My 131 abarth (never ending) story - 2017 season updates

[miro-1980]

Fiat campaigned a number 124 BS Spiders as a 'proof of concept' under a thin cover of 'private entries'. A season later they launched the official 124 Abarth and works teams.The 1608 was developed specially for this goal, reputedly by Abarth in order to learn more about the engine. Considering the double IDF setup, bronze valve guides etc I think this is quite plausible.

Tom,

Nice way of putting it. I understand it was really an Abarth, though never declared as ex-factory even though the service mechanics used cars with Torino registration plates and normal Fiat service team service jump suits. Very thin cover indeed...

I would like to get a copy of homologation papers for this car and the CSA Abarth as well ...

The use of 86 mm pistons is what I find fascinating because as far as I know no DOHC block ever had an 86 mm bore. Meaning : The block was machined at Abarth machined to 86 mm bore.

The copy of the '72 124 Abarth tech specs brochure I have ( Stradale) says 84x 79.2 and 1756 cc.
Same data is indicated on the list of FIA pre-WRC homologations. Yet the story is the car had 1839 cc and a 86 mm bore.

I have an opportunity to buy one of the early versions of the 124 Abarth engine. It is a CSA ( block 132 AC 4000 )but still with the 8 valve head. I am very tempted.... as this is a rare piece...

Anybody can help me with any suggest authenticity of the head on this engine. If the head is original from this very engine I will try to buy it ....

Miro

[miro-1980]

Re Rear suspension corrections.

I was surprised that the way the rear was adjusted forced the helper springs were full compressed yielding no function at all. With the very stiff springs the rear was perfect for perfect F-1 track - not for rallies.

springs old .jpg (58.22 KiB) Viewed 13191 times

We have selected new springs and helper springs which will make the rear less stiff and less bouncy , but still keeping the rear wheel on the road in all conditions.

springs new .jpg (48.02 KiB) Viewed 13191 times

We will also use "cones" we made on the top of the spring , just below the rear uniball type top mount.

cone .jpg (58.89 KiB) Viewed 13191 times

More to come ...

Miro

[miro-1980]

Re steering rods

The standard steering rods will be replaced by reinforced Gr 4 rods.

To illustrate this ...

Standard setup :

standard steering rods x .jpg (16.09 KiB) Viewed 13191 times

Note the standard steering rod end is female.

The modified (strengthened steering rods - Gr 4 ) :

gr 4 rod extension .jpg (11.04 KiB) Viewed 13191 times

Note : the extension gr 4 rods are female at both ends.As on the wheel side I will use rod ends with male thread and on the steering column I will machine the steering rod to shorten it and make a 14 mm threat to be accepted by the gr 4 extension rod.


Ultimately it will look something like this :

gr 4 modified rods 3 .jpg (11.16 KiB) Viewed 13191 times

I have checked the 131 parts catalog : from the looks of it the steering rods are the same on both sides as they have the same part number 4322913. ( any objections ? )

We will take the rods to machine from a spare power assisted steering rack. Hope they are the same.

More to come ...

Miro

[TomLouwrier]

hi Miro,

It is not paint, but adhesive labels. Do a web search for 'adhesive thermometer' or 'adhesive temperature strip' or 'indicator' or in fact 'adhesive temperature'-anything. They come in 10-piece packs and are disposable. You need the non-reversible type so you have a reading on the highest temperature reached during the stage. And yes: better safe than sorry, but we are likely taking this subject over the top a bit :-)

Regarding the pre-Abarth 'almost works' cars: reading the list you cited with the Gp4 homologation specs I guess we're already drinking from the same source. There are some books around (titles mentioned here and there on forums) that seem to contain some more information about this.

Funny thing: I put the Gp4 engine specs from your post in the engine comparison sheet I made some time ago for a discussion here about road vs rally vs F1 engines. It turns out that the Gp4 1608, 1750 and 1843 (8v) all have the same BMEP (state of tune) so you can clearly see they are one development, scaled up. The 16v and injection versions each take it up a notch. We have fellow members here who know much more about these engines and the 124's they went in.
The BS1 1608 is more tame, presumably for street drivability (midrange torque). The CS 1.8 and CSA 1.8 are somewhere in between. I wonder what the differences are, especially since the CS did not have very special cams and lost the double IDF's.


Regarding the original Abarth block/engine: all I can say is pick up your phone and call Guy if you're serious about it. As we say over here: "een beller is sneller' meaning 'a caller is quicker'....

regards
Tom

[Guy Croft]

"I have found an 1800 DOHC engine with a block casting number of 132 AC 40 000. The listings I have indicate this is an 1800 block used in 124 Abarths"

This is the correct model number for the engine first used in the 124CSA (Spider 124 Sport Abarth Rally), 8V TC 1756cc.

(From a copy of the Italian Ministry Of Transport Homologation papers Cert no. 11190 OM dated 10.01.1973)

Essentially - that engine was a standard production 1800 with 44 IDF and a (rather crude) tubular header.

You're going to get the engine 'Crofted', yes?

GC

[miro-1980]

Tom,

There is more to F-1 and Gr 4 than meets the eye ... LOL

In fact we have worked out the following solution to the diff cooling, based on the way they do it in F-1.
F-1 technical rules prohibit diff oil coolers. So the teams developed special air guides to increase the speed of air flowing under and around the diff . They achieve close to 20 C deg temp reduction due to this.

In fact diff oil coolers tend to get damaged too easily especially in rallies creating more problems than they solve. Mercedes tried it in one of its rally versions and gave it up as in tests but the coolers kept being perforated by rocks. Ultimately they switched to top temperature resistant oils. This reduced the temp diff oil temp to max 85deg C under most severe tests.

We will do the same. Specially formed fins and air guides before the diff will scoop air increasing its flow speed and pressure under and around the diff . It will also serve as additional diff protection.

I will get either the temp paint or the temp strips to monitor the diff oil temp.

Miro

[miro-1980]

This is the correct model number for the engine first used in the 124CSA (Spider 124 Sport Abarth Rally), 8V TC 1756cc.
You're going to get the engine 'Crofted', yes?
GC

But of course , Sir ..

M

[Guy Croft]

here's one I did earlier...

not fully dressed because it is not intended to run it for some time and the crank front pulley is a 'dummy' just to hold the cambelt on. Mick Wood already has enough parts around him to fit the GC toothed-belt alternator/water pump drive in time...

G

[miro-1980]

Perfect !

This is what I needed !

Thanks Guy (and Mick).

Miro

[miro-1980]

Gents,

Here is a pict update .

The work on rear is getting to its end.

The main caliper disks and springs are assembled.

PIC00539.JPG (68.29 KiB) Viewed 13132 times

PIC00540.JPG (62.96 KiB) Viewed 13132 times

The rear brace has been reworked and the turrets strengthened.

27062012.jpg (49.16 KiB) Viewed 13132 times

The holes you see are from un-welding a top of a brand new piece which will serve to strengthen the rear turrets.

The holes will be also used to weld the top top the original turret top.

The brace has been replaced by our own design. It will be wended in a manner which will keep the rear geometry stiff under bumps on a sharp quick turns.


Miro

[Walezy]

helper springs should be fully compressed, helper is used to adjust ride height of the suspension and might work good on full opening of the suspension as the last few cm of travel are made with small rebound force and this will keep the wheel in a small "holes" on the road without giving big hit which would occur with stiffer spring

[miro-1980]

Walezy,

Yes, in principle you are right... but the devil is in the details.

As they say there are two schools Pruszkow and Wolomin (LOL)

In effect it all depends on front or rear as well as all other parts (springs diameter, progressive or not) and finally what what you want to achieve , how will do use the car , will you change setup for different events, and different stages of the same event.

But in principle yes. Proper standard setup means fully compressed helper springs.

Miro

[WhizzMan]

Helper springs should not be fully compressed when the wheel is off the ground. With normal wheel on the ground, yes, then they should be compressed. They are there to make sure that the main spring stays in position, regardless of the position of the suspension. You could do it with a single spring and no helper spring, but that would make the first few cm of wheel clearance much softer, even with progressive springs.

[miro-1980]

... but that would make the first few cm of wheel clearance much softer, even with progressive springs.

WizzMan, cluld you please carify.

Does it mean that with the helper the first few cm of a bump caused travel the suspension will be stiffer ?

Miro

[Walezy]

I meant of course fully compressed when the car is put on the ground, so that the weight of the car will make those helpers compressed. there is no other way to make it as the helpers must be very soft springs, for example in my friend's civic typer r that has proflex suspension the helper is no more then 1mm thick steel.