Technical that old chestnut - disc break conversion, but on the cheap?

[ianoshea]

that old chestnut - disc brake conversion, but on the cheap?

Hi All -

This is my first post on the forum! I've owned my 72 L for 17 years this week. I got her when I was barely a teenager, 'restored' it for 2 years and by that time I was just about the legal driving age for Ireland.

Cut to 17 years later, and I'm about to (well, already started) to strip it to metal and do a full 'nut and bolt' resto. (@fiat500rebuild if you have Instagram!)

So - the age old question - disc brakes on a 500.. but cheaply..
I know there are kits, ranging from 5-800$.. but I just cannot afford that, nor do I think it's necessary. There must be a better way... I've read a lot about wheel sizes, 12" v 13" (v 10"), and using other Fiat models parts (Uno, Punto), and even using Ford parts.. but even after reading all the thread I can, I've yet to read one that definitively describes how to do a conversion, what's needed, from which cars, and what added complexity you might need to overcome (adaptor place for PCD adjustments, etc).


My Car
my car has 126 Hubs with the 98mm stud distance, and, I guess it must have 126 axles too (?)
It also has 13" alloys with very wide, low profile tyres, but I'm quite sure I'll change them for 12" rims.
I've also just ordered all new bushings for the steering rack and axles, new shocks (standard) and a new 5 leaf spring - which I'll be fitting soon (in other words, i'm not doing a rack/pin conversion).

so - I put it to the Fiat Forum; does anyone know what is an affordable (2-300$) self made kit to covert a 126 setup to front discs, and if so, can you share all the dirty details.

I'm thinking that is must be fairly easy to find Fiat Panda, Uno, Chinc cars in scrap yards, and take the right bits from them, and fit them to a 500 / 126 -

All input and thoughts very welcome!

 

[Toshi 975]

Re: that old chestnut - disc brake conversion, but on the cheap?

I do not think that you will find a cheap way to build a disc conversion for the he 12" rim size. If you stick to 13" rims it is possible to build a conversion for less than £100. If you search on the club126uk site you should find all the information there.

 

[the hobbler]

Yes, one can build up a set of front disc-brakes for a sensible sum---as for "cheap", that is debatable. As 'Toshi' mentioned, it is easier to build up your own discs for 13in wheels (which I have on my car) than it is for 12 in wheels. For the '12in' kits, the suppliers seem to either have special calipers (expensive) or use cut down Punto/Cinquecento calipers (dodgy). To make your own set for 13in wheels you will require a pair of adaptor plates, a pair of 2nd hand Punto/Seicento/Cinquecento calipers, a pair of 240mm discs and a selection of bolts and washers. If you can't find the adaptor plates (and 500 plates are different from 126 plates), I can supply you a copy of the drawing for '126 adaptor' plates. 2nd hand calipers are fairly easily available on e-bay, but you might have to spend time, and some money, overhauling them with new seals and pistons. Discs and pads are easily available commercially--standard Fiat parts, or good quality 'pattern' parts. As 'Toshi' also mentioned, look onto the "Club126uk" site--technical section--articles by "Rusty's Uncle" for a description as to how to put it all together. When fitting discs to the front (I do NOT recommend that you fit them to the rear), I would suggest that you also fit "braided-metal flexible brake hoses" all the way round. You will probably find that you can get away with still using the standard master cylinder, but you might find that you have to go to a 'dual-circuit' master cylinder, which does take quite a bit of 'fettling'. If you do retain the standard master-cylinder you might have to fit the smallest rear wheel cylinders (15.82mm/5/8in) because the calipers will 'absorb' quite a bit of the brake-fluid moved by the master cylinder.
As you can see, it IS possible to build up your own 'kit' of front discs, but it does require a fair bit of work. Let me know if you require a copy of the caliper-mounting adaptor-plate drawing.:bang:

 

[Peter Pick-Up]

www.mtecbrakes.com

www.helperformance.com

 

[Bleeding Knuckles]

Hi Ian, My car has 12" wheels with lowered springs, but I would counsel against using this size for the one fact that tyres are limited
My car also uses callipers from the X1/9 with a single 48mm piston but again to fit the rims the discs have been reduced in size (down to 210mm) to fit. I would stick to the 13" you have and go for the disc set from the Punto/Seicento/Cinquecento as Tom says. One thing I would advocate is the fitting of Braided brake pipes (BF Goodridge etc) I have just done Mine and the brakes have been tranformed

Ian.

 

[ianoshea]

Re: that old chestnut - disc brake conversion, but on the cheap?

my issue with the 13" rims is that the clearance isn't sufficient in the arches.. its so bad that the paint all around the arches is cracked from the wheels hitting against them..

If anyone knows how to get better clearance to allow proper use of the car with 13" wheels, I'm all ears, as i love the wheels themselves and would rather not have to buy all new 12" alloys

 

[ianoshea]

This is great information -

Thing is, as I just replied a moment ago saying, that I cannot seem to get the 13" wheels to fit the car - even with low profile tyres.. the wheels just hit the wheel arch and also rub on the inside of the arch itself.
I'm replacing the leafspring and all suspension bushings in the hope that a few extra mm will be enough to make the car correct - bu if you have any tips for getting the setup right with 13" wheels and 126 drums/discs, do tell - i'd love to know what arches you fitted, the suspension set up - and if you've managed to get it correct!

 

[Bigvtwin996]

This is great information -

Thing is, as I just replied a moment ago saying, that I cannot seem to get the 13" wheels to fit the car - even with low profile tyres.. the wheels just hit the wheel arch and also rub on the inside of the arch itself.
!

I have read most of the posts on here regarding wheel/tyre combinations and even with 12" wheels there can be clearance problems depending on tyre size...
As for brakes, one of the issues is the offset of wheels used on a 500, it is hard to explain but if you consider a mini that uses 10" wheels why is that easier than a 500, basically because the brake drum on a 500 is encased more by the wheel, where as on a mini the wheels are located further out from the caliper using a different offset, which means on a 500 you need a very small disk and small calipers that must fit inside the wheel to avoid clearance.. sure people use cut down disks and calipers and pads... but even a basic service pad change isn't off the shelf..
I have worked out a solution but with calipers costing £125 each and a custom hub it would not be cheap....
as you will see the solution chosen by most is 13" wheels and wider arches.

 

[the hobbler]

13in wheels CAN be used without wheel-arch extensions, but you will probably need to have the standard wheel-arch lip turned over (effectively removing them) and then have the wheel arches teased out. Unless you're a good 'body' guy, I would suggest that this is done by a body-shop--preferably one that is au-fait with classic/performance cars. You say you have low-profile tyres--what size are they? If you want to fit discs to the front (don't waste your time or money on fitting them to the rear) I would suggest that you try and retain your 13in wheels--particularly being that you like them! You will also have a lot more "cheap to buy" options (as I mentioned on a previous post) by retaining 13in wheels.
I wanted my car lowered, so I had the wheel-arches cut back and "bolt-on" group2 extensions fitted. The reason for "bolt-on"?--I came to the conclusion that (a) it would be easier to work on the brakes/suspension with the extensions removed and, (b) if they ever got damaged, it would be much easier (and cheaper) to fit new "bolt-on" extensions than having to have the whole corner of the car repaired. Done neatly, the "bolt-on" look very effective. My wheels are 5.5 x13 (original!) Cromadora.

 

[ianoshea]

Thanks for the input - much appreciated.

I did fit wider arches but still clearance is a major issue, and as I'm about to do a total resto on the car, I don't want to risk having the same issues again on the new body work and paint.

There must be a way to get the clearance correct and safe from damaging the body when driven.. I just have to dig deep and do some research !

 

[ianoshea]

thats a great idea - I'd love to see how yours looks - any pics ?

 

[AndrewHarvey]

Re: that old chestnut - disc brake conversion, but on the cheap?

Check out arch rolling.
They are undertaken by a mobile "come to you" service where the wheelarches are rolled to give better clearance for customised cars.
No need for paint after.
I also have clearance issues with "bolt on" arches.
I have a set of Borranni wheels with a deep dish.
They fit over 12" discs (I have discs front and rear) with adaptors but run super close to super wide arches...
If you don't need adaptors roll the arches...

 

[the hobbler]

Ian;
Drop me a line direct to my e-mail--- [email protected] with your e-mail address and I will send you pictures of my car with the extensions on and what has to be done to the wheel arches PRIOR to fitting the extensions. After a fair bit of fettling, I have no problems with tyres touching extensions, and I have 165x55 Pirelli P7 tyres on my 5.5 x 13 wheels--and my car is lowered.
Part of the problem with modern tyres (and the reason that I fitted the Pirelli tyres) is that they have, due to modern suspension design, very 'square' shoulders. With a 'swing-arm' suspension (small Fiats, Imps etc) this is NOT the design of tyre required---they need tyres with a 'rounded' shoulder--hence the use of the 'P7'.
Another very similar size of tyre is a 175x50x13--they have only a slightly smaller diameter/sidewall height, but every little bit helps!:bang: