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New drums already out of round?
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zuhandenheit
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PostPosted: Mon Sep 29, 2008 5:35 pm    Post subject: New drums already out of round? Reply with quote

My drums are only about three months old and already seem to be warped. I didn't put them on myself, and when they were first installed my rotors were warped, which is where I assumed the vibration was coming from.

But I fixed the front brakes, and it's still messed up. E-brake test verified that it is the rear brakes. It seems to be mostly one wheel.

I've heard that these drums are prone to warping.

Here's my real question: I'll be taking a long trip in a few days, and will hardly be able to make time to pull off the drums and get them resurfaced. I'd rather leave it alone for now.

Is it likely that they will become more warped if I don't do something about it right now?

Are there any other problems that could masquerade as out of round drums?

If I fix the drums, are they likely to promptly warp again? (as I said, I've heard rumors here about these drums warping easily)

thanks!
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Captain Pike
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PostPosted: Mon Sep 29, 2008 6:05 pm    Post subject: Reply with quote

Warped drums are scrap. Get a new one,sorry. Never hit a Vanagon drum with a hammer_____EVER. One blow can ruin them.
Pull the 42mm nut with the tire to gain leverage, then release the drum/hub.
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zuhandenheit
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PostPosted: Sun Dec 14, 2008 7:17 pm    Post subject: Reply with quote

I was getting ready to ask another question about drum brakes and then remembered this thread.

So, here's the deal: I pulled off the drums and had them turned. They were badly warped. (by the way, i did do this right before the afore-mentioned long trip)

When I told the guy who worked the lathe that they were only a few months old, he suggested that they might have been defective--he said he occasionally sees badly machined drums with off-center lug-holes.

The drums are now much better, but still feel slightly out of round. I'll get new ones when I have a little extra cash.

So, the question is--have any of you ever seen bad drums?

These were from gowesty. I'm certainly not going to give them a hard time about it, because it would be nearly impossible at this point to determine what caused the drums to fail.

Incidentally, one was much worse than the other.

I would also be interested in any other suggested explanations. I'm just curious what caused my brakes to so get messed up.
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Wildthings
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PostPosted: Sun Dec 14, 2008 7:31 pm    Post subject: Reply with quote

Did you have the drums turned after mounting them on the hub, but before installing them and running them? It is often necessary to do this.


Also. I have also seen hubs that couldn't be centered correctly in the lathe so if the drums were turned on the hubs they ended up out of round because of it. If this happens you need to find a different hub and try again.
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zuhandenheit
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PostPosted: Sun Dec 14, 2008 7:42 pm    Post subject: Reply with quote

Well, I had a shop put the drums on for me, and I really don't know what they did. If I could think of any way that they would be responsible, I would probably blame them--they sure didn't do a good job with the body work that i took it there for.

But why would it be necessary to turn new drums? Because of bad initial machining?
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Wildthings
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PostPosted: Sun Dec 14, 2008 7:51 pm    Post subject: Reply with quote

zuhandenheit wrote:
But why would it be necessary to turn new drums? Because of bad initial machining?


If the hubs aren't prefect then the hub/drum combo will be out of round if not turned together.
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Captain Pike
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PostPosted: Sun Dec 14, 2008 7:57 pm    Post subject: Reply with quote

zuhandenheit wrote:
Well, I had a shop put the drums on for me, and I really don't know what they did. If I could think of any way that they would be responsible, I would probably blame them--they sure didn't do a good job with the body work that i took it there for.

But why would it be necessary to turn new drums? Because of bad initial machining?

The shipper dropped them.
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zuhandenheit
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PostPosted: Sun Dec 14, 2008 8:16 pm    Post subject: Reply with quote

Wildthings wrote:
zuhandenheit wrote:
But why would it be necessary to turn new drums? Because of bad initial machining?


If the hubs aren't prefect then the hub/drum combo will be out of round if not turned together.


Ok, that makes sense.

Quote:

The shipper dropped them.


I actually thought about that . . . but, wouldn't it take a *really* serious drop?
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Terry Kay
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PostPosted: Sun Dec 14, 2008 9:01 pm    Post subject: Re: New drums already out of round? Reply with quote

<<My drums are only about three months old and already seem to be warped.
I didn't put them on myself,>>


And you didn't know if they were adjusted too tight, which caused them to heat warp


<<I've heard that these drums are prone to warping.>>

Who told you that?

<< I'll be taking a long trip in a few days, and will hardly be able to make time to pull off the drums and get them resurfaced.>>


You don't have an hour?
In the time it took you to post this message , and read all the replies, you could have them off, and cut already.

<<I'd rather leave it alone for now.>>

Good idea-- your next message will be --"How Come My Rear Shoe's Are Screwed Up?

<<Is it likely that they will become more warped if I don't do something about it right now?>>

Could be--plus the info mentioned above.

<<Are there any other problems that could masquerade as out of round drums?>>

Nupe.

<<If I fix the drums, are they likely to promptly warp again? (as I said, I've heard rumors here about these drums warping easily)>>

From who?

If the shoes are new, installed right, been radiused to fit the drums properly, and the shoes are adjusted right, you'll have no problems.

A set of shoes too tight in them drums will cause the drums to warp fast.

Pull the drums and get them cut---they won't ever self heal themselves.
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Last edited by Terry Kay on Sun Dec 14, 2008 11:28 pm; edited 1 time in total
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zuhandenheit
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PostPosted: Sun Dec 14, 2008 11:01 pm    Post subject: Reply with quote

Thanks for the reply.

Maybe I wasn't clear-- I did take the drums off and have them turned before my trip, which was several months ago. That helped significantly, but didn't entirely eliminate the pulsation. the guy working the lathe said that one drum was very badly warped and suggested the possibility that the drum's lug-holes were off-center.

Mostly now I'd just like to know what might have caused the original problem . . .

I guess that, as you mentioned, poor initial adjustment is a possible cause.

I'm totally new to drum brakes.

Oh, and regarding the alleged warp-proneness of these drums: that's something i've read here in a few threads. I'd rather not search around for whatever posts I've seen, so it would be fine with me if we just ignore that claim altogether.


Anyway, I guess I need to start over with a new set of drums and just hope that nothing else is messed up.
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Terry Kay
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PostPosted: Sun Dec 14, 2008 11:31 pm    Post subject: Reply with quote

Make sure the shoes fit the drum properly---

Shave the shoes so the whole thing fits onto the face of the drum evenly

No high spots to heat up & warp the drum.
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MarkWard
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PostPosted: Mon Dec 15, 2008 11:49 am    Post subject: Reply with quote

I am surprised you can feel a warped drum through the brake pedal. Because the rear hub is not part of the drum, there are a few reasons you could be having problems. Where the hubs cleaned properly before installing the new drums? Where the lug nuts torqued or hammered up with an impact gun? Was the person machining the drums experienced. Machining a drum without the center requires a bit of skill to get it centered. If the center of the drum had been distorted when it was first installed, that could cause it to sit crooked on the lathe. The drums on my Vanagon, sat rusting for 7 years, while the conversion was done. When ready to put the van back on the road. I replaced the brake hydraulics including new wheel cylinders, brake calipers and flex hoses front and rear. I reused the pads and shoes. I scuffed them with 80 grit sand paper. I also just scuffed the discs and drums. If any pedal pulsing was to be expected, it would have been on my van. It stops like new.

If you are buying parts from an online vendor and then bringing them to the shop to install or taking the van to a shop after you have done the work yourself, but have a problem. It is not fair to the vendor selling the part, the shop installing or troubleshooting the part, or to you. The expression is "Too many chefs".
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riceye
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PostPosted: Mon Dec 15, 2008 2:38 pm    Post subject: Reply with quote

I noticed a pulsation after removing the drums to check my rear brakes last year. I took them back apart and noticed that I had put the drums on in a position where the holes for the 8mm retaining bolts were not lined up (I previously removed the bolts to allow fitment of my alloy wheels).

I put the drums back on correctly, and the pulsation was gone.

Coincidence?
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skaaudivw
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PostPosted: Mon Dec 15, 2008 4:39 pm    Post subject: Reply with quote

I bought drums from AZ autohaus and they just barely didn't fit. so yes there are crappy drums out there. Lesson learned is by the best german stuff. It's all I buy now even all my kids toys are wooden german toys We tossed and the Chinese crap.
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zuhandenheit
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PostPosted: Mon Dec 15, 2008 4:58 pm    Post subject: Reply with quote

rsxsr wrote:
I am surprised you can feel a warped drum through the brake pedal. Because the rear hub is not part of the drum, there are a few reasons you could be having problems. Where the hubs cleaned properly before installing the new drums? Where the lug nuts torqued or hammered up with an impact gun? Was the person machining the drums experienced. Machining a drum without the center requires a bit of skill to get it centered. If the center of the drum had been distorted when it was first installed, that could cause it to sit crooked on the lathe. The drums on my Vanagon, sat rusting for 7 years, while the conversion was done. When ready to put the van back on the road. I replaced the brake hydraulics including new wheel cylinders, brake calipers and flex hoses front and rear. I reused the pads and shoes. I scuffed them with 80 grit sand paper. I also just scuffed the discs and drums. If any pedal pulsing was to be expected, it would have been on my van. It stops like new.

If you are buying parts from an online vendor and then bringing them to the shop to install or taking the van to a shop after you have done the work yourself, but have a problem. It is not fair to the vendor selling the part, the shop installing or troubleshooting the part, or to you. The expression is "Too many chefs".


Well, I can't really answer your questions, and yeah, that's because other people were involved.

I guess I knew that there would be some kind of problem, and that I should just do it myself. But I already had so much other stuff to fix, and the van was going to be at this shop anyway (for body work), that I decided to have them do this one other thing.

And of course the body work wasn't very good either. I probably could have learned to weld better than they did in the time they had the van. The windshield wasn't seated properly; there was bare (flash rusted) metal showing where they missed spots with their primer. etc. This shop has a good reputation. But oh well, lesson learned. At least my whining earned me a lower than estimated price. The owner of the shop is a nice guy.

Anyway, if the drums were bad, the problem should have been apparent when they first installed them. So, one way or another, I'm pretty sure that they didn't do a good job.
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zuhandenheit
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PostPosted: Mon Dec 15, 2008 5:02 pm    Post subject: Reply with quote

skaaudivw wrote:
I bought drums from AZ autohaus and they just barely didn't fit. so yes there are crappy drums out there. Lesson learned is by the best german stuff. It's all I buy now even all my kids toys are wooden german toys We tossed and the Chinese crap.


That's interesting. One thing I can add also--i should have said this already--before I had the drums resurfaced, I could spin the wheel and feel spots where the shoes touched the drum, with the parking brake disengaged.

After I had the drums turned, I adjusted the shoes all the way 'in,' and there was still a position of the wheel where I could feel very light contact between the shoes and drum. I did adjust the parking brake also, and am sure this wasn't the problem.

It was because of this that I concluded that the bolt-holes might be off center. I guess it could also be some issue with the hub.


Drum brakes confuse me.
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Randy in Maine
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PostPosted: Mon Dec 15, 2008 5:10 pm    Post subject: Reply with quote

I assume that you have also replaced the rubber brake lines?
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Ryan Alfonso
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PostPosted: Mon Dec 15, 2008 9:01 pm    Post subject: Reply with quote

hey zuhandenheit,

you're not alone. i went through this with two sets of drums recently. (4-5 months ago). seemingly high quality drums too (ATE). turned and it came back again, less so, but still there. consarnit. it's not just peddle pulsation, but squeek too.

So let's upgrade to discs!
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Terry Kay
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PostPosted: Mon Dec 15, 2008 10:58 pm    Post subject: Reply with quote

Hold it---
Once the center of the drum is riding on the hub---yea--the bolt holes can be to the right or left of the holes--but no way can they be off center.
The hub center's them on the shoes & backing plate.

The shoe sping loaded hold downs can be shifted to the right or left, but will center once the brake pedal is hit.

Just about the only way to get a drum good and off center is with heat.
From a torch to break them free off of the center hub, or with an overly exuberant brake adjustment, which will warp them pretty quick--and yes, you will get a pedal pulsation.

If the outfit that is cutting your drums has a quality brake lathe, ( Souix,or Blackhawk) there is no way that the drum can be cut off center.
You sure can't cut them with the hub in place--no way.
They can chuck the drum up with the proper adapter, and they will be as true as an arrow--
Plus the guy doing the job has to know what he's doing.

True up your shoe's--match them to the drums surface--get rid of the high spots in the shoe's.
It's a little time consuming, and you'll need the proper tools, but it'll square the rear brake problem away fast.
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zuhandenheit
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PostPosted: Tue Dec 16, 2008 10:00 pm    Post subject: Reply with quote

Ryan Alfonso wrote:
hey zuhandenheit,

you're not alone. i went through this with two sets of drums recently. (4-5 months ago). seemingly high quality drums too (ATE). turned and it came back again, less so, but still there. consarnit. it's not just peddle pulsation, but squeek too.

So let's upgrade to discs!


Yeah, forget these drum brakes!

Except that . . . i'm still a little concerned that problems can arise from unbalanced braking force (since the proportioning valve is designed for the drums)

anyway, I'm glad to know that I'm not the only one having problems.


Terry Kay -- thanks for your suggestions. You're right about the bolt holes: the drum does have to be centered on the hub, regardless. I think that rules out that possibility.
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