'73 Fiat Abarth 124 Rally - project

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miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Tom,

Any input will be most appreciated. The numbers are right ( at least they are accurate based on the homologation papers) .

Will be be glad to share the papers and you can verify my reading.

I however agree that it looks strange , on the surface.

I think that Stradale has floating single piston caliper ( very much like standard 125 ) while gr. 3 and gr. 4 were fixed Giriling or Lockheed . This is what it looks like in the picture.

The RS calipers also look right to me.

Will check the numbers again but the homologation papers do not specify "floating" or "fixed" - just give a number of pistons and all pictures in the papers showing upgrades from basic Stradale version show fixed calipers, to me

But will check the numbers again.

Also take into account that 1972 homologtion was quite liberal and followed the friction surface imitation rather than caliper construction

Miro
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TomLouwrier
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Re: '73 Fiat Abarth 124 Rally - project

Post by TomLouwrier »

hi Miro,

By all means, please PM them to me. I'd love to read them.

I've been trawling the web a bit and 911S's of the time had either cast iron or alloy ATE fixed calipers of 48mm. Rears would be 38mm or 42mm depending on year. 914's could have had 42mm fronts but that's a mid engined car. The cast iron ones could also be found on BMW 320's of that era. You would surely go for the alloy ones.

I'm not doubting your research or the official paperwork at all, but reality and engineering may well depart from what was written :-)
We had a quite similar discussion some 2 years ago regarding the setup on your 131.

regards
Tom
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miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Tom,

Under art 260 item "bb" of 1972 Appendix J you could use different brakes ( type and size ) provided they were offered as an option in your stradale version with no minimum sold needed.

"bb) Optional equipment which may be recognized without a minimum
production: (...)
- Brakes of different type and/or dimensions, which may include larger hubs
and spind les."


I have no data on optional equipment on 1973 124 abarths , but this sounds like an easy way of putting anything you want ...

I am sure the Italians knew how to handle such loophole :-)

Miro

PS: PM me your email address : the homologation file is too big to PM via a forum .

M
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TomLouwrier
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Re: '73 Fiat Abarth 124 Rally - project

Post by TomLouwrier »

Mailed you.

Yes, anything could be 'available' from Abarth as an option, meaning there would be some nice fancy brochure to show and maybe even the odd private team as customer. That would settle things within the rules.

T
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miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Replied with ( many !!! attachments)

Well, the rules were the same for everyone, so why not ...

Miro
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mickwood
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Re: '73 Fiat Abarth 124 Rally - project

Post by mickwood »

Gents - a note of caution here.
First, if you are looking to have FIA papers for this car, then some of the parts you are suggesting to use will make this anything on the scale of difficult to impossible.
A bit of background, to make it eligible for FIA sanctioned Historic rallying events you will have to prove that a car in exactly that spec was used in International Rallies in period (and for that purpose Group 5 cars and other prototypes like the Prototipo 2000 are specifically excluded!)
One thing that many people do not understand, is that you cannot cherry pick from a menu of eligible parts. Thus whilst the 124 CSA ran at one point with 50mm extensions, and at another point with 16 valve injection, you cannot run a car with that combination, because it never ran like that in period.
Looking through the discussions
a) what that means is that your original plan to follow the spec of a specific car is very sensible
b) …..but you should vary from that only with a lot of caution. For example, with regard to brakes, i think you could go to the vented front discs (as your car would still be consistent with early 74 spec cars, but the hydraulic handbrake might be a challenge
c) if you vary from that spec, you will have to prove that the items were used in period. For example i would note there is general consensus that the later 5 speed gearbox from the 131 is much better than the weaker unit fitted to the 124. That is undeniably correct, but sadly i have found no evidence that cars ran with that gearbox in 1975.
d) FIA go in great detail - for example it goes to the point that you will also have to use gear ratios which you can prove were used in period - that either means the standard box (which i would not recommend as i am pretty sure it would break pretty quickly) or you will have to get a set of bespoke straight cut close ratio internals using the ratios that the works team used. I have always used Colotti but only because all my gear clusters come from the sets actually made in Italy. I understand that some of Colloti's production is now being outsourced to China, so if you go this route then you will need to check the quality of what you get. i would also recommend not using the standard Colotti first gear on the layshaft as it is prone to breaking. I had some stronger ones made up here in the Uk, and (if you go that route) you can have one at what they cost me (I am not in this to make money). Alternatively, i I have good rallying friends who swear by the Bacci gear sets.
TomLouwrier
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Re: '73 Fiat Abarth 124 Rally - project

Post by TomLouwrier »

hi Mick,

Thanx for the info. I understand the constraints of FIA regulations and i'm sure Miro does it even better.

To be honest, I'm not really that bothered by what is and what is not allowed since I'm not competing. The old homologation papers give me a way of seeing the specifications for the different versions and years of the cars, that's it. From that I have my fun with the numbers so I get to understand what they changed and why. I use that knowledge for my own upgrades which are more likely street legal than FIA approved.
In this case the numbers don't seem to add up which is why I posted. Knowing Abarth used ATE calipers that were also bought by Porsche (a nicer way of saying 'they got them off a 911') is a lead to part numbers, OEM catalogues and thus dimensions and specifications. Claiming you should slap on scrap brakes from a 320i is not what I mean per se, but finding out that BMW got their parts from ATE too may confirm the specs and even yield an accessible source for those parts.

As for gearboxes: apart from the well known Colotti I found references to Cima as well. In the pictures these look like someone took the Fiat 124 box and used it to make sand cast clones of it, beefing things up here and there. Tell me if you want to know more; internet is a wonderful library but sources can be very unreliable. Readers may even take my words seriously :-)
I have absolutely no idea of homologation or availability of those boxes. Might as well be unobtainium.

It all depends on what Miro wants to achieve: a good replica or a fully eligible FIA approved racing car. He's calling the shots on that.

regards
Tom (now waiting for that mail to come in.....)
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mickwood
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Re: '73 Fiat Abarth 124 Rally - project

Post by mickwood »

Fully understood Tom.

I have spare sets of the ATE Aluminium callipers on the shelf so could easily check spec of what they originally used. left and right have different part numbers, but the only change is the attachment of the brake lines, and is easily changed.

I don't know whether ATE still make them but they do come available from time to time. If you buy used ones, then the key is the state of the bores - The seals are pretty robust but are still readily available - The weak link is the steel piston which can corrode (better to replace with new Stainless Steel pistons).

M
miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Mick,

What you wrote is extremely valuable!

And you are absolutely right , cherry picking is nice but will not work with FIA .

My discussion with Tom was of more general nature and there is and was no intention to build a car that "never was".

My intention is to follow this specific car specs as close to the 1973 Poland Rally winner as I can.

I foresee a problem with:

1- fuel tank - the tank was homologated vented brakes (as homologation for these was entered only in July 1974 ).This probably means a standard tank.
2- gearbox - using standard gearbox ( I have two) makes no sense so going for dog gear with the same ratios seems to be the only way set may be an expensive way
3- brakes - I would like to have a hydraulic hand brake , but I have no indication that the hand brake in this configuration was anything but mechanical integrated with a hydraulic caliper in the rear.

I sincerely appreciate your comments and suggestions.

China parts are of no interest to me and would definitely prefer a Bacci gear set.
I have also heard all positive comments on their work.

Miro

BTW are the ATE's spare by any chance ???

M
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Guy Croft
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Re: '73 Fiat Abarth 124 Rally - project

Post by Guy Croft »

Miro

the GC engine will shred a standard 124 gearset, I assume you plan to fit Italian-made gears..

I had a brand new 124 gearbox in 124 CSA all those years ago when I bought it in Turin, standard spec 1800 128bhp motor, lost second gear within months..

Apart from which ratios are utterly useless.

G
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Re: '73 Fiat Abarth 124 Rally - project

Post by mickwood »

Tom - out of interest can you send me photos of the CIMA box for the 124 - I am fully au fait with the various versions of the CIMA box as used on 131, but not the 124 version.

M
miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Guy Croft wrote:Miro

the GC engine will shred a standard 124 gearset, I assume you plan to fit Italian-made gears..

I had a brand new 124 gearbox in 124 CSA all those years ago when I bought it in Turin, standard spec 1800 128bhp motor, lost second gear within months..

Apart from which ratios are utterly useless.

G
Guy,

My experience with a 124 standard helical gear set is they are really fragile and using a standard box with a GC engine is not an option. The 131 standard box is panzer enough to use with my GC engine in 131 (with practically full torque available at 3K RPM) I am currently using 5.375 diff gear set and the ratios in standard 131 box suck. They box is strong enough but ratios are fully civilian for daily weekend driving. I fully appreciate the proper ratios, especially with only two diff gear ratios homolgated for this period (4.3 and 5.375) in 124.

I would expect the standard 124 gear set would be shaved off in matter of few hard driven spacial stages.

Incidentally I have put together a compilation if 124 and 131 homologted ratios for future reference :
131 gearbox .jpg
131 gearbox .jpg (95.02 KiB) Viewed 21185 times
124 abarth.jpg
124 abarth.jpg (64.54 KiB) Viewed 21185 times
For those that never experienced a useless gear set and a proper one these numbers will mean very little , but for me this is absolutely essential for proper setup of a rally car for a special stage. ( One day I will plug these numbers it my graph spread sheet to show what a dramatic difference they make in real life performance on a rally stage. )

I do not have to convince you or the experienced members of this forum but for the benefit of visitors to this forum who often are only starting their adventure with the world of rallying let me stress: There is a huge difference gear ratios make.

There is one think I would like these visitors to realize:

Car performance is made up of subsystems which are like a set of connected test tubes. You cannot modify one of them without effecting all the others. Unless all of them are of the same high capacity to perform you are putting too much stress on some and/or wasting capacity to perform by others. In the final analysis diff gears an gear boxes are as important in achieving the final balance as the engine and brakes.

Some of my friends wonder how come my car is so quick on stages (I always say : "I am a poor driver but I have a GC engine".

But the truth is : I also have mechanics who know a bit of physics and can divide and multiply numbers. With this engine and 3 ready to fit Abarth diffs sitting on my garage shelf (5.375, 4,625 and 4.30) and some 10 diff gearsets of other ratios ready to be fitted on a separate shelf we can configure the car for variety of driving conditions optimizing its performance.

But diff ration is only half of the calculation. The other half is gear box ratios. Hopefully there will be time I will have three CIMA/ Colootti/ Bacci gear boxes sitting on my garage shelf ready to be fitted - all with different ratios. THIS WILL BE RALLY HEAVEN).

Miro
Last edited by miro-1980 on September 30th, 2014, 12:57 am, edited 3 times in total.
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miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Tom,

Very interesting research. Thank you.

As Mick I am very interested as I have never heard of a CIMA box used in 124.

I researched the CIMA in 131 history and believe that it started when the Colotti housings started to brake very early on in 131abarth rally history. Collotti could not fix the problem and blamed the problems on the drivers , but CIMA studied the broken Colotti housings and designed their own. Problems disappeared and Fiat Abarth went for a full CIMA boxes the next season and stayed with them til the very end.

I do not think there was a similar problem with 124 ( or even if they had it they did not fully realize this yet). I now Andrzej Jaroszewicz and few other Polish drivers that had access to these cars broke a few.

For Fiat the 124 era was only a "WRC rally kindergarten" with a very sharp learning curve for their team of designers and mechanics. The real rally performance started with the 131 and there was no compromise on reliability and endurance. This is why there were so many strength modifications of 131. Not that it was weak , but to compete on a WRC level and win bigtime you need a panzer car. With so much money as Fiat invested into this project they expected no parts and components failure due to weak design. And Collotti proved early on it was a weak link. Thus CIMA.

Miro

PS: I will check out this Polish outfit with 124 abarth dog boxes. I think this may be based on FSO OBR ( Polish Motosport R&D Center) at one time headed by Andrzej Jaroszewicz. I know they had their own production of 124 abarth boxes. They had 3 ex-works 124 abarths and instead of buying the boxes (which apparently were not the strongest) for scarce hard currency they build their own. Incidentally, I am skeptical and if you ask me today I would rather pay 3 K for a Bacci box internals than by the local design for 2K but I will investigate and see who actually manufactures these boxes ,from what material , and what is the local experience with them.

I know for a fact that some of Abarth distributed performance gear boxes for Punto are made by a Serbian motorsport company. In Serbia they are cost 1/3 of what Abarth charges after just stamping Abarth logo ...so anything is possible.

M
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TomLouwrier
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Re: '73 Fiat Abarth 124 Rally - project

Post by TomLouwrier »

For the readers: Mick and I had some PM's and have concluded that Cima's were most likely never fitted to the 124. Technically possible, yes, but not within FIA rules where 'historically correct' is essential.
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Re: '73 Fiat Abarth 124 Rally - project

Post by Guy Croft »

If happens to be a Serbian 'Motorsport' company I am thinking of Miro,

AVOID.

G
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