Making the bus stop, part 2

Note: things get interesting halfway through the second page. Go ahead and skip forward.

A while back, I built a "little big brake kit" (LBBK) for my Vanagon. That's an upgraded caliper on a stock rotor. And by the time I'd finished, I'd changed my thinking. I present part 2: The Big Brake Kit.

You can read the first thread for some background and development. It worked out well enough but I haven't managed to get into a high heat situation yet. And because I can't leave well enough alone, I'm ditching it and moving on with the BBK variant.

Problems with the stock setup:

- rotor and hub are one piece, so rotor changes are a PITA and expensive
- the caliper hard lines are an odd setup that requires cracking open the hydraulic system to change the rotor
- rotor is solid, pads are small and heat control is a problem in the mountains
- parts availability is getting worse

The goals are:

- better heat dissipation with a vented rotor and aluminum caliper
- standard, commonly available parts sourcing
- easy maintenance
- reproducible (not a feature of how I built my LBBK brackets!)

There are big brake options available for the 1986+ vans, some from the factory (with availability problems) and some using repurposed OE parts from various junkyards. But the 1985 and older vans can't use those unless you change the front spindle, and those are only available used and are made of gold. There are also some options that involve machining the rotor off the stock hub and sliding a new rotor over top, but then you can end up with  a caliper that's far outboard (wheel fitment problems) and you push the wheel outboard (again with the fitment). You also rely on another OE rotor that may not be widely available unless you're lucky.

Warren got me thinking about a two-piece rotor setup. So here's the plan, based in large part on my LBBK.

- off-the-shelf common circle track rotor
- cut down the stock rotor to turn it into a hat
- AN brake lines
- Wilwood caliper with common pad shape

Here are the relevant dimensions for the rotors. Stock:

Wilwood 160-0471 rotor. 0.81" thick, 11.75" diameter, 6.38" lug ID, 8x7.00 bolt circle. Used in a bunch of "late model" circle track cars.

That seems like a solid way forward.  I like that fact it allows the replacement of the rotor and uses off the shelf parts for the key wear items.

Looks great.

I would think there are tons of late model Vanagon  spindles in German junk yards......

or more likely Eastern European junk yards where these buses would have got exported after failing to pass German inspection.....

but I like your idea  of using what you have as a "hat"

If you math, you will see the lug ID (6.38") is smaller than the wheel flange on the hub (167.5mm, aka 6.59"). I was pretty sure the gaps between the lugs would let me slide it on, but I'd feel pretty stupid if that wasn't the case. So, step 1 is making sure the rotor will actually fit.

$37.63 shipped. I pulled the wheel off the van and voila. First step is a go.

Next step is to take a close look at how this will actually mount. There are some tight clearances on the backside of the rotor that will become the new hat. Without disassembling further (I need this thing off the lift for a video shoot in a few hours), it looks like roughly 0.13" of clearance on the backside. Let's call that 1/8". A button head bolt (like this one) has a head that is 0.166" deep. So I may have to countersink the holes OR bolt directly to the cast iron "hat". Countersinking shouldn't be too bad, the hat is 0.512" thick and the Wilwood rotor is 0.375". That would let me countersink almost enough to make the head flush with the backside of the hat and still have a lot of meat left over. That seems better than bolting to threaded cast iron which is the other option. The one advantage to bolting directly to the hat is that it allows for safety wire on the bolt heads.

Now I order some stock rotor/hubs and get them machined down. I could use my old crusty ones but that seems shortsighted.

californiamilleghia said:

I would think there are tons of late model Vanagon  spindles in German junk yards......

or more likely Eastern European junk yards where these buses would have got exported after failing to pass German inspection.....

but I like your idea  of using what you have as a "hat"

You would think, but the pricing does not seem to reflect that. Still, this will allow a set of hats plus a set of caliper brackets to be sold, letting the buyer source all the other parts (AN lines, certain fittings, hardware) themselves and bolt it together. Easier than trying to find a 30 year old part halfway around the world just so you can use other obsolete parts.

More on the rotor ring mounting: Wilwood threads their aluminum hats. And as a friend pointed out, every iron block engine is held together by threads in cast iron. Heck, the wheel studs are threaded into cast iron. So maybe we go to the tapped holes in the hat with safety wire. I kinda like that better from multiple angles.

Keith excuse me for being a bit thick, but does plan become machine the original rotor down to 7" and then use best mechanical fastening practices to connect the Wilwood rotor to the original hub assembly?

Yes. The original rotor/hub becomes a hat for the two-piece rotor setup. It's the weakest part of the concept from an availability viewpoint since it's custom made, but since the bearings are separate it's pretty unlikely you'd have to replace the hat/hub for any reason other than maybe a massive wheel bearing failure that damages the housing. 

The OD for the hat/hub would be somewhere around 7.5" or 7.75". 7" is the bolt circle diameter, the inner diameter of the Wilwood ring is 8.34". I wouldn't want the hat to go right up to the Wilwood part for airflow, but you need a bit of meat for the holes.

Following with interest.  Dad has a 70-something that he is slowly restoring.  How far back would this mod be a viable option?

It may only fit the 1983-85 Vanagon aka T3. I think your Dad's van has more in common with Beetles. The spindles look quite different. I'm pretty sure EMPI has some options for them.

Well, well, well I see you've caught up to my way of thinking. I don't have the machining tools to have done this but it's been on my mind and a friends for a couple of years now. I'm now waiting for the finished product so I can get in line for the first group buy.

I think a group buy would be very much the right way to distribute these :) Really, I only want one set for myself but once the process is figured out and the models made for the bracket it should be easy to reproduce.

...and down the slippery slope you go.

Note that "reproducible" was on my list of goals right from the start here :) My first automotive aftermarket product was back in 1995 or so. I have no interest in becoming a major supplier of these things, but since it's just as easy to make 10 as it is 1, it would be rude to the other early Vanagon owners not to at least offer up the option of the difficult parts!

The rotor information and drawings are in the hands of our friendly neighborhood machinist. My coworker Brandon has both an early Vanagon and a lathe, but it's too small a lathe. I have actually used a car as a lathe in the past when polishing wheels (how do I have all my fingers?) but that won't work with a front hub and a RWD vehicle so thankfully there is a zero percent chance of that happening here.

Friendly neighborhood machinist decided that he did not have the right tools for the job. To chuck up the VW part in the lathe would require some custom adapters and it feels it would not be a reasonable cost even when amortized across a dozen or two rotors. He suggested a CNC mill and gave me a name. We have another couple of machinists that we use for work that also have the tools. So I'll shop this around a bit and see who we can find. 

Could the death wheel make the rotor fit on your coworker's smaller lathe?

His lathe is a tiny little desktop thing. Probably has a max diameter of 6". 

I'd be interested in a GB I think. I have a dream of towing my 914 behind my Westfalia and this would help.

Are you going wilwood calipers or from a production vehicle?  

Wilwood.

Every time I see this thread, my mind invariably goes here:

What's here is much more interesting. Carry on.

Talking to a coworker - the challenge for our machinist is chucking this thing up in a lathe. So maybe I can make/source an adapter. Basically a plate with a 5x112 wheel bolt pattern and a tube.

Question for the hive - can anyone think of a cheap Mercedes or VW that uses a stub axle we might be able to adapt? Here's one from a C36. 
 

Maybe I can help ... but I am not the quickest turn around. 

Let me know if you want me to give it a shot. 

Your friend with a desktop lathe should be able to turn an adapter for you, wouldn't you think?