Length of brake bleed screw nipple, does it matter?

Post Mon Apr 30, 2012 1:03 pm

Hi All

I'm replacing the bleed screws on the calipers of my 1987 pre-facelift 325i because most of them are rounded off and I don't want to risk getting them stuck!

I have bought a couple through the stealers, and some from ebay. I know that they are M7 x 1mm thread.

The original screws that came out are 30mm long, the ones BMW supplied are 35mm long and the ebay ones are only 26mm long.

My question is, does it matter? Is the length as important as dia. and pitch? Does it seal on the pointed end bit or the thread. If it is the pointed end bit, then I reckon the ones that are too long are okay but the short ones are not! Help

Cheers

Post Mon Apr 30, 2012 2:03 pm

They have to be long enough to 'bottom out' in the threaded hole, since the V shape at the end is the seal. Too long doesn't matter, within reason.

Post Mon Apr 30, 2012 4:21 pm

Excellent thanks.

Managed to source the correct ones today. Apparently there were 2 types of caliper on my model year. Dealer neglected to tell me this when I bought the last lot!

For future reference if anyone else might have same issue, correct part number for bleed screws on my calipers is 34 111 153 197 .... bargain at £5.70 each!! These are approx 30mm long.

Other part number, 34 111 121 206, same pitch and thread but 35mm long.