X1/9 Prototipo Specification

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
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Thomasg
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X1/9 Prototipo Specification

Post by Thomasg » Fri Nov 05, 2010 11:53 pm

I have an X1/9 in the final stages of preparation as a historic rally car, the specification is quite mild, basically a Group 3, 1300cc.

The long-term plan is to eventually create a full Prototipo replica but I am short on some specific details of the original still born Group4 Fiat.

I would be grateful if any forum members could fill in the blanks in my knowledge. I have two main queries regarding the original specification: -

Suspension
What uprights and hubs were used? Given that only the 1300cc X1/9 was in production at the time of the Prototipo development, Fiat was unlikely to have utilized standard items.

Brakes
I believe the brake set up (at least on the front) came straight from the Group 4 124 CSA Abarth. What specification would this have been? i.e. disc diameter/thickness, caliper manufacture, piston number/diameter etc.

If anyone has undertaken a similar project and would like to share any relevant information this would also be most welcome. I am also seeking particularly guidance on:

Transmission - Fiat used the Group 4 Beta gearbox, the homologated ratios of which had a very effective spread, but given that these are likely to be more rare than the proverbial hens teeth, a Montecarlo box is probably the only choice. Is anyone using a monte box? What is your experience with gear and final drive ratios?

Many thanks in advance for you response.

mickwood
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Re: X1/9 Prototipo Specification

Post by mickwood » Mon Nov 08, 2010 3:03 pm

I have a fair amount of stuff on this, but if you are planning on using in historic, you probably need to chat to HRCR (Paul Loveridge) regarding eligibility
You may also need to think about your budget if you want to use original spec parts.
Hub carriers - all special steel forgings - basically no chance to find. Not sure what you might be allowed to use instead - At rear 131 abarth Group 4 might be made to fit but they would set you back about Eur750 per corner for hub carrier alone!
Struts and dampers - again all special (Struts with adjustable spring pans - Fixed valve Corte & Cosso Inserts) - You may be able to get away making up some struts with period spec koni (i.e oil filled inserts, not Bilstein gas, and with inserts non adjustable)
Front brakes - same bells as Group 4 124 - 256mm by 20mm vented, but with very deep bells - were unavailable for many years but a small volume has been made recently in Italy - I think they are Eur500 a pair - contact Dirk Marcel at Ricambi Bielstein
Front calipers are two pot alloy - Forged calipers same as RS porsche - you can still find them if you are lucky - try Frances Tuthill
Rear brakes again same as Group 4 124 - 256mm by 10mm non vented but with provision for handbrake in the bell - I had some remade in Uk, and can put you in contact with supplier
Rear brake calaipers - steel ATE - same as period Alfa - Tony at MBG can get them
Rear handbrake parts - Special Abarth - used on late G4 124 and also on early G4 131 - will be hard to find (but they are spectacularly useless anyway)
Gearbox - proper straight cut close ratio internals for Monte Carlo box are still available from Paulo Colotti in Italy.

Guy Croft
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Re: X1/9 Prototipo Specification

Post by Guy Croft » Tue Nov 09, 2010 9:40 am

"Hub carriers - all special steel forgings - basically no chance to find. Not sure what you might be allowed to use instead - At rear 131 abarth Group 4 might be made to fit but they would set you back about Eur750 per corner for hub carrier alone!"

I think there may be some of these in the 'for sale' section, from member Miroslaw Miernik in Poland.

Thanks for your very informative post Mick,

G

Thomasg
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Joined: Thu Feb 11, 2010 10:30 pm

Re: X1/9 Prototipo Specification

Post by Thomasg » Tue Nov 09, 2010 6:14 pm

Thanks for that Mick, most interesting.

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