I would say its best to follow the best and I haven't seen anything like this on any race cars
just wondered if anyone had tried using ali to make the sierra inserts. I have a machine shop at my disposal and will be making some for myself.
thoughts ? comments ?
instead of going to all the hassle why not buy them off MK? i know i would
Cheers
James
quote:
Originally posted by auzziejim
instead of going to all the hassle why not buy them off MK? i know i would
Cheers
James
Luego charge about £66 IIRC for ali mushrooms, so sounds like a good idea to me!
One thing to consider is that steel tapers into ali tapers may be problematic because the steel can deform the ali. Presumably this can be got around
by choice of ali though.
Kingr
quote:
Originally posted by kingr
One thing to consider is that steel tapers into ali tapers may be problematic because the steel can deform the ali. Presumably this can be got around by choice of ali though.
Kingr
Luego ones are ali. They're quite pricey but I think that's because the top hole is offset and at an angle to enable you to tweak the
caster angle. Would be pretty tricky to make I expect?? No need to have that facility if you wanted to save the hassle tho.
Chris
[Edited on 28/5/03 by ChrisW]
quote:
Originally posted by ChrisW
Luego ones are ali. They're quite pricey but I think that's because the top hole is offset and at an angle to enable you to tweak the caster angle. Would be pretty tricky to make I expect?? No need to have that facility if you wanted to save the hassle tho.
Chris
[Edited on 28/5/03 by ChrisW]
quote:
Originally posted by James
MK ones are steel (hardened I presume) with an offset taper. £40 a pair.
ChrisW, it's easy to do the offset taper with a 4 jaw chuck in the lathe.
Cheers,
James
MK ones are not at an angle.
Is there a benefit to having an angle? If anyone know I'd be interested...
Cheers,
James
[Edited on 29/5/03 by James]
quote:
Originally posted by James
MK ones are not at an angle.
Is there a benefit to having an angle? If anyone know I'd be interested...
(well not that I can think of) I can only think its so that the balljoint has maximum movement in all directions when in the suspension is in a neutral position - I don't know
if this would be an issue though - my chassis is still sitting on the floor!
However, if this is the case then it would be severly limiting the amount of camber adjustment available from having it offset.
Dont know really, just my best guess!
I would also think that it would cause some uneven loading on the joint itself. I know they are designed to withstand massive forces but having the
tapered arm sitting @ an angle would be unnatural.
I would say its best to follow the best and I haven't seen anything like this on any race cars
Isn't the "angle" to ensure that the transit balljoint is central otherwise it has to be virtually at full angle of misalignment and
can lock up under extreme suspension bump.
I'm sure it was something like that...
Cheers,
Craig.
Just ignore me please....I just realised that there was a second page to the thread which already answered the question...Doh!
quote:
Originally posted by craig1410
Isn't the "angle" to ensure that the transit balljoint is central otherwise it has to be virtually at full angle of misalignment and can lock up under extreme suspension bump.
I'm sure it was something like that...
Cheers,
Craig.
Yes, that is what I was suggesting.
Cheers,
Craig.
Ok , makes sense.
but if you put the angle in the inserts and then you adjust the camber by rotating the inserts the angle will become twisted.
(confusing) anyone got a picture ???
I think I will follow the Mk approach and angle the threaded part of the top wishbone
[Edited on 29/5/03 by Glenn]
quote:
Originally posted by Glenn
but if you put the angle in the inserts and then you adjust the camber by rotating the inserts the angle will become twisted.
[Edited on 29/5/03 by Glenn]
> but if you put the angle in the inserts and then you adjust the camber by
> rotating the inserts the angle will become twisted.
No.
Well, yes, if you rotate the inserts, the angle will become twisted, but you don't adjust that way.
If your taper is on an angle you'd leave it set the one way (dead vertical at ride height for preference).
Angled or not, you'd adjust by screwing the top ball joint in and out of the threaded bit (technical term) in the top wishbone.
The advantage of angling the taper is that your top wishbone can then be straight.
Might be a minor strength / rigidity advantage?
- Greg H
quote:
Originally posted by kiwirex
> but if you put the angle in the inserts and then you adjust the camber by
> rotating the inserts the angle will become twisted.
No.
Well, yes, if you rotate the inserts, the angle will become twisted, but you don't adjust that way.
- Greg H
But not without affecting camber/KPI/Scrub radius...... Although you can compensate camber.
Kingr
quote:
Originally posted by kiwirex
> but if you put the angle in the inserts and then you adjust the camber by
> rotating the inserts the angle will become twisted.
No.
Well, yes, if you rotate the inserts, the angle will become twisted, but you don't adjust that way.
If your taper is on an angle you'd leave it set the one way (dead vertical at ride height for preference).
Angled or not, you'd adjust by screwing the top ball joint in and out of the threaded bit (technical term) in the top wishbone.
The advantage of angling the taper is that your top wishbone can then be straight.
Might be a minor strength / rigidity advantage?
- Greg H
quote:
Originally posted by kingr
But not without affecting camber/KPI/Scrub radius...... Although you can compensate camber.
Kingr
there is always some off-set to the dark side
The Kingpin inclination is the angle of the line that passes directly through the ball joints, so moving one in relation to the other will affect
this. Scrub radius, IIRC is the distance between the centre of the tyre, and the point at which the line through the ball joints intersects the
ground. Don't take these as gospel by any means, there are other people on this forum who know a lot more about these things, so I'll let
them correct me if need be, and tell you the extent to which these things will be affected. Basically, the crux of this is that you may be better off
design the insert to be static and adjusting the castor by making your wishbone brackets over-sized and packing them out with washers, allowing you to
move the wishbones back and forth a few mm.
Kingr
quote:
Originally posted by kingr
The Kingpin inclination is the angle of the line that passes directly through the ball joints, so moving one in relation to the other will affect this.
quote:
Scrub radius, IIRC is the distance between the centre of the tyre, and the point at which the line through the ball joints intersects the ground.
quote:
Don't take these as gospel by any means, there are other people on this forum who know a lot more about these things, so I'll let them correct me if need be, and tell you the extent to which these things will be affected. Basically, the crux of this is that you may be better off design the insert to be static and adjusting the castor by making your wishbone brackets over-sized and packing them out with washers, allowing you to move the wishbones back and forth a few mm.
Kingr
Glenn,
A couple of points to clarify:
quote:
correct but KPI is the angle measured as seen from the side
) quote:
This is genrally reffered to as king-pin offset
92 v 846 I make it. My point (yes there is
one...) is that it is "generally" referred to as scrub radius as far as I can see. quote:
No, I dont like the idea of shimming my wishbones, i know it's done but i would rather have my brackets correctly sized i just think it looks tatty.
quote:
Originally posted by craig1410
If you look from the side (assuming you mean side of the car) then you won't see the KPI angle at all. KPI is the angle formed between the vertical wheel axis and a line drawn through the upper and lower balljoints when viewed from the front. (Or from the side if you have 90degree steering lock
quote:
My book on suspension design by Des Hammill doesn't even have that term in the glossary, nor does the Race and Rally sourcebook by Alan Stanniforth. I've always heard it referred to as scrub radius (although the SAE do refer to it as Kingpin offset) and Kingr's description of it is spot on. Just don't start the argument again over whether zero scrub is optimum or not... By the way, try searching for "Kingpin offset" on google.com and then try "scrub radius" and see how many hits you get for each
quote:
That's fine if you have the means by which to accurately position your brackets to achieve the correct castor angle right from the start but that leaves you with another problem - what is the "correct" angle? Also, if the bodywork is fitted correctly then you can hardly see the suspension mountings and if you paint the edges of the washers black (or whatever colour your chassis is) then they look fine IMHO.
Cheers,
Craig.
Glenn,
Terminology is a wonderful thing isn't it?
Don't worry about a picture of KPI on my account since I have plenty of pictures in the above mentioned books.
As for Kingpin Offset, try searching on this forum for the term and you will only find your own reference to it. Search for scrub radius and
you'll find over three pages of hits. I'm not saying it isn't a synonym for scrub radius but just that "generally" it
isn't used in the context of this forum. Anyway, 'nuff said.
Finally on the castor adjustment, how do the race cars adjust camber? Surely they don't cut their chassis brackets off and weld them further
along each time they need to change castor angle? The only alternative that I can see is to use spherical bearings to swing the wishbones around as
used on the back of the Tiger Avon. Personally I don't see any problem with using washers, shims or machined spacers since the end result of
being able to set up the suspension correctly will more than make up for any "tatty"ness. I'll try to remember to admire your non-tatty
chassis mounts when I'm driving round the outside of you in the corners...
Only kidding mate, good luck with your build!
Cheers,
Craig.
Well just to clear it up, I have done a little drawing, It's in my photo archive so now weather your from the US, UK or abbojabbi you'll
know what I mean.
"a rose by any other name would still smell as sweet" unless it was called a stench-bush
The strange things is that 2 books by the same guy, Allan Staniforth, use different naming conventions.
[Edited on 31/5/03 by Glenn]
Glenn,
At the risk of appearing to be a real pain in the ass I have to say that I think the drawing just adds confusion. It describes KPI and scrub radius
fairly well but what on earth is it trying to show with respect to camber? It shows camber angle as being the angle between the wheel centreline and
some other arbitrary line.
Now if that other line happened to be normal to the road surface then it would make sense but as it is it doesn't make sense.
Here is a very quick diagram made in MS Paint to illustrate my point:
Anyway, I don't know about you but I'm bored with this contest of geometry teaching skills. I know what's what and I expect you do too
but neither of us are very good at describing it. Lets both stick to building cars and leave the teaching to Uncle Ron!
Cheers,
Craig.
Syd,
No, I've not had any revelations on the roll centre front. I did read a good webpage on the subject (
http://web.umr.edu/~formula/library/sae_paper/paper.html )
It talks about the dynamics of Roll and made me think of an interesting scenario. If the roll centre is above the centre of gravity then the car will
lean into the corners
This probably wouldn't be immediately useful since the suspension geometry of most cars would not induce enough dynamic camber on the outside
wheel in this scenario. If the roll centre and CofG coincided though, then theoretically you wouldn't get any roll at all. According to the above
webpage this is what the designers aim for and by getting them close to each other you can use lighter anti-roll bars or none at all.
Anyway, I'm not going to worry about it or I'll never get my car built!
Cheers,
Craig.
quote:
Originally posted by craig1410
Glenn,
At the risk of appearing to be a real pain in the ass I have to say that I think the drawing just adds confusion. It describes KPI and scrub radius fairly well but what on earth is it trying to show with respect to camber? It shows camber angle as being the angle between the wheel centreline and some other arbitrary line.
Agreed!
For the record the original MK insert (coloured blue ) was made from EN8 (high carbon steel). They where un-hardened. Ali and steel together do not
mix due to electrolitic action.