Hello all,

Would appreciate your advice please...

Having just spent best part of a day trying to work out why I cant get top rails
J1 and J2 to fit, have discovered that measurements are wrong in the Book,
but correct in the McSorley plans (1467 instead of 1476)..

Should I just forget the book and go from the McSorley plans ? Is there any disadvantage in doing this ?

No disadvantage at all!

Use Jim's plans for the angles and dimensions, and 'The Book' for general arrangement, build philosophy, etc.

happy building!

David

And so say all of us!

Jim's plans don't cover suspension, thats where the fun starts, front and rear

Incidentaly, while we're on the subject of suspension, I seem to recall the book suggests 14" shocks, which are way too big, and all the suppliers seem to go for less (GTS are 12", loloquality are 10", dampertech IIRC are 12". I couldn't find any previous reference to this on the forum before though. What has everyone else used?

Kingr

according to recent posts, lolo are 14 inch now....


atb

steve

I got mine from GTS Racing and had to do some mods to the upper mounting (front susp.) arrangement to get them to fit. The lower mount goes on the lower wishbone as you would expect but the top mount has to sit at an angle where it hits the top outer vertex of J1 and J2. This give maximum clearance between wishbone and spring although it is still very very tight (about 2mm clearance either side of spring.)

I have standard 'book' wishbones from Loloquality and a McSorely 7+4 chassis and ended up with a 6.25 inch ride height at full rebound which should give me around 5 inches (to bottom of chassis rails) when loaded up.

Here's a pic to explain better.
HTH,
Craig.

That angled mounting looks rather interesting. how is that fixed on there? Just curious.

craig10, what happens in droop, do the upper wishbones not foul the coils?
Have a look at the RHS shock mounts on the front of one of my Beetle chassis below, as an alternative mount.
Rescued attachment VW front end.jpg

Craig, something not right there m8... it my humble opinion, i also have just fitted same units to chassis and have not needed to do what you have done, also my clearance is fine. i shall try taking photo tonight, PS Im in Livingston area if its any help.

Cheers

Mine has the old lolo shocks and they were 12" open length. They work fine. What engine are you putting in the car. Get a couple of mates to stand in the engine bay on a plank or something and see how far your chassis drops, you might need to alter the position to the side of the rail to get your height without preloading the spring too much.

sorry about that.
Rescued attachment shock mount 1.jpg

Rorty,
I set the clearance at full droop so it is fine and clearance improves as the wishbone rises.

One reason my clearance is more of a problem is that the Lolocost wishbones use a heavier section tubing. I can't remember exactly how big but it is a few mm bigger for sure.

I had the option of mounting the shockers underneath J1 and J2 as shown in some designs but I didn't want my springs to be so far off the vertical as I think I'm right in saying that this goes against best practice. It will also (I think) place additional loads on the suspension mounts and to be honest I don't like the look of it, aesthetically. The GTS coilovers are quite pretty and I want them to be seen.

I did a number of calculations and loads of little sketches and to ensure that my desired ride height will occur at the point in the shocker stroke which is recommended by GTS Racing (dozracing) in their PDF file. I think from memory this gives me 1.25 inches of bump and 0.75 inches of rebound wrt ride height. I can adjust the spring seats to achieve this height once the car is at full weight.

I aimed for horizontal lower w/bone (mount to balljoint centre) and chassis parallel to the ground when setting ride height.

Have I err'd?
Craig.

We had a thread ages ago about the wushbones not giving enough castor angle, I killed 2 birds with one stone by making the upper wishbones with more setback and made of bent tube to clear the shock.

You can see the castor angle (exagerated by the camera angle) and the crazy scrub radius which I cannot get my head around at the moment - the cortina must have had the same!
Rescued attachment CastorClearance.jpg

Cheers Mark and yes I would do it all differently second time around as I expect most of us would...

The bent tube seems to be a good way to go although I suspect (no hard facts btw) that it won't be so strong as a nice triangular wishbone. I don't know if the difference is significant though.

As for your scrub radius, I wouldn't get overly concerned as I have what looks like the same "problem". My suspension book by Des Hammill (ISBN 1-903706-73-4) says that as long as the KPI line intersects the ground at the inside edge of the tyre then it is "acceptable" and only when it gets more than 1 inch inboard of the inside edge of the tyre is this "too much"
Bear in mind too that having zero scrub will give you a lifeless steering which won't load up under cornering the way that you would want. Having too much scrub may make it twitchy and somewhere in between lies the ideal.

I'll post another image in a minute which might further help to convince you.
Cheers,
Craig.

Here is the other pic which I took of the book by Des Hammill. Look at the geometry of the rather pretty suspensin system here. Not an ideal angle but you can clearly see that plenty of scrub is evident. Look how far the disc sits inboard!
I have just looked through the various publications I have here and many shots of Lotus 7 esque cars show lots of apparent scrub.

I don't know about you mate but I ain't worried just yet although I may avoid buying expensive wheels just yet...

My wheels are Capri Laser (RS Style) 13inch with 185 tyres by the way.

Cheers,
Craig.

Sorry for all the posts but I missed a couple of responses:

Blueshift, check my website for more detail but I basically tack welded the bracket where it hit before taking the shocker off to avoid heating the rubber bushes and then welded a piece of 25x3mm bar across the back of the mount to join it to the chassis tube (J1/2). This gives a very strong triangular structure and maximises clearance (what there is of it) to the spring coils. My website has more pics showing detail.

Hornet, I'd be interested to see what you have done to avoid this situation. I'm happy with it the way it is but come SVA time the inspector might not like the proximity to the wishbones of the coils. They do clear but as I said, only by 2mm each side at full droop. Should be okay as long as it doesn't foul I think (Anyone disagree based on SVA experience?) My SVA manual should get delivered any day now from Amazon so I will check the fine print on this then. I can always hack the top brackets off and weld underneath or something if necessary.

Thanks once again for all the feedback.
Craig.

I've always stood by my beliefs and theory on scrub radius, as it has always worked for me.
However, I'm always open to other proven results, which aparently, Hammill demonstrates with his book.
I'm going to add Hammill's book to my Book Wish-list!

Mark, are you absolutely positive you have the original wheels?

I think I will double check with ford on part numbers, I also have another set (alloys from a capri) which I will try

You are also going to find you need to hack an ugly hole in your nosecone to fit it over the modified bracket mount, don't know if that will bother you at all, as standard ones sit on the rail where yours is.

yours, Pete.

I don't know if this is relevant or not, but I always found that the steering on a Cortina left a lot to be desired.
I'm not talking design just the driving and handling.
They would get through front tyres at an alarming rate, probably due to scrub radius. They would wear the inside and outside edges of the tread.

Is this just my opinion or is it a case of beggars choice when looking for appropriate uprights?

Terry

Rorty,
I agree with most of what I recall from your previous posts on the subject. It is only when I started to look at other Locosts in various publications and at my own that I started to wonder. There is even a picture in the RC book 2nd edition which shows a "racing" locost which looks like it has lots of scrub as well!

When I say I'm not worried this is mainly because I have quite enough to worry about before we get down to this level of detail. There is an easy fix - use different wheels - so I'll worry later, if and when I find the handling to be a problem. My uprights came from a fellow LB forum member who I shall ask if he had any problems when they were fitted to his car.

The Des Hammill book is a good read and tends to be more "practical" than the Alan Staniforth book which I also own. Given your "practical, use what works" approach, I think you would appreciate it Rorty. Only downside is that the book was something like 17..99GBP IIRC.

Peteff,
I'm not too concerned about the "ugly" hole as I'd prefer to see my "pretty" shock/spring units more upright and prominent and I can make the ugly hole look less ugly with a bit of work hopefully. I can maybe build a little cowling over it or something...

Cheers all,
Craig.

Spyderman,
Interesting what you say on the Cortina handling, I've never driven one myself but somehow I don't find it difficult to believe that they didn't handle well (except the Lotus variant which I suspect was better)

However, I can't believe that there can be that much difference between one type of upright and another and most potential flaws could surely be corrected by the way the upright is mounted and which wheels are used etc. Yes you can get titanium custom made uprights which are a far cry from Cortina steel ones but in terms of basic geometry (ignoring ackerman stuff for now) there is only really KPI to worry about isn't there?

What I am trying to say is that just because the Cortina handled like a big bulky beast (which it was) doesn't mean that the uprights will doom all of us Locoster's to a similar fate just because we use them?

I don't want to state the obvious but can I assume that your Cortina tyres had enough air in them. Underinflation will cause excessive wear on the tyre shoulders. Just a thought...

Cheers,
Craig.

Craig,

My top front spring mounts are similar to yours - just not quite as neat - so you aren't the only one!!

Also - with engine/box in place (nearly running weight so to speak) spring bases are set in the middle (approx) of both high/low extremes (stronger springs will allow it to be unwound).

Did you get my email?

ATB

Simon

[Edited on 15/7/03 by Simon]

Craig,
I'm not knocking the Cortina uprights!
It's just that, if you are using something that is less than ideal in the handling stakes, then you should expect the results to be less than perfect.
Obviously the Cortina uprights have a less than ideal scrub radius, but this shouldn't stop you from having a reasonably handling car, after all yours will be a damn sight lighter than the donor.

I'm merely pointing out that the cortina uprights although useful (being one of the few suitable for double A-arms) is not necessarily perfect.
Just trying to help! If you realise that the donor parts have limitations then you won't expect too much from them!

Terry

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

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.

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..

quote:

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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..

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craig1410:

quote:

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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.

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quote:

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Originally posted by Spyderman
Didn't you ever notice the tyre squeel when turning, especially on smooth surfaces?

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quote:

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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...

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quote:

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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.

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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

quote:

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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).........

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[

In OZ, the standard was a straight 6!

quote:

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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!!

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quote:

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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

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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?

quote:

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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.

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quote:

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Originally posted by jcduroc

This is not cheating.

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quote:

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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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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

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