Brazilian Brake Drum markings

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planbracing
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Joined: April 28th, 2010, 8:07 pm

Brazilian Brake Drum markings

Post by planbracing »

Are there any markings that identify a Brazilian brake drum. I had a rear drum lose its splines on Sunday (DNF), this was the first time I was almost competitive at the regional level and I don't want to have that happen again (at least not because of a bad drum). I have ordered good drums to replace both rears, but would like to know if I could/should keep the drum on the car as a spare.
Gary Grubb
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FV80
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Re: Brazilian Brake Drum markings

Post by FV80 »

Gary,
I'm not positive, but I think that MOST drums are marked with SOMETHING that can determine their country of origin... but I wouldn't have a clue what Brazil might be using.
That said, I have no past experience to indicate that Brazilian drums are any worse than any others. It is HIGHLY likely that one or more of the following occurred.
1). Hub nut was not torqued adequately
2). Cotter pin (or hitch pin ... or whatever) was not properly inserted or became LOST ... possibly due to contact with another car/object (and the nut loosened).
3). The car became airborne at some point and ...when coming down caused the outer casting on the axle tube to move (along the axle) to an extent that negated previous torquing of the hub nut.

It is always POSSIBLE that something untoward was awry in that particular hub. But I wouldn't put ALL Brazilian drums into the trash just because that one "failed". I'm pretty sure that I've NEVER seen a drum that "lost it's splines" that was still properly torqued when it came in. If the faces on the inside and outside of the drum are still "just fine", then you might have the rare failure. But EVERY ONE that I've seen fail "spline wise" was LOOSE for one reason or another and THAT is what caused the failure.

YMMV,
Steve, FV80
The Racer's Wedge and now a Vortech, FV80
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jpetillo
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Re: Brazilian Brake Drum markings

Post by jpetillo »

I had a similar drum failure and for my case I agree with Steve that it was most-likely not torqued down properly. I did torque it down enough, but I'm guessing there was some debris between the surfaces that caused it not to seat squarely - didn't check for that. I now check/clean the faces on both sides of the drums as well as the nut and sand off anything that collects - takes seconds to do. I've never had a drum fail since. John
G.B.
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Re: Brazilian Brake Drum markings

Post by G.B. »

I agree with John and Steve, in my limited experience, this type of drum failure has generally been due to an insufficiently torqued axle nut.

Jim Schings sells a torque multiplier tool especially for this task. I have found it invaluable.
jpetillo
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Re: Brazilian Brake Drum markings

Post by jpetillo »

Yes, I have one of the torque multipliers. Can't go wrong for setting the torque - you get to use your torque wrench!
planbracing
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Joined: April 28th, 2010, 8:07 pm

Re: Brazilian Brake Drum markings

Post by planbracing »

The drum was torqued to 300lb via a torque wrench (3/4"drive) at the start of the weekend, with cotter pins. After the first race, which is when I now know the problem started, the cotter pin, which was there before the first race, was missing. I did snug (not torque) the nut so I could get another cotter pin in before the start of the second race (which was missing after the flat tow in).

I guess the questions I have is how often should I check the axle nuts? after each session? should I use something other than parts store cotter pins?

thanks for your input
Gary Grubb
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Re: Brazilian Brake Drum markings

Post by FVartist »

I use a bolt and nut. Remember cotter pins should never be reused, it would be like reusing toilet paper, not a good idea.
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FV80
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Re: Brazilian Brake Drum markings

Post by FV80 »

planbracing wrote:....
I guess the questions I have is how often should I check the axle nuts? after each session? should I use something other than parts store cotter pins?
thanks for your input
Gary,
I try to check the cotter pins after EVERY session (but sometimes I forget :-) ). If everything is correct, the nut should NEVER loosen on its own. The cotter pin should be 'free' and should not carry a load at all. I use HITCH pins and simply check to make sure the pin moves freely in the slot. If it is loaded, that means that something MOVED and EVERYTHING needs to be rechecked. If your nut is getting loose every session, something is wrong. The axle threads can be rolled over by overtorquing the nut. When that happens, the threads don't seat as deeply into the nut ... or the threads in the nut can sometimes strip out. Tightening it tighter just makes things worse.

Look CLOSELY at the threads on the axle (compare to a new one if possible). The nut should spin on by hand till it bottoms on the hub face - if it doesn't, you may have issues. I don't know if you've had the axle tube assembly apart, but it is also possible to FORGET to install the spacer that is behind the axle bearing. If that spacer isn't there, the nut will not tighten properly against the hub assembly causing significant grief and heartache.

Can't think of anything else that wouldn't be obvious ... except, maybe for a cracked drum - be sure to inspect it carefully around the casting hole - the one you DON'T use to adjust the shoes.

Steve, FV80
The Racer's Wedge and now a Vortech, FV80
To sign up in the FV Registry for updates about SCCA Formula Vee, please send me an email or PM with your name, location (city/state), make/model of car, phone # and any other appropriate info.
brian
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Re: Brazilian Brake Drum markings

Post by brian »

If the torqued nut gets loose, there's something else going on. 300# should not loosen unless: the mounting faces of the drum are crumbling, the splines in the axle are worn or twisted or, like Steve said, the casting has shifted. Inspect the splines very carefully and make sure the drum fits firmly. Sometimes on new drums the drum won't go on all the way and MUST be re-torqued after the first session. Any waviness in the splines, usually caused by contact, means it's time for a new axle. I can't speak for the Brazilian drums but the Germans always mark their stuff.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
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