BMW performance 6pot caliper question

Ianv · Post by **Ianv** » Sat Feb 09, 2019 3:47 am

Hi Guys,
Just brought some 6pot BMW calipers from a 135i and the brackets I need from Epytec to run these on my Z4M.

My questions is does anybody know what the purpose is of the two sticky down lugs at each end of the calipers?

Always thought that part looks a bit crap and I can't see what they are there. Removed one to have a look and there does not appear to be a reason for them, they are interchangeable left and right, solid with no fluid path through them and there is the small grove you can see on the pic below. Any ideas and can I take them off without causing a prematurely fiery death!

Ewazix · Post by **Ewazix** » Sat Feb 09, 2019 9:30 am

They are weights for harmonic balancing of the caliper. Removal will cause vibration in the front of the suspension due to the caliper being unbalanced..... apparently confirmed by a BMW tech and someone trying it out https://www.1addicts.com/forums/showthread.php?t=213914

It makes sense since they are clearly precision engineered parts rather than cosmetic covers and serve no structural purpose. Anyway they make the calipers even more distinctive and ballsy

Ianv · Post by **Ianv** » Sun Feb 10, 2019 12:01 am

Awesome, thanks for the reply.
That makes sense, they are heavy little blocks.
They can stay on then.

GuidoK · Post by **GuidoK** » Sun Feb 10, 2019 4:33 am

They are there indeed to counteract harmonic vibrations.
However...... whether they are needed or not is very very debatable.
Because on the german z4 forum there are loads that drive without them (I guess at least more than 20-30 users), they even made a small production run for little platelets to mount so that side of the caliper runs flush.
No reports on unwanted vibrations there (but that doesn't mean there's a theoretical situation possible that vibrations might occur).
So I guess you can go either way and do what you think looks best.

These weights are hardly ever seen on calipers at all. I think the only time I've seen them is on a specific ferrari:

Ianv · Post by **Ianv** » Sun Feb 10, 2019 7:41 am

Thanks Guido, I will test them with & without, see if I can tell the difference and report back later..
Well, once I have the correct adapters, the ones I had ordered are wrong.

Although now I've had a proper look, I think I could modify the standard adapter from the 135i with machined spacers to fit.

Ewazix · Post by **Ewazix** » Sun Feb 10, 2019 9:34 am

I hate a mystery! It looks like most brake manufacturers fit various designs of damping weights to fixed caliper brakes inc ferodo, Hella & Brembo etc. But it's not a thing on the floating calipers like those fitted to many BMW's. Most weights are not as obvious and on reflection I've had them on various cars but didn't realise what they were

apparently more for noise reduction than steering vibration.

I'm guessing that any changes to an original brake set-up will change the harmonic frequencies in the unit, so it can't do any harm to test with and without the weights.

https://www.hella.com/techworld/us/ti/D ... per-10860/

Z4-forum.com

Z4-forum.com