67King

Mark actually gave me a call this morning, and we spoke at length. To be clear (full disclosure and all that), his business is a Millers dealer, but he's still a valuable resource (and as I mentioned, Millers sells and EP GL5, as well). He converted everything over to the NT stuff 3 full seasons ago. Most of his racing is endurance racing, and on his 915's, he runs 75W140, rather than the 75W90. His first two years, he was running without an oil cooler, but added one last year as he was doing more enduros. On his 901's (e.g. a '65 2.0 he'll be running this year in some vintage racing), he runs 75W90's. In both cases, it is the fully synthetic, CRX NT. He does not run the LS stuff, which he finds is the enemy of synchros. He was quite adamant that the LS oils were bad.

His cars typically see 2,000 race miles per year, he changes the gear oil out at the end of every season. He has not had a failure, but has done a couple of gear ratio changes (I inferred that he did not rebuild these). That said, he does farm out his gearbox builds to Tuthill Porsche (http://www.francistuthill.co.uk/). Interestingly, Tuthill ended up converting over to Millers last year.

Matt, as to your specific problem, he mentioned that some of the R&P's are very weak. I wrote down that 8:32's are good, or maybe 8:35's, but that 7:32
s are notoriously weak. This seems consistent with what Steve said earlier, so you may want to reconsider that.

So, as always, YMMV. But I'd imagine this guy probably puts more race miles on these transmissions than all of us combined.

Also, Matt, he said he'd be more than happy to talk to you, or e-mail you. If you want his contact info, shoot me a PM, and I'll be happy to share it with you.

Matt Romanowski

Thanks for more info! The 914s all have 7:31 ring and pinion. I'll have to add up how many miles we did last year - I'm guessing 2k isn't too far off.

As a note for 901 people, I think I found the last new pinion bearing in the US. They've been on back order for 4 months, so hopefully this makes it live longer.

Edit - Our car did 1428.87 miles on the track last year.

spanky

Swepco for my cars. No others are allowed.

Sboxin

Has anyone had experience with the Swepco 203 -- the 201 with Moly added??

We have been advised to use this in our rebuilt 915 race box WITH Guard limited slip dif. The Moly is supposed to help the LS last longer.

Regards,

911Königin

Will it combat hand fatigue?

winders

I bet if you ask Matt at Guard, he will tell you that the moly will cause the LSD to not function properly.....

Scott

Sboxin

Scott,
Thanks,
You are correct -- He said do NOT use Swepco 203 with the Guard LSD.
Bottom line: always get your info from the source . . .

Regards,

winders

Any time! I am glad I could help. You could use 201 and 210.....but how would know not to use 203 and 212?

Have fun!

Scott

Eifeler

Late to thread but Redline Shockproof in both cars. Pushing 340hp+ through a 915 with no failures ever. Changed twice per year: Preseason and again when regearing for Daytona in fall.

GBoxguys

Swepco 210 for the track. It is the best oil we have found for the 901, 915, and 930 gearboxes.

Let me know if you have any problem finding it.

Erik Johnson

Matt Romanowski

Ran the Millers this weekend in our rebuilt transmission. No problems shifting or anything. The initial tests is good. I'll check back in at the end of the year and we'll see what we have. I'm expecing it to work well.

67King

Good to read. Thanks for the feedback, Matt! I'd assume failure mode of synchros is more long term than immediate, though, so I'm anxious to hear how it goes after you have some time on the gearbox.

Matt Romanowski

A quick early season follow up. The transmission is running around 225F (after adding some more cooling). We have around 575 miles on the transmission (355 laps) and have had no trouble with shifting (grinding, tough to get in, etc). Running great!

GTgears

Whomever advised you to run that gear oil with our LSD is giving you bad advice. We are very clear that you should NEVER run 203 with our LSD because the moly is too slippery. What's the point of an LSD if you put a gear oil in that doesn't let it lock?

201 or 210. Never 203.

Regards,

Matt Monson
Guard Transmission LLC

winders

Check out posts #66 and #67