Drum vs Disc

[jhenn4716]

Recently I witnessed a drum brake shatter during a race, leading to the car of course crashing and the tire go flying.

What are the chances of a catastrophic failure when using disc brakes? How often do we see these types of failures with drum brakes?

I'm not asking about cost, of conversion issues. Only as it relates to safety.

Thanks!

[sracing]

I think this has been answered here before but :

In all of the FST races I have been to (all of them ) I have never seen a rotor break or seen any catastrophic brake failure relating to the use of the current disc system.

[Steve Bamford]

Hamilton's brakes failed at Silverstone this year in Q2, he wasn't running disk brakes was he?

[sabre1fv]

While I can't directly answer your question, I can state that older VW rear drums can crack at the hole that is approximately half the distance from the center to the outside diameter (i.e. not the adjustment hole). These holes have a cast surface which is quite rough. I will grind them smooth in the hope of preventing a crack from starting. Over many years of racing I have never had one crack, but have seen cracks on other cars where the hole was not ground smooth.

While I'm certain that Jim is correct about the FST disk brakes, that probably isn't the best comparison. Likely the shattering was due to excessive flexing of the drum. The load path from the tire/wheel for a drum brake has a larger diameter that that for a FST disk brake, and as such imparts more flexing into a cast part that was never intended to handle such loadings.

-Jim

[problemchild]

If you are referring to FV/FST cars, you will likely not have the catastrophic result with the disc configuration because the caliper keeps the disc on. That is what happens when the splines strip and the nut loosens up or falls off.

By the tone of the initial comment, you could get the impression that drum failure is instant or spontaneous. I have never seen a FV drum "shatter." Like any race car, FVs need maintenance, awareness to issues particular to classes and brands of parts, cars, etc. I have changed a half-dozen rear drums in 35 years when I noticed cracking. They fail when cracks are not noticed, ignored, or otherwise, and people continue to drive despite the car slowing down due to the distorting/dragging drum. It's similar to continuing to drive with an overheating engine which just slows down until it seizes.

Education and maintenance make drum failure very unlikely.

[nbrigido]

While I have never seen a drum crack during a race. The comparison vs disc, might be a bit unfair.

Drums have been around for many years in Vee racing, Disc brakes are relatively new.

Age plays a big role in understanding what happened when there is a catastrophic failure.

How old were the drums that cracked?
How old were the other components?
Was there an issue that was ignored?

How long have disk brakes and associated components been in use, probably a lot less.

I am not saying this in a drum vs disc debate. or making light of a serious issue,but more in understanding the issue.

I have seen a brand new oil filter blow off during a race?
I have see a new tire let go?

[sracing]

While I have never seen a drum crack during a race. The comparison vs disc, might be a bit unfair.

Drums have been around for many years in Vee racing, Disc brakes are relatively new.

Age plays a big role in understanding what happened when there is a catastrophic failure.

How old were the drums that cracked?
How old were the other components?
Was there an issue that was ignored?

How long have disk brakes and associated components been in use, probably a lot less.

From my experience the newer Brazilian drums are far more prone to breakage. The older German ones seem to be much better. It is certainly not an age issue. (Since the German drums are usually 5 to 50 years old ) I don't think German ones are available anymore. There are some Italian ones available yet, I believe. But not enough statistical data to say one is better than the other.

Removing stress risers with a die grinder etc. does seem to help. As pointed out, disc geometry is completely different and this is not an issue.

Ongoing maintenance/inspection is a good idea but not fool proof. One good curbing hit can crack one and the next hit (etc) and the drum comes apart. Unless you stop in the pits after each bump, there is still some risk.

[sracing]

While I have never seen a drum crack during a race.

No disrespect meant at all, but... If you have never seen a drum crack during a race, you must not have been racing Vee for long. I have seen at LEAST 10 come apart in under 20 years during a race, and spotted at least another 20 cracked and about ready to come apart. It has happened in the run-offs, BD party races and many others.

I would be surprised if most EVERY Vee driver hasn't seen the cracks AT LEAST.
(BTW, I have not had one come apart in a race, but I have certainly replaced several after inspection revealed cranks.

I will admit that with non-slicks, it is not a big an issue. Far less G-Forces.

[problemchild]

One good curbing hit can crack one and the next hit (etc) and the drum comes apart. Unless you stop in the pits after each bump, there is still some risk.

I disagree with Jim's opinion. If I believed that statement to be true, then I would be in favor of switching from drums.

[BLS]

Is the rear drum issue confined to the aftermarket drums made in brazil/china? Has anyone cracked/shattered a german drum?

Richard Pare (ICP) makes rear drums that I believe will eliminate this problem.

[R. Pare]

I've supplied a few hundred drums to V racers over the last 16 or so years - first through Bob Lybarger, and now direct since he retired.

The current drums are pretty close to being totally bullet-proof - a couple of small design changes way back at the beginning and a couple material upgrades over the years have put them firmly in the "damned reliable" category.

A new batch of drums will commence machining sometime around the end of the year - massively overloaded until then with other work. Will announce here when they are ready for shipping.

[nbrigido]

No disrespect meant at all, but... If you have never seen a drum crack during a race, you must not have been racing Vee for long. I have seen at LEAST 10 come apart in under 20 years during a race, and spotted at least another 20 cracked and about ready to come apart. It has happened in the run-offs, BD party races and many others.

I would be surprised if most EVERY Vee driver hasn't seen the cracks AT LEAST.
(BTW, I have not had one come apart in a race, but I have certainly replaced several after inspection revealed cranks.

I will admit that with non-slicks, it is not a big an issue. Far less G-Forces.

None taken,

I have not been racing for a long as many of the people on this form.

I am just relaying my personal experience/observations.

I have cracked a drum, but it took a wall (corner 9 Mosport). Never having experienced Slicks, cannot comment on the Slicks/Radial difference.

[Bill Bonow]

In my history, the typical drum failure is not instantaneous. I'd bet 95% of the time a crack starts and grows over a few races before the drum comes apart. I have seen that other 5%, but its typically a pretty hard hit and attempted continue of racing that then results in failure another 2 or 3 corners later. Point being in many cases, it is poor inspection that results in the drum coming apart. That all being said, it's my opinion that only the later ribbed style ('65, '66 and '67) that tend to crack. The older OE VW German "smoothy" drums (up to '64) were my preference. They would typically bend rather than break. They were also lighter and narrower track.

FWIW, disc brakes in racing goes back better than 100 years (per Wiki) and the disc brakes used on that "other class" first came on street cars in the late 60's. The rears rotors are aftermarket but use VW calipers and have been out for about 20 years.

All that said, this is a dumb thread that once again, will go nowhere. The topic has been beat to death multiple times and disc brakes don't have a snowballs chance in hell of ever going on FV (safety issue or not). YMMV

[Jeremy Soule]

As a new guy Im finding this discussion very interesting and informative. Thanks all.

My take away is to "pay attention" to posable stress risers and inspect brakes often (disk or drum), and to pull-r-in after a thump on the track (probably lost some positions anyway).

[FVRacer21]

I finished a race at New Hampshire with a drum cracked 3/4 the way around (RR) Did not feel any vibrations or any other clue. I only had a bout 5 races on the drums, so I was checking the axle nuts but not even thinking about cracks. Also drums painted black may not show right away.

So now I will grind the oil sling hole (that is what it is for - don't ask me why),
practice on the cracked one with filling the hole somehow, (love to braze it but might be too hot)
and painting the drums either white or silver (any light color should work).

To run Thompson, I put on my 30 year + German drums that keep on going..

BTW, Steve at VSR told me about the "ring" test. So I taped the Brazilian drums and they sounded okay, even with a small crack, but the German drums rang like a bell -I recorded it on my smart phone to know what a good drum should sound like.

ChrisZ

[veefan]

BTW, Steve at VSR told me about the "ring" test. So I taped the Brazilian drums and they sounded okay, even with a small crack, but the German drums rang like a bell -I recorded it on my smart phone to know what a good drum should sound like.

I've been through the ring test also many times, Steve can usually hear a crack before he goes any further and uses the typical crack test stuff.

Anyone denying VW hubs can crack and cause a catastrophic failure, just needs to take a trip over to his shop. He usually has a fine display of tiny little hubs without about 80% brake drum sitting on one of his window sills.

[jpetillo]

By the tone of the initial comment, you could get the impression that drum failure is instant or spontaneous. I have never seen a FV drum "shatter." Like any race car, FVs need maintenance, awareness to issues particular to classes and brands of parts, cars, etc. I have changed a half-dozen rear drums in 35 years when I noticed cracking. They fail when cracks are not noticed, ignored, or otherwise, and people continue to drive despite the car slowing down due to the distorting/dragging drum. It's similar to continuing to drive with an overheating engine which just slows down until it seizes.

Education and maintenance make drum failure very unlikely.

This has been my experience as well, right down to the distorting/dragging drum feeling telling you something is amiss. There was ample warning. It was one of the latest Brazilian drums that seemed to have a bad casting. I don't know how to protect ourselves from defects/poor quality control other than to go with what we believe to be the better brands. There was a thread on this earlier this year, and people can refer back to that for more discussion. It seemed that the German and new Italian drums make the cut, and of course those from R. Pare.

The drums are some of the things I check for cracks, routinely. After going with the better brands I have never see a crack form on any of mine, but still check routinely.

About ringing, depending on the crack, a drum can still ring the same. They do not necessarily go sour tone wise if they're cracked. If they go sour, then they are definitely cracked, but just because they ring does not mean that they aren't. John

[problemchild]

This is one of these relative risks that all racers deal with. If you buy drums from a known source selling proven product, and keep an eye on the drums, then any risk of catastrophic failure is incredibly small. In my 35 years of FV involvement, I can count the number of "failed" drums I have seen on one hand, and none in my paddock spot. During that time, I have probably seen 100 blown engines, 50 wheels fallen off, 100 flat tires, a couple hundred sucked in or leaking rocker gaskets, 30 failed rear trailing arms, 30 failed modified pitman arms .... all with catastrophic potential and mostly self-inflicted human error root causes.

[Rolling Stone]

My drums are made by PEARL,I have a few problems with the skins at times but.....ooops!sorry...wrong forum

[Bob Posner]

I've used the Lybarger/Pare rear drums for 15 years. Replaced the first set after 100 races and retired them as spares,still perfect,virtually unworn and never remachined. I still look for cracks every weekend. Why anyone would use anything else is inexplicable.

[S Lathrop]

Maybe you guys need to get Richard Pare / ICP to make front drums and do another run of front spindles, spindles without holes for speedometers.

The spindles had a few other changes to make them less likely to bend and the drums certainly solved the drum issues with the VW rear drums that were available.

[veefan]

I'm just curious, how much are Richard Pare / ICP front drums or Lybarger/Pare rear drums?

[Bob Posner]

I have the ICP spindles also on one of my cars and the Palermo spindle savers on the other. Last I knew the ICP spindles were gone for good. The Palermo pieces are highly advised if the ICP spindles remain unavailable.

[veefan]

I'm just curious, how much are Richard Pare / ICP front drums or Lybarger/Pare rear drums?

Whats the price?

[BLS]

Send a pm to Richard (comment #11) and I'm sure he will give you a price.

[R. Pare]

Drums price ( rears only - no fronts) is $135 each, plus shipping.

I stopped doing spindles when the steel foundry that was 3 miles away closed down - the next closest is about 130 miles away. I might reconsider making some again if there aren't any decent alternatives available, but the way more profitable parts of the business keeps me more than busy.

[Johan W]

Hamilton's brakes failed at Silverstone this year in Q2, he wasn't running disk brakes was he?

In 28 years we(SA Vees) had none...zero failures on any formula vee disk brake system. You're probably aware that their(F1) system is way different then the disk brakes we're using in the lower categories.

However with the drum braked numerous failures like mine heading into Barbeque bend, Kyalami in 1979. They had to dig me out between the straw and catch fence. Also just a few months ago a failure on Ward's Vee I believe.

[Johan W]

The drums are some of the things I check for cracks, routinely. After going with the better brands I have never see a crack form on any of mine, but still check routinely.

About ringing, depending on the crack, a drum can still ring the same. They do not necessarily go sour tone wise if they're cracked. If they go sour, then they are definitely cracked, but just because they ring does not mean that they aren't. John

Bill Vallis changed my Vee's brake drums three months ago after he found one with a hair line crack. Probably a good idea to check on a regular basis.

[veefan]

What the heck, I'll stir the pot a little, yes many have raced for 10,20,30+ years and never had a failure, but clearly other people have had failures... otherwise why bother to crack test if you're not worried about a failure?


So the drums that don't crack are $135 each so $270 for just the rear set of drums... hum...

Total rear disk brake conversion... $223.00? yep!
http://www.appletreeauto.com/DISC-BR...EAR-22-2862-0/


Fronts?

Wow! 221.99??? double hum... and keep the king pin beam?
http://www.appletreeauto.com/ECONOMY...-BRAKES-A1003/



OMG now we need to think about 4 bolt rims...

tons of used VW 4 bolt rims on the market,, but why not new???

http://www.ebay.com/itm/Late-Chrome-...904e87&vxp=mtr




Savin a little cash and not buying $250 pairs of carbo stuff...

how about some nice rims...

http://www.appletreeauto.com/EMPI-8-...VER-00-9557-0/

[Diamond Level Motorsports]

I think you meant "link pin beam", not king pin.

This makes way to much sense to be actually considered........

[Amon]

Vee fan,

You might want to read Bill Bonow's last paragraph from his latest post (#13) and
take it to heart.

Mark

[veefan]

Vee fan,

You might want to read Bill Bonow's last paragraph from his latest post (#13) and
take it to heart.

Mark

That's exactly why I posted...

Round and round we go... but in this case, we all know how this will end up...

[Pi_guy]

You want to change a class that has been fairly stable for 50 plus years. The item you want to change is not a safety improvement, it really will not help the car as it has enough brakes as it is.
The major point I want to make is I have never seen a upgrade that stays at the price posted there is always one or two items that drive up the price.
The final point would be it would cause cars to be made mentally obsolete since they did not have the latest upgrade. Reducing the number of entries would be a bad thing.

The upgrade money would be better spent on track time and entry fees.

[jhenn4716]

Thanks everyone who posted something on this post. The intent was really related to education vs the whether FV should or should not switch to disc brakes.

I do not have the experience that many of you have and that was the first time I'd seen a drum brake come apart. I have seen posts in the pasts about drum's cracking but had never really connected the two till this incident.

Like Jeremy, I'm more educated now on what to look for when inspecting my brakes components.

Thanks all