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dobryan 
Samba Member
Joined: March 24, 2006
Posts: 17306
Location: Brookeville, MD
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 Posted: Sat May 07, 2022 7:57 am Post subject: Re: Brake job woes |
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If you swapped drums from side to side and the problem followed then it sounds like you have a drum that is slightly out of round. Pretty much any old school auto machine shop should be able to 'turn' that drum to get it true. They basically put it on a special lathe machine that takes a small amount of material off the inside contact surface to make it perfectly round.
I would bring them both drums if you decide to do this.
If I am off base I am sure others with more experience will correct me. 
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Dave O
'87 Westy w/ 2010 Subaru EJ25 (Vanaru) and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
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https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
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https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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do.dah
Samba Member
Joined: August 27, 2015
Posts: 862
Location: Washington
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| Posted: Sat May 07, 2022 1:10 pm Post subject: Re: Brake job woes |
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I think you did a fine job of following the extremely over detailed Bentley.
The thing is, drums are not the same as disc, they tend to have a slight rubbing/drag, especially when freshly installed.
Drag is probably somewhat subjective. I wouldn't be greatly concerned about slight rubbing during a part of the rotation.
When I do my drums, I adjust the star until the drum doesn't really turn well by hand, then I back off 1-3 clicks so the drum turns well by hand. There may be a slight rubbing on part of the rotation, at which point, I may or may not back off one more click.
After that, I drive to the top of my driveway, put it in neutral, apply some brake pressure, and roll back 10-15ft, setting the shoes and letting the brake hardware adjust the brakes. You can do the same thing on a level surface, you just have to slip the clutch some.
Then, drive around some and feel if there is a noticeable temp difference between sides.
Then, have a beer.. |
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khughes
Samba Member
Joined: July 13, 2013
Posts: 914
Location: Phoenix AZ
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| Posted: Sat May 07, 2022 1:46 pm Post subject: Re: Brake job woes |
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| dobryan wrote: |
If you swapped drums from side to side and the problem followed then it sounds like you have a drum that is slightly out of round. Pretty much any old school auto machine shop should be able to 'turn' that drum to get it true. They basically put it on a special lathe machine that takes a small amount of material off the inside contact surface to make it perfectly round.
I would bring them both drums if you decide to do this.
If I am off base I am sure others with more experience will correct me. |
I installed the "extra heavy duty" drums that VanCafe was selling 5 or 6 years ago. Both were a bit out of round and needed trued. Seems like it has become more common over the years. I would definitely take both in - super easy to chuck it up on the lathe and check it. And of course you'll kick yourself if you still have some pulsing after turning just one...
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'86 Westy FAS GenV Turbo (Marvin) |
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Vancouveria
Samba Member
Joined: September 28, 2020
Posts: 22
Location: Puget Sound
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| Posted: Mon May 09, 2022 9:15 pm Post subject: Re: Brake job woes |
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I took the brake drums to the NAPA machine shop down the street. The machinist said one of them was the most out of round he’d ever seen on a brand new drum.
Got them installed and took a test drive, and the pulsing is gone.
The last step on this brake job will be to adjust the handbrake, since with the new drums I have to pull the handle up further than it should have to go. Bentley here I come… |
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dobryan
Samba Member
Joined: March 24, 2006
Posts: 17306
Location: Brookeville, MD
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Howesight
Samba Member
Joined: July 02, 2008
Posts: 3426
Location: Vancouver, B.C.
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| Posted: Tue May 10, 2022 6:52 pm Post subject: Re: Brake job woes |
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| Vancouveria wrote: |
I took the brake drums to the NAPA machine shop down the street. The machinist said one of them was the most out of round he’d ever seen on a brand new drum.
Got them installed and took a test drive, and the pulsing is gone.
The last step on this brake job will be to adjust the handbrake, since with the new drums I have to pull the handle up further than it should have to go. Bentley here I come… |
I had poor brakes on my rig for years. I remedied that about six months ago. It turns out that I had always installed my rear brake parts in the incorrect configuration, without knowing. When all the parts are correctly installed, the factory Vanagon drum brakes are amazing!! The only real knock against drum brakes is the limited ability to shed heat when they are used heavily or for long periods like mountain down-grades. Even Class 8 trucks are only now switching over to disk brakes. On performance cars, drum brakes do not give enough stopping power or cooling efficiency and have a huge weight penalty. But your Vanagon is not a performance car.
The most commonly-used rear disk brake system for replacing Vanagon rear drum brakes is the Girling system. It's crap. How do I know? Because most of the Audi's I have owned over the last 20 years used the Girling units and if they are set up perfectly with all new parts, they are adequate at best as a parking brake. As a service brake, they are fine. On Westfalia's we are not racing around and are far more concerned that our vans don't roll into the river at night when we are parked in camp.
Back to my drum brake saga. I suppose it took me so many years to correct the drum brakes on our rig because I had no expectations that a Vanagon could ever brake decently. When installing my home-brew Girling G-60 front brake calipers and rotors, (cast-offs from when I upgraded my URS6 brakes to Porsche units), I thought I would give one more huge push of effort to get my rear brakes up to par.
I got new slave cylinders, new quality linings, new drums (they were not out of round), and new parking brake cables. I carefully cleaned and lubed the automatic adjuster mechanism. These items probably all helped, but the single most important change I made was to carefully install all the springs and other bits in the intended orientations. This is critical because without doing this, the automatic adjuster system WILL NOT WORK.
I am glad to hear turning your brake drums resolved the pulsing. Now, before you waste any time playing with parking brake adjustment, be sure that the automatic adjuster is doing what it is designed to do. With the brakes free (ie: no pressure applied to the brake pedal), pull up on the parking brake lever and release it all the way, say, thirty times. You will feel the slack disappearing. Then depress the brake pedal a few times hard. Then take a drive and apply the service brake. Then reverse the van, gathering some speed and hit the service brakes again. Now repeat the procedure described above with the parking brake lever. If you installed all the parts correctly and the automatic adjuster is properly installed and lightly lubed, this will get the brake shoes into perfect adjustment. By the way, Vanagon drum brakes will almost always drag a little after each application and then will slowly retract to the point where there is very little drag. This explains why city driving will usually leave your drums hot to the touch, but highway driving will let them cool close to ambient temps. Drum brakes are self-energizing on the leading shoe, so the shoes always end up moving around in a way that is totally unlike disk brake linings which are very closely controlled by the caliper.
If the parking brake lever is still too high for your liking after the above procedure, then do adjust at the proportioning arm, but most of the time, that is simply not necessary.
Given my own brake odyssey, I sincerely hope this helps.
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'86 Syncro Westy SVX |
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 24395
Location: NYC/Upstate/ROW
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| Posted: Wed May 11, 2022 3:29 am Post subject: Re: Brake job woes |
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| o add some more context: I’ve only driven about 20 miles of in-town driving since working on the brakes. While driving I did check the brake drum temperature frequently - it was slightly warm to the touch but not blistering hot. |
Warm is fine. You might want to run them for a while and see if they wear in to good performance.
The beginner mistake is trying to eliminate all drag. This will leave the shoes way too far out from the drum. Once the radii match, you will tighten to full bind, then release 2 notches only
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