'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 »

Guy,

I certainly have nothing Chinese, Serbian or even Polish in the 131 and will keep the 124 the same way.

I keep it "junk free" and in this sense it is clean as a whistle. This is your school, remember !

Even all my Italian parts are vintage not current production, so no worries mate.

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

Post by Guy Croft »

:-)

GC
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Re: '73 Fiat Abarth 124 Rally - project

Post by Rallyroller »

Hi Miro

I have been reading this with interest. As usual great information.
My rally project seemed to stall for some time, and I am only now just getting started again. Front suspension nearly on now and axle about to go in.
Re homologation- Mick is correct about FIA documents. Also it depends what you want to achieve. My car is being built for the UK historic stage rally championships. It is a BS – i.e. with a rear solid axle. Technically these did not have the same brakes as the Abarth- however- I have managed to get the ATE 911 callipers to fit with currently available correct size discs (I mean diameter and thickness). As Mick says- the FIA would not allow it- but I am not sure too many people would pick up on the technicalities. Until I start winning things I don’t think it will be an issue. Mick used a 131 box in his Spider but got dispensation for it. Not sure a scrutineer would know the difference. I am sure that in the 70’s somewhere in Italy somebody modified a Spider1600 with the works style brakes, 131 box etc etc and went rallying. Getting documents to prove it may be more difficult.
Perhaps we are lucky in the UK- as our historic championship runs classes for historic cars- without FIA papers. You have to prove any part was available and used in period, which leaves the door open a little. These rules also offer a little more freedom. We can use re positioned alloy tanks, Perspex windows etc without reverting to homologation papers. Interestingly that is also where it can go wrong. Hydraulic hand brakes on their own are not allowed in UK rallying. There is plenty of evidence that they were used in the mid 70’s but due to current road regulations, there has to be an alternative mechanical means of holding the brakes on. ( My car was rallying in the mid 70’s with a hydraulic handbrake only.) Now I have to get a mechanical linkage some how.
As usual Tom has come back with some great information. I do have the homologation papers for the BS Spider. Interestingly the brakes on that were much different. They used 3 pot callipers all round. The spec was 3 x 48 front on 246 dia discs and 3 x 34 rear on 230mm discs ( both discs 9.6mm thick. ) The callipers appear to be on top of the axle with what looks like the original single pot calliper still in place ( perhaps for the handbrake). Also the front brake calliper appears to be at the top of the disc. I was told these callipers were from a Fiat 2300.
Regarding gear ratios, there are 2 alternatives listed in the 1971 papers- one set of ratios is the same as the grp4 papers of 1972, but another alternative set is listed as well. ( The last one in Miros list dates from 1971.) The 1800 engine, was also homologated for the “Sport Spider” in 1973. (If anybody wants a copy of the 1600 Sport Spider papers- send me a private e mail.)

Nigel.
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TomLouwrier
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Re: '73 Fiat Abarth 124 Rally - project

Post by TomLouwrier »

hi Nigel,

If those 3-piston calipers were indeed 2300 derived, then the same calipers were also used on the Fiat Dino and the DeTomaso Pantera. Large cast iron things. They have a integrated mechanical handbrake acting on two small extra pads. Same system as on many Jags.

I've found rebuild kits that contain 2x34mm and 1x54mm pistons per caliper. That would tally, because the surfaces come out at 1816mm2 vs 1810mm2; perfect balance either side of the disc. Why 2 vs 1? Probably to save space between disc and wheel, the eternal problem with fitting large calipers under a relatively small wheel. More space on the inner side of the disc so fit a single 54mm there.
The 54mm means an increase of 27% clamping force over a 48mm caliper at same line pressure (1810mm2 vs 2290mm2). Combined with 246 mm discs (about as large as will fit under a 13" wheel) you will get 137% braking compared to the standard 48mm/227mm combo.


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

Post by miro-1980 »

The project is really starting:

Goodies arrived:
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80 kg pf steel can make man real happy

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

Post by TomLouwrier »

Good stuff!!
80 kg of steel can make man real happy
or, to put it slightly dfferent:
80 kg of steel can make real man happy

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

Post by miro-1980 »

Guy Croft wrote:Kindly DO NOT fit Cat Cams pulleys to my engine!

Thank you very much.

Mick's unit has GC design true-vernier STEEL pulleys already, made for me years ago by Titan.

G
I certainly will not put anything on or in your engine without your approval, of corse

Miro

PS: Just out of curiosity, is there a specific reason.

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

Post by mickwood »

Miro - A lot of good stuff there!

Rear Dampers are modern Bilsteins - these are designed for small diameter springs - you may need larger spring platforms for 124
Front dampers look like Bilstein Stradale version as they have rubber bush at boo tome end. G4 version has rose joint. The rubber may be right for 73 version, but check they have right G4 damping rates. Bilstein will be able to tell you from serial number.
Anti Roll Bars front and rear look good - the drop links should be rose jointed not solid
Front lower suspension arm mounts are the proper deep Gr4 versions - good find
Arms themselves look like new Repro of early Gr4 - I suggest to check they are properly reinforced as i have had had them bend
Front Brake reactions bars look right - hubs look right
Rear centre mount - cannot tell from the photo whether it is the deep or shallow version - G4 normally had deep version, but mine has shallow version with an 18mm Spacer to create the same geometry so its not a problem whichever version you have
Diff Output shafts look right
the Rear hub carriers look like the stradale version which is probably right for a 73 car
Beware the rear outer drive shaft axles - I have had two break in the last two years so have stopped using original 40 year old stuff and had them remade in UK. Same dimensions, but materials and workmanship have moved on so these are probably 25-30% stronger.
Rear lower reverse wishbones are definitely straddle but May be right for 73 car. Suggest have them crack tested and - as Guy says, i would double up the reinforcement at the outer end
I see you have newly remanufactured spindles and rubber bushes - probably better than the needle roller set up and will fit the arms you have
Rose jointed drag like are right - they are very light tubing so don't let anybody think they can jack the car up on them (as one guy did to one of mine some years back!)
.
miro-1980
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Re: '73 Fiat Abarth 124 Rally - project

Post by miro-1980 »

Mick,

Really appreciate your comments.

Basically the idea was to get G4 set but to make the project proceed I had to take what is available.

Also , while I ma now quite familiar with differences between gr4 and Stradale in 131 , but as regards the 124 is still something I am learning.

The use of rose joints is in gr4 and rubber bushings in stradale is clear (based on my 131 Abarth experience) but for instance in my 131 we opted for bushings not to make the car too stiff (I have limited trust in a 40 year old chassis desire reinforcement welds and wanted some dumping on the wishbones. (I saw an old rally car crack practically in half from being all rose joint suspended.


So I am quite happy with Stradale parts for the time being. Once I get it all installed and get the car on the wheels I will have time to upgrade to gr. 4. If I waited to get all gr. 4 parts it would take me years to complete , and I want to have the car on wheels and rally-ready for the next season.

I have some problems with nomenclature.

Re: Dampers - I treat these as temporary , we will see how they behave and deal with it often some experience. I have a great guy here in Warsaw who is a n agent for Bilstein. He has been doing shocks for all our leading rally teams for the last 40 years , he will help.

Re: reinforcements fully agree that safety is always a top priority. I am very personally very careful of any weakness in the suspension/brake steering system. Thus we will reinforce some parts like engine mounts, arms mounts, the cross member under the engine (as indicated in homologation papers). Any repro part will be very carefully inspected. Actually are working with a local university team of scientists that deal with cars and engines helping them with a key project by doing some field tests for them. This gives us have easy access to class scientific lab facilities and equipment ( i.e. the most modern engine dyno in Poland ). We always check all safety-critical components (especially original Abarth 197'0s parts) for internal cracks in their industrial GE X- ray machine. We also check all safety critical welds in any parts we install.

Re: Front Brake reactions bars - actually we have only one and will have to manufacture the second. I think we will actually make two, to make sure the performance under stress and vibrations will be actually exactly the same.

Re: Front hub - Glad this is OK !

Re : Rear center mount : I am not sure id this is shallow or deep and in case this is a shallow one will ask you for some guidance how to put the spacer

Re: Diff Output shafts - glad they look OK to you . I have several spare sets diff shafts and axis shafts for my 131 ( any chance they will fit ?)
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Re: Rear hub carriers - They are likely Stradale. They have only one set of mounting holes for only one caliper. This will mean we will have to use a caliper with a mechanical hand brake ( or opt for in-line hydraulic hand brake - facing all associated issues). For the time being these hubs is all we have so no option here.

Re : Rear lower reverse wishbones - glad I chose an early 124 Abarth version ! We will make sure these are reinforced as per Guy's suggestion !

Re: spindles : at least they will fir what I got. I thin I have a standard 124 set or two ( but they would not be the same , would they ?

Re; Rose jointed drag - I was actually thinking about either reinforcing those or manufacturing a reinforced set as we did for 131

Now tell me what I am missing (except for brakes) . I see nothing to hang the diff. Anything else?

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

Post by miro-1980 »

I see also missing:

1. front upper arm
2. top and bottom ball joints for the front arm
3. drag mounts

Anything else ?

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

Post by Guy Croft »

Hi Miro

get those rear struts modified to accept large diameter springs as Mick mentioned, you will never get small diameter springs to work, been there, done that..

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

Post by miro-1980 »

Hallo Guy,

Will try to work with my Bilstein man to modify them.

Do I take it right that the adjustable ring has to be changed for one with larger diameter to support large diameter spring , or there is more to it?

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

Post by mickwood »

Miro

Rear spring pans - yes they just need to be larger diameter to accommodate the larger diameter spring. the locking rings will be fine.

Front upper wishbones are same as Stradale, but with localised strengthening - I will try and send you photos, but am going away on Monday night for a couple of weeks so a bit of a last minute rush right now. The list of parts that i have - and prices - will sadly have to wait until i get back

Front of Rear Diff is hung from the transverse carrier that you have - same style as 131. (but obviously different shape) Mounts for this are welded to chassis so you will have to fabricate them - again i have photos somewhere

Rear of rear diff is hung from a mount that is welded to chassis, again similar style to 131 (but different shape) - i have photos

Front Mounts for Drag links are (from memory) basically the same mounts as used for rear axle location rods on CS1. I think they are bolted to chassis (but I may be thinking 131 here) again i have photos

One thing you will have to fabricate is the mounts on the chassis for the rear end of the brake reaction rods on front suspension. Again i have photos

Top and bottom Ball Joints are same pattern as CS1, but the Gr4 ones are reputedly made of better steel. They are remade and available in Italy.

Re the Pivot Rod at the outer end of the lower rear suspension arm a) The CSA Stradale uses the pivot rod from the CS1 lower Front suspension wishbone. So that is readily available. What you have bought, however, is some stronger bespoke machined pivot rods, that are still compatible with the CSA Stradale arm and bushes, but which should be stronger - they look to be the ideal choice for your plans.

Diff output shafts - There were so many different patterns fitted to 124 and 131 over the years. The flange diameter varied, the thickness varied, the bolt drilling varied (some with 8mm and some with 10mm - some using bolts some using cap head screws), The Shaft thickness varied (and with it the number of splines etc etc. They key is making sure that what you have is compatible, recognising that the whole set up will only be as strong as the weakest component. the standard spline size with the 8mm Capheads should be fine for even a good torquey 8 Valve engine, provided you avoid putting too much snatch load through it and (as i am sure you know) the biggest snatch loads tend to come when jumping the car on tarmac with sticky rubber.

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

Post by miro-1980 »

Mick,

Thank you again for taking time to help me.

I wills study what you wrote in detail later on tonight ,

In the mean time just great thanks to you.

The project is going exceptionally well and we have plenty to do so everything we discussed can wait.

Just enjoy your trip.

Thanks Miro
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Erik Bredius
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Re: '73 Fiat Abarth 124 Rally - project

Post by Erik Bredius »

Hi Miro,

sorry for not looking after the forum for such a long time!

My car is an early (0ct 1972) one, probably used by Fiat as a press car. It was owned by Fiat till 1989! It's completely build as a stradale, with exactly the aluminium parts Mick mentioned. My whipermotor cover is also steel. It lacks some round holes in the chassis member under the radiator wich are perhaps only there in later cars (and there is certainly no trace of later replacement!). Being a production engineer i know that because all these cars were in fact specials means that even in the 'standard' stradale there are lots of differences during time.

Though of course front and rear suspension on my CSA is completely different to the BS and CS (standard spider) the brake callipers both front and rear are 100% the same as on my CS spider and BC coupe.

I'm not at all so deep into special rally parts as you are yourself but if you want me to do some measurements on my indeed nice and original CSA I would be happy to do so for you!

Erik
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