Abarth 695
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Can a disk brake conversion be done with 10" wheels?
Technical Disc brakes possible with 10" wheels??
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Technical Disc brakes possible with 10" wheels??
babbo_umbro
Established member
Why would you want 10" wheels? Car would look really odd with anything smaller than 12".
The original factory Abarths based on the Fiat 500 (595 & 695 series) all had 12 inch wheels and drum brakes. Carlo Abarth was criticised at the time for paying more attention to the engine development than any other aspect of the cars, particularly the brakes.
Using 126 front hubs and 12" wheels, conversion to front disc brakes is possible as I've done it myself. The braking is better, though would be further improved with a bigger bore master cylinder.
The conversion to 126 front and rear hubs is very worthwhile as not only do you get a standard stud pattern, but also wheels that will take the wider and more modern 145 tyres rather than the 125 pizza cutters.
Occasionally you see these cars fitted with 13" wheels and appropriately adjusted body clearance and guard flaring.
Each to his own,
Chris
Using 126 front hubs and 12" wheels, conversion to front disc brakes is possible as I've done it myself. The braking is better, though would be further improved with a bigger bore master cylinder.
The conversion to 126 front and rear hubs is very worthwhile as not only do you get a standard stud pattern, but also wheels that will take the wider and more modern 145 tyres rather than the 125 pizza cutters.
Occasionally you see these cars fitted with 13" wheels and appropriately adjusted body clearance and guard flaring.
Each to his own,
Chris
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babbo_umbro
Established member
When you say "better" do you mean reduced pedal travel and better feel, or better retardation? If the former, a bigger diameter master cylinder will help, but if - as I suspect - you're looking for more effective brakes you actually need a smaller diameter master cylinder.
Yeah, you're right hydraulic effectiveness, as gauged by generated pressure, is inversely related to master cylinder bore amongst other things and yes, without a valid track comparison the overall effectiveness cannot be quantified, but given that the swept area is much greater you might think that the brakes should be 'better'.
As the engine in my car puts out significantly more power than the standard 500 engine and therefore the top speed is also greater, I went to the effort of modernizing the brakes under the advice of a local hydraulic company. Part of that was to increase swept area and then convert to front discs. I initially had 126 front drums which were OK. Having changed them for discs, subjectively the the car stops faster.
I didn't want brakes that had too much hydraulic efficiency as I didn't want to be in a situation where the rear locks up thus necessitating a proportioning valve or split system or other such complexity.
Generally I'm very happy with the brakes now. I don't use the car for track work even though it is quite quick for it's engine size. The brakes work reliably, efficiently and to my mind effectively.
I have a larger bore m/c which I may try sometime if I think that the brakes are too good (eg: grabbing and locking) but at present I'm happy with them.
Sorry this post is a bit long, but in amongst the science there is also a degree of subjectivity which needs explanation. As I said before, each to his own.
Regards,
Chris
As the engine in my car puts out significantly more power than the standard 500 engine and therefore the top speed is also greater, I went to the effort of modernizing the brakes under the advice of a local hydraulic company. Part of that was to increase swept area and then convert to front discs. I initially had 126 front drums which were OK. Having changed them for discs, subjectively the the car stops faster.
I didn't want brakes that had too much hydraulic efficiency as I didn't want to be in a situation where the rear locks up thus necessitating a proportioning valve or split system or other such complexity.
Generally I'm very happy with the brakes now. I don't use the car for track work even though it is quite quick for it's engine size. The brakes work reliably, efficiently and to my mind effectively.
I have a larger bore m/c which I may try sometime if I think that the brakes are too good (eg: grabbing and locking) but at present I'm happy with them.
Sorry this post is a bit long, but in amongst the science there is also a degree of subjectivity which needs explanation. As I said before, each to his own.
Regards,
Chris
PointFiveO
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Could be wrong but to my knowledge all the racing 500s seem to have 10' wheels, not sure why!
Colm.
Colm.
Abarth 695
Member
I thought Abarth did do some 10" wheels not that mine are as they are steel.
I found this on ebay though in Italy. Less powerfull than the 12" ones but must better than drums.
http://www.ebay.co.uk/itm/FIAT-500-...682?pt=Ricambi_automobili&hash=item4ab84a18e2
I found this on ebay though in Italy. Less powerfull than the 12" ones but must better than drums.
http://www.ebay.co.uk/itm/FIAT-500-...682?pt=Ricambi_automobili&hash=item4ab84a18e2
This post contains eBay links which may earn a commission at no additional cost to you.
The Abarth literature that I have states that they had 12" wheels shod with 125 tyres, but like you, I think that quite a few were converted ex-factory. Not sure why either. Maybe it's a racing thing if you can't get a close ratio gearbox. I'll dig around and see what I can find.
The original Mini Mokes here in Australia had 10" wheels that were quickly replaced by 13" wheels to improve road comfort - we have a lot of potholes out here.
Chris
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Axel Gerstl (Biburg, Germany) have 10" rims for Abarths as well as front and rear disc conversions. Beware though, they are not cheap.
https://webshop.fiat500126.com/index.php/katalog/showarticles/220100-2-rims_und_wheel_caps.html
Still can't find whether they were originally factory fitted or aftermarket.
Chris
https://webshop.fiat500126.com/index.php/katalog/showarticles/220100-2-rims_und_wheel_caps.html
Still can't find whether they were originally factory fitted or aftermarket.
Chris
PointFiveO
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All the older race footage I've seen seems to feature cars with 12" wheels whereas in all the more recent race footage the cars seem to have smaller
(10" ?) but wider rims. See attached. Love the old home movies.
Colm.
http://www.albumcinquino.it/adria_26_aprile_2009.html
(10" ?) but wider rims. See attached. Love the old home movies.
Colm.
http://www.albumcinquino.it/adria_26_aprile_2009.html
Abarth 695
Member
Great video thanks for sharing.
Love the last one too more my cup of tea.
MOT due tomorrow then registration hope to get all through for the car being road worthy next week.
Love the last one too more my cup of tea.
MOT due tomorrow then registration hope to get all through for the car being road worthy next week.
Abarth 695
Member
Ok I am getting confused, can some one tell me what size the bolt pattern is on the newish 12" wheels i.e. the disk conversion where you don't need an adapter. And can some one tell what it is on the old type. I am starting to think that the standard disk conversion could work on these 10" wheels.
The 126 hubs have a 4x98mm bolt pattern whereas standard 500 hubs are 4x190mm.
The 'flangies' are adapters that bolt onto the standard hubs and permit the fitting of 126 wheels. They also necessarily alter the offset.
My front discs clear the inside of the 12" wheels by about 3mm so I'd think that the 10" wheels would need smaller diameter discs.
Chris
The 'flangies' are adapters that bolt onto the standard hubs and permit the fitting of 126 wheels. They also necessarily alter the offset.
My front discs clear the inside of the 12" wheels by about 3mm so I'd think that the 10" wheels would need smaller diameter discs.
Chris
hudsonhenry
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It is indeed possible to do a disk brake conversion with 10" wheels, i've just done a conversion myself. There are two ways of doing it, the first is to buy a kit off the shelf,Nanni's do a kit but its expensive:
http://www.fiat500sport.com/brakes/...bo-front-brake-rotor-conversion-kit-0182.html
The other way is to make your own kit which is what I've just done. I think I have spent about £300 doing mine but its not an easy job. There is very little room inside a 10" wheel so first you need a very small disk. I used Citroën GS rear disk. The calipers are from a Ducati Paso 903 and the hub was custom made by the same guys who made the wheels for me. The mounting plate is custom made by me.
It all only just fits into the wheel with about 3mm to spare! The other thing that needs doing, if you want a decent inset on the wheels, is the arms in the kingpins that the track rods fix to need shortening so that they sit inside the wheel, I have seen some racers in Ital cut and weld them at 90 degrees but that would change the Ackermann angle.
Abarth did offer 10 inch wheels as an option on some of the Assetto Corsa models but they would have run with drums.
There is not a massive difference in diameter (17mm) between a 10" wheels with a 165 70 10 tyre and a 12" stock wheel but the choice in tyre compounds is much more extensive as its the same size as a classic mini.
Some people like the chunky look of the 10" wheel others prefer 13" wheels with lower profile tyres, its a matter of personal taste...
Hope that helps a little
Nigel
http://www.fiat500sport.com/brakes/...bo-front-brake-rotor-conversion-kit-0182.html
The other way is to make your own kit which is what I've just done. I think I have spent about £300 doing mine but its not an easy job. There is very little room inside a 10" wheel so first you need a very small disk. I used Citroën GS rear disk. The calipers are from a Ducati Paso 903 and the hub was custom made by the same guys who made the wheels for me. The mounting plate is custom made by me.
It all only just fits into the wheel with about 3mm to spare! The other thing that needs doing, if you want a decent inset on the wheels, is the arms in the kingpins that the track rods fix to need shortening so that they sit inside the wheel, I have seen some racers in Ital cut and weld them at 90 degrees but that would change the Ackermann angle.
Abarth did offer 10 inch wheels as an option on some of the Assetto Corsa models but they would have run with drums.
There is not a massive difference in diameter (17mm) between a 10" wheels with a 165 70 10 tyre and a 12" stock wheel but the choice in tyre compounds is much more extensive as its the same size as a classic mini.
Some people like the chunky look of the 10" wheel others prefer 13" wheels with lower profile tyres, its a matter of personal taste...
Hope that helps a little
Nigel
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Brilliant.
The process that you must have gone through coming up with a combination of Citroen disks, Ducati calipers and a custom hub and still having a whopping 3mm clearance really says something.
If I had come up with this I would have a third made up so I could put it on the mantlepiece....
Love the photos, can't wait to see more.
Regards
Joe R
The process that you must have gone through coming up with a combination of Citroen disks, Ducati calipers and a custom hub and still having a whopping 3mm clearance really says something.
If I had come up with this I would have a third made up so I could put it on the mantlepiece....
Love the photos, can't wait to see more.
Regards
Joe R
Abarth did offer 10 inch wheels as an option on some of the Assetto Corsa models but they would have run with drums.
Very nice
Chris
Abarth 695
Member
Great pics and great restoration. Thank for the info very helpful. Love the wheels, do mind if I ask how much?
hudsonhenry
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I would love to claim credit for thinking the whole thing up but I didn't .... I saw the Nannin kit and based my conversion on that. It did however take ages and lots of looking at motorbikes to work out where the calipers originated. The disks took a while to find, lots of searching for small thin disks that might work, the GS ones fitted the bill and as we were maching the hubs from scratch they could be made to fit.
The hubs and adaptor plates are however one offs, the hubs were machined by Force racing who also made the wheels. The adaptor plates are all mine.the calipers were stripped painted and all the seals, bolts, pistons etc replaced. I may still change them for 4 pot mini sport calipers yet but I will see how these perform once the car is back on the road.
The wheels were £140 each which I don't think is too bad for a custom made item, we also have a Smart Brabus roadster coupe and the wheels for that are about £350 each!
Nigel
Abarth 695
Member
So I am now putting this fireblade engine and I was debating if having 12" or 13" wheels would give me more stopping power? Is it worth sacrificing the look I want for the extra safety and cheaper modification?
Anyone done disk brakes conversion for the rear too?
Anyone done disk brakes conversion for the rear too?
hudsonhenry
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What look are you after? I have a front disk conversion and a set of 6 revolution wheels with 4x98 stud pattern, four are 13x6 and two are 13x7's. They are all for sale if you are interested.
As for rear disks, I've not done a conversion myself but there are plenty of kits for sale in Italy or it should not be too difficult to engineer one.
Nigel
