'69 Bus Front Drum Issues

hambone · Post by **hambone** » Tue May 05, 2009 8:04 am

Whilst braking, there is a klunky-pulsey-gritty-grindy sound probably caused by out of round drums. You can actually feel the shoes pulsing, which shifts to a klunky squeal as you stop. This actually caused one of the springs to break (it was really old anyway).
Shoes are about 2 years old, with plenty of material left. Adjusting the brakes does not help.

I should probably replace the drums. And the #@%% shoes again (with decent German this time). I remember being cautioned to "never turn drums on a lathe". Is this valid? Am I forced to buy new Brazilian drums?

Geez that's expensive, $90 each:
http://www.busdepot.com/details.jsp?par ... 211405615C

$75 here
http://www.wolfsburgwest.com/cart/Detai ... 211405615C

gettin cheaper, $60
http://www.aircooled.net/new-bin/viewpr ... 0943644626

dtrumbo · Post by **dtrumbo** » Tue May 05, 2009 9:26 am

Bob, I think I have a pair of drums that may be in better shape than yours. I took them off the '70 when I installed the disc-brake conversion. I'll put my peepers on them and see if they're German and what condition they're in. If they turn out to be serviceable, I'll sell 'em to ya for lots less than you've been seeing. That'll at least get ya through the summer for sure.

hambone · Post by **hambone** » Tue May 05, 2009 9:27 am

Great! Lemme know.

(assuming they haven't been turned 1000 times)

vwlover77 · Post by **vwlover77** » Tue May 05, 2009 9:31 am

My understanding is that drums can be turned as long as the maximum diameter (as cast into the drum) is not exceeded. Good luck finding a shop to do it, though. Seems everybody wants to replace drums and rotors instead of machining them.

dtrumbo · Post by **dtrumbo** » Tue May 05, 2009 10:03 am

hambone wrote:Great! Lemme know.
(assuming they haven't been turned 1000 times)

I'll mic 'em, takes pics and let you decide.

vwlover77 wrote:My understanding is that drums can be turned as long as the maximum diameter (as cast into the drum) is not exceeded. Good luck finding a shop to do it, though. Seems everybody wants to replace drums and rotors instead of machining them.

I'm lucky. I have a shop near my house that can and does turn drums and rotors. I've used him a couple of times now. It used to be just about every FLAPS had a machine shop in the back. No more. Sad.

hambone · Post by **hambone** » Tue May 05, 2009 10:06 am

Les Shwab will turn them if in spec, $18 a drum. Maybe I should try first? New or good German sure is enticing though.

Post by **Amskeptic** » Tue May 05, 2009 4:23 pm

hambone wrote:Les Shwab will turn them if in spec, $18 a drum. Maybe I should try first? New or good German sure is enticing though.

Hey boy. What about our IAC® cross-hatch sanding method™ first. As mentioned before on this very forum, many many many many many times it is merely the build up of glaze and shoe dust. You clean the backing plates of all dust, lightly sand the linings until they are a consistent flat finish (no shiny) then 45º in one direction then 45º in the other direction consistent scratch pattern, wipe down with GumOut, do it again, slap er together, adjust the brakes and absolutely torque your wheel lugs in a cross-pattern to correct spec and be on your way with metal intact. Labor-intensive love. . . it's the air-cooled Volkswagen way.
Colin

hambone · Post by **hambone** » Tue May 05, 2009 8:31 pm

This is a deep pulse though, it seems like more than sanding is needed. You can really feel the out of roundness as you brake.

chitwnvw · Post by **chitwnvw** » Tue May 05, 2009 8:48 pm

I rode with him, it is indeed a deep pulse.

Post by **Amskeptic** » Tue May 05, 2009 9:36 pm

hambone wrote:This is a deep pulse though, it seems like more than sanding is needed. You can really feel the out of roundness as you brake.

If it is the retardation of the vehicle that is pulsing, then do my sanding trick.
If it is the pedal kicking up against your foot, then maybe you are in need of a truing.
Colin

Bookwus · Post by **Bookwus** » Wed May 06, 2009 7:45 am

Hiya Bob,

I was told by an old Volkswagen hand to take a careful look at an OEM drum before carting it off to a machine shop for trueing. VW had a bevel cast into the drum contact surface rim. If that bevel is still there you can further true out the drum. No bevel? The drum is at the end of its useful life.

ps.............whoops, just read Don's comment. I think we are talking about the same thing.

hambone · Post by **hambone** » Wed May 06, 2009 8:03 am

Yeah it's pretty extreme, pedal jerking about. I'd imagine I need to repack the bearings after all that messing around and machining.

dtrumbo · Post by **dtrumbo** » Wed May 06, 2009 9:36 am

O.k. so here be the foto's. They're both jen-you-wine VW. They still have the bearing races as well as a little bit of grease still in the hubs. One of them has some surface rust, but sanding them as Colin prescribes or having them turned will remedy that. As far as their useful life, I don't know. I measured, but my measuring tools aren't as precise as they need to be to make this determination. I didn't read this post about the bevel so I can't say for sure if they still have life in them from that perspective. Perhaps we can tell from the pics, but they didn't turn out as good as I'd hoped. I must be a little jittery in the morning since every damn one of these pics is out of focus. Then again, maybe they're in focus to you and it's just me.

Anyway, on with the show.

I know the jury is still out on whether or not you even need new drums, but I promised pictures, so there you have it. These babies ain't goin' no where so there's no rush at all. Let me know if you need me to take better pics or look at anything specific, I'm happy to do it.

hambone · Post by **hambone** » Wed May 06, 2009 9:40 am

Thank you for taking the time to do that.
I think I'm going to try the local trip first, and if that doesn't cut it I'll take you up on them. Really appreciate all your help.

Bookwus · Post by **Bookwus** » Wed May 06, 2009 10:08 am

dtrumbo wrote:........Let me know if you need me to take better pics or look at anything specific, I'm happy to do it.

Dick is a prince among men. Take it from me, the King of this, that, and the other.

Itinerant Air-Cooled

Itinerant Air-Cooled

'69 Bus Front Drum Issues

'69 Bus Front Drum Issues