leto
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| posted on 15/7/03 at 04:55 PM |
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Hello!
I have done my best to measure the Cortina upright. This is not a easy task, and I don't trust my result to be 100%.
Anyhow, according to my results...
The king pin angle is around 5 degrees (4.8 calculated), this will give a large scrub radius with almost all rims. It will take an offset of around
-120mm to get zero scrub with 13" rims.
Still I don't think Mr Champion made a bad choice, because there is not much to chose from. I am sure builders on other continents can testify
to that. For a low budget, easy to build, ford based project, there simply is no other alternative.
However, I am a little curious about what what the Ford people had on there mind when it was designed. 
Happy building!
Leif 
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craig1410
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| posted on 15/7/03 at 06:01 PM |
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Spyderman,
You seem to think I was having a go which I wasn't, I was just trying to point out that no matter how bad the uprights may or may not be, they
can usually be compensated for by adjusting other factors so that the end result is close to optimum. This was assuming that the uprights were
designed in a sensible way to begin with...
However.....
Having seen Leto's post that suggests Kpi to be only 5 degrees I may have to change my mind. In the Des Hammill book it says, "Consider
the optimum range of Kpi to be between 9 and 12 degrees, with 10 degrees being usual."
If your calculations are correct then the angle designed in by Ford is way off!! This susprises me that they could have got it so wrong and, no
offence, but I will have to do some measuring of my own to confirm your figures. I don't doubt your figures but it is just so far away from what
I'd expect. I'll let you know what I make it. Don't take this the wrong way but I hope you are wrong... 
I suppose the good thing is that this may open up the door to a whole new range of wheels from the front wheel drive fraternity as these tend to have
bigger offsets. It may also require that a larger rolling circumference wheel/tyre combination is used as this would raise ride height and reduce
scrub radius too.
My rear axle could accommodate wheels with more offset as my rear track is 57.8 inches (52" for Escort) and the chassis is only +4" over
book. Therefore I should have 1.8 inches (46mm) to play with before fouling the arches (if you follow the math). That would let me go to 35/38mm
offset or so quite comfortably which would open the door to wheels from Sierra's and Mondeo's and Fiesta's etc. This could work out
quite well!!
Cheers,
Craig.
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Viper
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| posted on 15/7/03 at 06:47 PM |
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I allways thought the MK4/5 cortina handled very well, it turned in well and had predictable oversteer when pushed.
And as for champions choice..it wasn't... take a look at pre lit westfields..
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Spyderman
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| posted on 15/7/03 at 10:58 PM |
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quote:
Originally posted by Viper
I allways thought the MK4/5 cortina handled very well, it turned in well and had predictable oversteer when pushed.
And as for champions choice..it wasn't... take a look at pre lit westfields..
Didn't you ever notice the tyre squeel when turning, especially on smooth surfaces?
Always sounded like Starsky and Hutch whenever manouvering in carparks.
Terry
Spyderman
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Rorty
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| posted on 16/7/03 at 01:43 AM |
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craig1410:
quote:
I suppose the good thing is that this may open up the door to a whole new range of wheels from the front wheel drive fraternity as these tend to have
bigger offsets. It may also require that a larger rolling circumference wheel/tyre combination is used as this would raise ride height and reduce
scrub radius too.
You'll also be into the realms of making longer front wishbones to keep the track the same.
All in all, a good plan! Just think of the benefits longer wishbones would have with regard to Metalastic bushes, room for coilovers etc.
The bearings shouldn't groan too much as the all in weight is a fraction of the origional.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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TheGecko
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| posted on 16/7/03 at 01:46 AM |
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quote:
Originally posted by Spyderman
Didn't you ever notice the tyre squeel when turning, especially on smooth surfaces?
My old Corona did that for a long time too and was hard on tyres. Once a competent wheel aligner fixed the ~10mm of toe-in (caused by hitting a kerb)
it was much quieter Perhaps the Cortina you drove was not a perfect example of Dagenham's finest product.
Obligatory project update: My engine and gearbox have arrived at the freight depot (40km across town) and my mate with a trailer has been arranged to
collect tomorrow. With that all in hand for final measurements I can make a start on my chassis within the next week or so. Finally
Dominic
Brisbane, Australia
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leto
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| posted on 16/7/03 at 05:51 AM |
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quote:
Originally posted by craig1410
...............
However.....
Having seen Leto's post that suggests Kpi to be only 5 degrees I may have to change my mind. In the Des Hammill book it says, "Consider
the optimum range of Kpi to be between 9 and 12 degrees, with 10 degrees being usual."
If your calculations are correct then the angle designed in by Ford is way off!! This susprises me that they could have got it so wrong and, no
offence, but I will have to do some measuring of my own to confirm your figures. I don't doubt your figures but it is just so far away from what
I'd expect. I'll let you know what I make it. Don't take this the wrong way but I hope you are wrong...
I sincerely hope so to
I have doubts in my figures and have remeasured several times but the results are about the same and still way out of line  So please, give it a
try, I will be very pleased if proven wrong
quote:
I suppose the good thing is that this may open up the door to a whole new range of wheels from the front wheel drive fraternity as these tend
to have bigger offsets. It may also require that a larger rolling circumference wheel/tyre combination is used as this would raise ride height and
reduce scrub radius too.
205/60-15" and ET 45 (Audi rims) gives a scrub radius of 75mm and a ride hight of about 155mm, with a book frame.
Offset don't seam to be related to fwd/rwd, some Citroen and Peugeot have small offsets (ET<20) while Ford (european) usually have larger
offsets.
Happy building!
Leif
[Edited on 16/7/03 by leto]
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timf
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| posted on 16/7/03 at 01:12 PM |
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having read the post about the cortina kpi i did some measurements and calcs
measurents as on a sierra and calcs from the drawing posted in vipers photo archive
on ther car the kpi base on mcpherson strut measures about 10.5 degrees and paper calc using the drawing with adaptor calcs to 10.9 degrees.
the lotus cortina vvarient MK1,mk2 where based on mcpherson strut fron suspension and not double wishbone.
when i drove a cortina i noted that they turned in very quickly then went into severe understeer very quickly.
Tim
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Alan B
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| posted on 16/7/03 at 04:48 PM |
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quote:
Originally posted by craig1410
....... I don't find it difficult to believe that they didn't handle well (except the Lotus variant which I suspect was better).........
Lotus did a Mk3/4/5 Cortina?????..
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Viper
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| posted on 16/7/03 at 05:20 PM |
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[
Lotus did a Mk3/4/5 Cortina?????..
No only MK1 & 2..
I believe there was a v8 mk4/5 Cortina in the south african market, biggest we had (unless some one knows better) was the 2.3 cologne V6.
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Rorty
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| posted on 17/7/03 at 01:11 AM |
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In OZ, the standard was a straight 6!
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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jcduroc
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| posted on 17/7/03 at 01:39 AM |
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quote:
Originally posted by craig1410
However.....
Having seen Leto's post that suggests Kpi to be only 5 degrees I may have to change my mind. In the Des Hammill book it says, "Consider
the optimum range of Kpi to be between 9 and 12 degrees, with 10 degrees being usual."
If your calculations are correct then the angle designed in by Ford is way off!!
From drawings the KPI of thr Cortina Mk3 upright is 4.3º (top balljoint eye at 4.2º, lower one at 4.4º).
This is confirmed by an horizontal difference of 12.66 mm over a height difference of 168.39; do your trig...
Also from drawings the hub mounting face is 97.1 mm away from the upright face; with an ET38 wheel and a 600 mm diameter tire scrub radius is ±91
mm!...
I guess someone has to check this on a real Cortina Mk3/4/5 (those which have double wishbones).
Cheers, João
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leto
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| posted on 17/7/03 at 09:23 AM |
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quote:
Originally posted by jcduroc
From drawings the KPI of thr Cortina Mk3 upright is 4.3º (top balljoint eye at 4.2º, lower one at 4.4º).
This is confirmed by an horizontal difference of 12.66 mm over a height difference of 168.39; do your trig...
Also from drawings the hub mounting face is 97.1 mm away from the upright face; with an ET38 wheel and a 600 mm diameter tire scrub radius is ±91
mm!...
I guess someone has to check this on a real Cortina Mk3/4/5 (those which have double wishbones).
Cheers, João
Hello, João!
You have drawings!  That is a little bit like sheeting you know but I don't mind at all, getting reliable dimensions is worth very much to
me. So many thanks for what you have shared!
From what I can understand the dimensions refer to the holes (eyes?) for the joints. Will check them this afternoon.
There is only two dimensions missing to make the layout complete, one, I think, can be reconstructed from your info on scrub radius. But i would
really prefer to have them in figures. So can you please, give the horizontal and vertical offset for one of the points on the KPI?
Any info. on the "steering arm" would also be much appreciated.
Cheers, a cup of amber will be raised to your honor, Leif
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Mark Allanson
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| posted on 17/7/03 at 04:50 PM |
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As far as I know, the KPI is there to give you a camber change with weight transfer on lock, so a car with little suspension movement will need less
KPI, ideal!
Or am I missing something?
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jcduroc
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| posted on 19/7/03 at 01:07 AM |
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quote:
Originally posted by leto
You have drawings! That is a little bit like sheeting you know but I don't mind at all, getting reliable dimensions is worth very much to
me. So many thanks for what you have shared!
From what I can understand the dimensions refer to the holes (eyes?) for the joints. Will check them this afternoon.
There is only two dimensions missing to make the layout complete, one, I think, can be reconstructed from your info on scrub radius. But i would
really prefer to have them in figures. So can you please, give the horizontal and vertical offset for one of the points on the KPI?
Any info. on the "steering arm" would also be much appreciated.
This is not cheating. The fact is that I have drawings which dimensions I never could verify because I'm still chasing a Cortina Mk3; therefore
I will not publish something that might be eroneous and be responsible for it.
However I'm willing to share everything I might know (if anything) with fellows Locostbuilders.
E-mail me off list and I'll seek to help with the dims I have.
Cheers
João
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leto
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| posted on 19/7/03 at 06:17 AM |
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quote:
Originally posted by jcduroc
This is not cheating.
Sorry just a bad joke.
quote:
The fact is that I have drawings which dimensions I never could verify because I'm still chasing a Cortina Mk3; therefore I will not publish
something that might be eroneous and be responsible for it.
However I'm willing to share everything I might know (if anything) with fellows Locostbuilders.
E-mail me off list and I'll seek to help with the dims I have.
Cheers
João
I understand that you don't want to publish anything you do not trust, I did hesitate on sharing my measuring as I knew it was not correct. I
was hoping to find something to compare it with.
Have had a look at a upright. The height difference of 168.39 agrees with the Cortina upright. The horizontal difference is hard to measure with any
accuracy, something within 10 - 15 mm.
I will E-mail you of list.
Best regards
Leif
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kiwirex
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| posted on 19/7/03 at 08:53 AM |
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Mark Allanson:
> As far as I know, the KPI is there to give you a camber change with weight transfer on lock,
> so a car with little suspension movement will need less KPI, ideal!
I think it's also there to reduce (or get right) the scrub radius. I.e. difference between centre of tyre and line between upper & lower
balljoints (kingpin) extended to the ground.
Bigger scrub radius = heavier steer + more feel.
Again, on a light car, the cost of bigger scrub radius is probably minimal anyway.
Cheers
- Greg H
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Mark Allanson
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| posted on 19/7/03 at 05:44 PM |
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If you look at a citroen 2CV on full lock, the outer wheel is at almost 45 degrees negative, this is because when actually turning, the car is at 45
degrees and trying to wear off its door handles!, but the road wheel is almost vertical
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