So I decided to replace the stock 964 calipers with 993 versions mainly for heat advantages for DE. I have the 993 calipers mounted but have not been able to find a reference to the torque specs when attached to a 964 with an adapter. I am hoping that one of our fellow Rennlisters will be able to give me some insight on this.
What do I torque this adapter to?

What do I torque the 993 caliper to on the adapter?

The old dirty stock caliper - happy to see it replaced

The 928 rotors fit perfectly

993 calipers look like beasts in comparison with the stock caliper

 

A few more pics...
The new RS29 pagids are much bigger than the old 964 RS29 pads - looking forward to trying them out at Limerock in April.

Here is how the 993 calipers and rotors look with the CCW

And again..

 

How much is the conversion costing you? Never realized/noticed the big size difference between the two!

-Don

 

304mm rotors so not a huge difference but the caliper and pistons are somewhat bigger.

We had this torque question about a year ago. I think the answer was 85nm for both bolts which is the value from the manual and is well short of the full torque you can put on a m12 12.9 bolt. http://www.cncexpo.com/MetricBoltTorqueNm.aspx I was concerned that the torque might need reducing when mounting into aliminium, but apparently not.

 

The conversion is probably one of the cheapest "brake upgrades" for the 964. There is no big difference in pricing related to the rotors and pads compared to stock set up - maybe $60 extra for pads and rotors. 993 C2 calipers come up for sale all the time and you might find them in good condition for about $300-500. The adapters from Rennline will set you back $200. So for me, this upgrade is costing me ~$500 in total discounting the fact that I was going to have the rotors and pads replaced anyway.

There is a possibility that after the caliper update many will opt to also convert to the 993 master cylinder (I'm fully prepared for this but want to see how the pedal feels before I go that route). The good news is that the 993 master is a lot less expensive than a replacement 964 master.

 

Thanks Alex - yes I too consulted the manual and noted the 85Nm (but this is bolting into threads in the wheel carrier which is not aluminum). Not wanting to take the risk I have asked Rennline to provide me with torque specs. I would guess that 85Nm would be appropriate for the adapter bolt to the wheel carrier but at the same time guessing it should be less torque for the caliper bolt to the adapter.

 

I think the point is that for steel-on-steel you could theoretically torque a 12.9 m12 to ~146nm, at a mere 85nm any downward adjustment for the aluminium (i've seen suggestions around -30% depending on the grade of aluminium) isnt necessary. The other critical factor is the amount of thread engagement, i've seen info that no adjsutment to torque is needed for 6series ali as long as you have say 2x the bolt diameter thread engagement.

Anyway I didn't feel qualified to make the final decision so I think we checked with 9m in the end who confirmed 85nm for all the bolts.

Sensible to check with the suppliers of your bracket though.

 

Did you do the rear calipers?

 

Nope - just the fronts based on input from Dan Jacobs.

 

Great info. If I don't hear anything to the contrary from Rennline, I'll torque all bolts to 85 Nm. I appreciate the input - thanks!

 

63 ft-lbs

Marc

 

my first thoughts are 85NM for the adapter to wheel carrier and 95NM for the radial bolts from calipers to the adapter. I think i did so, but my adapters are made from steel...

regards

 

Sounds reasonable and more in line with with I was guessing. Where did you get this number from?

 

Porsche 964 Technical Specifications book like this one.

Marc

 

Interesting. Care to share the info/input that he provided you?