Technical Discs or Drums

[fiat500]

The subject is cropping up quite frequently here and on Facebook.

The objectives in fitting disc-brakes are laudable and as always, each to his or her own and why shouldn't people fit them?

I can well appreciate the pleasure and satisfaction involved in designing, obtaining and fitting the required parts, but is it really necessary and are there any negative implications in doing so?

There is an argument that because modern cars have disc-brakes, we might get caught out with sudden braking of other vehicles. But I wonder why we are driving so close to other vehicles and whether most people actually use major roads particularly frequently? In any case, I can assure anyone that the standard brakes have never caused me any concern over many miles of motoring; even on major roads in the South of England.

The fact that many 500s have upgraded engines is quoted as a reason to fit discs, But even when Fiat went up to the heavier 126 BIS with a 703cc engine they saw no reason to fit discs. I have owned one of those cars and never felt any inadequacy in the braking ability. Even the modern 500 has drums on the rear. The brakes are matched to the power output and weight of a vehicle.

The Fiat 500 may tempt you to drive "aggressively", but in comparison with any modern car, even at full stretch it is no more aggressive than a cuddly, stuffed "Tigger". Anyone who expects it to behave like a modern car and who fits discs as part of an approach towards achieving modern performancei will miss many of the subtle and indefinable pleasures of driving a more or less standard 500,

If you do drive your car really hard,because the discs give you that surety, safety implications aside, you're going to pass on more stresses and increase wear on other components in the system; thus the upgrade road gets steeper.

I'm not suggesting that owners should leave the cars alone because of any purist beliefs about originality or such.It's simply that I want to promote the cars' native abilities, particularly to the many new owners of Fiat 500s who appear to be so much younger than me that they have obviously got no memory of the fact that this car was a star long before all the amazing modern upgrade potential existed.

If you've got surplus time and/or money and want to get stuck in, far better to work on detailing all of the mechanical and electrical systems to make what you're already endowed with is as safe and as reliable as possible.

 

[F123C]

I recall the Fiat 600 and 850 saloons, both heavier and faster cars, had drum brakes all-round. I also remember being able to squeal the front tyres on my slightly modified 600, but that might have been because I ran on crossply tyres. (and remoulded, to boot , 'twas all I could afford on apprentice wages).

Also bear in mind that Fiat were afaik one of the first manufacturers to fit self-adjusting drum brakes on small cars, a big improvement back in the day - anybody remember struggling with seized square-headed adjusters e.g. Mini, or the nuisance of having to jack up the car to take up the adjustment every few weeks?

As regards modifying a 500, my view would be 'to each, his (or her) own'.
I used to modify cars back in the day while working as an apprentice Mechanic. The more I learned, the more I realised how little I knew compared with the Engineers and Designers at the factory - they tried to achieve the best mix of power, economy, driveability and RELIABILITY, all the while being constrained by costs (production and anticipated selling price of the car). I'll take reliability over a possible? power increase any day....

AL.

 

[MOD500]

I have been mulling it over and prodding the subject for over 2 years, the whole time I have been driving my 500, sometimes gently sometimes fast and I always have had faith in the brakes.


Brake fade and brake shoe adjustment are the main disadvantages with drums. I have only suffered brake fade while being towed.


brake systems are balanced where the piston size of the rear systems is proportional to the piston size of the front to prevent the rear from locking up first, or the rear not applying enough braking force before the front locks up. This can be fixed with a brake bias system in line, but it's another thing to complicate the process.


Having said all of that, I still want disk brakes, but I'm not sure I have ever been able to justify it!

 

[Bigvtwin996]

my only reasoning to fit disks would be to lower maintenance, as pointed out the adjustment etc... added changing pads is far less involved than shoes...
but just shoving some calipers and disks off something because it is made b fiat is similar to the VW crowd that fit anything from Porsche because of the strange belief it will make their boxes on wheels perform like Porsche's....

The same logic would apply to almost any other modification I would consider...

I see little point (for me) to have something highly tuned so it performs like a 1.4 Fiesta.. I would buy a 1.4 Fiesta.... but each to their own, and I know people who strive to achieve the maximum possible from an engine or car or bike...

Again for me the ideal would be to have best of both words... one car that is literally driveable every day, and the odd scratch or spec of dirt did not matter and another totally original for those sunny days where you can go park up and let people see some art/history on wheels...

Variety is the spice of life...

 

[fiat500]

my only reasoning to fit disks would be to lower maintenance, as pointed out the adjustment etc... added changing pads is far less involved than shoes...

I'm still wondering how many miles it will take me before the huge challenge of changing the front brake shoes will take place....they were still looking good at around 27,000 miles.

Given the mileages that I am aware of, your average 500 owner, (who from what I'm reading, these days is quite likely to be farming-out this highly technical replacement job to a specialist garage in any case) will be doing that once every 100 years....that's if they don't get tired of the 500 and move on to something more powerful such as...............basically, any other car.

By the way, I'm not trying to undermine your project.. I know enough of the background to know you're approaching it in a professional and practical way and I suspect you will get the balance right.

 

[Bigvtwin996]

I'm still wondering how many miles it will take me before the huge challenge of changing the front brake shoes will take place....they were still looking good at around 27,000 miles.

Given the mileages that I am aware of, your average 500 owner, (who from what I'm reading, these days is quite likely to be farming-out this highly technical replacement job to a specialist garage in any case) will be doing that once every 100 years....that's if they don't get tired of the 500 and move on to something more powerful such as...............basically, any other car.

By the way, I'm not trying to undermine your project...you're approaching it in a professional and practical way and I suspect you will get the balance right.

I agree however driving a car frequently as you do does often help keep everything working correctly.... and if you leave a car for months over winter then I have always experienced some form of brake binding even on modern cars.... and this tends to be the rear drums... technically drum brakes are more efficient than disks, disks are primarily used because of their size/compactness and ease of maintenance...
What is used to stop 7.5tons +

 

[phoenix1]

When taking my 500 L with 650 engine out for the first time I was horrified at the response from them and I have two other classics with drum brakes.
So I was going down the rout of fitting disc brakes. However after a little use they were great ,I could actually make the nose of the car drop. I try to leave
all my cars as standard as possible. My car was a complete build it came as a completely dismantled car so all brake lines shoes and cylinders were all new
so may be that helped. The only thing I have done is change to rack and pinion because getting a good right hand drive box is impossible nearly. Persevere

P.S. I have just put a pair of coversion plates on Ebay to covert to disc.

 

[the hobbler]

Apologies Peter for my delay in responding to your comments. Oooh, you little contrarian you (note,my friend,I didn't call you a little old contrarian!). I totally agree with you in that in 95% of the time, the Fiat 500's drum brakes are completely adequate for the performance parameters of the car. However, i bought my car with the intention of converting it into a '695ss replica. Having worked at Radbourne Racing and been involved in the tuning of 500s, I decided to grow old disgracefully and build myself a 'smile on my face' fun machine.
Since the 500 came out, the speed of traffic, and the lack of patience of some drivers, has increased dramatically. The 500, even in standard form, can keep up with most city traffic, but when it comes to stopping behind modern cars with disc brakes ABS and BAS systems in place, it is not difficult to have a real "whoops" moment. I live in a city (Chester) where the drivers are, generally speaking, very polite--but ruddy dangerous. They seem to ignore the colour showing on the traffic lights, regularly continuing AFTER the lights have turned red and have given me some moments where the additional braking ability of the disc brakes on my car has been fully utilised! I have a pair of friends who have a stable of Riley cars, one of which is a 'Kestrel'. With its 6 cylinder, 1,500cc engine, it can fairly easily keep up with the flow of traffic, but has to be driven very defensively due to the fact that it has 'rod' brakes which are no match for modern brakes, a fact not understood by a lot of modern drivers who seem to think that if it can GO as fast, it can STOP as fast, a situation that i have suffered on occasion in the Fiat.
I don't think that having disc brakes on a 500 makes the driver "more aggressive", but there are times when I think that they are a useful addition to the performance envelope of the car. I wouldn't dream of telling somebody that they HAD to have them to be safe, but I would assist anyone who asked for my help to fit them.
And that, young Peter, is my contribution to the 'contrarians'

 

[fiat500]

Apologies Peter for my delay in responding to your comments.

I have a pair of friends who have a stable of Riley cars, one of which is a 'Kestrel'. With its 6 cylinder, 1,500cc engine, it can fairly easily keep up with the flow of traffic, but has to be driven very defensively due to the fact that it has 'rod' brakes which are no match for modern brakes

No need to apologise Tom as I don't demand a response from anyone; it's just enjoyable to be able to debate these things.

Regarding older cars as examples, I've recently had the pleasure of navigating for my brother in a 4.5 litre Lagonda from the thirties and it has rods, cables and drum-brakes. He drove it in a very aggressive competitive manner over a distance of 750 miles over three days and there didn't seem to be any braking allowance made by him or anyone else, because the brakes are well designed and perfectly maintained........absolutely massive, finned drums. Cars have always been designed to get the best performance from whatever technology was available (at the right price) at the time and Lagondas were/are every expensive).

Maybe I would see it differently if I lived in a huge, modern city like Chester, but where discs might be really useful is when descending some of the exceptionally steep roads that I deliberately choose to drive on?

As you can tell, I'm not embracing modern technology quite as easily as you do, but then again, that's why I like old cars.

Photo of me looking even older than I am as we went through a car-wash.

 

[the hobbler]

Really liked your picture of the Lagonda being used 'competitively'. For many years, as an impecunious London copper, our family car was a Lagonda M45 saloon. Not only was this used as the family car (in those days, if a copper could afford a car it was an old one that he kept running on a shoe-string) but father rallied it---classic, navigation, night rallies on public roads. The brakes, as you mentioned, were huge, finned drums and one of the reasons that they were so good was the fact that Lagonda were among the very first manufacturer to fit servo assistance. The shoes were operated (if my memory is correct) by a '2 lobed cam'; each of the lobes (1 each end of the cam) pushed a shoe out at the top.The down-side of this method of operation was that if the cam lobes/brake shoe was worn,the cam could 'lock' in the (I believe) horizontal position.This not only totally locked the brake on at that corner, but made it a real bugger to remove the drum! Another reason for having good brakes was that the M45, even in saloon form was a very quick car for its day---when "The Motor" magazine road tested the car, it was adjudged to be not only the fastest standard saloon the magazine had tested, but a genuine 100mph vehicle. I can remember my father BACKING OFF at 90mph on the old 'Dicker straight' on the Eastbourne road, and that was about 60 years ago.
One of the joys of this Forum is that we CAN discuss things that we agree/disagree about in an amiable manner---long may it continue.