New Rear Drum issues

[robin.richard]

Hello,

Have to replace my rear driver’s side large nut brake drum. Original VW drum got scared because I didn’t check and change my rear brake pads soon enough. Measuring the drums they clearly have been turned before and will be out of spec if they are turned again.

I ordered a rear drum from a popular VW parts dealer. First impressions were the drum looked to be of high quality. Label indicated the drums were from a Danish / German company (same company that makes the exhaust sets) but there was also EMPI and Brazil on the label. So I really don’t know where they are from.

The issue is the drum doesn’t slide on the axle. The original drum is easily installed and removed but this new drum only goes on about an inch or two. I used a wire brush and solvent to clean all parts. I’ve applied a thin coat of anti-seize to both drum and axle splines. I even used a rubber mallet and could only get it about 1/4 on. At that point I needed a puller to get it back off.

The parts company is sending a replacement, so that’s good, but is this normal with new drums? I have replaced a rear drum before but don’t remember it being this hard to install. Am I missing something?

-Rich
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[robin.richard]

Here are some photos of the drum in question:

-Rich
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[Eric&Barb]

[Culito]

I have had to file the spline "landings" (grooves) in new drums.
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Copyright CJ Industries, Inc.
'64 standard w/2.0L type 4
'62 bug

[robin.richard]

[Eric&Barb]

[Chuey]

[robin.richard]

I’ll wait for the replacement to show up. Hopefully it will fit better.

Problem is I’m dead in the water until I get a drum to fit. It’s a particular bummer given the good weather and a holiday today. 😎
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[BonTonRoulet]

Sometimes even with older used drums too much anti seize or grease can make for a tight fit of a drum on the splines. Sometimes you just have to rotate the drum before trying to fit it to try a different set of splines to match up. Once you find the spot that works the best you can match mark the drum snout and axle end with a paint marker before you fit the nut and cotter pin.
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[BarryL]

[berpsta]

Looks like a lotta meat left on the old hubs for them to be machined and not that badly pitted or worn

[Eric&Barb]

[Eric&Barb]

New spec for rear brake drums is 9.055 with plus or minus .008".

Wear limit is 9.113".

So that means only 0.058" difference. That is less than 1/16" of an inch, and keep in mind that is in a circle of the drum. So when being lathed if the cutter is moved 0.031" (AKA 1/32") even on a new drum that cuts out all of the usable "meat of the drum and is therefore worn out.

Personally waiting for the new laser tech of today to come down in price that is being used for very expensive parts like WW2 aircraft engines to add on new material to bring them back in spec. Got a small pile of original VW drums to get that done on.
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[Erik G]

it is somewhat normal to file the drum. sucks but a lot of new parts need modifications. Or buy NOS
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[BarryL]

I would just sand the gloss of the old drum with 80 grit.

[Culito]

[Ojai63dbl]

<edited> I ran into this problem last year and seems to be a problem since at least 2018

https://www.thesamba.com/vw/forum/viewtopic.php?t=696974&highlight=new+drum+tight


I had the same issue on my new >64 drums with two different brands (Italian and Danish (?)) from two separate reputable dealer. Wolfsburg confirmed this is an issue and recommended filing.

I ended up having to file the drum spline on drum with Prussian Blue dye to make the fit (Just remember to mark drum as this will be specific to axle spline).

Unfortunately even after working on it a few days for both sides, while it was close I still had to encourage (press or rubber mallet) the drum onto axle and use a puller to remove the drum from axle.

Couldn't use the originals as I stepped up from a 63 1-Ton to a 64 tranny for the better reduction box gearing

[robin.richard]

Finally got the replacement brake drum. It was a replacement from the same manufacturer and it fit like a glove. I’m glad I waited a few extra days and didn’t decide to file the drum splines on the first new drum that clearly didn’t fit.

Here is a photo of the manufacturer shipping case for the replacement drums:

Here is a photo of the OG VW drum. I wish I could save it but I think it’s too far gone. I have someone that will turn it for free so I’ll probably give it a shot. Current measurements are 9 13/16” across and average 10.95mm thickness around the inside edge. Hard to get the thickness measurements with the inside ridge getting in the way. What do you think, is there enough meat to have this drum turned?

-Rich
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[Eric&Barb]

[robin.richard]

Eric&Barb,

Doesn’t hurt to try. Otherwise it would just end up in the recycling bin anyway.

I wondered if I cleaned it up with some sandpaper would it work? If I had nothing else and was in a pinch.

Both my front drums are VW and now both my rear are aftermarket. Need to find some rear VW drums locally.

-Rich
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