry of your upright, the castor angle will be the same whether you use cortina or sierra.

Camber may be different however.. and there is an issue with the balljoint taper being at a funny angle in the top of the sierra upright which may well require a redesigned wishbone so that the top balljoint has enough travel. There was an active thread about that recently.

I understand about the angles - I was actually considering the measurement in mm (or inches) as that would presumably vary if the sierra upright is a different height to the cortina one.

ah, I think I see what you mean. good point, and I don't know.

quote:

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Originally posted by blueshift
ah, I think I see what you mean. good point, and I don't know.

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