Austin

Careful here...
The breather 996.107.491.91 is also available from PCNA, if you need one, we can supply at $45, but contact your warranty provider first, GT3 front and rear main seals aren't the same as the RSR, which it was designed for. Furthermore, Motorsport does not recommend 996.107.491.91 for Cup Cars, only for RSR equipped engines, although it's listed in the newer 03, 04, 05, Cup Car parts films. Running extra crankcase pressure will accelerate the ability of the engine to develop oil leaks in it's current form at the FMS and RMS. If your dealer will support it and install it, as it's available from PCNA, then go for it.

The RSR crankshaft seals are reinforced in ways the stock aren't, as well as fitting 1mm closer to the crankshaft without using a spring. I wouldn't recommend this mod unless your dealer is willing to warranty the engine for leakage with it, or it's for an engine being rebuilt every 40-70 hours.

The RS crankshaft pulley goes for $68, you'll need the RS pulley retainer bolt as well. If you're removing your AC then you'll need smaller belt, otherwise the size is the same.

Austin

cosmos

As always Austin amazes me with his wealth on information.

I am sold on the RS pully.

Thanks Austin!!!

DCLee

FWIW, I did a new seal as a precaution when I did the breather mod-- the one on the car was seeping ever so slightly at 2k street mi.

(And yeah, Austin is DA MAN... around here, we call him "the new Viken... )

Lee in D.C.
'04 RS Clone

Cupcar#12

good info austin, PMSNA recomended the FMS for the mod i am going to do (it's a bit different than the gt-3 part, custom but tested by PMS) but updating the RMS to the RSR part seems like a good idea as well - Any ideas if the current 996 RSR RMS will fit the 964 cup G50/10 combo - if not i will go with the 993 evo RMS.
The pulley system i am running is a triple system http://www.carreracupusa.org/street/...ne/Sengine.htm
Changing to the single RSR pulley has no draw backs as long as the harmonic balance remains stable, in my case. The 92 cups use a smaller battery and are therefore already prone to under charging and dead batteries.
the rotational weight savings in that case would be worth it to me in that case.

Austin

Thanks all for the kind words!
Rob,
The word on the seal is that the 964 Cup would likely use the same 90x110x12 size seal, but the engine # would be the best way to determine which to install, if yours has the M64.50 it calls for the 90x110x11mm. Since Motorsport is not yet interested in selling the RSR engine components without a full engine attached to them, (even seals right now) the 993 EvoRMS would be the way to go.

For extra info, the regular 996 3.4 and 3.6, and the 997 and 997S RMS is a much different dimension from the GT3, 993, 964 cases (different case and crankshaft manufacturing dimensions, and the rest is history).

Now why is it that we still call the Rear Main Seals what we do, although in 911 type cars they face the front?

Cupcar#12

I just happen to have my engine number handy 62 N 81 362 M64.03 - Euro RS/Cup for 1992
so it is 993 Evo unless i can dislodge an RSR seal from PMNA.

Thanks for the info/confirmation
the 996 gets whatever the latest part numbers are for RMS (there have been what, 4 so far, scary....) Hopefully it won't need until the clutch goes (another 30k Miles would be good there)

Glen

I think some clarity may be needed. The RSR/late Cup(03-05 long rod motor) crankcase breather is the same thing. The Main seal on the 04-05 Cup is what You want is double lipped and identical to the RSR seal. The crankcase breather valve can be installed on the early Cup(AND MK1 GT3) with no ill effects. If the RMS begins to seep/leak it will only do so when the engine is stopped, it will not leak when running. We have done this on 3 early cars so far and not one of them has leaked yet. All these cars we did it from the top with no trans removal yada yada...I carry a late seal with me all the time for when/if it does begin to leak.

On a seperate note and one to pay attention to, is the heat exchanger that sits on top of the GT3 motor is prone to vibration cracking at the ears and will show itself by leaking a bit of coolant onto the top of the engine. You may not notice it unless You smell it or are loading the car on a trailer or jacking it at an angle and some of the coolant will run off onto the ground and make You think scary thoughts. This heat exchanger can also be replaced from the top and should be closely inspected when doing the crankcase breather mod. When the exchanger tabs fail it is not catastrophic btw, it just usually allows one corner of the exchanger to fift up and allow some seepage of coolant past the o rings. You want to watch those exchangers and if the car has any sort of mileage or hours, it should be replaced with the one off the motor kept as a spare.

Rob if You need the seal let me know and I will send it Your way, no problem.

Cupcar#12

Great - thanks Glen I might take you up on that for the seal (i have the FMS at the house along with the oil breather gizmo - Not a porsche MS part ((Yet)))
And i am making headway finally on dislodging the wing from Va. (along with my 964, a spare 356c race motor i had done, & some other stuff) - shipment should occur in the next 2 weeks for everything (they are moving building and need it out of there)

Glen

Let me know what You need and I will get it sent Your way. If You need the breather also just let me know.
Best regards,
G

JasonAndreas

Austin,
Would it be possible to order the 993-EVO RMS and 996-RSR FMS from you? The transmission in my 964-RSA developed a crack so I'm pulling the engine later today and I need to replace the FMS to fix a leak anyway.

JasonAndreas

Here are some better photos of the 1-way crankcase breather.









and here are some photos of the rear main seal (RMS) from the 996-RSR







I will post some photos of the regular RMS as soon as I pull mine from the engine. The major difference seems to be the lack of a spring on the RSR RMS? I'm still waiting on the FMS from a 993-GT2-EVO.

JasonAndreas

Here is the regular "964" style RMS. There are three differences I've noticed, 1) the inner lip is substantially larger than the 996RSR version, 2) there is a spring around the inner lip (red arrow in the 3rd image below) and 3) the regular 964-RMS does not have a dust cover(? -- the white thing on the backside of the 996-RSR seal).

Sloth

They used a 993 RMS (same as 964??) when they repaired my RMS the second time. It also had the spring thingy to keep the tension.

Robert Linton

One more point, to make the valve most efficient you should use either the GT3 RSR oil pump or the oil pump from the GT1 (installation of the latter requires quite a bit of modification).

Bill Verburg

I've been following this thread w/ great interest. I am familiar w/ the theory behind this mod and it's implementation in oiher race motors. But do not understand why the c/c pressure would be higher than normal, the whole point is to create more of a partial vacuum in the c/c, thus reducing widage, no?