Front drum part number

[jstoezel]

Hi:

I read a while back on this forum that they are different quality front drums brakes available on the market (and some will chatter). When looking at this link http://www.cip1.ca/SearchResults.asp?Se ... ch1=Search, I understand not all drums are the ones to use for FV, but the price difference is quite big. From $49 and up.

Which part number do you recommend?

Jean

[tiagosantos]

From that page, I think there's really only 2 options:

http://www.cip1.ca/ProductDetails.asp?P ... D615%2DAGR german made, 89 bucks

or

http://www.cip1.ca/ProductDetails.asp?P ... %2D615%2DA Brazilian, 50 bucks

I'm currently using the Brazilian ones cause they were cheap and I was having a bad month when I bought them hehe... I get the impression they will eventually crack but I keep an eye on them and look for cracks before every session. Looking at SR's website though, they're the same ones that Jim lists so maybe they're not that bad!

[SR Racing]

Front drums have never been a big issue as far as breakage. It was the rears that had most of the problems. We carry the fronts in brazillian and haven't had any problems. We pay a bit more to get the rears in German or Italian whatever are available. We haven't had any issues with those either.

[brian]

I think you guys may be confusing rear drum issues with the fronts. In my experience, rarely do front drums crack. Frankly, I've never seen one crack. That said, one mistake many make is to not have the drum turned once the bearing races are installed. One would think the entire drum is machined on a common center and it shouldn't matter; but it does. As a matter of practice, our brake shop always trued the drum to the races. Not doing so can lead to "chattering" Tell your machine shop just true the drum with a fine cut. When checking drums, hang the drum on a metal hanger or welding rod and strike it with hammer. The drum should ring like a bell and the sound should sustain. (musical term for last a while). If you get a thud or a shortened ring, find another drum. It may well have a void in the casting or a crack. The major difference between Brazilian and German drums will be in the accuracy of the machining and durability. On Brazilian drums, I always heat the drum to install the bearing races to prevent splits. A MAP torch is really handy for this kind of stuff. I've run both but prefer the German with Carbotech cause they wear better.

[tiagosantos]

I knew the rears were prone to cracking, but for some reason thought the fronts weren't all that strong either - noticed a local driver had a nasty crack on one of his front drums recently, which 'confirmed' my belief. Glad to know it's not as common as I thought

[jstoezel]

We had a guy crack a front drum last year. From what I understand it was a new(ish) drum from CIP.

[tiagosantos]

Guess the canuckistanis are pretty tough on the little buggers!

[jstoezel]

I need to provide a correction: I just spoke with the guy that broke a drum at the track, and he broke a rear one, not a front one as I thought.

So I will be saving myself $100 and I will be ordering the Brazilian type.

[jstoezel]

Hi Tiago:

The track at Gimli is very bumpy, it's hard on the cars. It uses part of an old air strip where the famous Gimli glider crash landed. Here's a lap of it:
http://www.youtube.com/watch?v=IlIqUidYy6Y

Feel free to comment on how the front end rolls, and how the shocks bottom. I posted the video a few days ago as I wanted to get advices from one of the best FV driver around .

While driving, I never realized how much roll the front end was developing, or even I never noticed the shocks were bottoming. The only thing I knew was that the car oversteered a lot during the cornering phase (see the corrections in most fast corners). The bump at the apex of T1 doesn't help.

Jean

Guess the canuckistanis are pretty tough on the little buggers!

[jstoezel]

Disassembled the from end today to find that I had a broken sway bar, no wonder there was so much roll...

It doesn't look like the welds penetrated very deep. The holes they drilled to get the welds to penetrate are still partially visible.

Any tips on how to repaire this bar?

[ external image ]
[ external image ]
[ external image ]

[FV80]

Any tips on how to repaire this bar?

Jean,
Repair should not really be any problem at all on that bar. Grind off all the 'flange crap' on the square end and grind an angle around the end of the tube. Drill a hole completely through the tube end so that you end up "looking at" the 'inserted' part of the square end through the holes. (There appears to be a hole that has been welded over in the picture, but it did not penetrate to the 'insert end' of the square end - it SHOULD have). Reassemble and have a good tig welder, reweld it - including through the newly drilled holes ... that was obviously NOT done (properly) last time. (make sure the square ends are "square" with each other before the welding starts <g>).

Steve, FV80

[jstoezel]

Back to rear drum part numbers CIP lists this:

http://www.cip1.ca/SearchResults.asp?se ... =25&page=1

Could somebody confirm this is the type to get (BDC markings)? http://www.cip1.ca/ProductDetails.asp?P ... -501-615-D

Thanks,
Jean

[brian]

Note that the seller says "or equivalent", chances are it's the Brazilian unit. If you're not really going to lean on the brakes and use carbotechs, the Brazilian are fine. If, like me, and tend to heat up the drums once in a while, the German tends to have better memory, meaning that it tends to warp less from heat cycles, and they wear less with Carbotechs.

[jstoezel]

Hi Brian:

Thanks for the reply. Like you said, the descriptions can be misleading.

Are these the only German drums on the page I pointed to:
http://www.cip1.ca/ProductDetails.asp?P ... 01-615-AGR

Even on sale it seems a bit expensive...

Jean

Note that the seller says "or equivalent", chances are it's the Brazilian unit. If you're not really going to lean on the brakes and use carbotechs, the Brazilian are fine. If, like me, and tend to heat up the drums once in a while, the German tends to have better memory, meaning that it tends to warp less from heat cycles, and they wear less with Carbotechs.

[brian]

Yes, it says German but the picture is a rear drum. If the price is over $100 it's probably German. Yes the price is much higher but it will be a drum that will last many years.

[SR Racing]

The drums look different to me. The 211 part number appears to be for a bus. Not sure of they work or not for your rear axles and brakes.
The 111 part number is the correct application but appears to be Brazilian.

[jstoezel]

A follow up to this post.

I ordered this front drum type about a year ago: http://www.cip1.ca/ProductDetails.asp?P ... -405-615-A. After about 45 sessions noticed one of them was cracked almost all the way around. It wasn't involved in any crash, just used on a rough track.

No catastrophic failure, not necessarily saying this is a bad product but apparently they can crack.

Jean

[csingletary01]

I have had a front drum failure this season at Texas World Speedway. It was a left front which is the least loaded at TWS. The drum had 6 weekends of vintage racing with hoosier vintage tires. I now check my drums for cracking on my prerace weekend inspections. It just could have been a very isolated problem.

[jstoezel]

So one of those front drums I had bought after I started this thread broke. Or I should say cracked. I noticed the crack while torquing the wheel about 15min from the start of a race. Seems like they lasted about 1 season, or 30 races (plus practices and qualifying). I had changed both at the front with the same model at the same time. The other one seems fine for now.

Meanwhile I have been using those BDC-stamped at the rear, they came with the car when I bought it 4 seasons ago. Who know how old they are. My understanding is that they are cheap ones, they have yet to crack though.

What is the consensus with drums? Is it the luck of the draw for any type (including the expensive ones), once in a while they crack, whatever brand they are? Or is it that you never see one of the expensive ones fail?

Unfortunately the price difference between the el cheapo and the ones that LRE makes (or the company that took over) is such that somehow this is not a straightforward decision, at least for me (shipping and border fees adds to the already big price tag).
It's almost like if I could replace cheap ones every season it would still be less expensive than getting expensive ones. That is if they don't crack right from the get go.

What is the cracking due to? Is it purely random, or is it due to stress, like heating up the brakes too quickly, or shocks? That one drum was on a wheel that came apart from the car when I broke a spindle, the race week-end before.


Jean

[SR Racing]

It is purely the casting process and/or the materials used. (how much carbon, cooling time, heating temps etc. during manufacturing. No heating that you could ever achieve via braking would ever make a difference. There are processes that can eliminate these stress points, but it takes a LOT of heat or super cooling. Not something you will get in a VW drum.

After manufacturing there are always some points that are under stress in the material. Depending upon where those stress risers are and how much beating it takes will determine when and if it cracks. It is a bit unusual for the fronts to crack due to the design.

Unless you buy a drum that has been built/cast for FV racing, it is something you live with.

[brian]

Let's be clear about which drums we're talking about. Rears crack as a result of side loading and poor finishing. Prior to the US made rear drums we would radius the adjustment and oil weeping holes to reduce stress risers and they would live longer. Most of the time, rear drum cracks begin at one of the mentioned holes and migrates.

Front drums are a different issue. Lately I've been seeing a lot of heat checked front drums and it seemed to start with the later generation Carbotechs. I'd post a picture but it appears to be beyond my skills. Heat checking looks like little black clouds floating on the contact area. It it's really bad, you'll see little cracks running around as well. Heat checking is caused by an aggressive shoe material, poorly arched or mismatching shoes to the drum and dragging shoes. Often a heat checked drum will cause chattering or vibration under braking. If your brakes kinda "honk" or make noise when cold, the drums are probably heat checked. You can sometimes feel a bad drum by gently applying the brakes at slow speed and if the brake pedal moves up and down under your foot, it's a drum issue. Under heavy braking with a hot system these traits may not be able to be felt but I believe this vibration is what is cracking front drums, and the Brazilian drums seem to be more susceptible.

I will post the results of my shoe testing as I run different configurations.

[SR Racing]

I think we are talking two different things.. (not unusual here).

The checking brian is talking about is not a drum breaking issue. We see this checking on TransAm etc cars with disc brakes. As Brian points out, it is a pad/shoe agressiveness issue. (and to some degree a drum/rotor composition issue.)

The drum breakage issue is unrelated directly. Again as Brian says it is a stress riser, G-load issue.

[CitationFV21]

Jean,

Which wheels do you run? And what do you torque them to?

ChrisZ

[brian]

here's the picture I mentioned earlier. You can see the dark areas in the contact area.[ external image ]

While not common, a over heated drum can develop cracks and eventually fail. I have seen heavy truck drums explode from overheating. But the issue here is why are we seeing cracking on fronts after being so rare in the past. As I mentioned, I have seen an increase in heat checking in front brake drums and have seen two crack in recent times. While the side loading is an issue, I don't think it's the major cause of this recent increase. The Brazilian parts have always been suspect and I personally avoid them. I'm no engineer but I do know this high heat we're experiencing is ruining the strength of our drums.

I'm leaving on vacation tomorrow but when I get back I will post pictures of a grooving procedure to reduce the heat on drums. My old partner in the brake shop and I talked and while we may not be the only people on the planet who remembers brake drums, we remembered a grooving procedure we did on heavy applications and race cars. Basically the grooving allows the superheated gases coming out of the hot shoes a chance to get away from the shoes and drums keeping things a bit cooler. Many years ago, when we still used asbestos, Velvatouch metallic shoes had these grooves built in. If you want to try something before I get back, visualize around 5 equally spaced 45 degree grooves less than 1/8" deep across the face of the shoe. Direct the grooves so that the forces of the wheel push the shoe against the backing plate. Imagine rain tire grooves and their orientation and you'll see how tire direction will interact with the grooves. You can use a small ball grinding bit or a hand file to make the grooves.

[jstoezel]

Thanks for the replies.

What Brian mentioned about heat cracking on the front drums is similar to what I had heard, but somehow a different result. I heard that the contact patch of the drum would heat very quick with Carbotechs while the part that is connected to the spindle would stay relatively cold. Somebody may have mentioned it on this forum actually, I don remember where I heard it from.
I only use Carbotechs at the front, not the rear.

Brian, what do you mean by "we would radius the adjustment and oil weeping holes to reduce stress risers".
I guess you are referring to those holes in the face of the drum (5 and 10 o'clock)

[ external image ]

I never saw cracking like Brian picture, the failure I saw on the front drum is a crack all around the spindle axis.

ChrisZ, I use custom wheels built for the Canadian FV series (WCMA and F1200). There's 2 models available, I have the older type. I torque at 55lbs.