993 RS calipers ?
#46
If you move bias to the back you can use it profitably if the car is lowered and stiffened and has an effective lsd(4 channel abs helps). If not perhaps the tt is a better choice for you, even though you are leaving a lot of potential on the table.
Of course you can also do as many track guys do and juggle f/r pads w/ different friction characterisics, the most popular for guys w/ the smaller piston rears is to use a higher friction pad in back.
Not get off topic here, but what do you mean by "effective LSD"? Care to elaborate? Is the one I mentioned above (Guards LSD 50/80) suitable for a 2wd 993TT? I assume it is overkill for a mostly street car but it's also nice to know that your car is properly setup once you take her to the track.
Also using different pads is a good idea. For example if you use 993RS/TT front and 993RS rear, why not use a performance pad like Pagid up front and just the standard pad in the rear to shift stopping power forward? I will be using the standard pads all around though since I HATE brake squeal and standard seems to be the ticket to minimize squeal..
#47
...Not get off topic here, but what do you mean by "effective LSD"? Care to elaborate? Is the one I mentioned above (Guards LSD 50/80) suitable for a 2wd 993TT? I assume it is overkill for a mostly street car but it's also nice to know that your car is properly setup once you take her to the track.
Also using different pads is a good idea. For example if you use 993RS/TT front and 993RS rear, why not use a performance pad like Pagid up front and just the standard pad in the rear to shift stopping power forward? I will be using the standard pads all around though since I HATE brake squeal and standard seems to be the ticket to minimize squeal..
Also using different pads is a good idea. For example if you use 993RS/TT front and 993RS rear, why not use a performance pad like Pagid up front and just the standard pad in the rear to shift stopping power forward? I will be using the standard pads all around though since I HATE brake squeal and standard seems to be the ticket to minimize squeal..
GT can rebuild them to perfomance spec, w/ better friction disks and higher break away torque spec but cannot change the basic 40/64 or whatever spec.
Both 4 plate Porsche Motorsports lsds used in the /3x transmissions and the Guard GT lsds are effective out of the box. 50/80 w/ performance disks and high break away torque is more of a track only lsd. As I noted earlier even the current batch of RSRs has backed down to 40/60 w/ high breakaway torque specs w/ 6 - 8 friction discs.
break away torque is an artefact of the assembly process. There are sets of driven and drive plates that rub on each other creating breakaway forces. They come in various thicknesses and are preloaded by the stacked tolorances. Obviosly worn disks are thinner, reducing the initial breakaway torque w/ use, hence the double strike against the oem street lsds which are set up loose and quickly get looser w/ use..
the 40/60 # comes from the machined angles in the outer load carrying members that the pinions ride in, different angles cause different levels of dynamic pressure on the stacked discs. The spec is given as drive / coast levarage.
#48
Both 4 plate Porsche Motorsports lsds used in the /3x transmissions and the Guard GT lsds are effective out of the box. 50/80 w/ performance disks and high break away torque is more of a track only lsd. As I noted earlier even the current batch of RSRs has backed down to 40/60 w/ high breakaway torque specs w/ 6 - 8 friction discs.
#49
Thought I'd resurrect this thread w/ some additional info
I went through and calculated the actual brake torque exhibited by all the various 993 brake setups, all are @ 70bar line pressure. It turns out that 993RS is not as rear biased as I had at first thought and in fact is right inline w/ the bias exhibited by all 911s up through '83, i.e. 1.491
I went through and calculated the actual brake torque exhibited by all the various 993 brake setups, all are @ 70bar line pressure. It turns out that 993RS is not as rear biased as I had at first thought and in fact is right inline w/ the bias exhibited by all 911s up through '83, i.e. 1.491
Last edited by Bill Verburg; 01-28-2013 at 10:18 PM.
#53
I need some of details that aren't usually published
piston sizes of course and effective rotor size, if this last isn't available the rotor and pad sizes can be used
#54
Rennlist Member
Few questions... Since the 993tt rear caliper has smaller pistons, and less breaking torque then the 993 rear caliper, is the primary purpose of switching to tt rear calipers just to be able to run larger rotors, and therefore better heat dissipation characteristics?
Also, if the regular 993 system is at 1.640 f/r ratio without the 40 bar p/v, why run it at all? It seems to me that 1.640 is not far off from early 911 territory.
Also, if the regular 993 system is at 1.640 f/r ratio without the 40 bar p/v, why run it at all? It seems to me that 1.640 is not far off from early 911 territory.
#55
Correct, I run the 993RS setup on my '76 w/o a p/v it is fine that way. Someday I'll experiment w/ the 993
#56
Race Car
F: 355 x 32
R: 332 x 32
Pads:
F & R: 131.56 x 71.12 (Same as RS/TT Rears All around)
I'll get you the caliper piston details tonight.
No rush, just interested to see.
#60