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Fiat 126 Blackbird - Front End
T66 - 9/12/09 at 05:26 PM

I am shopping for Cortina uprights for my Fiat, I would like new units for a car in the 550kg region.

The rallydesign ones have caught my eye @ £195 a pair.

Wozsher will be supplying wishbones (I hope).

Anywhere else to consider ?


I would prefer to buy everything from the same place in one go , ie brakes,hubs and so on , if possible.

britishtrident - 9/12/09 at 06:03 PM

As you will have next to know weight over the front wheels Cortina geometry won't really suit your car.

aitch - 9/12/09 at 06:14 PM

quote:
Originally posted by britishtrident
As you will have next to know weight over the front wheels Cortina geometry won't really suit your car.


can you elaborate, whats wrong with the geometry? im doing a BEC mid engine and planning on taking the same route, although i will have a little more weight o the front.

and also if the geometry is not right then what would be a better option ?

aitch

T66 - 9/12/09 at 06:33 PM

Yes would like to know more on your thoughts Trident ?

T66

britishtrident - 9/12/09 at 07:53 PM

Cortina geometry isn't exactly known for good self centering it was design to provide light steering on a heavy car (some Cortinas had very heavy iron block V6 engines) without PAS.

If you look at the steering geometry used on old small rear engine cars like the Hillman Imp & Davrian you can see how they generated self centering
What is needed is an upright that is light, easy to dial in a lot of caster and has a larger king pin inclination than the the Cortina. These days such things are a bit thin on the ground so the only option is to look at what is available from FWD cars or mid-engined sports cars like the MGTF.

The interesting thing is the MGTF uses Metro uprights with a dummy spindle to act as a live stub axle in place of the CV joint. I believe the uprights are swapped left to right and the steering arms unbolted and changed over.

T66 - 9/12/09 at 08:15 PM

Ok....

The reason I have looked at the RD uprights is they come with more castor built in ontop of the stock Ford items.

Unless I am wrong of course.


Point noted re the MGTF uprights, I will have a look about.


Anyone else want to join in ??

grassracer - 9/12/09 at 08:55 PM

Try www.berrisford.co.uk
or www.drdracing.co.uk

Fabricated uprights/alloy hubs used for racing where mid engined is the norm not the exception, not sure about road use but can't see why not really

aitch - 9/12/09 at 08:57 PM

i dont understand the whole geometry issue, would be nice to get some advice other than thats not right,

ive looked at diagrams of the uprights "original" and they show the ball joints offset bottom being furthr back than the top with the steering arm horizontal !! is this how they should be or should they be in line vertically? and what are the differences in handling/ self centering?

aitch

JEPY - 9/12/09 at 10:19 PM

I'd picked up a pair of sierra uprights for a 126 conversion but must admit I hadn't given much thought yet to suspension geometry.

Will have to get me book out and sketch it out I think.

T66 - how far are you into the conversion?

J

redscamp - 10/12/09 at 01:43 AM

what about vauxhall viva?
too old school?

britishtrident - 10/12/09 at 07:50 AM

A lot of self-centering is generated by king pin inclination rather than caster.

T66 - 10/12/09 at 09:32 AM

I am buying up the parts over the next few months, Retropower are doing the big bits/initila build up

And I finish off the car.


The front wishbones are going to come from Wozsher

I will be speaking with MNR & RD about these issues raised here.

The rear arms are coming from Berrisford



cheers

aitch - 10/12/09 at 09:59 AM

quote:
Originally posted by britishtrident
A lot of self-centering is generated by king pin inclination rather than caster.


suspension geometry is new to me, can you explain king pin inclination?

is the top ball joint being further forwards than bottom ball joint?
looks about 5degrees in the sierra oprights?

aitch

smart51 - 10/12/09 at 11:47 AM

quote:
Originally posted by aitch
quote:
Originally posted by britishtrident
A lot of self-centering is generated by king pin inclination rather than caster.


suspension geometry is new to me, can you explain king pin inclination?

is the top ball joint being further forwards than bottom ball joint?
looks about 5degrees in the sierra oprights?

aitch


KPI is the top ball joint being further towards the centre line of the car than the bottom. 10° is a typical figure.

Castor angle is the top ball joint being closer to the rear of the car than the bottom one.

britishtrident - 10/12/09 at 03:10 PM

Not sure what the KPI was on the Cortina but it wasn't much something like a couple of degrees.

One of the side effects of adding negative camber is that it also increases KPI ---- the only exception to this I can think of is the offset mushroom conversion on a Sierra style strut.

[Edited on 10/12/09 by britishtrident]

aitch - 10/12/09 at 05:47 PM

quote:
Originally posted by smart51
quote:
Originally posted by aitch
quote:
Originally posted by britishtrident
A lot of self-centering is generated by king pin inclination rather than caster.


suspension geometry is new to me, can you explain king pin inclination?

is the top ball joint being further forwards than bottom ball joint?
looks about 5degrees in the sierra oprights?

aitch


KPI is the top ball joint being further towards the centre line of the car than the bottom. 10° is a typical figure.

Castor angle is the top ball joint being closer to the rear of the car than the bottom one.


Hi Smart51

can i just confirm, you say top ball joing closer to the rear of the car although all the drawings i see of the sierra uprights have the top ball joint closer to the front of the car, steering arm forwards, brake caliper rear??

thanks
aitch

smart51 - 10/12/09 at 06:50 PM

quote:
Originally posted by aitch
Hi Smart51

can i just confirm, you say top ball joing closer to the rear of the car although all the drawings i see of the sierra uprights have the top ball joint closer to the front of the car, steering arm forwards, brake caliper rear??

thanks
aitch


Look here for a pic and description of castor angle. top ball joint should be further back than the bottom so that the line that intersects the two falls on the floor in front of the tyre.

mad-butcher - 10/12/09 at 07:06 PM

recommended reading
competition car suspension by allan staniforth

tony

britishtrident - 10/12/09 at 09:56 PM

Stainforth's orignal book "High Speed, Low Cost" shows how to use Mini parts for a midi single seater.

MikeRJ - 10/12/09 at 10:01 PM

quote:
Originally posted by aitch
can i just confirm, you say top ball joing closer to the rear of the car although all the drawings i see of the sierra uprights have the top ball joint closer to the front of the car, steering arm forwards, brake caliper rear??


That definitely doesn't sound right, have you got a link to a pic that shows this?

The object of castor is to build in the same effect that castors have on shopping trolleys etc. To do this the point at which the steering axis intercepts the ground has to fall in front of the centre of the tyre contact patch. The only way you can achieve this to any noticeable degree is to have the top balljoint behind the bottom one (i.e. further to the rear).

aitch - 11/12/09 at 08:56 AM

quote:
Originally posted by smart51
quote:
Originally posted by aitch
Hi Smart51

can i just confirm, you say top ball joing closer to the rear of the car although all the drawings i see of the sierra uprights have the top ball joint closer to the front of the car, steering arm forwards, brake caliper rear??

thanks
aitch


Look here for a pic and description of castor angle. top ball joint should be further back than the bottom so that the line that intersects the two falls on the floor in front of the tyre.


yes that sounds right after some reading, i had made the wrong assumption tht the steering arb was horizontal.
was out for a ride on my bike yesterday and realised its like the steering rake "andgle of th forks" i get it it now

aitch

T66 - 11/12/09 at 10:47 AM

Same as your bike then, so you did know...

NS Dev - 27/11/10 at 10:53 AM

quote:
Originally posted by britishtrident
Not sure what the KPI was on the Cortina but it wasn't much something like a couple of degrees.

One of the side effects of adding negative camber is that it also increases KPI ---- the only exception to this I can think of is the offset mushroom conversion on a Sierra style strut.

[Edited on 10/12/09 by britishtrident]


Digging up an old thread here, but stmbled across it looking for something else!

Have to say, regardless of KPI, I never had ANY issue with self centering or feedback on my old grasstrack car, and I ran cortina uprights on that, and you could pick the front end up by hand easily!!!

I have built the front end of the fiat with plenty of castor adjustment potential, and I'm quite sure it will be fine.

its looking pretty smart, think Ivan (T66) will prob post some updates on here sometime soon!

scootz - 27/11/10 at 11:04 AM

I think he's keeping (some of) us in suspenders!

I've had a sneak preview and it looks fabby-do!

MikeR - 27/11/10 at 10:03 PM

I saw it a couple of weeks ago when i popped into Retro power .... I liked it, but not as much as the 'beetle' they've got in

[Edited on 27/11/10 by MikeR]

T66 - 2/12/10 at 04:45 PM

Nice to see the little Fiat is of interest , I was due a visit to Nat & cal this week for a car update & beer but the weather has put paid to that...

Here it is with a wheel or two on, to give the general idea of what we are doing.

I doff my hat to Nat & Cal for the progress they have made so far, I am waiting of a few updated pictures and promise to upload them when I get them.










Minicooper - 2/12/10 at 08:32 PM

Hello,
What are you using for the drive to the rear wheels, I can see some sort of transmission there

Cheers
David

T66 - 2/12/10 at 09:09 PM

quote:
Originally posted by Minicooper
Hello,
What are you using for the drive to the rear wheels, I can see some sort of transmission there

Cheers
David





Its secret at the moment - Ssssssssh say nowt

scootz - 2/12/10 at 09:14 PM

I was tempted to answer in your absence Ivan, but had a feeling you were keeping it quiet!

T66 - 2/12/10 at 09:35 PM

quote:
Originally posted by scootz
I was tempted to answer in your absence Ivan, but had a feeling you were keeping it quiet!




Hahhaha - I doubt Nat & Cal could ever patent whats in the back of the Fiat , but hats off to them both, Just hope it works lol.



My mind is focused on Blue Book Regs at the moment, cages, footprints, and plates and stuff....










NS Dev - 6/12/10 at 09:47 AM

LOL don't panic Ivan!!

Re. the transmission, come on, have a guess, somebody on here will recognise it!!!

have a look on our website for more pics:

retropower fiat build

Minicooper - 6/12/10 at 06:08 PM

Range Rover Classic 4/4.2V8 1989-1995 transfer box, 3.2 ratio is spot on for a bec depending on wheel size of course.

How heavy is it?

Cheers
David

NS Dev - 6/12/10 at 06:49 PM

quote:
Originally posted by Minicooper
Range Rover Classic 4/4.2V8 1989-1995 transfer box, 3.2 ratio is spot on for a bec depending on wheel size of course.

How heavy is it?

Cheers
David


Spot on!!

Around 30kg

Not light, but then that includes the diff, plus you don't need any chassis around the diff area to resist the tension forces on the chain. (and that soon gets pretty heavy) plus it should be maintainance free

Minicooper - 7/12/10 at 06:12 PM

quote:
Originally posted by NS Dev
quote:
Originally posted by Minicooper
Range Rover Classic 4/4.2V8 1989-1995 transfer box, 3.2 ratio is spot on for a bec depending on wheel size of course.

How heavy is it?

Cheers
David


Spot on!!

Around 30kg

Not light, but then that includes the diff, plus you don't need any chassis around the diff area to resist the tension forces on the chain. (and that soon gets pretty heavy) plus it should be maintainance free


30 kgs that's not to bad, the quaife boxes are 24kgs without oil you would also need to add a coupling of some sort to that
This one
http://www.quaife.co.uk/catalogue/products/qba2r they do have a reverse as well which is obviously very useful on a bike engined car but at £2,000 plus just for the box not cheap

I looked at these sorts of boxes when I was looking for a alternative cheap, reliable and quiet transfer box, I saw the 1.2 ratio and dismissed them, I completely forgot about the other ratio!

The morse chains chains are very strong reliable and quiet, I had one on a 7.8 litre Oldsmobile with no problems

Cheers
David

NS Dev - 7/12/10 at 10:50 PM

I nearly did the same thing, then I thought that maybe in some way running in low ratio would be a problem, then thought that of course it wouldn't, its just an epicyclic, no different to a typical auto box!

The coupler is the tricky bit, but after a couple of days farting about, I happened on "Coventry luck" as I now call it, whereby everything in engineering is made there!! I ended up calling a gearcutters about splining a coupling, and when I happened to mention what it was for (and thus its source, i.e. R380 gearbox tailshaft) they said "oh, yea we make those for Land rover!!!" so no problem there then!!

T66 - 10/12/10 at 08:21 PM

quote:
Originally posted by NS Dev
I nearly did the same thing, then I thought that maybe in some way running in low ratio would be a problem, then thought that of course it wouldn't, its just an epicyclic, no different to a typical auto box!

The coupler is the tricky bit, but after a couple of days farting about, I happened on "Coventry luck" as I now call it, whereby everything in engineering is made there!! I ended up calling a gearcutters about splining a coupling, and when I happened to mention what it was for (and thus its source, i.e. R380 gearbox tailshaft) they said "oh, yea we make those for Land rover!!!" so no problem there then!!





Like I said earlier in the post......


" I doff my hat to Cal & Nat"



I like Coventry Luck , not heard that before. But its true !!