New calipers for my 411

raykinsella · Post by **raykinsella** » Wed Nov 19, 2008 5:45 pm

I'm looking for new calipers for my 411. If available does it matter if they are 411 or 412 - will either model's calipers fit either model?

Bill K. · Post by **Bill K.** » Wed Nov 19, 2008 8:41 pm

There are differences between 411 and 412. You may want to consider BMW 320 calipers as an upgrade as you would not need to modify the caliper coming from a 411 spindle.

http://www.shoptalkforums.net/viewtopic.php?t=96741

If you want to rebuild your 411 calipers, I can set you up with a pair of rebuild kits.

raykinsella · Post by **raykinsella** » Fri Nov 21, 2008 6:34 am

So if I went online I could buy new BMW 320 calipers and they would bolt right on to my 411, no modifications? What year 320? Any?

I have a caliper rebuild kit but not sure I am technically proficient enough to rebuild them. My current calipers work okay but I just inspected the pads and noticed the boots around the pistons are rotted away. I'm sure they are the originals in a 37 year-old car.

wildthings · Post by **wildthings** » Fri Nov 21, 2008 8:52 am

411 calipers are readily available as they are shared with the Type 3.

raygreenwood · Post by **raygreenwood** » Fri Nov 21, 2008 9:18 am

There is absolutely nothing to rebuilding calipers. Restoring is a different story if yours are damaged or pitted in the wrong areas. You simply need som 600-grit paper, some 1000 grit paper some 2000 grit paper and/or 000 grade steel wool. Take the pistons out. Use a soft or blunt o-ring hook to remove the sealing ring. Split the calipers....make sure you keep the small o-rings labled to the recesses they came out of because most kits do not have these sealing o-rings that go between the caliper halves...and you will be putting them back where they came from. They rarely need replacing even at 30 years age.
Mark the pistons and get them back in the same caliper half they came from. Take some 50/50 water and muriatic acid mix. Submerge each caliper half and disolve all rust. Immediatley rinse and wash with soap and water....then WD-40 to get rid of all moisture...then use a solvent like mineral spirits to clean off the WD-40. Dry with compressed air.
Inspect.

Pits in the bottom or walls of the cylinder mean nothing and will have no effect on the efficiency of the piston or brakes. However...pits that bridge between the cylinder wall and the edge of the seal groove may cause leakage of pressure behind the seal..... if the pit from the wall..continues into a rust pit across the seal groove and up behind the seal. Clean out the seal groove with a brass brush on a dremel tool...not steel. Dust with compressed air....then start with 600-800 grit paper and lap the cylinder to get rid of any crusty pits or high spots. Just lightly.
Use 1000 then 2000 grit...and steel wool if necessary to polish the cylinder and piston to almost a mirror finish. You do not want to remove excessive metal...and ....honing marks and/or honing are 100% unnessesary and do nothing but remove excessive metal and leave a rough finish.
Unlike an engine cylinder....there are no rings that ride on the cylinder walls to require hone marks for break-in. Its all about how smooth the sealing surface is on the piston and how easily and smoothly the piston travels.....because the ring seal seals on the piston....not the other way around. The smoother and more identical you make both caliper halves toe each other.....and both calipers to each other....the better balanced and less pulling you have from your brakes side to side. Wet all seals with fresh brake fluid and reassemble. Mind the position of the piston with reference to the locating/anti-rotation plate on the outside. Only assemble with brake fluid if you are going to almost immediately reassemble the brakes and bleed them. If not...use brake paste, because the small amount of assembly fluid will absorb water and start surface rusting. Or...if you have no brake paste.....assemble with fluid, fill teh caliper with fluid and cap teh holes...andstore upright until you install and bleed. It takes me about an hour per caliper.
Be sure what you are doing I took a look at that thread from 2006. If you have a 411...you cannot use the 412 calipers without swapping on 412 steering knuckles. There is an offset because the rotors are different. You cannot just swap rotors because the spindles they fit on are also different.
Wally noted that he is using....in those pictures....the 412 rotors. I asked in that thread because it did not look quite clear in the picture....and Wally noted that those rotors are indeed 412 late rotors with the raised ring. Because of the offset difference....I cannot see the 320 calipers fitting 411 rotor spacing if they also fit 412 rotor spacing. Not without shimming or changing the mounting point where teh caliper bolts on.Ray

raygreenwood · Post by **raygreenwood** » Fri Nov 21, 2008 9:26 am

Not all type 3 calipers fit 411's. Only late type 3 calipers. Ray

Post by **Marc** » Sat Nov 22, 2008 2:14 am

Yes, the common 311 615 107/108 calipers used as replacements for `66-`71 Type III (and in Type I disc-brake conversion kits) which are still being made in Brazil and China will not fit a later Type III or a 411 - the bolt pattern and pad are larger on the later caliper. You'll need the 107B (left) and 108B (right).

Here's a guy who put 1978–1983 BMW 320i calipers on his `73 III, those should also work on the 411:
http://www.covin.co.uk/bmw_caliper_conversion.htm

raykinsella · Post by **raykinsella** » Sat Nov 22, 2008 6:29 am

Thanks for all this input everybody! I see that on ebay there's a company called Mofoco that lists rebuilt calipers for 72-73 type 3s and for 411s. The picture looks right - I don't know how to put a link right here but they're easy enough to find on the ebay site. Can an idiot like me install new calipers by himself? Would I have to bleed the brakes and so need an extra hand?

raygreenwood · Post by **raygreenwood** » Sat Nov 22, 2008 10:46 am

Installing calipers is as simple as two 17mm bolts and and 11mm flare wrench. Look for rebuild kits and rebuild what you have. I have very little trust in most rebuilt calipers. I have seen way too many poor jobs.
This is because it is soooo simple to rebuild calipers that a great many people just take old calipers blow the pistons out with compressed air...dump them all in a vat of solvent....put new seals in....and paint them.
About half of the rebuilt calipers I have opened up were junk. They usually have pits that span the seal groove...or serious rust lines that scored teh bore. Yes...they will work...but usually are harder to bleed and are sticking and drag when they are like this.

The cheapy caliper rebuild companies...get these calipers that were probably not even good cores....as cores.....because someone else opened them up and probably realized they were junk....so used them as cores.

Proffesiional companies go as far on some rare calipers....as reboring...and putting oversized pistons in. There is even a company that makes stainless pistons and sleeves. Great if you are racing or restoring a concourse level car....but totally unnesscary on teh street.

Just take out your calipers...but a 1/2" block of wook between the pistons...mount the caliper in a vise.....and blow the pistons out with compressed air and then tell us what you see. Find a rebuild kit and new hardware first.
There are Teves kits (ATE) a few rare FAG kits and you might find some NOS Schafer kits that are made specifically for either a Teves or FAG cylinder. Ray