Christmas in July! 930 Limited Slip from Matt Monson at Guard Transmission.


When you run a 911 gear box in a mid-engine configuration, you have the either run the box upside down or flip the ring gear to get it to spin the other direction. For a 930 transmission, this requires significant machining to both the ring gear and the case. This is the stock ring gear before machining.


Here is a stock Diff sitting in the case. You can see part of the area that the case has been machined.


Ring gear chucked up on the lathe.


Cutting hardened steel...molten lava coming off.


After about 45mins of cutting...back of the ring gear cut to fit the case. There was additional cutting required after this, but didn't get a picture of it.

Another thing we wanted to do was use the same hydraulic throw-out bearing parts that were used on the previous transmission. To do this we had to machine about 8mm off the guide tube mounting location in the bell housing.


Cut thru the case in one part...nothing a bit of welding can't fix.


After a significant amount of welding and some more machining. The burn marks are from the epoxy melting.


Additional material added to the inside for strength.


Throw-out bearing guide tube mounted in place after significant modification.


Hydraulic throw-out bearing mechanism in place.


Because I am using the dual-plate clutch set-up, I had to source a early short bell housing mainshaft which has more spline engagement. Interestingly enough, this early mainshaft had a sealing surface machined in the bell housing area that allowed for the use of a 915 style input shaft seal and guide tube.


930 Shaft installed with the 915 release bearing carrier in place. Clearances are tight!


Hydraulic throw-out bearing in place for the last time. New fittings and lines with 45deg bends to run out the back of the bell housing.

Another modification that we made was to make this box a 2-speed for Autocross applications. I did this on the 901 and it worked great. For this application, we ditched all the stock shift rails, yokes, etc. and just made a longer shift rod that came out the back of the transmission directly. This also reverse the shifter throw to make it match what I had on the 901.


New shift rod location with a bung welded to the nose cone to hold the seal.


The longer shaft is the new one machined to match the stock rod.


Now that we have all the parts in place, it was time for assembly. I left out the majority of the parts associated with 3/4 gear. I also cut out the center splined area for the reverse gear to further cut weight.


Dog gear parts. This transmission has no syncro's which will improve the shifting speed significantly over stock.


Transmission almost together and sealed up. Total weight with fluid was 116lbs...so I only gained 38lbs over the 901 set-up.

Here is a plate we fabb'ed up to hold the vehicle speed sensor and the clutch lines.


Transmission in place, everything hooked up, ready to fire!


Success! After a couple of passes down my street I gave it a nice sponge bath.

Looks damn good.

As a first time out after such an amount of work, a National Tour event is not the ideal place......but there it is. Hope you find a co-driver & get some time on it on Friday, hopefully the bugs are few.......then the best of luck to ya.

.....Yes it does!!....some fine work

Good luck man!

Show the world what a nearly stock 914 can do!

John

hah! thats definitely better than what i had in mind! looks beefy and it should hold up for the life of the car and afterwords. good luck with that beast, looks like it should be a helluva lot of fun to drive!

-Brant

Here is a video from this weekend Autocross with the PacNW Region PCA in Packwood, WA. Took TTOD with this run and had an even faster run in the "fun" runs later in the afternoon.

http://youtu.be/UNr9tqK0LrI

I think if you push the right pedal harder it will go faster. LOL.

Video doesn't do justice to how fast its really going.

Congrats on getting the new transmission fitted and operational. Car goes like a rocket.

How did your co-driver do with the new setup?

truly epic modified mayhem! i love this monster

Here is the "fun" run video where I pushed the car another 0.5secs faster. You can see in a couple of spots where I run out of first gear and I am riding the rev limiter. You can also see towards the end where I am running out of front end grip due to aero load from the rear wing. Time for some front end aero improvements.

https://www.youtube.com/watch?v=gtSSZLxkqtI

A bit of additional info:

Brit's rev lmiter is set at 8400 rpms......that is right around 60 mph in first & 90odd mph in second. At this point, this car is not good enough to trophy at the SCAA Nats in XP. He still needs to pick up around 1.5sec per run to run at the pointy end of the field.

Apparently, this is meaningless drivel to causal AXers.

Where are you going to find 1.5 seconds?

Wow, reminds me of the F1 ride-along videos, not the same world I live in. That's the real rare-air end of things so I don't have any experience, but I'm having a hard time imagining a whole 1.5 seconds. Maybe because I can't stop thinking about how happy I'd be to go "just" that fast?

Are you sure, JP? Do you have other car's times on the same course, or some other way to compare? Seems several orders of magnitude faster than the same car with the Porsche suspension and the six.

Drive it harder, tighter and smoother through the corners. Don't rely on the point and shoot approach.

The time is there, just have to become one with the car, which will not be easy as the speed transition is somewhat brutal.

A couple of the DP guys Brit runs against locally are "at the pointy end" of their class at the Nats.......2 sec slower than the XP winner (a nice round number). I'll admit that this is not a scientific measurement but PFCE. (Pretty ******* Close Enuff)

Right now I think ithe 1.5 sec is the aero and the nut behind the wheel.
Brit's had very little practice with the current set-up....tain't like riding a bicycle, eh?
He now has to school hisself about the building/tuning the car & not just driving. He's making up ground on them DP guys..... Last year he was behind them....not now.....progress is gud. Right now he finds himself into a high speed aero understeer....new ground to plow.

That said, one can understand that the XP winner is not sitting on his hands either.

Whatever. I, for one, am impressed. I saw the car while under construction last year. The knowledge, the willingness to try things, the attention to detail as things came up and were changed on the fly, everything just oozes focus and dedication, combined with forward out-of-the-box thinking. If that second and a half needs to be found, I'm sure it will be! Soon.

The Cap'n

The most recent changes have really improved the cars performance. I now have a transmission that can take the power...which means I can turn the power up to where the turbo is the most efficient. The motor is now much more responsive and pulls hard. My issue here is gearing choices which is easy to fix...just need to find the gear I want to go with.

The last couple of events I have started pulling away from the fastest competition here in the PacNW. At the National Tour I raw timed the 780whp Nissan GTR by a healthy margin, at the ProSolo I raw timed the fastest DP cars in the country by over a second, and this past weekend I raw times another very quick DP by at least 2secs. With more time behind the wheel and not under the car I am getting faster.

I would say that the additional time needed to catch the fastest XP cars is half car setup and half driving. High speed understeer seems to be the biggest limiter at the moment. I am also about 40lbs overweight and I have plans for that.

-Britain

Hey Randal...you going to make the Medford Enduro event this year?

-Britain

I've met you--you don't have the weight to lose! Maybe the car does, but...

I have no idea if lower-speed experience means anything to where you are right now, but you still seemed to be a little behind the car in a number of spots, like in the slaloms. The "fun run" was better in that regard, but I could see the push in the sweepers.

In my car, I'd just try to drive around the push (drive deeper into the corners, etc.) but you have a lot more options open to you.

I think you've got another half-second on that particular course that I can see, but it's all in little dribs and drabs. More that that will have to come from improving the car some more (the high-speed push you mention) and from driving stuff that I'm not good enough to see.

--DD

I thought the same thing about the slalom when I watched the video. However, if you listen to the motor you can hear that I am accelerating thru the slalom which puts me right where I want to be on the exit. You no longer need to lift rotate like you have to do on stock 914 suspension. That is a 26pace slalom and I am on the rev limiter which is about 62mph.

-Britain

I'm planning on going Britain. Hope you'll be coming as well to uphold or improve upon your great time last year.

I'm doing pushups every day now, so no limp arms at the Fall event!

Reminds me of a question I had. Are you really installing a Guard limit slip as opposed to a torque bias differential? I got rid of all the understeer I had with the Guard LS when I installed the Guard TB. For Autox Guard's TB's really work; I mean I haven't had any under steer since I went with the TB and Avons. In fact I haven't even figured out the limits yet.

Post #502 pic shows a TB diff.
Note the helical cut gears visible through the slots in the housing.

Yep...Guard TBD! Best option for AX.

Magic really.

Check out britain's YouTube page. He has some new uploads of recent runs with the new gearbox.

The Where2Race Porsche 914 had a great outing this past weekend at the NWR SCCA Solo Autocross #7 in Packwood, WA. Took overall top time both days and grabbed 2nd in PAX on Sunday. The course was fast and challenging, with several opportunities to make mistakes. The car ran great, new gearing was much better. Here is a video of my fastest run...enjoy.

http://youtu.be/oFl0zJtdnQM

Wow. Britain, I'm proud that I post on the same board that you do.

Yeah, me too.
Folks might like to know your speed in gears.....the limiter was talkin' at ya in first.
Didn't hear in it second. Looked pretty damn fast to me tho.

According to my calculations, should be 62mph in first and 80mph in 2nd. I just got a new data logging set-up with GPS to get accurate speed info.

-Britain

Here is my video from the Siskiyou Sports Car Club Fall Enduro 2013. It is 5laps around a large kart track in which you hit speeds a touch over 90mph down the straightaway. I have been working to make my car faster every year and this year I finally broke the 21year overall track record set in '92 with a time of 3:38.115secs.

Here is a breakdown of my runs over the years:
2010: Porsche 2.7L Engine/Porsche Suspension: 3:52
2011: Subaru 2.0L Engine/Porsche Suspension: 3:49
2012: Subaru 2.0L Engine/Lotus Suspension: 3:42
2013: Subaru 2.0L Engine/Lotus Suspension/930 Trans/Aero: 3:38

http://www.youtube.com/watch?v=Jg7KmOfUolk...eature=youtu.be

Here is another video showing side by side lap comparison between my co-driver Alan Wizemann and myself. He did a great job and this video should really help him improve his time next year.

http://www.youtube.com/watch?v=lmECCM5ppqo...eature=youtu.be

Good lord! It looks like it's quite hard to effectively use all of the power that thing has.

And you didn't exactly leave a lot of time out on the track, did you?

I still remember instructing you in your very first autoX ever--wasn't it at a WCR? The 1.7 with the "OH PLEASE SOMEONE GET ME A SWAY BAR" suspension. (And I think you even beat my time in my 2.0!!)

--DD

Wow, what a ride. But both you guys need to work on conditioning. See the way your heads snap back whenever you accelerate? That car's stronger than you are! To the gym!!

We are definitely not worthy!



John