BMW calipers

Discuss with fans and owners of the most luxurious aircooled sedan/wagon that VW ever made, the VW 411/412. Official forum of Tom's Type 4 Corner.
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Wally
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BMW calipers

Post by Wally »

Inspired by this article:

http://www.pelicanparts.com/techarticle ... lipers.htm

If it works that well for 914's, it surely must do s/th for the 412 :roll:
Anyways, as locating a pair of rebuild 320 calipers was way more easy than for a 412, I located these and fitted them:

Image

Image

You can also see the bmw spring in addition to the bmw caliper.. :oops:

Funny thing is that the pelican article mentions that the LATE 914 models have slightly different spindles, which neccesitated modification of the bmw caliper by milling of some material of the 'ears' of the bmw caliper.
Now, I had to have that done as well!!
So that would conclude that the late 412 seems to have more in common, caliper and spindle-wise, with the late (post '72) 914 than the early 914 ('70-'72)...
Just an observation.

The bmw caliper may be a nice upgrade if the 944 rear disk brake works out (Bill, take notice haha!)... :roll:

I haven't driven with the set-up as is (stock rear drums, but with about 1mm bigger wheel cylinder: 23mm superbeetle) yet, but I already know that the skinny 155 tires will not be up to it :lol:

Regards,
Walter
T4T: 2,4ltr Type 4 Turbo engine, 10.58 1/4 mi in a streetlegal 1303

"Mine isn't turbo'd to make a slow engine fast, but to make a fast engine insane" - Chip Birks
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raygreenwood
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Post by raygreenwood »

Yes, that is correct, The late 914 and 412...that would be after August of 72 share the same spindle dimensions, caliper and rotor. The early 914 and 411, share the same spindle dimensions caliper and rotor.

Which rotor is that in teh picture. It appears to be the early 914/411 rotor as it does not have the raised strengthening ring around the hub....or it does and I just can't see it because of the centercap.Ray
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MGVWfan
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Post by MGVWfan »

Good to see another T4 nut going after a brake upgrade. I've got a set of those BMW calipers in the attic waiting for me to get unbusy to have them machined and installed. Keep us posted on your progress.
Lane
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Abingdon's Finest)
76 Plymouth Duster /6 (runs like a top)
99 New Beetle 2.0 (never gives any trouble)
04 Golf TDI (45 MPG)
09 JSW (love it, love it, love it!)
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Wally
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Post by Wally »

raygreenwood wrote: Which rotor is that in teh picture. It appears to be the early 914/411 rotor as it does not have the raised strengthening ring around the hub....or it does and I just can't see it because of the centercap.Ray
It is a new one from an old stock of s/body and the same model as the one that came off, so it should be a late one. It has a raised ring for centering. I suppose it is strengthening as well.
T4T: 2,4ltr Type 4 Turbo engine, 10.58 1/4 mi in a streetlegal 1303

"Mine isn't turbo'd to make a slow engine fast, but to make a fast engine insane" - Chip Birks
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raygreenwood
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Post by raygreenwood »

Yes. That ring is very important. It makes the late rotor much stiffer. It allowed the use of the late model caliper with thicker pads and without the centering pin and clutch inbside of the piston chamber that the late type 3 used. That mechanism, is probably what caused the type 3 version of the caliper to be manufactured in a smaller width all around.

Its hard to say wether the ring itself gave a good deal more stifness...or wether the ring fitting into the middle of the wheel effectively "triangulated" the wheel and rotor into one more ridgid assembly. Ray
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func412
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Post by func412 »

How does the brake pads fit to the brake disc? I mean, does the diameter of the brake disc reach brake pads fully when assembled.
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Wally
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Post by Wally »

func412 wrote:How does the brake pads fit to the brake disc? I mean, does the diameter of the brake disc reach brake pads fully when assembled.
I think it fits better, as the pad now covers the 'whole' width of the disk, maybe 0,5-1,0 mm over the edge, which is no concern. The original pad left appr. 2mm on each side untouched.
T4T: 2,4ltr Type 4 Turbo engine, 10.58 1/4 mi in a streetlegal 1303

"Mine isn't turbo'd to make a slow engine fast, but to make a fast engine insane" - Chip Birks
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Wally
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Post by Wally »

raygreenwood wrote: Its hard to say wether the ring itself gave a good deal more stifness...or wether the ring fitting into the middle of the wheel effectively "triangulated" the wheel and rotor into one more ridgid assembly. Ray
I think vw discovered, as did Porsche, that especially at the front, a well balanced wheel is essential and hub-centering is the most efficient way to achief this. Porsche uses hub-centering also for the rear wheels :roll:
T4T: 2,4ltr Type 4 Turbo engine, 10.58 1/4 mi in a streetlegal 1303

"Mine isn't turbo'd to make a slow engine fast, but to make a fast engine insane" - Chip Birks
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raygreenwood
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Post by raygreenwood »

I'm sure that was a big plus for the centering ring as well. The 412 stayed better balanced than my 411..But I do know that the main purpose of the extra ring on that particular rotor was to counter flexing. Its in the factory literature. I'm just not sure if it accomplished it through just the strategic addition of more metal in the ring....or the bracing is gave with the wheel.Ray
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Wally
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Post by Wally »

Ok, I thought VW made the rotor stronger by making them thicker for the 412 as they went from 10 mm to 11 mm.
A thicker disk does more against warping imho.

Reagrds,
Walter
T4T: 2,4ltr Type 4 Turbo engine, 10.58 1/4 mi in a streetlegal 1303

"Mine isn't turbo'd to make a slow engine fast, but to make a fast engine insane" - Chip Birks
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raygreenwood
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Post by raygreenwood »

Yes, that is correct also. The late rotor was better in all dimensions than the early one. The caliper was better....and the pads were thicker. Ray
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