Brake caliper torque values

mskar · 07-27-2002, 08:55 AM

Anyone happen to know the correct torque value(s) for putting the front and rear brake caliper halves back together? Can't find it in Bentley or forum search...

Thanks...

Bill Verburg · Bill Verburg's Garage

The last time they were published was in '77. At that time the M8 bolts used on the A caliper was 34 NM, the M6 bolts used on the rear M was 22 NM. The late Brembos are a whole nother thing

mskar · 07-27-2002, 07:46 PM

Thanks Bill, they keep this information locked up in the same vault that contains the whereabouts of Jim Morrison I guess?

dickster · 07-27-2002, 11:08 PM

just in case anyones thinking about it, you're not supposed to split them as far as i was aware?

mskar · 07-28-2002, 11:11 AM

I wasn't paying attention to what I was doing and started splitting the calipers instead of removing them. They seem to have gone back together ok. The only gaskets are 4 ring gaskets which seal the passageways between each side and the spacer in the middle, mine were still soft and pliable after 18 years!

The conversion of the above, btw, from http://www.ex.ac.uk/cimt/dictunit/cctorq.htm is 25.1 ftlbs

Early_S_Man · 07-28-2002, 11:53 AM

Early 'M' calipers used M7 'Ribe' fasteners, not M8!

Bill Verburg · Bill Verburg's Garage

Per the 76/77 Technical Specification book, the rear caliper case bolts are; fillister head case bolt 6mm, grade 12.9,torque to 22Nm in at least 2 steps

I just went out to check on a pair I have in the garage, Yes they're Ribe head and yes they're 6mm. I have no info before or after as they convienienly left that info out of all of the subsequent versions of the spec books, nor is it in the Bentley book.

mskar · 07-28-2002, 07:59 PM

Since I only split the driver's side front, I checked the passenger side front with my torque wrench, probably not very accurate but those were torqued much higher, around 40-45 ft-lbs.

Bill Verburg · Bill Verburg's Garage

The correct torque for the A front used thru '83 is 34NM(~25 lb-ft). The later wide A used from 84-89 will be different. You can not judge tightening torque by measuring breaking torque, those poor bolts are clogged with mung and have begun to chemicaly bond to the caliper!

Also those are Ribe head bolts not torx. Use the correct tool, it is not found in most tool boxes. If you have to use the torx, replace the bolts with equivalent torx head bolts

mskar · 07-29-2002, 05:13 AM

Thanks Bill, and... you are right, a Ribe set does not appear in my box, maybe explaining why I took a 1 hour "Sears Penalty" yesterday to replace my snapped T-30 socket?

Basically, the calipers were clean (prepped for painting with Brake Kleen and wire brushed) and I used the torque wrench to measure the other caliper after having having loosened then retightened (based on visual position) each bolt. They all seemed to move at around the same torque setting afterwards which was around 43 +/-. I went on the low side and just tightened to 40ft-lb.

I have not finished the brakes yet so if anyone out there has the correct values for the 84-89 front calipers out there, do share...