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Teutonic

Dog Gear Set for 915 Transaxle

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Hey All,

Brena Corse (http://www.brenacorse.com/) are in the final stages of development of a complete dog engagement gearset for the 915 transaxle. There seems to be some demand among the historic racers. All of their other dog set gearboxes are top quality,. They have been in the game a while. The Australian Distributors are chasing expressions of interest for a first run of them. Final costing is approx a week or 2 away. I have put my name down for a set. They are chasing a few more customers to commit to get the first production run going. If this is of interest for your track Porsche running a 915 feel free to drop me a PM and I can pass on details as they come to hand. I expect to see a full set of gears with some ratio choices and final drive options. 

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Good question, 

typically you wouldn't rate a dog box for the street. But I guess it depends on your own level of tolerance and how much street driving you intend to do. They always require a very crisp throw. Also can get more dog wear with slow speed shifts rather than fast ones. Brena uses a 4 dog design for memory which does enhance smooth shifting. The gear profile will also make a difference. I will get confirmation on this but as its race focused I expect they will be straight cut gears so you will get gear whine. The volume varies based on the cut of the gears. Eg Hollinger typically noisy, quaife not so much. 

Here is some incar of a different brand dog box that Tuthils tried. 

 

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On 5/31/2018 at 12:52 PM, clutch-monkey said:

Oooh

will be useful when I get mine rebuilt! 

How streetable would this be?

Forget street-able. If the ratios are good ones (which they should be) you need to be at max revs to make it work and to shift easily,which means you'd be revving the ring out of it on the road which is impractical.

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^^^ Yeah, its difficult to say but wont be cheap... but what Porsche transmission solution is???. Really interested to see how your subie box works out. Could be a really good alternative as they are a nice shifting box.  I have been looking for something better than a 915 for ages. The current box in it has all the good gear and I think is about as good as a 915 gets. Still falls short of a proper synchro box. Yeah you can drive around its short comings, but there is a reason Porsche ditched the balk rings in favour of a proper synchros. I looked at G50 conversions. I reckon there wouldn't be much change from 20-25k once it was in. So then things escalated and i was like, maybe a 997 cup sequential gearbox. Just missed out on one for 25k. But probably another 5-10 by the time its running in the car. So if there is a good dog kit and it can be in the car for around 15k, its starting to not sound too bad. 

 

will be sure to update with any other info. 

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So a little more news. Mr RPJ is pretty on the money re cost. The complete gear sets are looking like approx 11k. If the rest of your box is in decent condition it will be approx a 2k exercise to get them in there. Really depends on what is found to be needed once it’s in bits. Note these gears replace all the usual things that wear like baulk rings and sliders etc. 

It seems helical cut gears are also an option, so a box that operates with similar noise to stock (other than shifting) is a possibility. Given 915s aren’t in the habit of tearing driven teeth off gears, straight cuts shouldn’t really be required. Seems most failures are around the baulk rings/synchro side of the gears. My preference would be for the quieter operation if it doesn’t compromise durability.  They would look to do shallow angle helicals to reduce side loading over stock. The usual upgrades of billet side cover, bearing carrier and a Wevo gate shift would be recommended. 

They should be available in the new fin year so looks like I will be the Guinea pig. Strain gauge shifter and flat shift enabled. Could be a bit of fun :) The 4 Dog system they use (developed with Ralliart Europe) is apparently really easy to shift compared with more traditional 6 dog designs. My hope is it will be something manageable for my use which is typically weekend blasts and circuit and tarmac rally work. Stay tuned. 

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Yeah,

that was my feedback. If you don’t need to go straight cut for the added strength then why do it. 

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yeah my next thought is with the subi box fitting a ppg 1-2 gear set. that would give you a brand new box that shifts smooth and has a super strong 1-2 for less than a worn out 915. ill keep you posted

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On 6/8/2018 at 5:10 PM, Teutonic said:

^^^ Yeah, its difficult to say but wont be cheap... but what Porsche transmission solution is???. Really interested to see how your subie box works out. Could be a really good alternative as they are a nice shifting box.  I have been looking for something better than a 915 for ages. The current box in it has all the good gear and I think is about as good as a 915 gets. Still falls short of a proper synchro box. Yeah you can drive around its short comings, but there is a reason Porsche ditched the balk rings in favour of a proper synchros. I looked at G50 conversions. I reckon there wouldn't be much change from 20-25k once it was in. So then things escalated and i was like, maybe a 997 cup sequential gearbox. Just missed out on one for 25k. But probably another 5-10 by the time its running in the car. So if there is a good dog kit and it can be in the car for around 15k, its starting to not sound too bad. 

 

will be sure to update with any other info. 

I just had a short bellhousing G50 conversion done on my car whilst the engine was being rebuilt. Was about 10k net after 915 trade in with Stan. That includes a new lsd, clutch, flywheel, clutch pedal. 

The g50 is so much more user friendly. You can actually get second on a downshift without a perfect rev match! 

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Wow James,

thats an excellent price. Did you get a fee for the weight difference between the two?

a G50 at that price is definitely worth considering. Much metal work mods or did the shortened bell housing sort that? 

Mans assume just a bit of work with a hydraulic clutch pedal etc. 

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17 hours ago, Teutonic said:

Wow James,

thats an excellent price. Did you get a fee for the weight difference between the two?

a G50 at that price is definitely worth considering. Much metal work mods or did the shortened bell housing sort that? 

Mans assume just a bit of work with a hydraulic clutch pedal etc. 

Not sure about the weight difference, I didn't weigh them. Interwebs reckon about 20kgs not including the flywheel. Stan reckons he sold me a very light flywheel. It does seems to rev pretty quick.

The engine is further back in the chassis though. Needed a G50 engine hanger. I only just got the car back. Not sure how much this effects the handling. Have changed heaps of suspension bits  and have not driven the car in 18 months. First drive was pretty good car is certainly much quicker with a 3.8 and motec. 

I lucked in to a box that already had a short bell housing. I think there was only a small section that needed a bit of hammer. The only other tricky bits were the clutch pedal and gear shift selector extension. The mechanic had to fabricate some bits for both.

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