Ducman82

That's what I'm thinking.

GregBBRD

My son (who had no clue about what the difference between a Porsche syncro and a Borg Warner syncro was) has now driven both style gearboxes. (He has an "83 that we "restored" mechanically, except for the gearbox.)

When I suggested that I could install a Borg Warner style syncro gearbox into his car, if he liked that feeling better, thought that I'd been hit on my head. He said that he liked "feeling" the syncros and liked knowing if he was completely engaged into a gear or not...and if he was in the right gear.

Thanksgiving we are going to rebuild his '83 box.

blown 87

While I wont argue about the gearboxes, I wonder if Kyle knows how many times and how hard you have been hit in the head?

Glenn M

What kind of power can the early 5 speeds handle?

Tom. M

I wasn't even running my track car too hard (82 trans with S4 engine..335rwhp 380ft-lbs)...couldn't even get three laps before the trans totally locked me out of any gear... coast down and finally got some gears back. That was with stock fluid. Put in redline lt weight shockproof and it did better but still locked me out. Swapped in a G28/55 GT transmission...and good to go....

The early transmissions only seem to hold 4.5 quarts of fluid..the later ones..about 8....

Ducman82

deeper internal pan or something?

Mike Simard

My 79 box would get stuck if I shifted 3-4 with vigor. Of course this would happen during a race when it was important. After coasting and figiting for a few seconds it would go into gear again and everyone is gone.
When I tore the box down it seems like the shift forks could allow both 2nd and 3rd to try to engage at the same time if the shift motion wasn't proper as the thingy moves out of the 2nd fork and into 3rd.
The 87 box I put in had more fail safe shift fork movement that makes it unlikely to move the new gear fork until the old one is disengaged.

GregBBRD

I'm not saying that used 20 year old gearboxes (of either type) work well in race cars.

Probably the newer the gearbox, the better odds you will have of it working well.

The Borg Warner gearboxes seem to need syncros, in the lower speeds, at about 80,000 miles, especially if they were driven in the city. The Borg Warner boxes seem to have better syncro life. (I personally think that is has as much to do with the clutch design as the syncro design.) So, the odds of finding a "virgin" Borg Warner gearbox is easier than finding a "virgin" early gearbox.

Properly set-up early gearboxes, with good parts, function fine.

That being said, I've taken a lot of gearboxes apart, over the years, and it is rare to find a gearbox that has been apart that has all the pieces in the correct spots. It absolutely amazes me how much people can screw these things up!

I had an early box apart a couple of weeks ago, that the customer had rebuilt 60,000 miles before. (It had 80,000 miles on it, the first time it was rebuilt). It had never shifted properly into 1st gear, the entire time this customer had owned it (He bought it at about 70,000 miles) and he thought that this was just the way these gearboxes were. The gearbox had many "issues"...some of which were almost funny....but the problem with 1st was that the rebuilder had installed 1st gear brake band backwards and had used a 930 stop, instead of a 928 stop....and the builder was a 928 expert!

I corrected all the problems and it shifts like a hot (although slightly notchy) knife through butter.

The customer is thrilled.

James Bailey

The Porsche design syncros were a big source of income to Porsche in the early years as they licensed them to other car builders. It was a very good design for the time. Problem is few if any of us have driven a 928 with a new "old " gearbox.....As Gregg points out may have been "rebuilt" improperly or with only a few new parts trying to work with old worn ones so they might be somewhat better after the rebuild but not working as intended.
I was of the impression that the later syncros would tolerate abuse somewhat better but really can not cite any real evidence of that. Greg certainly knows far more about syncros that anyone else I know.....even if he has been hit in the head a few time too many

Mike Simard

I had one sitting around the shop and always thought the shifter shaft poking out the back looked odd. It just looked like a galvanized bar from Home Depot or something.
One day curiosity got me so I measured it and it wasn't the same size as a shift coupler, it was an inch size. Well turns out the part actually was a galvanized Home Depot bar! Somebody took the trouble to make it but couldn't be bothered to source a metric bar let alone a hardnened one. They rolled shim stock around it to compensate for the diameter difference.
Nothing suprises me anymore.

James Bailey

Yes, you just have to shake your head and wonder WHY ????

dprantl

If it were true that the DD clutch is what kills the early transmission syncros, the syncros in borg-warner transmissions in '85'-'86 cars would also be affected. Of the 12 or so years I have been into 928's, I have not ONCE seen an original early 5-speed transmission with over 100k miles where the syncros for at least 3 gears were not shot. I know dozens of 928's with the original later transmissions with over 100k miles where the syncros were just fine. The '86 I owned for 8 years and drove daily to a total of 80k miles, the transmission shifted the same when I sold it at ~180k miles as it did when I bought it at ~100k miles. The car came with a pretty extensive set of records and no mention of any transmission work. The GT I have now is just about to cross 240k miles and I can make 0.5 second shifts easily looking at my ST2 logs, also with no evidence of any transmission work (not to mention the car is generating over 300lb.ft of rear wheel torque at 1,500RPM and I exercise that often). So... I have no idea where anyone gets the idea that at 80k miles the borg-warner transmissions need new syncros.

Sorry, but insinuating that the older transmissions have good syncros like the newer transmissions and may actually be better is really spreading misinformation. It doesn't matter how they "feel", because in 60k miles there will be nice crunching sounds going along with that feeling.

Dan
'91 928GT S/C 475hp/460lb.ft

BC

:Rolleyes: Seriously? Misinformation? "It doesn't matter how they feel"? Really? GB has factual information, historical knowledge, and has actually had dozens of each kind apart... - Other than driving a later car on the road, do you have comparable experience enough to be suggesting his (experienced based) OPINION is false?

I have rebuilt an early box. Honestly, with the prices of parts in general, and specifically for rebuild pieces for the later boxes, I'd just stick with an early box. You can buy them for 400 or 600 bucks all day long, and keep them "in stock" in rebuilt form for when anything else breaks. There was a GT box on ebay (used) for 4k. For how much a corvette-box swap would be - that may become a normal option.

dprantl

In this case, mechanics that tear down transmissions are obviously doing so because there was a problem to begin with. Yeah, if that borg-warner transmission is having issues and it is brought to GB for disassembly, it's pretty clear issues will be found. What about the vast majority of others that do not have any issues that are on the road every day? Can anyone show an early original transmission with over 100k miles that does not need 1st and/or 2nd gear syncros? Anyone? How about 150k miles? 200k?

Dan
'91 928GT S/C 475hp/460lb.ft

GregBBRD

Clarification/Summary....Dan's post indicates "confusion":

The Borg Warner syncros do last longer on the street. Great syncros for "lazy street driving". Great upgrade for street driven luxury cars.

The "Porsche Design" syncros will almost always be "crunchy" by 80,000 miles. They are "notchy" from the beginning. This design syncro is significantly more difficult to shift, on the street. As the vehicles became more expensive and Porsche had to "appeal" to "non-sports car types", they had more and more complaints about these syncros.

I personally prefer the "Porsche Design" syncro "feeling" over the absolute lack of "feeling" on the Borg Warner syncro. So does my son.

"Porsche Design" syncros last longer and will be more consistant, in race applications than the Borg Warner syncros design. The "external" lubricating/cooling of the "Porsche Design" syncro is greatly superior to the "internal" lubricating/cooling of the Borg Warner design. (A few laps at a short race course with lots of shifting will make this immediately evident...the Borg Warner box will "crunch" in every gear change....permanent damage to the syncros/gears occurs.

If a Porsche design syncro is damaged, 95% of the time it will require replacement of the syncro only (as long as it hasn't been worn out/grinding for years). 95% of the time, when a Borg Warner design syncro is damaged, the "tapered" area (cone) that is attached to the gear will also be damaged and require replacement of the gear/engaging teeth. We installed new gears into the 993 RSR transmissions with great regularity, because of this.

I'm not trying to "sell" anything here. I'm just passing on my experience and my views. Although I've been "doing this" for a couple of days, now, I am not insisting that anyone pay any attention to what I think or prefer.

I personally raced a 915 equipped Porsche (Porsche Design Syncros), for many years....and never replaced a syncro. Certainly, over the course of these years, I "stuck" the transmission into the wrong gear several times. I knew this immediately and never released the clutch. The "feedback" is immediate and obvious.

I also personally raced a 964 Porsche (Borg Warner Design Syncros) for years. I replaced many gears and syncros. Worked on cooling the transmission extensively, which helped, but never "cured" the problem. Over the course of those years, I also "stuck" that transmission into the wrong gear several times....without a clue that it was in the wrong gear. I blew up clutches, I bent valves, I caught intake systems on fire. There is a complete lack of any "feedback" from this style transmission. One can virtually stick it into any gear at any speed, when the syncros are in good condition.