Technical Disc Brake Mod??

[Bleeding Knuckles]

Greetings All, The subject of Disc Brake Mod's to the 500 has been covered multiple numbers of times on the forum, but I thought I would cover what has been done to my car
I have been greasing the front legs today and decided to investigate the slightly 'different' mod to my brakes while the wheels are off, I have also noticed that the dual grease nipples on the nearside leg are on the rear side and the offside leg has them on the front?? No idea why
The first pic shows the complete brake and caliper, the eagle eyes will notice that the outside of the caliper housing has been ground away and I assume that this is for wheel proximity clearance.
I have determined that the Caliper at least is a fiat item by part number and belongs to the 124,128,131,X1/9 family. This is a single piston sliding caliper with the piston being 48mm. The second pic shows two spacers fitted of 4.7mm each, likewise on the other side (wheel location?). Removal of the caliper and pads is simple. Pic three shows the Brake carrier, this is bolted to an adaptor plate that uses the bolt locations for a drum brake back plate. The last pic shows the adaptor plate and a late 126 (77-on) hub. The brake disc is only 200mm in diameter which is perplexing because the family size used is normally 227mm Any ideas folks?? I have found that the nearside disc is very slightly warped and causes a little squeak when the brakes are applied at low speed, not yet decided if I can live with it or go for an upgrade including braided steel pipes. I have added a pic of the brake caliper too.
I'll continue with the pipe change later.

Ian.

 

[Bigvtwin996]

they have been spun down to the size..
the smallest 4x98 rotor diameter is 227mm

you should see what some of the conversions in Italy do...
cut down calipers and pads as well...

 

[fiat500]

Similar to my 900e discs that I photographed yesterday:
https://www.fiatforum.com/850t-900/447003-disc-brakes.html

 

[Toshi 975]

The stub axles are made with the grease nipples on one side so you end up with one pointing forward and one back. The discs will be 227 that have been machined down to that size. Many people do not realise that you cannot get replacements straight off the shelf. I have got two brand new sets of those calipers that I bought years ago when experimenting with conversions and ended up using Cinquecento calipers so they are still in their boxes.

 

[Bleeding Knuckles]

Thanks for the replies, I have found some 200mm discs on-line, but am unsure if they will fit the hub - may have to do some accurate measuring I do know that there are a few mod kits that use a 215mm disc, so I shall have to check if the wheel will take them. Thanks for the offer Dave could you pm me a cost please.

Ian.

 

[Toshi 975]

Got two pairs of these callipers , new Fiat parts & not recon ones. Can post in UK for £75 all in.

 

[Bleeding Knuckles]

Got two pairs of these callipers , new Fiat parts & not recon ones. Can post in UK for £75 all in.

Thanks Dave, I'll consider it.

Ian.

 

[Toshi 975]

I have got 5 sets of new Fiat 227mm discs that I had machined down to 210mm some years ago. That is the same size as the discs that are on the conversion you get from Ricambio for the 500.

 

[Bleeding Knuckles]

I'm waking up this thread to council opinion from those members with disc brakes fitted on the front of their 500 I am looking to replace the pads on my Fiat X1/9 calipers as they are worn, but also because they display little initial bite. I really have to stomp on the pedal hard to get decent retardation - I appreciate that todays systems work better and I'm not wishing to get the same feel as modern brakes, I just want more bite from cold without having to pull a hamstring to achieve it. So, what material are you using on the rather light 500?? EBC, Ferodo, OEM, Brembo or what???

Ian.

 

[the hobbler]

The problem is Ian, practically all production cars (I do realise that certain 'small number 'sports cars do not use servos) use servos, so you get a strong brake operation with relatively low pedal pressure. With the 500, you have no servo, so to get pads to work you have to push hard. The answer might be to have a conversation with a pad supplier (somebody who knows what he is talking about) as it may be that in order to get good low-speed/cold brake operation you have to use a softer pad. Pad wear might be accelerated a bit, but as the car is so light, this may not be a much of a problem. I have a pair of Cinquecento calipers which I will be using when I fit discs on my 500 over the winter. It will be interesting to hear what pads you eventually go for and their performance.

 

[dragonwagon]

With the 500 being so light at the front it may not really benefit from having a disc conversion as good initial bite may translate into premature lock up....anyone remember the early Lancia Montecarlo? Personally, I'll be looking to upgrade the drums to improve their performance, which when all is said and done will be quite sufficient to tame the fearsome 30ish bhp I have in mine !

 

[Hobo1960]

Have a look at this post on the Fiat 500 owners club forum.

http://www.fiat500club.org.uk/clubchat/viewtopic.php?f=1&t=7934

I recently replaced all the hydraulics and shoes on my 500F and was really disappointed with the lousy brakes. I ended up stretching the springs by 4mm and the brakes are now superb. Earlier in the summer at a car show, I had a chat with a retired Fiat mechanic who had worked on the cars when they were new. We chatted about the brakes and disc brake conversions. He said that he couldn't understand the point of fitting disc brakes as you'd no longer have the self servo action of the drum brakes and would need to apply more pressure on the pedal. I'm confident that my brakes are now more than capable of stopping a 30 bhp fiat.

 

[Bleeding Knuckles]

Greetings, as part of the brake upgrade I am changing the brake pipes all round. I acquired a Bf goodridge 126 set of braided pipes from Mr E.bay very good quality at a price : and so far have fitted the front items. a simple enough job, but the goodridge pipes use a threaded fitting with a nut above and below the bodywork support, this is a 1000% better solution than the iffy push-on clip of the original pipes the whole fitting is tight, next the rear pipes .

Ian.

 

[AndrewHarvey]

These are a great upgrade that i have fitted to all my classics over the years. Vastly superior pedal feel.
I fitted them to my track prepared 911 and it was worth 50 horsepower- such was the improvement.

 

[Bleeding Knuckles]

These are a great upgrade that i have fitted to all my classics over the years. Vastly superior pedal feel.
I fitted them to my track prepared 911 and it was worth 50 horsepower- such was the improvement.

Hi Andrew, yep I'm hoping for an improvement too and I'll change the pad material and see if the balance between the front and rear is good. With the weight at around 530kg (ish) I think the late (larger) 126 rear drums will stay standard. I'm looking at EBC pads as their range is extensive and I may increase the size of my rotors as there is room in the caliper and wheel - it will not be by much maybe 10mm, but enough to give the caliper piston and thus pad a good grip. I don't believe that my application requires drilled or ventilated rotors - I don't want to stand the car on it's nose

Ian.

 

[AndrewHarvey]

Haha! My car has front and rear discs , braided hoses and an upgraded master cylinder! On its nose indeed!
I have not investigated pad materials / makes yet - but am aware of the huge differences to braking they can bring.
My calipers are all Fiat - so should be able to choose later

 

[Bleeding Knuckles]

Been burning the midnight oil of late, with plenty of research into Disc pad materials and applications. All I can now say is that it's a damn nightmare After a considerable amount of time I can quote from an initial ten differing pad makers with a range of OEM replacement, fast road and race applications :bang::bang: But, it does seem that with a little patience and logic one can arrive at some sort of initial conclusion prior to actual testing of individual pads on the car
For the most part, OEM brake pads are equipped with a .3 or .4 friction coefficient while performance brake pads are equipped with a .4 or .5 friction coefficient. More modern ceramic brakes on an F1 car might have an even higher level depending on the requirement at the time. I have found a small example on the web that relates to the lotus elise (see chart)

Friction Levels
Mintex M1144 Mintex F6R Pagid RS14 Pagid RS 15
Cold 0.44 0.28 0.44 0.50
At 100°C 0.45 0.28 0.47 0.57
At 300°C 0.46 0.28 0.49 0.54
Max 0.46 0.40 0.54 0.62
Constant working temperature
100–500°C 100-800°C 400–800°C 400–800°C
Max temperature for short period only
500°C 800°C 800°C 900°C

You can see that the Mintex M1144 from cold maintains almost a constant coefficient to 500ºC but above the max temp they will start to break up. It should be noted that the Lotus is a heavier car at some 725kg against the 500 at some 560kg (max) and the 126 at 580kg the breaking effort and thus the temperature required to maintain high braking levels with some pads can only come with a racing application. There are many pads that will not be road legal and meet the ECE R90 certification, but it seems that for a fast road application with good cold 'bite' and constant friction levels (in a lightweight car) that the Mintex 1144, Pagid RS14 and Ferodo DS2500 are worth testing. Other factors can and will effect braking efficiency - Caliper, Rotor and brake fluid boiling point. While noise and dust debris will be secondary they matter too. Before I get to the thorny issue of my choice I need to determine how my brakes will operate with standard OEM pads fitted and the replacement of the rubber pipes with good quality braided items (Bfgoodridge) this may tip the balance toward a slightly more aggressive OEM replacement rather than a fast road choice. Also, I must consider that my front brakes came from a Fiat application (131) that weighed 950kg - not far off double that of the 500 and that my Rotors have been reduced in size to 200mm. I'll service the callipers and once I've tested the new pipes I'll get back.

Ian.

 

[Bleeding Knuckles]

New braided pipes are on - a bit of a faff on the rear left I had to remove both short metal pipes and the flexi pipe from the three way block as the union was starting to round off a bit of application with the vice helped!!!! Have noted that the front pads are GALFER 139 FF ???? Anyone heard of this company, they seem to be Spanish with quite a large catalogue???? Produce a lot of sintered pads, but I don't seem to be able to identify my number??? back later.

Ian.

 

[AndrewHarvey]

What calipers are you running Ian?

 

[Bleeding Knuckles]

What calipers are you running Ian?

Hi Andrew, mine are from the X1/9, 128, 131 series using a Bendix 48mm piston, the body of the caliper has been reduced for wheel clearance, (see pic earlier) but with my wheels there is plenty of room so maybe it was done for 10" wheels?????

Ian.