Another issue that affects the shifting performance is the clutch. It must release completely under all circumstances. Any hint of lube on the disc or even just being nice and shiny from proper light use can cause the disc to stick to the flywheel or pressure plate under some conditions. When that happens the syncro has to overcome the sticktion of the disc. You feel this as “hard to get into gear.” The G50 is much more tolerant than earlier 901/911/915/930 Porsche patent syncros.

Still another thing to consider is temperature effects on the hydraulic clutch system in addition to the linkage upgrade. LA probably doesn’t see the temperature variations that the guys in Canada see.

Best,
Grady

Thanks Tyson. The hidden part of the question is I have some 75w-90ns that I was planning to use in .... a .... 915 ... GASP!

The very knowledgeable tech at Red Line suggested that I use that and add concentrated friction modifier "to taste".

I have heard of people with good success with this stuff, but they didn't have an LSD in their 915.

and the LSD in my 915 is very active (has been rebuilt), I get some chatter pulling away from slow corners, with swepco in there now.

I guess the only issue is if I add enough friction modifier concentrate to appease the diff, it might be too much for the synchros.

I am surprised that the SWEPCO protects the R&P etc better tham M1 or Red Line, though.

Racers using a variety of racing transmissions (some of them Porsche transmissions) have returned to the highest quality dino oil they can find, after having serious issues with both synth brands you mention. (One such guy is mentioned in an upcoming Porsche & 911 World mag).... Anyhow, in Porsche pro racing, the techs presently favor synthetics, and favor M1 heavily over Redline.

Thanks Geary, any other examples of super quality dino, maybe CENEPCO, others?

Sounds like M1 is the way to go.

No oil can "cure" a mechanical wear problem.

Some synthetics and/or blends can help a balky trans cold shift behavior as the synthetic lube behaves more like a properly warmed mineral oil over the entire temperature range. Synthetics by nature (and design) are more consistent across a temperature range.

Porsche transaxles and their lubrication requirements are a little more complex than a basic transmission / rear gear set up in a conventional front engine rear drive car. The lubricant has to have the proper GL-4 properties to let the sychros work properly AND have GL-5 extreme pressure additives to keep the ring and pinion protected. Throw in LSD clutches which have their own lubricant requirements and it gets really complicated. It is a delicate balance and every car is different. Therefore, there is no one magic lubricant that does it all well for all cars and thus numerous anecdotal stories of what product worked well for so and so.

I use Amsoil products and have used Amsoil series 2000 75W90 gear lube in an old semi tired 915, also in a very tired 901, and in an old 944 race car. It did pretty well in the 915 but did not help the 901 much as it was too far gone. It kicked a$$ in the 944. I currently have a 915 LSD with Swepco in it and it works fine cold but gets a little notchy when hot. Go figure. I also have some Amsoil Severe Gear 75W90 lube on the shelf right now that I am eventually going to put in my LSD 915. It is reportedly specially formulated for transaxles. One of our fellow Pelicanites (s2pr) has it in his rebuilt 915 right now and so far it seems to be doing pretty well. I'll report on how works in my car when the time comes.

As I said above there is no magic lube for our cars.

Don

Capt Carerra might be right that it has more to do with series sponsorship than anything else. Go to the SCCA runoffs and Redline is everywhere.

Also keep in mind, race teams are dealing with newly rebuilt race boxes. The application is very different than our worn street boxes.

Don

Good point. I think all new street "911"s out of Germany were filled with Mobil 1 for a period of time, and probably for free. (They may come with a different oil today.) However, the oil at the track isn't free. Mobil 1 is used because the teams have more faith in that brand of oil. BUT, it isn't the exact same oil that you'll get in the quart containers.

My 87 does the same thing when its cold - hard to get into second until it warms up then everything is fine. Changing fluid is on my to do list.

Dorscheman ,
I had that problem last year on my 89 911 until my new wrench changed the tranny fluid to Redline . Super smooth . It took about two weeks of driving until I felt a big difference .


Vinnie in Ventura
1989 911 Silver Anniversary

Andy,
I have a G-50 with LSD, and have no problems (grabbing/chatter) with 75w-90ns Redline.

Nine9six,

here is what Tyson said, I have the same tranny set up as you:




quote:
--------------------------------------------------------------------------------

cbeers wrote on 10-13-2005 04:42 PM:
Hey Tyson,

In case you don't get back to the thread, I have an '87 with an LSD.

For Redline, I DON'T want "NS" right?


Thanks,

Chris



That's correct. But you can mix NS and regular to get the desired shifting and LSD slippage.

thanks Nine9six, can you ever tell your LSD is working (at the track, or with one wheel on a slippery surface, etc? How many miles on your car?

Thanks!

Great real world experiences here guys! Very nice feedback.

Grady brings up a good point here. Something for others to consider for sure. My car currently suffers from this.

How to test? With the car idling in neutral, on level ground, no brakes applied (that includes the parking brake), push in the clutch and slowly put the gearshift into first. Slowly is important. If the car wants to move forward ever so slightly? The clutch is not fully disengaging.

The solution is to check/adjust the pushrod length of the master cylinder to make sure it's at factory spec. If in spec, adjust the eccentric cams in the pedal box linkage accordingly. I'll post a picture of the page from the Bentley manual showing this procedure.

How did my car get like this? Because i'm a dumba$$ and adjusted the eccentric linkage in the pedal box when I replaced my master cylinder. The reason being, I hoped to adjust the friction point of the clutch pedal by doing this. Didn't work. At the last DE I attended, I crunched more gears than i'd care to admit. :mad:

Oh. My reason for posting was to confirm that before I mis-adjusted my clutch engagement, my car would always clunk 2nd gear on the first (and only the first) time going into 2nd when cold. It wouldn't crunch or grind. Kinda weird.

My experience with the Redline formula:

Dave Granquist @ Redline recommended the 75W90 and 1 quart of Lightweight Gear Oil. I questioned the NS and he claimed the NS wasn't really necessary because the Porsche LSD's don't typically suffer from chatter like others do.

I use off the shelf Mobil 1 75W90 and have no LSD. Shifts great up until I screwed up the clutch and started crunching gears @ 4000 RPM+ when downshifting at the DE events........ :(

As I've posted in another thread, mine 55K mile G50 had the typical notchiness going into second (when cold), so I put in Mobil 1 (75W90) about a year ago and saw no improvement. I recently decided to try Redline 75W90NS, and it's now a bit worse. I'm going to try Amsoil, but for my car, Mobil 1 worked better than Redline (...no affiliation, I like both lines of products).

Follow up with pics from the Bentley which show the cam linkage to which I was referring

http://forums.pelicanparts.com/uploa...1130471776.jpg

http://forums.pelicanparts.com/uploa...1130471794.jpg

http://forums.pelicanparts.com/uploa...1130471809.jpg

http://forums.pelicanparts.com/uploa...1130471822.jpg