915 Improvement book

[sc_rufctr]

Just an idea but has anybody thought of writing a complete book of how to rebuild, improve and update a 915 gearbox?

Just imagine a book that has a step by step process for rebuilding these gearboxes so they are as good as they left the factory. So much has been written about these gearboxes that it's confusing and difficult to get the information you need sometimes.

Wayne's book of "How to rebuild and modify the 911 engine" could serve as a template.... Come on Mr Wayne, Why haven't you done this?

Also..How hard would it be to make a conversion kit to update the 915 internals to the later G50 design?... Just imagine a kit for about $8,000 USD that updates the 915 to more modern G50 internals. Same external dimensions with a hydrolic clutch option. Now that would be something I would more than consider for my car... There must be 10s of thousands of 915 gearboxes still on the road.

I'm new here so I hope I haven't asked a stupid question.

[Steve@Rennsport]

Thats a valid question without a clear, defined answer,...


The problem is that current replacement rebuild parts are nowhere made as precisely as the originals back in the time Porsche produced the 915 and its no longer a foregone conclusion that a rebuilt 915 transmission will function and shift as well as when new.

There is now an element of judgement and long-term experience required to ensure a successful outcome that cannot be gleaned from a book or manual.

Like many things, its not as simple as it may appear,.........

[sc_rufctr]

Thanks Steve

I'm a complete novice when it comes to gear boxes. I have rebuilt a non synchromesh gearbox for a Fiat 500 I once owned. That was fun and simple considering I had a second gearbox to cannibalise for parts.

The Haynes manual is vague and there is no procedure for adjusting the shift forks. I have found lots of information on here about that subject so I guess I'll do heaps of reading and start ordering parts.

I have a "Renshift", WEVO mounts, Swepco oil and a precision joint on the shift rod of my 1978 911. I'm considering going to the new WEVO black pillows for some added compliance.

All of these upgrades have improved things. The biggest improvement was the Renshift but the next step would be a disassemble and inspection with a view to replacing what has worn out.

The good news is I can shift without grinding and it stays in gear. The most annoying issue is that once the gearbox has warmed up it can be difficult to get out of a gear when down shifting . Like going from 3rd to 2nd. Any ideas?

[ninesixfour]

Originally Posted by sc_rufctr

The most annoying issue is that once the gearbox has warmed up it can be difficult to get out of a gear when down shifting . Like going from 3rd to 2nd. Any ideas?

Sounds like it's time for that rebuild which will cost a lot less than $8000.

[sc_rufctr]

I agree that a rebuild would be a lot less than $8,000.

I was quoted $3,000 for a full rebuild but that's with me taking the gearbox out of my car and delivering it to the workshop...

But I should ask you... Would you pay about $8,000 for a conversion kit that would update the internals of your 915 to modern standards?

Qhaife make a six speed kit for my other car. It's a VW Golf VR6. The kit retails for about $3,649.95 and seems like a bargain considering the closer ratios and 6th gear.

http://www.mjm********.com/catalog/product_info.php?cPath=2_6_15_42_152_5391&info=Quaife_10.310.210_6-Speed_Synchromesh_Gear_Set&products_id=1034

http://www.quaife.co.uk/

Why hasn't some progressive company done something similar for the 915?

BTW: I have priced a G50 short bell housing conversion for my car... About $12,000 all up including the new shifter and pedal box.

[SpeedracerIndy]

Originally Posted by sc_rufctr

I agree that a rebuild would be a lot less than $8,000.

I was quoted $3,000 for a full rebuild but that's with me taking the gearbox out of my car and delivering it to the workshop...

But I should ask you... Would you pay about $8,000 for a conversion kit that would update the internals of your 915 to modern standards?

Qhaife make a six speed kit for my other car. It's a VW Golf VR6. The kit retails for about $3,649.95 and seems like a bargain considering the closer ratios and 6th gear.

http://www.mjm********.com/catalog/product_info.php?cPath=2_6_15_42_152_5391&info=Quaife_10.310.210_6-Speed_Synchromesh_Gear_Set&products_id=1034

http://www.quaife.co.uk/

Why hasn't some progressive company done something similar for the 915?

BTW: I have priced a G50 short bell housing conversion for my car... About $12,000 all up including the new shifter and pedal box.

$3,000 seems a little high. I rebuilt mine in my garage for $1,200 including a new clutch. I've been quoted $1,800 for a basic rebuild by a very well respected local shop. I can see it getting to $3,000 if you get into bearings and sliders, ect, but you shouldn't need that unless it's really been abused. Try rebuilding a G50 for even $3,000. I bet it can't be done. The 915 has to be one of the cheapest transmissions to rebuild for a performance car like the 911.

To answer your $8,000 question: I probably wouldn't spend $8,000 for a kit to upgrade the internals of the 915. My dad has an 88 and (in my opinion) I don't think it shifts much better than my rebuilt 915. Not $8,000 worth anyway. Plus, if I had $8,000 to spend right now, I'd probably put it towards a 993 fund!

I just added a Rennshift housing, and it made a HUGE difference. It still doesn't shift like my S4, and never will, but it is certainly better than any other 28 year old car I've ever driven.

I would think there have been a lot less 915 transmissions made than Golf transmissions over the years, and maybe that is why you find so many more options for the Golf. Isn't it one of the most mass produced cars in history?

[Zeke]

Wayne has stated that a transmission book would not fill the page requirement that appears to be existent. There are two others that have said they will write this book. We'll have to wait and see.

[ninesixfour]

I have no affiliation and have not used this firm but they advertise a 915 synchro replacement for $700 not including removal and reinstallation and there would obviously be shipping charges. Maybe some others that have used them can chime in.

Bodymotion

[RWebb]

my understanding is that you often or usually cannot simply replace the synchros, but that other components need to be replaced at the same time

otherwise more expensive parts will be worn out....

IIRC, Grady posted on that a while ago

[otto in norway]

I'm planning on a servic on my 915 this spring, an sure would like a "how to" book on the subject. (Guess I'll have to learn as I go along)
I think it would be possible for someone who has done this sometimes to at least explain the gears / internals, and how to disassemble and assemble it. If you throw in some pointers ragarding what to look for, once opened, along with some upgrade solutions, this would be a bonus!

But I think it's just not regarded as a task common enough to really make any sales on this kind of book...?

All I know is I would like a "how to service your 915" book too!

[Bill Douglas]

I'll buy the beers, Fishcop provides the gearbox, and I'm sure we could have the book out there by the end of the weekend

[efhughes3]

Go to Rennlist and look up Pete Zimmermann's "what it really costs" thread about trans rebuilds. He makes the valid arguement that there is no such thing as a free lunch when rebuilding a 915. He says that you don't "rebuild" one of these for anywhere near $1000 or even $2000 dollars-you only are freshening some of the parts.

[rfn026]

The book market is so bad that no publisher would even consider doing a book on the 915 transmission. It's almost impossible to even get a marque book published today, let alone a book that only deals with a part of a single car.

Every author I know is watching sales do a nose dive. We're going to be lucky if any more Porsche books are ever published. There will always be a few very expensive books published at very high prices. David Bull publishing is a good example of where the book market may end up. The mass market book has a very questionable existence.

Richard Newton

[sc_rufctr]

The dollar amounts I quoted are all in Australia dollars.

We pay more for anything Porsche than you lucky Americans...

[RoninLB]

Jims Sims wrote and posted about 30 printed pages on how he rebuilt his 915 a few years ago.

I can't find it in search

It was great

[sc_rufctr]

Do you know Jims Sims "user name"?

[Fishcop]

Originally Posted by Bill Douglas

I'll buy the beers, Fishcop provides the gearbox, and I'm sure we could have the book out there by the end of the weekend

I've got two gearboxes sitting here ready to go

[RoninLB]

Originally Posted by sc_rufctr

Do you know Jims Sims "user name"?

"Jim Sims"


it was so good my printed copy was never returned. It was lost

[javaschlava]

Got in touch with Jim Sims, he's awesome. Sent me this post.
Mark

All the Way Into 915 & Comin Out (Long)

[RWebb]

see also Porsche Wiki (beta): How-To: Porsche 915 Transmission Repair Tutorial

and Part II of the same

- if somebody put all the threads on tranny rebuilds together & edited them....