FBIII

My 1980 Euro S has a trashed 5 speed. What year and model # transmissions would be a direct fit without having to change torque tubes. Are the transmissions any stronger/better as the model numbers increase or is it just transmission length, final drive ratios and the point where they go to borg warner syncros.

SMTCapeCod

Improved synchros/smoother shifting 85 and up. You know, after Porsche gave over the helm of the design to an engineering firm.... ;-)

IIRC the housing is a direct bolt in, clutch variations aside...and maybe torque tube splines?

However, the later US gear ratios are likely not as advantageous for getting off the line.

There's a thread/blog on a 928 restoration/resurrection that promised some info on rebuilding older transmissions, you may want to stay tuned for that and then weigh the costs/benefits of rebuild v. replace.

Mark Anderson

Are you sure you have a G28:05? Some 1980's came with 03's

BC

When working properly, the Porsche Sycnhros are fine. Rough and hard-feeling, but fine and solid. Its the dual disk clutch that killed them, and they also wear a bit quicker I think, because of they way the ramp engages. The dog teeth are rarely replaced, so that destroys the joy of a rebuild.

FBIII

If I wasn't so freeking old I would say yes its an 05. But I will check again to make sure, write it down and stick the post it to my farhead.

checkmate1996

I rebuilt my 05 - at a cost of about $4k and many, many months. Some parts are now NLA. I rebuilt everything except the 4/5 gear. It's very hard and notchy when shifting, but feels very strong. I posted a thread a while back when I was rebuilding. Check it out. It may help in your decision process. It does come down to the beast you know versus the one you don't know. Best of Luck!

Lloyd

I have a G03 from a car that had 60k on the speedo. I bought it as a spare for my race car, but never used it. The gears look good from the top inspection cover but can not guarentee all of the synchros ect. Price would be $375 plus shipping. Located in Greenville SC. Also have a free spinning 1979 torque tube for $100.

GregBBRD

I still have a couple brand new (factory new, not rebuilt) '85/'86 Borg Warner gearboxes....direct fit for your '05. One with a limited slip and one without.

The Fixer

FBIII, you sure it's trashed, thought mine was but just needed some maintenance
and Mobil LS syn gear oil that Greg recommended.

The night i bought it I barely could get it in gears 2 & 3 driving it home from VA late at night,

After a replacement TO lever bushing and adjustments, shifting very nice now.
Matt

GregBBRD

Most all of these transmissions.....even the Borg Warner boxes....are now mostly all very high mileage transmissions and are all starting to show syncro/engaging teeth/bearing/gear problems.

Actually, it has gotten very difficult to find a used transmission worth hauling home and spending the time and effort to install, and the problem gets worse, as the years go by.

The dismantlers know this. In the "early" days, they were buying low mileage cars that were involved in accidents......getting a good used transmission was relatively easy. Now they are buy worn out, high mileage "junkers" that aren't worth the cost of "restoring". The odds of getting a good used transmission from one of these high mileage "junkers" is very low.

Big difference in the quality of the used pieces that come off of a low mileage "wreck" and those from a high mileage "junker".

The really unfortunate part of the whole thing is that Porsche is now running very low/is out of stock on many transmission parts. The result is that rebuilding one of these transmissions is getting more and more expensive....and difficult.

I was talking to one of the owners of a local VW transmission rebuilding facility (very well known) a couple of weeks ago. He says that they are now taking apart 8-10 "core" transmissions just to be able to build one good transmission. The "good" part is that millions of VW transmissions were built and they buy complete inventories of these things, from junk yards...thousands at a time. And, perhaps more importantly, they have a huge "aftermarket source" of bearings, syncros, things like that.

Not as many 928 "cores" out there.....And the number of units made ensures that there will, most likely, never be an "aftermarket" source of pieces. Yes, dedicated people, like me, are building new pieces for these vehicles, every year...however, from a pure "business standpoint", this is stupid. The return on the "investment" for tooling (not to mention the minimum number of pieces that need to be made to make it economical to build the items) is very poor, for the 928 application, simply because of the number of vehicles that exist.

Take one piece that is required and should be changed each time a gearbox is rebuilt....5th gear bearing. Porsche has a very limited amount of bearings for the very early transmissions ($600 each), a limited amount of bearings for the '85/'86 transmission (cheap...always has been), no bearings for the '87-'95 transmissions. These are custom bearings....not generic. They have to be custom made in large batches to be economical to make. Porsche isn't going to remake them....and if you call *** or SKF....they won't remake it....Porsche owns the rights. Yes, someone could go to Japan and have a high grade replacement made.....but you are going to have to order 5,000 units. So, now you've got 50-100K invested to reproduce one single part....that you probably will never sell enough of to even re-coup your investment.

There's the problem....multiplied by hundreds of pieces.

It would appear, to me, that the "future" use of these cars is going to depend on transmission parts....and the automatics are going to be far easier to get parts for.....Mercedes built millions of these [in the "generic" form....of course, the Porsche part of the automatics unit (differential section) isn't so plentiful, but they are generally very robust.]

Rob Edwards

1982 to 1995: 29685 automatic transmissions, worldwide, vs. 13426 5-speeds

About half of the surviving automatics are on the shelf at 928Intl.


Worldwide 5-speed production by Transmission type:

G28.05 2773
G28.07 1725
G28.08 1518
G28.10 109
G28.11 1424
G28.12 2045
G28.13 1017
G28.55 2091
G28.57 645

BC

Wow. Ebay is showing the same sort of evidence. There was a time it was much easier to find used parts that were going cheap.

Not so much now.

FBIII

Here are my symptoms: Have to hold it in Reverse. Reverse doesn't seem to engage fully.
Pops out of 2nd and 4th when you let off the gas.
1st and 2nd syncros are terrible.
A very noticeable wine in the lower gears.
No self centering of the shifter.
I think that is everything.

GregBBRD

Leave it to Rob to make the numbers "real".

So, there's 3753 total "late" 5 speed gearboxes. How many of those are no longer in cars (wrecked or junked)?

So if you need a minimum of 5,000 pieces for the 5th gear bearing to be made.....how many can you sell?

My son's sons will be still selling them....and if all the remaining cars get driven the same amount they are driven today, perhaps somewhere around when my son is my age, the "family" breaks even on the cost of having them made?

Doesn't make any sense....it's never going to happen....that ship sailed long ago....done....finished.

Soon, there will be none of those bearings and there will be transmissions apart.....that need a bearing, but can't get one.

I pick this one example, because I have a customer (who now lives locally, but used to live in Northern California) that had his '87 transmission apart for a year (at a shop).....trying to find a bearing. He finally found me and I sold him one of the very last ones I had.

Porsche ran out of the main shifting spring....which breaks routinely. They are going to run out of syncros. The amount of gear they have left can be counted on your hands.....you don't need to use your toes.

Hell yes, running working examples of these cars are going to be very valuable.....it's inevitable.

I keep telling people to look at what 356SC's are worth.....if you can find one. And that 356 was about as complex as a current day riding lawnmower.

That's the future of the 928 GTS and 928 GT cars......the remaining 928's are just going to have the value of the everyday 356's.

checkmate1996

Greg - how much have you looked into 3d printing and being able to make small production runs using that technology?